Induction of covalent DNA modifications and micronucleated erythrocytes by 4-nitroquinoline 1-oxide in adult and fetal mice.

Pregnancy and development are known to modify carcinogenesis. Little is known about the mechanism for the modulation. These studies investigated the relative sensitivity of nonpregnant, pregnant, and fetal mice to the induction of covalent DNA modifications and micronucleated erythrocytes by 4-nitroquinoline 1-oxide (4-NQO). Our results revealed that 4-NQO was bound to guanine nucleotides of DNA in all maternal and fetal organs tested. The adduct levels ranged from 2-60 base modifications per 10(9) DNA bases when 4-NQO was administered s.c. Overall, 4-NQO bound preferentially to DNA of the maternal tissues compared with that of the corresponding fetal tissues, with the exception of the liver. The adduct levels in maternal and fetal organs fell into 3 distinct levels. The greatest binding was in maternal lungs and pancreas (the target organs for carcinogenesis). The lowest binding levels were in maternal liver and all fetal organs studied. Gestation age at the time of 4-NQO treatment did not produce a significant effect on the amounts of adduct formation in the tissues examined, with the exception of placenta and bone marrow. Chronic treatment did not affect binding preference. At the cellular level, 4-NQO treatment induced twice the frequency of micronucleated erythrocytes in the bone marrow of pregnant mice compared with the nonpregnant mice and fetal liver, on a mg/kg basis. However, the polychromatic erythrocytes of fetal liver were more sensitive than those of adult bone marrow to the induction of micronuclei, when adduct levels were taken into account. A positive correlation of organotropsim between 4-NQO-induced DNA adducts and carcinogenicity was observed for maternal tissues, but not for fetal tissues. Fetal tissues, overall, lack the enzymes to metabolically activate 4-NQO. Fetal cells elicit greater biological responses, compared with adult cells, at equal adduct levels. This study reveals that the effective doses in maternal and fetal tissues may differ and, therefore, will be a better basis for further understanding the molecular mechanism of transplacental carcinogenesis.

Detection of 8-hydroxy-2'-deoxyguanosine in deoxyribonucleic acid by the 32P-postlabeling method.

Using synthesized 8-hydroxy-2'-deoxyguanosine 3'-monophosphate as a marker, the 32P-postlabeling method was adapted with minimum modifications for the analysis of 8-hydroxy-2'-deoxyguanosine (8-OH-dG) content in deoxyribonucleic acid (DNA). This method allows the analysis of one 8-OH-dG per 10(4) DNA nucleotides with only 10 pmoles of nucleotides required. The amounts of 8-OH-dG in DNA detected by the postlabeling method correlated well with the electrochemical detection method but were consistently lower.

Studies on the antiviral activity of propagermanium with immunostimulating action.

The effects of propagermanium (3-oxygermylpropionic acid polymer) on various virus-infected mice were investigated. Propagermanium did not inhibit the multiplication of various DNA or RNA viruses in vitro. Oral administration of propagermanium in mice infected with herpes simplex virus type I (HSV-1) significantly prolonged the mean survival days. The efficacy of propagermanium at doses of 1 and 10 mg/kg daily was 13.4 +/- 2.3 and 14.2 +/- 2.3 mean survival days in comparison with 7.7 +/- 0.5 mean survival days at control group. In vaccinia virus-infected mice, oral doses of propagermanium ranging from 0.2 to 10 mg/kg suppressed the number of pocks on the tail which induced by the virus. Propagermanium (0.5-10 mg/kg) orally given to HSV-1-infected mice induced cytotoxic T lymphocytes (CTL) against HSV-1 antigen. In addition, propagermanium (1-10 mg/kg) enhanced interferon-gamma (IFN-gamma) induction in mice treated with Mycobacterium bovis (BCG). In mice spleen cells cultured with Concanavalin A, 0.1 to 10 micrograms/ml of propagermanium stimulated interleukin 2 (IL-2) production. It seems likely that the antiviral activity of propagermanium was exerted via enhancement of host immune resistance against viral infection.

A simple single-tube procedure of PCR assay for the detection of hepatitis C virus RNA.

We developed a simple single tube procedure using the PCR (polymerase chain reaction) for the detection of hepatitis C virus RNA. The entire reaction from RNA extraction to PCR occurred in one tube; this was made possible by the use of more than 1,000 micrograms/ml of proteinase K for RNA extraction, instead of the acid-guanidinium thiocyanate-phenol-chloroform method. All necessary reagents were added to the tube, and PCR products were not removed from the tube until the end of PCR, although opening of the tube during the procedure could not be avoided. Therefore, cross-contamination which might theoretically take place during transfer of products between tubes never occurred. This method detected about 1 chimpanzee infectious dose of HCV in H strain plasma.