Prediction of cardiovascular disease by abdominal obesity measures is dependent on body weight and sex--results from two community based cohort studies.

AIM: To study waist-hip ratio (WHR), waist circumference (WC), sagittal abdominal diameter (SAD), and waist-hip-height ratio (WHHR) as predictors of CVD, in men and women stratified by BMI (cut-off ≥25). METHODS AND RESULTS: A cohort of n = 3741 (53% women) 60-year old individuals without CVD was followed for 11-years (375 CVD cases). To replicate the results, we also assessed another large independent cohort; The Malmö Diet and Cancer study - cardiovascular cohort (MDCC, (n = 5180, 60% women, 602 CVD cases during 16-years). After adjustment for established risk factors in normal-weight women, the hazard ratio (HR) per one standard deviation (SD) were; WHR; 1.91 (95% confidence interval (CI) 1.35-2.70), WC; 1.81 (95% CI 1.02-3.20), SAD; 1.25 (95% CI 0.74-2.11), and WHHR; 1.97 (95% CI 1.40-2.78). In men the association with WHR, WHHR and WC were not significant, whereas SAD was the only measure that significantly predicted CVD in men (HR 1.19 (95% CI 1.04-1.35). After adjustments for established risk factors in overweight/obese women, none of the measures were significantly associated with CVD risk. In men, however, all measures were significant predictors; WHR; 1.24 (955 CI 1.04-1.47), WC 1.19 (95% CI 1.00-1.42), SAD 1.21 (95% CI 1.00-1.46), and WHHR; 1.23 (95% CI 1.05-1.44). Only the findings in men with BMI ≥ 25 were verified in MDCC. CONCLUSION: In normal weight individuals, WHHR and WHR were the best predictors in women, whereas SAD was the only independent predictor in men. Among overweight/obese individuals all measures failed to predict CVD in women, whereas WHHR was the strongest predictor after adjustments for CVD risk factors in men.

Reasons for non-participation in population-based abdominal aortic aneurysm screening.

BACKGROUND: A population-based screening programme for abdominal aortic aneurysm (AAA) started in 2010 in Stockholm County, Sweden. This present study used individual data from Sweden's extensive healthcare registries to identify the reasons for non-participation in the AAA screening programme. METHODS: All 65-year-old men in Stockholm are invited to screening for AAA; this study included all men invited from July 2010 to July 2012. Participants and non-participants were compared for socioeconomic factors, travel distance to the examination centre and healthcare use. The influence of these factors on participation was analysed using univariable and multivariable logistic regression models. RESULTS: The participation rate for AAA screening was 77·6 per cent (18 876 of 24 319 men invited). The prevalence of AAA (aortic diameter more than 2·9 cm) among participants was 1·4 per cent. The most important reasons for non-participation in the multivariable regression analyses were: recent immigration (within 5 years) (odds ratio (OR) 3·25, 95 per cent confidence interval 1·94 to 5·47), low income (OR 2·76, 2·46 to 3·10), marital status single or divorced (OR 2·23, 2·08 to 2·39), low level of education (OR 1·28, 1·16 to 1·40) and long travel distance (OR 1·23, 1·10 to 1·37). Non-participants had a higher incidence of stroke (4·5 versus 2·8 per cent; P < 0·001) and chronic pulmonary disease (2·9 versus 1·3 per cent; P < 0·001). Daily smoking was more common in residential areas where the participation rate for AAA screening was low. CONCLUSION: Efforts to improve participation in AAA screening should target the groups with low income, a low level of education and immigrants. The higher morbidity in the non-participant group, together with a higher rate of smoking, make it probable that this group also has a high risk of AAA.

The association between plasma homocysteine and coronary heart disease is modified by the MTHFR 677C>T polymorphism.

