Differential exposure to N-ethyl N-nitrosourea during pregnancy is relevant to the induction of glioma and PNSTs in the brain

Pre-mating exposure with hesperidin protects N-ethyl-N-nitrosourea-induced neurotoxicity and congenital abnormalities in next generation of mice as a model of glioma

Chemical carcinogen-induced oxidative stress has a key role in cell signaling linked to the development of cancer. Oxidative stress leads to oxidative damage to cellular membranes, proteins, chromosomes and genetic material. It is thought that compounds like hesperidin with high antioxidant and anticancer potential can reduce development of cancer induced by chemical carcinogens via neutralizing their oxidative damages. We investigated protective effect of hesperidin against N-Ethyl-N-Nitrosourea (ENU)-induced neurotoxicity, congenital abnormalities and possible brain cancer after exposure of mice during pregnancy as model of glioma. The mice were divided to four groups; control (normal saline), ENU (40 mg/kg daily for three consecutive days from the 17th to the 19th of pregnancy), hesperidin (pretreated with 25 mg/kg for 30 consecutive days, before mating) + ENU and hesperidin alone. Developmental toxicity parameters (the number of pregnant mice, stillbirths, abortion, live and dead offspring), behavioral tests (novel object recognition, open field and elevated plus maze) were performed. Moreover, the activity of butrylcholinesterase and acetylcholinesterase enzymes, oxidative markers and histopathological abnormalities were detected in brain tissue. Our data showed that conversely, the pretreatment of hesperidin reduces various degrees of developmental toxicity, neurobehavioral dysfunction, neurotoxicity, oxidative stress and histopathological abnormalities induced by ENU as a neurotoxic and carcinogenic agent in the next generation. In conclusion, pre-mating exposure with hesperidin may open new avenues for prevention of primary brain cancer in next generation and could be valuable for enhancing the antioxidant defense and minimizing the developmental and neurotoxicity of DNA alkylating agents.

Preclinical Models and Technologies in Glioblastoma Research: Evolution, Current State, and Future Avenues

Glioblastoma is the most common malignant primary central nervous system tumor and one of the most debilitating cancers. The prognosis of patients with glioblastoma remains poor, and the management of this tumor, both in its primary and recurrent forms, remains suboptimal. Despite the tremendous efforts that are being put forward by the research community to discover novel efficacious therapeutic agents and modalities, no major paradigm shifts have been established in the field in the last decade. However, this does not mirror the abundance of relevant findings and discoveries made in preclinical glioblastoma research. Hence, developing and utilizing appropriate preclinical models that faithfully recapitulate the characteristics and behavior of human glioblastoma is of utmost importance. Herein, we offer a holistic picture of the evolution of preclinical models of glioblastoma. We further elaborate on the commonly used in vitro and vivo models, delving into their development, favorable characteristics, shortcomings, and areas of potential improvement, which aids researchers in designing future experiments and utilizing the most suitable models. Additionally, this review explores progress in the fields of humanized and immunotolerant mouse models, genetically engineered animal models, 3D in vitro models, and microfluidics and highlights promising avenues for the future of preclinical glioblastoma research.

Effect of UV-light exposure duration, light source, and aging on nitroguanidine (NQ) degradation product profile and toxicity

Previous studies have reported increased aquatic toxicity of UV-degraded nitroguanidine (NQ), but many details underlying the dynamics of NQ degradation and toxicity remain unknown. These data gaps represent critical barriers to assessing the environmental relevance of laboratory-generated UV-degradation results and extrapolation to environmental risk. In the present study, the toxicity of NQ increased with increasing proportional degradation of the parent compound. Specifically, while the LC50 of undegraded NQ was 1485 mg/L, the toxicity at the lowest degradation level examined (7% parent compound degraded) increased by nearly two-orders of magnitude (LC50 = 17.3 mg/L) and increased by nearly three-orders of magnitude (LC50 = 6.23 mg/L) in the highest percent NQ degradation (90%) treatment. Similar LC50 values between immediately tested and aged (8-13 days) NQ degradation products suggested the degradation product(s) causing the toxicity were stable, although concentrations of nitrite and nitrate increased after aging. Finally, experiments where NQ was degraded in natural sunlight confirmed increased toxicity in environmentally relevant D. pulex exposures; however, the two-order of magnitude increase in toxicity (LC50 = 21.3 mg/L) at 53% degradation was less than NQ degraded by a laboratory photoreactor by a similar percentage (46% degraded). Identification of principal toxic agents in the UV-degraded NQ product mixture remains a critical data gap. Mass balance calculations were generated for our experimental results and literature values revealing difficulty in accounting for all NQ degradation products. Products with suspected high potency in D. pulex were identified which require further testing including: nitrosoguanidine, nitrosourea, and hydroxylamine. SYNOPSIS: The toxicity of NQ increased with increasing UV-degradation where toxicity-inducing degradation products were stable over 1-2 weeks; increased toxicity was validated from natural-sunlight degradation of NQ, however toxicity was lower than UV-photoreactor degraded NQ; and the identity of specific toxic UV-degradation products remains elusive where carefully-designed mass-balance experiments and toxicity testing are needed to provide definitive identification.

A Meta-Analysis of Calcium Intake and Risk of Glioma

BACKGROUND

A meta-analysis was conducted to investigate the correlation between calcium intake and the risk of brain tumors (especially glioma).

METHODS

The PubMed, Web of Science, and Embase databases were searched for relevant papers on the association between calcium intake and glioma as of August 22, 2021. The odds ratio (OR) with a 95% confidence interval (CI) was calculated using a random-effects model. Egger's test was conducted to assess publication bias.

RESULTS

The meta-analysis includes four studies. The meta-analysis showed that calcium intake and the risk of brain tumors have a significant negative relationship (OR = 0.28; 95% CI: 0.11 to 0.72; P = 0.008). Dose-response analysis showed that for every 100 mg/day increase in calcium intake, the risk of glioma decreased by 7% (OR = 0.93; 95% CI: 0.88 to 0.98). In addition, compared with humans without calcium intake, when calcium intake is 455 mg/day, 800 mg/day and 1000 mg/day, the risk of glioma is 0.65 (95% CI 0.43, 0.97), 0.55 (95% CI 0.37, 0.82) and 0.37 (95% CI 0.15, 0.86).

CONCLUSION

There is a significant negative association between calcium intake and brain tumors (especially gliomas), but more high-quality studies are needed to verify these results.