Analysis of DNA fragmentation in mouse embryos exposed to an extremely low-frequency electromagnetic field

Effects of extremely low-frequency electromagnetic fields (ELF-EMFs) on DNA damage in biological systems are still a matter of dispute. The aim of the present study was to investigate the possible effect of electromagnetic field exposure on DNA fragmentation in cells (blastomers) of mouse blastocysts.

Eighty female NMRI mice were randomly divided into 2 groups of 40 animals each. The control group was left unexposed whereas the animals in the EMF-group were exposed to a 50-Hz EMF at 0.5 mT 4 h per day, 6 days a week for a duration of 2 weeks. After the 8^th day of exposure, the female mice in both groups were superovulated (with injections of pregnant mare serum gonadotropin and human chorionic gonadotropin) and then mated overnight. At approximately 4 days after mating (102 h after the human chorionic gonadotropin treatment), blastocysts were obtained by flushing the uterus horns. The mean numbers of pregnant mice, blastocysts after flushing, blastomers within the blastocysts, and the DNA fragmentation index following staining in both groups were compared using statistical methods (SPSS, the Chi-square test, the Student's t-test and the Mann-Whitney U-test, P < 0.05). The results showed that the mean number of blastocysts after flushing was significantly decreased in the EMF-group compared to that of the control group (P < 0.03). The DNA fragmentation index was significantly increased in the EMF-group compared to control (10.53% vs. 7.14%; P < 0.001). However, there was no significant difference in the mean numbers of blastomers and numbers of pregnant mice between the EMF-exposed and control group. Our findings indicate that the EMF exposure in preimplantation stage could have detrimental effects on female mouse fertility and embryo development by decreasing the number of blastocysts and increasing the blastocysts DNA fragmentation.     

Balancing on the crest – Evidence for disruption of the enteric ganglia via inappropriate lineage segregation and consequences for gastrointestinal function

Normal enteric nervous system (ENS) development relies on numerous factors, including appropriate migration, proliferation, differentiation, and maturation of neural crest (NC) derivatives. Incomplete rostral to caudal migration of enteric neural crest-derived progenitors (ENPs) down the gut is at least partially responsible for the absence of enteric ganglia that is a hallmark feature of Hirschsprung disease (HSCR). The thought that ganglia proximal to aganglionosis are normal has guided surgical procedures for HSCR patients. However, chronic gastrointestinal dysfunction suffered by a subset of patients after surgery as well as studies in HSCR mouse models suggest that aberrant NC segregation and differentiation may be occurring in ganglionated regions of the intestine. Studies in mouse models that possess enteric ganglia throughout the length of the intestine (non-HSCR) have also found that certain genetic alterations affect neural crest lineage balance and interestingly many of these mutants also have functional gastrointestinal (GI) defects. It is possible that many GI disorders can be explained in part by imbalances in NC-derived lineages. Here we review studies evaluating ENS defects in HSCR and non-HSCR mouse models, concluding with clinical implications while highlighting areas requiring further study.     

妊娠晚期腹腔注射酸性磷酸缓冲液对两个近交系小鼠繁育生理影响的对比分析

目的对比分析妊娠晚期腹腔注射缓冲液对近交系SPF级C57BL/6J（B6）和BALB/c（B/c）小鼠繁育生理的影响。方法 B6和B/c小鼠随机、全同胞兄妹2∶1/1∶1（♀/♂）过夜同居交配,观察交配方式、阴栓与受孕率的关系;受孕鼠在妊娠的第17.5天（妊娠0d=交配后当天）接受腹腔注射酸性磷酸缓冲液,观察注射对母鼠及胚胎的作用及子鼠从离乳到8周的早期生长发育情况。结果 B6较B/c雌鼠的受孕率高（29.4%vs.21.1%[2∶1],33.2%vs.29.7%[1∶1]）;交配后10 d～14 d,根据雌鼠增大的腹部、结合体重来判断受孕较观察阴栓更为准确;比较而言,妊娠晚期腹腔注射对B6母鼠及胚胎的影响较大,表现在离乳子鼠数量减少（4.7±3.1 vs.6.1±2.1,P=0.231）,离乳时两性别的子鼠体重（g,雌性：11.7±1.1 vs.12.7±1.5;雄性：12.8±1.3 vs.13.6±1.5）显著降低（P均〈0.05）及两品系子鼠早期生长发育的方式显著不同（P=0.000）。结论近交系小鼠繁殖生理存在品系差异;两品系受孕鼠对妊娠晚期腹腔注射的耐受不同,并可能影响实验动物产后的哺乳过程及子鼠的早期生长发育。     