OBJECTIVE: An elevated level of total plasma homocysteine (tHcy) has been associated with risk of coronary heart disease (CHD). The level of tHcy is affected by lifestyle, in addition to genetic predisposition. The methylene tetrahydrofolate reductase (MTHFR) 677C>T polymorphism (rs1801133) is among the strongest genetic predictors of tHcy. We examined whether the association between tHcy and CHD is modified by the MTHFR 677C>T polymorphism. DESIGN AND SETTING: Data from two case-control studies of first-time myocardial infarction (MI), Stockholm Heart Epidemiology Programme (SHEEP), and for MI and unstable angina, INTERGENE, were analysed in parallel. PATIENTS: THcy was determined in a total of 1150 cases and 1753 controls. INTERVENTIONS: None. MAIN OUTCOME MEASURES: The outcome comprised first-time MI and unstable angina, subsumed as CHD. Logistic regression was used to investigate the association between tHcy and CHD, and its modification by genotype. RESULTS: High tHcy was confirmed to be a risk factor for CHD in both studies. In SHEEP, the association between tHcy and MI was observed in MTHFR 677 C-homozygotes (OR=1.4, 95% CI 1.2 to 1.6, for a difference by 1 SD of log tHcy) and in heterozygotes (OR=1.3, 95% CI 1.1 to 1.6) but not in T-homozygotes, independent of smoking, physical activity and obesity. An effect modification of similar magnitude was observed but not statistically significant in the smaller INTERGENE study, and confirmed in a meta-analysis of both studies. CONCLUSIONS: Two Swedish case-control studies showed that the association between elevated tHcy and CHD was confined to carriers of the MTHFR 677 C-allele, which could have implications for the efficiency of tHcy-lowering treatment.

Novel and established anthropometric measures and the prediction of incident cardiovascular disease: a cohort study.

OBJECTIVES: The aim of this study was to compare novel and established anthropometrical measures in their ability to predict cardiovascular disease (CVD), and to determine whether they improve risk prediction beyond classical risk factors in a cohort study of 60-year-old men and women. We also stratified the results according to gender to identify possible differences between men and women. Furthermore, we aimed to replicate our findings in a large independent cohort (The Malmö Diet and Cancer study-cardiovascular cohort). METHODS: This was a population-based study of 1751 men and 1990 women, aged 60 years and without CVD at baseline, with 375 incident cases of CVD during 11 years of follow-up. Weight, height, waist circumference (WC), hip circumference and sagittal abdominal diameter (SAD) were measured at baseline. Body mass index (BMI), waist-hip ratio (WHR), waist-hip-height ratio (WHHR), WC-to-height ratio (WCHR) and SAD-to-height ratio (SADHR) were calculated. RESULTS: All anthropometric measures predicted CVD in unadjusted Cox regression models per s.d. increment (hazard ratios, 95% confidence interval), while significant associations after adjustments for established risk CVD factors were noted for WHHR 1.20 (1.08-1.33), WHR 1.14 (1.02-1.28), SAD 1.13 (1.02-1.25) and SADHR 1.17 (1.06-1.28). WHHR had higher increases in C-statistics, and model improvements (likelihood ratio tests (P<0.001)). In the replication study (MDC-CC, n=5180), WHHR was the only measure that improved Cox regression models in men (P=0.01). CONCLUSION: WHHR, a new measure reflecting body fat distribution, showed the highest risk estimates after adjustments for established CVD risk factors. These findings were verified in men but not women in an independent cohort.

Regional variation in the incidence of abdominal aortic aneurysm in Sweden.

BACKGROUND: The risk factor profile is similar between patients with abdominal aortic aneurysm (AAA) and coronary heart disease (CHD). CHD is more common in the north of Sweden. It is unknown whether similar regional differences in the incidence of AAA exist. The aims of this study were to investigate whether there is a regional gradient of AAA incidence, and to compare time trends and the frequency of interventions between regions. METHODS: Swedish citizens have a 12-digit personal identification number. The Swedish Hospital Discharge Register covers inpatient care (diagnosis, admission, procedure codes, sex, date of birth, county). Population size was obtained from the central statistical bureau. Regions were south, mid and north. RESULTS: All records for 1990-2005 were extracted and 35 418 individuals with AAA were identified (74.8 per cent men). The highest age-standardized incidence (102.7 per 100,000) was found in men in the north region. The age-adjusted incidence ratio for men in the north region compared with the south was 1.38 (95 per cent confidence interval 1.34 to 1.42). Similar differences were found in women: incidence ratio for north compared with south region 1.39 (1.07 to 1.81). The proportion treated was larger in men and varied by region: 46.9 per cent of men in the mid region compared with 43.7 per cent in the south received treatment (P < 0.001), whereas 29.8 per cent of women in the north region versus 25.4 per cent in the south had an intervention (P = 0.001). The incidence did not increase over time. CONCLUSION: The higher incidence of AAA in the north of Sweden corresponds well with reported CHD patterns. The incidence of AAA in the population did not increase significantly over time, in contrast to the increasing intervention rates.

