Benzo[a]pyrene-induced DNA-protein crosslinks in cultured human lymphocytes and the role of the GSTM1 and GSTT1 genotypes

We investigated the influence of glutathione S-transferase M1 (GSTM1) and glutathione S-transferase T1 (GSTT1) polymorphisms upon DNA-protein crosslinks (DPC) induced by benzo[a]pyrene (B[a]P) in cultured human lymphocytes. Lymphocyte samples were collected from 30 healthy nonsmoking hospital administrative workers. DPC was detected with KCl-SDS assay and the distributions of GSTM1 and GSTT1 were determined by polymerase chain reaction. B[a]P was found to induce a significant dose-responsive increase in cytotoxicity and DPC regardless of the genotypes (p<0.05). We did not find statistically significant genetic modification effect of GSTM1 and GSTT1 polymorphisms in the cytotoxicity and DPC formation (p>0.05). In terms of the genes examined, the level of cytotoxicity and DPC formation were found to be highest in the GSTM1-null and GSTT1-null cells. In conclusion, B[a]P induced a significant increase in the cytotoxicity and the level of DPC formation in cultured human lymphocytes. Our findings suggest that DPC could be used as a biomarker of B[a]P exposure.     

De novo chromosomal aberrations in the fetus; genetic counseling and clinical outcome

The aim of this study was to examine the incidence and clinical outcome of de novo chromosomal aberrations retrospectively and provide useful data for genetic counseling in the prenatal cytogenetic diagnosis. We found 17 cases of de novo chromosomal aberrations in 5501 cases of prenatal cytogenetic analysis and reviewed the karyotype, further study, medical records, fetal ultrasound findings and clinical outcomes. Out of the 17 de novo chromosomal aberrations, 5 had balanced reciprocal translocations and 12 had unbalanced translocations characterized as deletion, addition, or marker. In the case of the five balanced reciprocal translocations, 3 cases without abnormal ultrasound findings were carried to term after comprehensive genetic counseling. Neonates were phenotypically normal and clinical examinations were normal. Two cases with abnormal ultrasound findings were terminated therapeutically. Twelve cases of unbalanced translocations were terminated except one case with a mosaic marker chromosome. High resolution fetal ultrasound and detailed cytogenetic and molecular study will be adjunctive tools for predicting the karyotype/phenotype correlations of fetuses with de novo chromosomal aberrations, although they have limitation to find all phenotypic effects.     

Effects of hyperin, isoquercitrin and quercetin on lipopolysaccharide-induced nitrite production in rat peritoneal macrophages

The extract of the root of Acanthopanax chiisanensis Nakai is used for the treatment of inflammation. To analyse the action mechanism of this extract, the effect of hyperin (quercetin-3-O-beta-d-galactose) isolated from the ethyl acetate fraction of the root of A. chiisanensis on nitrite production and induction of inducible nitric oxide synthase (iNOS) in lipopolysaccharide (LPS, 1 microg/mL)-stimulated rat peritoneal macrophages were examined. The effect of the structurally related compounds, isoquercitrin (quercetin-3-O-beta-d-glucose) and quercetin (an aglycone of the two compounds) isolated from the extract of the leaves of Vaccinium koreanum Nakai was also examined to compare the effect. It was shown that hyperin inhibited the LPS-induced iNOS expression and nitrite production. Of the three compounds, quercetin showed the most potent inhibitory activity. The phosphorylation of p44/42 mitogen activated protein kinase (MAPK), p38 MAPK and c-Jun N-terminal kinase (JNK) were also inhibited by these compounds. These findings suggested that hyperin in the extract of the root of A. chiisanensis inhibits nitric oxide (NO) production through inhibition of the expression of iNOS by attenuation of p44/p42 MAPK, p38 MAPK and JNK, and thus participates in the antiinflammatory activity of the extract.     

Prevalence of Heterophyes nocens and Pygydiopsis summa infections among residents of the western and southern coastal islands of the Republic of Korea

To determine the distribution and prevalence of heterophyid fluke infections on coastal islands of the Republic of Korea, fecal specimens were collected from 4,179 people residing on 45 islands in the West (Yellow) and South Seas and examined using the formalin-ether and Kato-Katz techniques. Eggs of Heterophyes nocens were found in 459 (11.0%) residents of 42 islands, with an average number of eggs per gram (epg) of feces of 79.6. Eggs of Pygidiopsis summa were found in 49 (1.2%) on 12 islands, with an average epg of 253.0. The egg-positive rate for H. nocens was the highest on Chungdo (32.6%), followed by Imchado (27.3%); P. summa was most prevalent on Imchado (15.2%). The majority (78.9% [362 of 549] of those infected with H. nocens and 81.6% [40 of 49] of those infected with P. summa) of those infected were adults more than 40 years old. Adult flukes of these species were recovered from residents of Imchado by treatment with praziquantel and purgation. Our results indicate that H. nocens and P. summa are indigenous to the southern and western coastal islands of the Republic of Korea.     