Plasmodium berghei: parasite clearance after treatment with dihydroartemisinin in an asplenic murine malaria model

Clinical reports indicate that malaria-infected asplenic patients have a reduced capacity for parasite clearance despite intensive antimalarial therapy. The aim of this study was to evaluate the efficacy of dihydroartemisinin in an asplenic murine malaria model. Mice were inoculated with Plasmodium berghei parasitised erythrocytes and received a single dose of dihydroartemisinin 56 h later, at 2-5% parasitaemia. Haematology, liver biochemistry and histopathology of key organs were performed to evaluate organ response to malaria infection. The nadir parasitaemia occurred 20 h after dihydroartemisinin administration, falling 2.8- to 6.0-fold and 2.7- to 6.9-fold in asplenic and intact mice, respectively, (10-100 mg/kg). Histopathology indicated increased stimulation of liver function/activity during malaria infection of asplenic mice (as compared to intact mice). Overall efficacy of single-dose dihydroartemisinin treatment in asplenic mice was similar to intact mice although the rate of recrudescence in asplenic mice was significantly greater than intact mice at 30 and 100 mg/kg. The asplenic murine malaria model could be used in pre-clinical studies of splenic function and clearance of malaria parasites, pathophysiological studies or antimalarial drug efficacy in asplenia.     

Ontogenesis of gastrin cells in the pyloric antrum and duodenum of the mouse

Summary Ontogenesis of gastrin cells was studied in the pyloroduodenal mucosa of the mouse using anti-human G17 serum, R-1301, and anti-human G34(1–15) serum, R-2703. R-1301-immunostained cells first appeared in the pyloric mucosa of 14-day-old fetuses. Cells stained with both R-1301 and R-2703 appeared immediately after birth, and gradually increased in number to the adult level. Most R-1301-reactive cells were also reactive to R-2703, whereas some cells that reacted with R-1301 exhibited very weak or no reaction with R-2703. The discrepancy between these two immunoreactivities is discussed.In the duodenum, a considerable number of R-1301-reactive cells were present from the perinatal stage and through out adult development. A few R-2703-reactive cells were seen in the duodenum of young mice but not of the adult.     

Schistosoma mansoni and Fasciola hepatica: Cross-resistance in mice with single-sex schistosome infections

Primary Schistosoma mansoni single-sex infections in mice, i.e., either male only or female only, did not stimulate any detectable level of heterologous resistance to challenge with Fasciola hepatica after 22 to 76 days, while statistically significant resistance to a challenge with F. hepatica was demonstrated in the presence of patent mixed-sex S. mansoni infections. Simultaneous infections with S. mansoni and F. hepatica induced a statistically significant reduction in the number of schisto-some worms established, i.e., the burden being reduced by 40.1 and 43.9%, respectively. There was no reduction of the F. hepatica worm burden. Similar features could be observed with a time interval of 48 hr between the S. mansoni infection and the F. hepatica challenge, i.e., the schistosome burden being reduced by 34.2 and 45.6%, respectively. Furthermore, simultaneous infections with S. mansoni and F. hepatica induced a statistically significant reduction of the egg production capacity per paired female schistosome worm as compared with that of the S. mansoni control group. Tissue egg counts of the various intestinal sections were reduced by 92.8–99.6%.     