The association between fibrinogen haplotypes and myocardial infarction in men is partly mediated through pleiotropic effects on the serum IL-6 concentration.

BACKGROUND AND OBJECTIVES: Fibrinogen haplotypes have been associated with risk of myocardial infarction (MI), independently of plasma fibrinogen concentration, and experimental data indicate that fibrinogen exerts pleiotropic effects on interleukin 6 (IL-6) production. Also, the coagulation factor XIII (gene symbol F13A1) Val34Leu haplotype tag single nucleotide polymorphism (htSNP) has been reported to exert pleiotropic effects on serum IL-6 concentration and to be associated with risk of MI. Therefore, in the present case-control study (a substudy to the Stockholm Heart Epidemiology Program), the effects of the fibrinogen gamma (FGG) 9340T>C [rs1049636], fibrinogen alpha (FGA) 2224G>A [rs2070011] and F13A1 Val34Leu [rs5985] htSNPs on concentrations of plasma fibrinogen and serum IL-6 and risk of MI were assessed. RESULTS: There were no associations between these SNPs and the plasma fibrinogen concentration. In contrast, in male controls the FGA 2224G>A htSNP was significantly associated with serum IL-6 concentration (P < 0.05). Also, in men the FGG-FGA*1 haplotype (containing the major FGG 9340T and FGA 2224G alleles) was associated with increased risk of MI [adjusted odds ratio (OR) 95% confidence interval (CI): 1.29 (1.02, 1.62)] and with higher IL-6 concentrations, whereas the least common FGG-FGA*4 haplotype (containing the minor FGG 9340C and FGA 2224A alleles) conferred lowered risk [adjusted OR (95% CI): 0.70 (0.57, 0.86)] and lowered IL-6 concentrations. In women, fibrinogen haplotypes were not associated with risk of MI after adjusting for cardiovascular risk factors. CONCLUSION: In healthy men, fibrinogen haplotypes are associated with serum IL-6 concentrations in a manner consistent with their impact on MI risk.

The G-455A polymorphism of the fibrinogen Bbeta-gene relates to plasma fibrinogen in male cases, but does not interact with environmental factors in causing myocardial infarction in either men or women.

OBJECTIVES: To elucidate the association between a genetic polymorphism of the fibrinogen Bbeta-gene (G-455A) and plasma fibrinogen levels and myocardial infarction (MI), respectively. In addition, to explore potential synergistic gene-environment interactions involving this polymorphism--until now, these data were unavailable. DESIGN SETTING AND SUBJECTS: This case-referent study of subjects aged 45-70 and living in Stockholm includes 834 men and 346 women with first-time MI and 1034 men and 494 women randomly chosen as referents from the population. The cases were identified between 1992 and 1994 at the 10 emergency hospitals in Stockholm County. MAIN OUTCOME MEASURES: MI and plasma fibrinogen levels. RESULTS: Crude analyses associated a high level of plasma fibrinogen with an increased risk of MI in both men and women. However, the relative risk decreased after controlling for other risk factors. The multivariate-adjusted odds ratio (OR) (95% confidence interval) was 1.6 (1.2-2.3) for men and 1.5 (0.9-2.6) for women. Presence of the A allele at the G-455A polymorphic site indicated higher plasma fibrinogen levels than the presence of the G allele, but the difference was only statistically significant for male cases. The -455A allele was not associated with an increased risk of MI. Furthermore, there were no strong indications of synergistic interaction between the G-455A polymorphism and any of the environmental exposures considered. CONCLUSIONS: In this large number of MI cases and referents, a high level of plasma fibrinogen was independently associated with increased risk of MI in men but not in women. The presence of the A allele at the G-455A polymorphism of the fibrinogen Bbeta-gene was not associated with increased risk of MI, and no synergistic gene-environment interactions were detected.

Family history of coronary heart disease, a strong risk factor for myocardial infarction interacting with other cardiovascular risk factors: results from the Stockholm Heart Epidemiology Program (SHEEP).

