Identification and quantitation of benzo[a]pyrene-DNA adducts formed in mouse skin

The DNA adducts of benzo[a]pyrene (BP) formed in vitro were previously identified and quantitated. In this paper, we report the identification and quantitation of the depurination adducts of BP, 8-(benzo[a]pyren-6-yl)guanine (BP-6-C8Gua), BP-6-N7Gua, and BP-6-N7Ade, formed in mouse skin by one-electron oxidation, as well as the major stable adduct formed via the diolepoxide pathway, BP diolepoxide bound at C-10 to the 2-amino of dG (BPDE-10-N2dG). Identification of the depurination adducts was achieved by HPLC and fluorescence line narrowing spectroscopy. The depurination adducts, BP-6-C8Gua (34%), BP-6-N7Gua (10%), and BP-6-N7Ade (30%), constituted 74% of the adducts found in mouse skin 4 h after treatment with BP. The stable adduct BPDE-10-N2dG accounted for 22% of the adducts. Treatment of the skin with BP-7,8-dihydrodiol or BP diolepoxide yielded almost exclusively the stable adduct BPDE-10-N2dG. When BP or BP-7,8-dihydrodiol was bound to RNA or denatured DNA in reactions catalyzed by rat liver microsomes, no depurination adducts were detected. The profiles of stable adducts were similar both qualitatively and quantitatively with native or denatured DNA. With activation of BP by horseradish peroxidase, the profiles of stable adducts differed with native and denatured DNA. The total amount of adducts with denatured DNA was only 25% of the amount detected with native DNA. No depurination adducts were detected with denatured DNA or RNA in the peroxidase system.(ABSTRACT TRUNCATED AT 250 WORDS)

Manning criteria in irritable bowel syndrome: its diagnostic significance

BACKGROUND

Irritable bowel syndrome is one of the most commonly encountered gastrointestinal disorders, for which there are no established diagnostic criteria. Thus, a diagnosis of IBS is made by exclusion of any organic diseases. Recently, important attempts for the positive diagnosis of irritable bowel syndrome by questionnaire surveys of physical symptoms have been made. We performed a questionnaire survey to evaluate the diagnostic value of the Manning criteria and to observe the major symptoms in irritable bowel syndrome.

METHODS

A symptom questionnaire which consisted of 22 items, including 6 cardinal symptoms of the Manning criteria, were answered by 172 outpatients who had gastrointestinal complaints. According to a final diagnosis based on independent clinical evaluation, all patients were categorized in three groups: irritable bowel syndrome group, nonulcer dyspepsia group and organic gastrointestinal disease group. The results of the questionnaire were analyzed for each group.

RESULTS

The sensitivity and specificity of the Manning criteria for the diagnosis of irritable bowel syndrome were 67% and 70% if three or more items were regarded as positive. The mean score and overall frequency of the Manning criteria were significantly higher in irritable bowel syndrome group than in nonuclear dyspepsia (p < 0.01) or organic gastrointestinal disease group (p < 0.05). Among subgroups of the irritable bowel syndrome group, the pain-predominant subgroup showed a significantly higher score and overall frequency than the painless subgroup (p < 0.05).

CONCLUSIONS

The Manning criteria would be useful as a simple and reliable backup tool for the diagnosis of irritable bowel syndrome and seem to be more useful in pain-predominant subgroup. More detailed history-taking should prevent unnecessary extensive investigations for the diagnosis of irritable bowel syndrome.

Identification and quantitation of benzo[a]pyrene-DNA adducts formed by rat liver microsomes in vitro

The two DNA adducts of benzo[a]pyrene (BP) previously identified in vitro and in vivo are the stable adduct formed by reaction of the bay-region diol epoxide of BP (BPDE) at C-10 with the 2-amino group of dG (BPDE-10-N2dG) and the adduct formed by reaction of BP radical cation at C-6 with the N-7 of Gua (BP-6-N7Gua), which is lost from DNA by depurination. In this paper we report identification of several new BP-DNA adducts formed by one-electron oxidation and the diol epoxide pathway, namely, BP bound at C-6 to the C-8 of Gua (BP-6-C8Gua) and the N-7 of Ade (BP-6-N7Ade) and BPDE bound at C-10 to the N-7 of Ade (BPDE-10-N7Ade). The in vitro systems used to study DNA adduct formation were BP activated by horseradish peroxidase or 3-methylcholanthrene-induced rat liver microsomes, BP 7,8-dihydrodiol activated by microsomes, and BPDE reacted with DNA. Identification of the biologically-formed depurination adducts was achieved by comparison of their retention times on high-pressure liquid chromatography in two different solvent systems and by comparison of their fluorescence line narrowing spectra with those of authentic adducts. The quantitation of BP-DNA adducts formed by rat liver microsomes showed 81% as depurination adducts: BP-6-N7Ade (58%), BP-6-N7Gua (10%), BP-6-C8Gua (12%), and BPDE-10-N7Ade (0.5%). Stable adducts (19% of total) included BPDE-10-N2dG (15%) and unidentified adducts (4%). Microsomal activation of BP 7,8-dihydrodiol yielded 80% stable adducts, with 77% as BPDE-10-N2dG and 20% of the depurination adduct BPDE-10-N7Ade. The percentage of BPDE-10-N2dG (94%) was higher when BPDE was reacted with DNA, and only 1.8% of BPDE-10-N7Ade was obtained.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanism of metabolic activation of the potent carcinogen 7,12-dimethylbenz[a]anthracene

