cagA-Positive Helicobacter pylori Populations in China and The Netherlands Are Distinct

The aim of this research was to study whether and to what extent Chinese cagA-positive Helicobacter pylori isolates differ from those in The Netherlands. Analysis of random amplified polymorphic DNA (RAPD)-PCR-assessed DNA fingerprints of chromosomal DNA of 24 cagA-positive H. pylori isolates from Dutch (n = 12) and Chinese (n = 10) patients yielded the absence of clustering. Based on comparison of the sequence of a 243-nucleotide part of cagA, the Dutch (group I) and Chinese (group II) H. pylori isolates formed two separate branches with high confidence limits in the phylogenetic tree. These two clusters were not observed when the sequence of a 240-bp part of glmM was used in the comparison. The number of nonsynonymous substitutions was much higher in cagA than in glmM, indicating positive selection. The average levels of divergence of cagA at the nucleotide and protein levels between group I and II isolates were found to be high, 13.3 and 17.9%, respectively. Possibly, the pathogenicity island (PAI) that has been integrated into the chromosome of the ancestor of H. pylori now circulating in China contained a different cagA than the PAI that has been integrated into the chromosome of the ancestor of H. pylori now circulating in The Netherlands. We conclude that in China and The Netherlands, two distinct cagA-positive H. pylori populations are circulating.     

Validation of alternative methods for developmental toxicity testing

Developmental toxicity testing according to current international guidelines involves exposure of pregnant animals, mostly rats and rabbits, and subsequent assessment of toxic effects in their fetuses. Alternative methods have been developed since the early 1980s. They include cell differentiation assays using either primary cell cultures or immortalized cell lines. At a higher integration level the development of organ anlagen in vitro has been employed in assays for developmental toxicity. The most complex assays in this area make use of isolated postimplantation rodent embryos which are cultured in vitro during the phase of major organogenesis. The possibilities for their application as toxicity screens have been investigated in various validation studies. The most elaborate validation study of embryotoxicity assays carried out to date included the embryonic stem cell test EST, the limb bud micromass MM, and whole embryo culture WEC. In each test 20 chemical compounds were tested in four independent laboratories. The results have shown a marked success in the reproducibility of results. The extrapolation of these results of a limited set of chemicals to a generalized judgment of the tests for the world of chemicals remains a matter for further discussion.     

Effects of soy-derived isoflavones and a high-fat diet on spontaneous mammary tumor development in Tg.NK (MMTV/c-neu) mice

Phytoestrogens such as isoflavonoids and lignans have been postulated as breast cancer protective constituents in soy and whole-grain cereals. We investigated the ability of isoflavones (IFs) and flaxseed to modulate spontaneous mammary tumor development in female heterozygous Tg.NK (MMTV/c-neu) mice. Two different exposure protocols were applied, either from 4 wk of age onward (postweaning) or during gestation and lactation (perinatal). In the postweaning exposure study, mice were fed IFs or flaxseed in a high-fat diet. In addition, flaxseed in a low-fat diet was tested. Postweaning exposure to IFs and flaxseed tended to accelerate the onset of mammary adenocarcinoma development, although tumor burden at necropsy was not changed significantly. Perinatal IF exposure resulted in enhanced mammary gland differentiation, but palpable mammary tumor onset was not affected. However, tumor burden at necropsy in the perinatal exposure study was significantly increased in the medium- and high-IF dose groups. Comparison of both exposure scenarios revealed a strongly accelerated onset of tumor growth after perinatal high-fat diet exposure compared with the low-fat diet. This study shows that breast cancer-modulating effects of phytoestrogens are dependent both on the background diet and on the timing of exposure in the life cycle.     

Developmental immunotoxicity of di-n-octyltin dichloride (DOTC) in an extended one-generation reproductive toxicity study

Developmental immunotoxicity assessment is considered ready for inclusion in developmental toxicity studies. Further evaluation of proposed and additional assays is needed to determine their utility in assessing developmental immunotoxicity. In this study, a wide range of immunological parameters was included in an extended one-generation reproductive toxicity protocol. F(0) Wistar rats were exposed to DOTC via the feed (0, 3, 10, and 30mg/kg) during pre-mating, mating, gestation and lactation and subsequently F(1) were exposed from weaning until sacrifice. Immune assessments by several immune parameters were performed at PNDs 21, 42 and 70. The T cell-dependent antibody response to Keyhole Limpet hemocyanin (KLH) was assessed following subcutaneous immunizations with KLH on PNDs 21 and 35 and the delayed-type hypersensitivity response (DTH) against KLH was evaluated at PND 49. No effects were found on PND 21. While effects on lymphocyte subpopulations in the thymus were only observed in the 30mg/kg group on PND 42, effects on lymphocyte subpopulations in the spleen were found in the 30mg/kg group on both PNDs 42 and 70. The DTH response already showed an effect at 3mg/kg and was the overall critical endpoint. The results from this study support the inclusion of splenocyte subpopulation parameters in developmental toxicity studies and identified the DTH response as an important functional parameter.     

Testing strategies for embryo-fetal toxicity of human pharmaceuticals. Animal models vs. in vitro approaches : A workshop report

Reproductive toxicity testing is characterized by high animal use. For registration of pharmaceutical compounds, developmental toxicity studies are usually conducted in both rat and rabbits. Efforts have been underway for a long time to design alternatives to animal use. Implementation has lagged, partly because of uncertainties about the applicability domain of the alternatives.     

The potential of molecular diagnosis of cutaneous ectopic schistosomiasis

A 28-year-old woman presented with extensive erythematous lesions on her back after visiting Malawi. Skin biopsies showed ova, which could belong to Schistosoma spp. Sequencing of the Schistosoma 28S rRNA gene, extracted and amplified from paraffin biopsies, identified DNA of Schistosoma haematobium. Cutaneous ectopic schistosomiasis can present with extensive lesions and should be considered in the differential diagnosis of skin lesions in returning travelers. Microscopy and serology are the classical methods to obtain a diagnosis. Alternatively, molecular methods can be a valuable new tool for diagnosis and species determination.