We explored the relation between family history of coronary heart disease and the risk of myocardial infarction in a case-control study of subjects, 45 to 70 years of age, living in Stockholm, Sweden. Our cases comprised 1091 male and 531 female first-time acute myocardial infarction patients who had survived at least 28 days after their infarction. Referents were randomly selected from the population from which the cases were derived. The adjusted odds ratio (OR) of myocardial infarction was 2.0 (95% confidence interval [CI] = 1.6-2.6) for men reporting > or = 1 affected parent or sibling, compared with men with no family history of coronary heart disease, and 3.4 (95% CI = 2.1-5.9) for those reporting > or = 2 affected parents or siblings. The corresponding OR for women were 2.1 (95% CI = 1.5-3.0) and 4.4 (95% CI = 2.4-8.1). We found evidence for synergistic interactions in women exposed to family history of coronary heart disease in combination with current smoking and with a high quotient between low-density lipoprotein and high-density lipoprotein cholesterol (>4.0), respectively, which yielded adjusted synergy index scores of 2.9 (95% CI = 1.2-7.2) and 3.8 (95% CI = 1.5-9.7), respectively. Similarly, in men we found evidence for interaction for the co-exposure of family history of coronary heart disease and diabetes mellitus. Our study shows that family history of coronary heart disease is not only a strong risk factor for myocardial infarction in both sexes, but that its effect is synergistic with other cardiovascular risk factors as well.

A peptide-doxorubicin 'prodrug' activated by prostate-specific antigen selectively kills prostate tumor cells positive for prostate-specific antigen in vivo.

We covalently linked doxorubicin with a peptide that is hydrolyzable by prostate-specific antigen. In the presence of prostate tumor cells secreting prostate-specific antigen, the peptide moiety of this conjugate, L-377,202, was hydrolyzed, resulting in the release of leucine-doxorubicin and doxorubicin, which are both very cytotoxic to cancer cells. However, L-377,202 was much less cytotoxic than conventional doxorubicin to cells in culture that do not secrete prostate-specific antigen. L-377,202 was approximately 15 times more effective than was conventional doxorubicin at inhibiting the growth of human prostate cancer tumors in nude mice when both drugs were used at their maximally tolerated doses. Nude mice inoculated with human prostate tumor cells secreting prostate-specific antigen showed considerable reductions in tumor burden with minimal total body weight loss when treated with L-377, 202. This improvement in therapeutic index correlated with the selective localization of leucine-doxorubicin and free doxorubicin in tissues secreting prostate-specific antigen after exposure to L-377,202.

Dose-related changes in the profile of ras mutations in chemically induced CD-1 mouse liver tumors.

We investigated the role of dosing regimen on ras mutations in chemically induced CD-1 mouse liver tumors. The spectra of ras gene mutations in liver tumors that were induced by 15 daily i.p. injections of 7,12-dimethylbenz[a]anthracene (DMBA), 4-aminoazobenzene (AAB), N-hydroxy-2-acetylaminofluorene (N-OH-AAF) or N-nitrosodiethylamine (DEN) were compared to those previously obtained for tumors induced by a single but higher dose of each carcinogen. The principal assay used was a direct tumor analysis involving sequencing of polymerase chain reaction (PCR)-amplified tumor DNA; additional mutations that were present in only a small fraction of tumor cells were detected using a transfection assay or a PCR-engineered restriction fragment length polymorphism method. Spontaneous liver tumors had a relatively low frequency of ras mutations, all found in Ha-ras codon 61, and most of these mutations were present in only a small fraction of tumor cells. With the exception of multiple-dose DEN, each group of single- and multiple-dose carcinogen-induced tumors exhibited a higher frequency of ras mutations compared with spontaneous tumors. For AAB, N-OH-AAF and DEN, the dosing regimen was found to affect significantly the profile of ras mutations. For each of these carcinogens, the multiple-dose tumor group (versus single-dose group) had fewer Ki-ras and N-ras mutations and more tumors in which the Ha-ras codon 61 (C-->A) mutation was present in a large fraction of cells. Our results demonstrate that the dosing procedure can materially affect the pattern of ras gene mutation in mouse liver tumors.

Induction of minisatellite DNA rearrangements by genotoxic carcinogens in mouse liver tumors.