The DNA adducts of 7,12-dimethylbenz[a]anthracene (DMBA) previously identified in vitro and in vivo are stable adducts formed by reaction of the bay-region diol epoxides of DMBA with dG and dA. In this paper we report identification of several new DMBA-DNA adducts formed by one-electron oxidation, including two adducts lost from DNA by depurination, DMBA bound at the 12-methyl to the N-7 of adenine (Ade) or guanine (Gua) [7-methylbenz[a]anthracene (MBA-12-CH2-N7Ade or 7-MBA-12-CH2-N7Gua, respectively]. The in vitro systems used to study DNA adduct formation were DMBA activated by horseradish peroxidase or 3-methyl-cholanthrene-induced rat liver microsomes. The biologically-formed depurination adducts were identified by high-pressure liquid chromatography and by fluorescence line narrowing spectroscopy. Stable DMBA-DNA adducts were analyzed by the 32P-postlabeling method. Quantitation of DMBA-DNA adducts formed by microsomes showed about 99% as depurination adducts: 7-MBA-12-CH2-N7Ade (82%) and 7-MBA-12-CH2-N7Gua (17%). Stable adducts (1.4% of total) included one adduct spot that may contain adduct(s) formed from the diol epoxide (0.2%) and unidentified adducts (1.2%). Activation of DMBA by horseradish peroxidase afforded 56% of stable unidentified adducts and 44% of depurination adducts, with 36% of 7-MBA-12-CH2-N7Ade and 8% of 7-MBA-12-CH2-N7Gua. Adducts containing the bond to the DNA base at the 7-CH3 group of DMBA were not detected.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevalence of antibodies to hepatitis C virus in patients with various types of liver diseases

BACKGROUND

Hepatitis C virus (HCV) is known to be a major cause of non-A, non-B hepatitis (NANBH) and is thought to be an important causative agent of serious liver disease. Recently the role of HCV in the development of various liver disease is suggested.

METHODS

Sera from 222 patients with various liver diseases had been kept frozen at -20 degrees C until the test. Anti-HCV was detected using the ABBOTT HCV EIA Test System (ABBOTT Co., America) following the manufacturer's instructions. The assay uses a recombinant HCV antigen (C 100-3) synthesized in yeast.

RESULTS

HCV antibodies (anti-HCV) were detected in 35 (31.5%) of 111 HBsAg-negative patients. The prevalence rate of anti-HCV was 61.9% (13 out of 21 patients) in chronic hepatitis, 29.1% (14 out of 48) in liver cirrhosis, 26.3% (5 out of 19) in hepatocellular carcinoma and 13% (3 out of 23) in acute hepatitis was far less (3 out of 111 patients, 2. 7%) than that of HBsAg-negative patients (p < 0.01). In this group, anti-HCV was detected in 2 (5.1%) out of 39 liver cirrhosis, 1 (1.9%) out of 52 chronic hepatitis, among them 47 were biopsy-proven chronic active hepatitis, and none of 20 hepatocellular carcinoma.

CONCLUSIONS

These data suggest that, in Korea, 1) coinfection of HCV and HBV is infrequent, 2) HCV might be an important cause of HBsAg-negative chronic hepatitis, 3) HCV is seemed to be a less likely important factor associated with liver cirrhosis or hepatocellular carcinoma in HBsAg-negative patients, but further prospective study with a large population is necessary.