Isolation and culture of cells derived from human cerebral microvessels

Summary Microvessels were isolated from non-neoplastic human cerebral cortical fragments resected for treatment of intractable seizure disorder. The microvessels were incubated in modified Lewis medium with 20 or 30% fetal bovine serum. Within 1–2 weeks, two cell populations emerged from the isolates. One type of cells had polygonal morphology, showed density-dependent contact inhibition at confluence in vitro, showed lectin-binding characteristics of endothelium (but only moderate positivity for factor VIII antigen), demonstrated induction of -glutamyl trans-peptidase when exposed to astrocyte-conditioned media, and responded to insulin by a pronounced increase in DNA synthesis. The other variety of cells grew in vitro more slowly in irregular strands separated by clear zones, showed ultrastructural features of smooth muscle, and isoelectric focusing of cell proteins revealed the presence of smooth-musclespecific -isoactin. Both types of cells could be serially subcultured. The ability to isolate and grow the two cell types, tentatively identified as human cerebral microvascular endothelium and smooth muscle, may facilitate studies of human blood-brain barrier function as well as the pathogenesis of cerebral microangiopathies unique to the human brain.Funded by Canadian Heart Foundation, Heart and Stroke Foundation of Ontario and UCLA Biomedical Research Support Grant     

Ostreopsis cf. ovata in the Gulf of Gabès (south-eastern Mediterranean Sea): morphological,molecular and ecological characterization

In the last few decades, the frequency of the toxic benthic dinoflagellate Ostreopsis cf. ovata proliferation has increased in the Mediterranean Sea. These blooms are associated with harmful effects on human health and the environment. The present work provides the first long term study on the spatio-temporal distribution of O. cf. ovata in relation to physical parameters in the Gulf of Gabès coastal waters (south-eastern Mediterranean Sea), as well as its morphological, molecular and physiological features. The strains of O. cf. ovata were identified morphologically by light and epifluorescence microscopy. The morphology and the size range of cultured strains were similar to those described regarding O. cf. ovata isolated from the Mediterranean Sea. The ultrastructural analysis of O. cf. ovata cells using the transmission electron microscopy showed the presence of numerous vesicles (VE) containing spirally coiled fibers (SCFs) connected to the mucus canal (CH). The phylogenetic tree based on the internal transcribed spacer region containing the 5.8S rDNA (ITS-5.8S rDNA) revealed that O. cf. ovata strains were placed into the Mediterranean/Atlantic clade. In addition, O. cf. ovata toxicity was evaluated by the mouse bioassay and a dose level ≥ 4 × 10⁴ cells was found to be lethal to mice. The examination of the O. cf. ovata occurrence in the Gulf of Gabès at a large temporal scale (1997–2012) revealed a clear seasonal pattern with dominance from midsummer (July) to late autumn (November). Furthermore, a positive correlation was found between the abundance of O. cf. ovata and salinity, whereas no correlation was found as regards temperature. The occurrence of O. cf. ovata was only detected at salinity above 35 and the highest concentrations were observed at 45. Laboratory experiments confirmed such a result and showed that isolated O. cf. ovata strains had optimal growth at salinity ranging between 35 and 45, with its peak at 40.     

气雾攻击法感染结核病小鼠模型的建立及其综合评价

目的 模拟自然感染方式建立结核病小鼠模型,并对其病理变化进行综合评价.方法 通过气雾攻击方式将结核分枝杆菌H37Rv接种至C57BL/6J小鼠体内.在感染后的4周、6周、8周对小鼠进行micro-CT活体动态扫描,无菌分离肺脏和脾脏,肉眼观察病变情况,活菌菌落计数,组织病理检测(HE和抗酸染色).结果 肉眼观察和micro-CT扫描发现,不同时间小鼠肺部感染情况逐渐加重,至感染后第8周时病变弥漫至整个肺部;HE染色肺组织出现弥漫性肉芽肿样实变;抗酸染色可见结核分枝杆菌.结论 通过大体病变、病理、影像、菌落计数几个方面对建立的小鼠模型进行综合分析,证明利用气雾攻击法感染的结核病小鼠模型建立成功;该模型在形成病变时与结核患者的情况存在一定差异,对其完善的综合评价有助于在相关研究中对该小鼠模型的合理应用.