Adherent cells generated during long-term culture of human umbilical cord blood CD34+ cells have characteristics of endothelial cells and beneficial effect on cord blood ex vivo expansion

Hematopoiesis depends on the association of hematopoietic stem cells with stromal cells that constitute the hematopoietic microenvironment. The in vitro development of the endothelial cell from umbilical cord blood (UCB) is not well established and has met very limited success. In this study, UCB CD34(+) cells were cultured for 5 weeks in a stroma-free liquid culture system using thrombopoietin, flt3 ligand, and granulocyte-colony stimulating factor. By week 4-5, we found that firmly adherent fibroblast-like cells were established. These cells showed characteristics of endothelial cells expressing von Willebrand factor, human vascular cell adhesion molecule-1, human intracellular adhesion molecule-1, human CD31, E-selectin, and human macrophage. Furthermore, when comparing an ex vivo system without an established endothelial monolayer to an ex vivo system with an established endothelial monolayer, better expansion of total nucleated cells, CD34(+) cells, and colony-forming units (CFUs)-granulocyte-macrophage and CFUs-granulocyte-erythroid-megakaryocyte-macrophage were found during culture. This phenomenon was in part due to the fact that a significant reduction of apoptotic fractions was found in the CD34(+) cells, which were cultured on the adherent monolayer for up to 5 weeks. To gather quantitative data on the number of endothelial cells derived from a given number of CD34 cells, we performed limiting dilution assay by using Poisson distribution: the number of tested cells (linear scale) producing a 37% negative culture (logarithmic scale) is the number of cells containing one endothelial cell. By this method, one endothelial cell may be found from 314 CD34(+) cells after 5 weeks of culture. These results suggest that the UCB CD34(+) cell fraction contains endothelial cell precursors, establishing the hematopoietic microenvironment and providing the beneficial effects through downregulating apoptosis on UCB expansion protocols. These observations may provide insight for future cellular therapy or graft engineering.     

Effects of the GSTM1 and GSTT1 polymorphisms on the relationship between maternal exposure to environmental tobacco smoke and neonatal birth weight

The purpose of the investigation was to determine whether genetic polymorphisms in enzymes that metabolize exogenous chemicals modulate the effects of environmental tobacco smoke (ETS) exposure on birth weight. A survey was conducted from 2000 to 2001 among 266 pregnant women who were hospitalized for delivery and on their singleton live births. We determined maternal GSTM1 and GSTT1 polymorphisms by polymerase chain reaction and measured the urinary cotinine of pregnant women at delivery by radioimmunoassay. Birth weight was found to decrease significantly with increasing concentrations of maternal urinary cotinine (P < 0.05). The interactive effect of exposure to ETS and the presence of the GSTT1 polymorphism was found to be significant by multivariate analysis (P < 0.01), whereas the interactive effect of exposure to ETS and the presence of GSTM1 polymorphism did not reach statistical significance (P = 0.21). A combination of the GSTM1-null and the GSTT1 null-genotypes was found to exacerbate the effect of maternal exposure to ETS on birth weight more than the presence of either genotype alone. Our data indicate that maternal exposure to ETS negatively affects neonatal birth weight, and the adverse effect of maternal exposure to ETS on neonatal birth weight could be modified by the maternal metabolic genotypes, GSTM1 and GSTT1.     

Chemoprevention of Gastrointestinal Cancer: The Reality and the Dream

Despite substantial progress in screening, early diagnosis, and the development of noninvasive technology, gastrointestinal (GI) cancer remains a major cause of cancer-associated mortality. Chemoprevention is thought to be a realistic approach for reducing the global burden of GI cancer, and efforts have been made to search for chemopreventive agents that suppress acid reflux, GI inflammation and the eradication of Helicobacter pylori. Thus, proton pump inhibitors, statins, monoclonal antibodies targeting tumor necrosis factor-alpha, and nonsteroidal anti-inflammatory agents have been investigated for their potential to prevent GI cancer. Besides the development of these synthetic agents, a wide variety of the natural products present in a plant-based diet, which are commonly called phytoceuticals, have also sparked hope for the chemoprevention of GI cancer. To perform successful searches of chemopreventive agents for GI cancer, it is of the utmost importance to understand the factors contributing to GI carcinogenesis. Emerging evidence has highlighted the role of chronic inflammation in inducing genomic instability and telomere shortening and affecting polyamine metabolism and DNA repair, which may help in the search for new chemopreventive agents for GI cancer.