We investigated whether somatic rearrangements in minisatellite DNA are more frequent in chemically induced mouse liver tumors than they are in spontaneous tumors. CD-1 mouse liver tumors were induced by either a single dose or 15 consecutive daily doses of 7,12-dimethylbenz[alpha]anthracene, 4-aminoazobenzene, N-hydroxy-2-acetyl-aminofluorene or diethylnitrosoamine (DEN). Using DNA fingerprinting analysis, we found that the single- and multiple-dose carcinogen treatments caused a 2- to 5-fold higher frequency of minisatellite DNA rearrangements compared with that found in spontaneous tumors--with the exception of single-dose DEN tumors, which showed no increase in rearrangements. Our results suggest that DNA fingerprinting may be a valuable assay for differentiating certain chemically induced tumors from spontaneous tumors.

Heterologous and homologous protection against influenza A by DNA vaccination: optimization of DNA vectors.

We have recently shown that direct injection of DNA can be an effective vaccine strategy eliciting both humoral and cell-mediated immune responses. Vectors were designed specifically for vaccination by direct DNA injection and refined to improve plasmid production in Escherichia coli. The vectors consist of a pUC-19 backbone with the cytomegalovirus (CMV) IE1 enhancer, promoter, and intron A transcription regulatory elements and the BGH polyadenylation sequences driving the expression of the reporter gene CAT or influenza A nucleoprotein (NP) or hemagglutinin (HA). The respective vectors expressed high levels of chloramphenicol acetyltransferase (CAT) and NP in tissue culture, and yielded 14-15 mg of purified plasmid per liter of Escherichia coli culture. Immunization of mice with the NP and HA expression vectors resulted in protection from subsequent lethal challenges of influenza using either heterologous or homologous strains, respectively.

Targeted delivery of peptide epitopes to class I major histocompatibility molecules by a modified Pseudomonas exotoxin.

Cytotoxic T lymphocytes (CTLs) expressing the CD8 surface marker recognize peptides in association with major histocompatibility complex (MHC) class I molecules. Although most peptides expressed on MHC class I molecules are derived from self- or virally encoded proteins, delivery of exogenous proteins to the cytosol can result in their being processed for presentation to CTLs on MHC class I molecules. We describe two fusion proteins (PEMa and PENP), consisting of the binding and translocating domains of Pseudomonas exotoxin A (PE), fused to peptide epitopes from influenza A matrix protein and nucleoprotein, respectively. These fusion proteins were internalized and processed by MHC class I-positive target cells, resulting in sensitization of target cells for lysis by peptide-specific CTLs. A point mutation known to interfere with intoxication by wild-type PE also reduced the ability of PEMa to sensitize target cells. Fusion of peptide or polypeptide epitopes with PE provides a potential means of eliciting CTLs without the use of self-replicating agents, as well as a useful probe for studying MHC class I-restricted antigen processing.

Activation of the Ha-, Ki-, and N-ras genes in chemically induced liver tumors from CD-1 mice.

We compared the profile of ras gene mutations in spontaneous CD-1 mouse liver tumors with that found in liver tumors that were induced by a single i.p. injection of either 7,12-dimethylbenz(a)anthracene (DMBA), 4-aminoazobenzene, N-hydroxy-2-acetylaminofluorene, or N-nitrosodiethylamine. By direct sequencing of polymerase chain reaction-amplified tumor DNA, the carcinogen-induced tumors were found to have much higher frequencies of ras gene activation than spontaneous tumors. Furthermore, each carcinogen caused specific types of ras mutations not detected in spontaneous tumors, including several novel mutations not previously associated with either the carcinogen or mouse hepatocarcinogenesis. For example, the model compound DMBA is known to cause predominantly A to T transversions in Ha-ras codon 61 in mouse skin and mammary tumors, consistent with the ability of DMBA to form bulky adducts with adenosine. Our results demonstrate that the predominant mutation caused by DMBA in mouse liver tumors is a G to C transversion in Ki-ras codon 13 (DMBA is also known to form guanosine adducts), illustrating the influence of both chemical- and tissue-specific factors in determining the type of ras gene mutations in a tumor. 4-Aminoazobenzene and N-hydroxy-2-acetylaminofluorene also caused the Ki-ras codon 13 mutation. In addition, we found that N-nitrosodiethylamine, 4-aminoazobenzene, and N-hydroxy-2-acetylaminofluorene all caused G to T transversions in the N-ras gene (codons 12 or 13). This is the first demonstration of N-ras mutations in mouse liver tumors, establishing a role for the N-ras gene in mouse liver carcinogenesis. Finally, comparison of the ras mutations detected in the direct tumor analysis with those detected after NIH3T3 cell transfection indicates that spontaneous ras mutations (in Ha-ras codon 61) are often present in only a small fraction of the tumor cells, raising the possibility that they may sometimes occur as a late event in CD-1 mouse hepatocarcinogenesis.