Comparative laser spectroscopic study of DNA and polynucleotide adducts from the (+)-anti-diol epoxide of benzo[a]pyrene

A recently developed methodology [Jankowiak, R., Lu, P., Small, G. J., and Geacintov, N. E. (1990) Chem. Res. Toxicol. 3, 39-46], which combines fluorescence line narrowing spectroscopy at 4.2 K with non-line-narrowed (S2----S0 laser excitation) fluorescence spectroscopy at 77 K and fluorescence quenching, is used to characterize adducts formed from (+)-anti-BPDE and the alternating copolymers poly(dG-dC).poly(dG-dC) and poly(dA-dT).poly(dA-dT), the nonalternating poly (dG).poly(dC), single-strand poly(dG), and the oligonucleotide d(ATATGTATA). Detailed comparisons of the fluorescence spectra and quenching (with acrylamide) of the properties of the adducts with those of (+)-anti-BPDE-DNA adducts are made. Fluorescence spectra of the trans and cis isomers of the adduct formed from guanosine monophosphate and the adducts of d(ATATGTATA) are used to assign the stereochemistry of the two major DNA adducts as trans-N2-dG moieties which occupy two different DNA sites. Evidence for the existence of minor cis-type guanine adducts is provided. Finally, a fourth type of DNA adduct (minor) is identified and assigned as trans-N6-dA.

A noninstrumented quantitative test system and its application for determining cholesterol concentration in whole blood

A novel noninstrumented technology has been developed for quantifying analytes of clinical interest in biological fluids. Application of this technology is exemplified by the development of a quantitative cholesterol test with performance equivalent to state-of-the-art instrumented methods. The assay chemistry combines two separate processes located in different areas of a test strip: enzymatic action on serum cholesterol to produce hydrogen peroxide (5 x 10 mm enzyme reagent pad) and quantification of the hydrogen peroxide (5 x 70 mm measurement region). Color bands are formed in the measurement area through the use of a redox-coupled indicator system. The height of the color band on the strip is directly proportional to the sample cholesterol concentration. A one-step cassette contains all components necessary to run the test and includes blood filtration and automatic sample measurement, so that unmeasured finger-stick whole-blood specimens can be analyzed by the non-technically trained user. The test is complete in less than 15 min, is read visually like a thermometer, and gives results that are in excellent correlation with established instrumented methods.

Identification and quantitation of 7-(benzo[a]pyren-6-yl)guanine in the urine and feces of rats treated with benzo[a]pyrene

The major identified benzo[a]pyrene (BP)-DNA adduct formed by cytochrome P-450 contains BP bound at the C-6 position to the N-7 position of guanine (BP-N7Gua). This adduct is rapidly depurinated from DNA. When rats were treated with [14C]BP, about 0.02% of the administered dose of BP was excreted as BP-N7Gua in feces and urine within 5 days. Chloroform extracts of the urine and feces were analyzed by high-pressure liquid chromatography. The structure of the adduct was established by cochromatography with electrochemically prepared BP-N7Gua and by fluorescence line narrowing spectrometry. This study represents the first demonstration that BP-N7Gua is formed in vivo in animals treated with BP.

A noninstrumented quantitative test system and its application for determining cholesterol concentration in whole blood

A novel noninstrumented technology has been developed for quantifying analytes of clinical interest in biological fluids. Application of this technology is exemplified by the development of a quantitative cholesterol test with performance equivalent to state-of-the-art instrumented methods. The assay chemistry combines two separate processes located in different areas of a test strip: enzymatic action on serum cholesterol to produce hydrogen peroxide (5 x 10 mm enzyme reagent pad) and quantification of the hydrogen peroxide (5 x 70 mm measurement region). Color bands are formed in the measurement area through the use of a redox-coupled indicator system. The height of the color band on the strip is directly proportional to the sample cholesterol concentration. A one-step cassette contains all components necessary to run the test and includes blood filtration and automatic sample measurement, so that unmeasured finger-stick whole-blood specimens can be analyzed by the non-technically trained user. The test is complete in less than 15 min, is read visually like a thermometer, and gives results that are in excellent correlation with established instrumented methods.

A non-flow cytometric system for detecting antibodies and cellular antigens in blood

The system described here can distinguish between single and agglutinated erythrocytes by use of a non-flow fiber optic fluorometer. The method is capable of detecting cell-surface antigens and antibodies to cell-surface antigens present in blood. Significant features include high-efficiency fluorescent dyes that intercalate into cell membranes, a stretching membrane for transport and mixing of samples, charged colloidal magnetite for magnetic separation of erythrocytes, and an immersible fiber optic probe for measuring fluorescence associated with cells in a 1-nL volume of a bulk solution. We describe the application of the system to automation of ABO/Rh grouping and antibody screening.