Inter-laboratory comparison of turkey in ovo carcinogenicity assessment (IOCA) of hepatocarcinogens

In three independent laboratories carcinogens (diethylnitrosamine, DEN, 4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone, NNK) and non-carcinogens (N-nitrosoproline, nicotine) were evaluated in turkey eggs for in ovo carcinogenicity assessment (IOCA). Compounds were injected into aseptic fertilized eggs. After incubation for 24 days, foci of altered hepatocytes (FAH), some with a pseudoglandular structure and/or signs of compression of the surrounding tissue were observed in the fetal liver. All laboratories were able to distinguish unequivocally the hepatocarcinogen-exposed groups from those exposed to non-carcinogens or the vehicle controls, based on the pre-specified evaluation parameters: tumor-like lesions, pseudoglandular areas and FAH. In addition to focal changes, only the carcinogens induced hepatocellular karyomegaly. Lower doses of the carcinogens, which did not induce FAH, were sufficient to induce hepatocellular karyomegaly. After exposure to 4 mg DEN, gall bladder agenesis was observed in all fetuses. The IOCA may be a valuable tool for early investigative studies on carcinogenicity and since it does not use rodents may complement chronic rat or mouse bioassays. Test substances that are positive in both rodents and fertilized turkey eggs are most probably trans-species carcinogens with particular significance for humans. The good concordance observed among the three laboratories demonstrates that the IOCA is a reliable and robust method.     

Defective co-stimulation and impaired Th1 development in tumor necrosis factor/lymphotoxin-alpha double-deficient mice infected with Candida albicans

To define the immunological functions of tumor necrosis factor (TNF) in Candida albicans infection, TNF/lymphotoxin (LT)-alpha double-deficient mice were assessed for susceptibility to systemic or gastrointestinal infection and parameters of innate and adaptive Th immunity. When compared to wild-type mice, TNF/LT-alpha-deficient mice were more susceptible to either type of infection caused by virulent or low- virulence C. albicans cells. Susceptibility to infection correlated with impaired development of protective Th1 responses, in spite of the production of bioactive IL-12. The occurrence of predominant Th2 responses was associated with both impaired antifungal effector functions of neutrophils and a defective expression of co-stimulatory molecules on macrophages. All functions were improved upon administration of recombinant TNF-alpha, also resulting in increased resistance to infection. These findings indicate that the protective effect of TNF-alpha in candidiasis relies on the induction of antifungal Th1 responses, possibly occurring through stimulation of antifungal effector functions and co-stimulatory activities of phagocytic cells.      

重度卵巢过度刺激综合征1 3例临床分析

目的：总结重度卵巢过度刺激综合征（ovarian hy-perstimulation syndrome,OHSS）临床表现、发病机制及相应的治疗方法。方法：回顾性分析13例重度OHSS的临床资料。结果：重度OHSS发生在超排卵治疗后，临床表现为腹胀、恶心、腹水、胸水、少尿、血液浓缩、水电解质及酸碱平衡紊乱、氮质血症。经严密观察、输白蛋白、扩容及放胸腹水等治疗后治愈。移植日已出现OHSS者将胚胎冷冻保存。结论：防治重度OHSS的关键在于预防，一旦发生OHSS，经严密观察和及时治疗可治愈；迟发OHSS与妊娠有关。     

Mosaicism in sporadic neurofibromatosis 2 patients

More than half of neurofibromatosis 2 (NF2) patients represent de novo mutations which could have occurred at either pre-zygotic or post- zygotic stages. A post-zygotic mutation can result in mosaicism. In four sporadic NF2 patients, we found NF2 mutations in only a portion of corresponding leukocytes. In two other sporadic patients, no mutations were found in leukocytes but constitutional NF2 mutations were suggested by identical mutations in different tumors from each patient. We screened leukocyte DNA from a total of 16 inherited and 91 sporadic NF2 patients, and found NF2 mutations in 13 (81%) of the former and in 46 (51%) of the latter cases. The 30% difference in the rate of detection of mutations ( P = 0.051) might be partially explained by mosaicism in a portion of sporadic NF2 patients who carry the mutations in such a fashion that their leukocytes are unaffected. Among sporadic cases, we found mutations more frequently in patients with severe phenotypes (59%) than in patients with mild phenotypes (23%) (difference of 36%, P = 0.007). Mosaicism might be more common in the latter patient group since small populations of mutation-bearing cells can in some cases result in mild phenotypes and can also lead to difficulties in identifying mutations. No mutations were found in eight patients suspected of having NF2. Mosaicism with an extremely small population of affected cells may explain the incomplete phenotypes in some of these patients and the lack of mutations in their leukocytes. These findings suggest that mosaicism is relatively common in NF2 and may have important implications for diagnosis, prognosis and genetic counseling.      

The SEIRA spectroscopy data of nucleic acids and phospholipids from sensitive- and drug-resistant rat tumours

It is known that tumour progression towards drug resistance is one of the main factors resulting in the failure of cancer treatment. As tumour progression is based on the genetic instability, the study of the structure of nucleic acid from tumour cells is of great importance both for basic knowledge and for biomedical application. We applied surface enhanced infrared absorption spectroscopy (SEIRA) of nucleic acids on gold substrate and essentially increased the sensitivity of IR spectroscopy. We observed numerous changes in infrared spectra of DNA from sensitive and resistant cells that reflect drastic changes in molecular structure of DNA from tumour cells. The DNA from resistant cancer cells could be characterised as rigid structure, the structure of DNA from sensitive cancer strain seems to be flexible and after application of anticancer drugs drastically changes and approaches to the structure of helix forms. The molecular structure of lipids from resistant and sensitive cancers after application of anti-tumour drugs is also modified. Thus, we observed a disordering in the lipid chain packing from resistant cells after application of cisplatin and, in some cases, formation of phospholipid-Pt complex.