Polymerase chain reaction/sequencing analysis of ras mutations in paraffin-embedded tissues as compared with 3T3 transfection and polymerase chain reaction/sequencing of frozen tumor deoxyribonucleic acids.

The efficiency of detection of H- and K-ras mutations in 27 CD-1 mouse liver tumors by direct sequencing of polymerase chain reaction (PCR)-amplified DNA isolated from formalin-fixed and paraffin-embedded tissues was compared with that after assay by both NIH 3T3 transfection (followed by sequencing of amplified transformant DNA) and direct sequencing of PCR-amplified DNA isolated from frozen tumors. Some tumor samples were chosen for comparison because they contained ras mutations that were detected by either NIH 3T3 transfection or sequencing of PCR-amplified DNA derived from frozen tumors, but were not detected by both techniques. The efficiency of detecting K-ras mutations was similar for sequencing of amplified fragments derived from both paraffin-embedded tissues and from frozen tumors. However, these two techniques differed in their efficacy for detection of H-ras codon 61 mutations. Furthermore, this difference appeared to be mutation-specific: the sequencing of amplified products from paraffin-embedded tumor tissues allowed increased detection of CAA to AAA mutations but decreased detection of CAA to CTA mutations relative to sequencing of amplified fragments derived from frozen tumor DNA. Direct sequencing of PCR products from paraffin-embedded sections was more sensitive than NIH 3T3 transfection for detection of activated K-ras genes containing codon 13 mutations but less sensitive for detection of activated H-ras genes containing codon 61 mutations. In summary, direct sequencing of amplified DNA from either frozen tumors or formalin-fixed, paraffin-embedded tissues can be more sensitive than NIH 3T3 transfection for detection of codon 13-activated K-ras genes. However, it appears to be less sensitive than NIH 3T3 transfection for detection of certain activating H-ras mutations. Depending upon the questions being asked of the data, each of the methods can provide useful information about ras gene mutations in tumor samples. The apparent differences in sensitivities between the methods is not yet understood, but such differences should be considered in the analysis of data obtained when only one method is used.

Murine p53 intron sequences 5-8 and their use in polymerase chain reaction/direct sequencing analysis of p53 mutations in CD-1 mouse liver and lung tumors.

Inactivating point mutations and small deletions in the p53 tumor suppressor gene have been found in human liver and lung tumor--derived cell lines and tumors. However, little evidence has been reported concerning inactivation or mutation of the p53 gene in mouse primary tumors. To examine CD-1 mouse liver and lung tumors for mutations in the p53 gene, we first sequenced p53 introns 5-8 so that polymerase chain reaction amplification and sequencing primers located within the introns could be prepared. Use of these primers prevented amplification of the mouse p53 pseudogene and allowed sequencing of exons 5-8 in their entirety as well as their intron-exon junctions. DNA isolated from CD-1 mouse tumors was amplified and directly sequenced using nested primers. Nine spontaneous hepatocellular carcinomas (HCCs) and 34 chemically induced HCCs (induced by single intraperitoneal injections of N-nitrosodiethylamine [DEN] [8 HCCs], 7,12-dimethylbenz[a]anthracene [DMBA] [8 HCCs], 4-aminoazobenzene [8 HCCs], and N-OH-2-acetylaminofluorene [10 HCCs]) were examined for mutations in exons 5-8 of the p53 gene. In addition, 12 spontaneous, 10 DMBA-induced, and 13 DEN-induced lung adenocarcinomas or adenomas were analyzed for mutations. No mutations were found in any of the tumors examined. However, a mutation was demonstrated at codon 135 in the positive-control plasmid LTRp53cG(val). The results of this study suggest that inactivation of p53 is unlikely to play a major role in murine lung or liver carcinogenesis. However, inactivation of p53 may occur at a very low frequency, or it may occur as a late event and therefore be present in only a very small number of the tumor cells, rendering it undetectable by this method. Lastly, although few p53-inactivating mutations are found outside of exons 5-8 in human tumors, it is possible that these murine tumors contained mutations outside of this region and were therefore missed by our approach.

Activation of the Ki-ras gene in spontaneous and chemically induced lung tumors in CD-1 mice.

As part of an evaluation of the effectiveness of using ras mutation analysis for distinguishing carcinogen-induced from spontaneous tumors, we examined the profile of ras gene point mutations in spontaneous, 7,12-dimethylbenz[a]anthracene (DMBA)-induced, and N-nitrosodiethylamine (DEN)-induced lung tumors from Crl:CD-1(ICR)BR (CD-1) mice. Although all of the lung tumors were assayed for mutations in the Ha-ras, Ki-ras, and N-ras genes (codons 12, 13, and 61), only Ki-ras mutations were found, which is consistent with other studies that have noted a strong preference for Ki-ras gene activation in mouse, rat, and human lung tumors. We found that spontaneous CD-1 mouse lung tumors had a very high frequency of Ki-ras gene activation (17 of 20 tumors; 85%), distributed among codons 12 (5 of 20), 13 (1 of 20), and 61 (11 of 20). DMBA-induced lung tumors had a slightly higher frequency of Ki-ras gene mutations (16 of 16; 100%), again distributed among codons 12 (5 of 16), 13 (2 of 16), and 61 (9 of 16). However, seven of the DMBA tumors had mutations qualitatively different from those found in spontaneous tumors. In contrast to DMBA-induced tumors, DEN-induced tumors had a lower frequency of Ki-ras mutations (36%) when compared with spontaneous lung tumors, suggesting that DEN primarily induces lung carcinogenesis by a mechanism other than ras gene activation. Thus, although spontaneous and induced CD-1 mouse lung tumors have a strong tissue-specific preference for carrying an activated Ki-ras gene, the nature of the initiating carcinogen can influence the frequency or profile of Ki-ras mutations.

DNA fingerprinting of 7,12-dimethylbenz[a]anthracene-induced and spontaneous CD-1 mouse liver tumors.

Determining to what degree chemicals and environmental agents contribute to the development of cancer would be materially enhanced by the ability to distinguish chemically induced tumors from those that arise spontaneously. Using DNA fingerprinting as an assay, we investigated whether somatic DNA rearrangements are more frequent in chemically induced mouse liver tumors than they are in spontaneous mouse liver tumors. Tumors were induced by a single i.p. injection of 12-day old male Crl:CD-1(ICR)BR (CD-1) mice with 20 nmol/g 7,12-dimethylbenz[a]-anthracene and were harvested 9 to 12 months after injection. Spontaneous tumors were obtained from 94- to 98-week old male CD-1 mice. We detected 8 rearrangements in 14 7,12-dimethylbenz[a]anthracene-induced tumors, which corresponds to a high rearrangement frequency of about 2% (of the minisatellite bands examined). Furthermore, 6 of these rearrangements included complete band losses which must have occurred early in tumor development. However, only 2 band changes were observed in 15 spontaneous tumors, and both changes were intensity shifts which may represent rearrangements that occurred later during tumor progression. Histological examination showed that the higher frequency of rearrangements in 7,12-dimethylbenz[a]anthracene-induced tumors versus spontaneous tumors was not related to differences in the degree of tumor progression or malignancy. Our results suggest that DNA fingerprinting may be a valuable assay for differentiating certain chemically induced tumors from spontaneous tumors.

A mucin containing the X, Y, and H type 2 carbohydrate determinants is shed by carcinoma cells.

Monoclonal antibody BR 15-6A directed to the Y carbohydrate determinant (Fuc alpha 1----2Gal beta 1----4GlcNAc(3----1Fuc) beta 1----3Gal beta 1----4Glc beta 1----1Cer) reacted with the cell surface and conditioned media of colorectal and breast carcinoma cell lines. Double determinant immunoassays using BR 15-6A as detector antibody showed that the Y determinant is part of a high molecular weight mucin that coexpressed other carbohydrate antigens based on a type 2 chain (X, H type 2). Type 1 chain carbohydrates such as sialylated Lewisa, Lewisa and Lewisb blood group antigens were predominantly expressed on a separate mucin molecule as determined by double-determinant immunoassays with other anticarbohydrate monoclonal antibodies. The X, Y, and H type 2-bearing mucin was present in conditioned media of the majority of colorectal carcinoma cell lines and in all three breast cancer cell lines tested. Thus, monoclonal antibodies against X, Y, and H type 2 determinants are potentially useful in the serodiagnosis of gastrointestinal and breast cancer.