The difference between hypertension determined by self-report versus examination in the adult population of the USA: Continuous NHANES 1999-2016

BACKGROUND

Studies have considered the validity of self-reported hypertension relative to hypertension detected by examination; no study has explored trends in the difference between these two measures. Our objective was to calculate these differences overtime within subpopulations of the USA.

METHODS

We included non-Hispanic white, non-Hispanic black and Hispanic adults who participated in the National Health and Nutrition Examination Surveys from 1999 to 2016, in the analysis (N = 44 333). We subtracted self-reported hypertension from hypertension detected by examination to calculate blood pressure difference (BPD). We fit weighted linear regression models that included important covariates along with all combination of two- and three-way interactions to predict the BPD. We used the fitted lines of the models to depict the patterns of differences in the different subpopulations.

RESULTS

Age ≥ 45 years, lack of annual clinical visit, body mass index (BMI) < 25 and time were important factors associated with increased BPD.

CONCLUSIONS

People who are ≥ 45 years, have normal BMI, or do not have annual medical visits are more likely to have a bigger BPD. We can use the calculated BPD, to adjust estimates of the prevalence of self-reported hypertension.

The association of metabolic syndrome and QRS|T angle in US adults (NHANES III)

BACKGROUND

Spatial QRS|T angle is a predictor of cardiovascular events. Those with metabolic syndrome have an increased risk of cardiovascular morbidity and mortality. This study investigated the association between metabolic syndrome and spatial QRS|T angle.

METHODS

We obtained data from the National Health and Nutritional Examination Survey III on 6,249 adults. We calculated spatial QRS|T angle from the standard 12-lead electrocardiogram and classified it as abnormal, borderline, or normal. We identified metabolic syndrome if at least three of the following were present: abdominal obesity, elevated blood pressure, elevated triglycerides, decreased high-density lipoprotein (HDL), and impaired fasting glucose. We used weighted logistic regression to estimate the effect of metabolic syndrome and its components on QRS|T angle while stratifying by gender and adjusting for age, race, smoking status, heart rate, PR, QT, and QRS interval, and QRS amplitude.

RESULTS

Among men and women, metabolic syndrome, the number of components present, elevated blood pressure, and impaired fasting glucose were positively associated with QRS|T angle. Among women, decreased HDL and abdominal obesity were also positively associated with QRS|T angle.

CONCLUSIONS

This study suggests that persons with metabolic syndrome may be at increased risk for ventricular arrhythmias. The use of spatial QRS|T angle to assess this cardiovascular risk is warranted.

The Association between Salt and Potential Mediators of the Gastric Precancerous Process

Background: The process by which salt affects the gastric precancerous process has not been adequately studied in humans. Methods: We investigated the effects of salt on gastric inflammation, epithelial damage, the density of Helicobacter pylori infection, and gastric epithelial cell proliferation, all of which may be mediators between salt and gastric precancerous/cancerous lesions. These potential mediators were measured using gastric biopsies as: (a) the density of polymorphonuclear and mononuclear cells (gastric inflammation), (b) mucus depletion (gastric epithelial damage), and (c) the severity of H. pylori infection. Salt intake was measured with spot urine samples (using urinary sodium/creatinine ratios), self-reported frequency of adding salt to food, and as total added salt. Results: The average sodium/creatinine ratio (at baseline and post-treatment at five months) was associated with increased epithelial damage over the 12-year follow-up period among those with a greater severity of chronic inflammation and among those with continued H. pylori infection after treatment at five months. This association was stronger when both severe gastric inflammation and H. pylori infection were present at five months (ß: 1.112, 95% CI: 0.377, 1.848). Conclusion: In humans, salt was associated with an increase in epithelial damage in stomachs with more severe previous H. pylori-induced chronic inflammation.

Association between Dietary Salt Intake and Progression in the Gastric Precancerous Process

Gastric cancer is the third leading cause of cancer mortality worldwide. Studies investigating the effect of salt on gastric cancer have mainly used self-reported measures, which are not as accurate as sodium/creatinine ratios because individuals may not know the amount of salt in their food. Using data from a prospective cohort study, we investigated the effect of salt intake on progression to gastric precancerous lesions. Salt intake was estimated by urinary sodium/creatinine ratios, self-reported frequencies of adding salt to food, and total added table salt. We repeated the analyses among groups with and without Helicobacter pylori infection. We did not observe a positive association between salt intake, measured by urinary sodium/creatinine ratio, and overall progression in the gastric precancerous process (adjusted risk ratio (RR): 0.94; 95% confidence interval (CI) 0.76-1.15). We did observe an association between salt intake and increased risk for progression to dysplasia or gastric cancer overall (adjusted risk ratio (RR): 1.32; 95% confidence interval (CI): 0.96-1.81), especially among those who continued to have H. pylori infection at the five-month follow-up (adjusted RR: 1.53; 95% CI: 1.12-2.09), and among those who had persistent H. pylori infection over 12 years (adjusted RR: 1.49; 95% CI: 1.09-2.05). Salt intake may increase the risk of gastric dysplasia or gastric cancer in individuals with H. pylori infection.

The relation of blood lead and QRS-T angle in American adults

The QRS-T angle is a key ECG predictor for ventricular arrhythmia. Lead has a strong relation with cardiovascular diseases; however, no study has been conducted to investigate the association between lead exposure and QRS-T angle. Thus, we explored this association in a population-based representative sample: NHANES III. We used the standard 12-lead ECGs to calculate Spatial QRS-T angles. Blood lead concentration was measured using graphite furnace atomic absorption spectrophotometry method. We conducted multivariate weighted logistic regression to adjust for impaired fasting glucose, hypertension, poverty index, age, race, and smoking status. We found that when the log of blood lead increased by one unit, the odds of an abnormal QRS-T angle increased by 34% among men and 4% among women. We suggest the use of QRS-T angle deviation among those who are exposed to lead to detect individuals at risk for adverse cardiovascular outcomes such as arrhythmias.

Excess lung cancer occurrence in poultry plants. Occupational risk factors: Findings for oncogenic viruses exposure and other occupational exposures

Certain viruses naturally infect and cause cancer in chickens and turkeys. Humans are widely exposed. The viruses cause cancer in primates, and transform human cells in vitro, but it is not known if they cause cancer in humans, mainly because of the lack of epidemiologic evidence. We conducted cohort mortality studies of workers in poultry slaughtering/processing plants across the United States, because they have the highest human exposures. An excess of lung cancer and other deaths was recorded in the poultry workers. Here, we report on a case-cohort study of the lung cancer deaths nested within these cohorts, that was conducted to provide epidemiologic evidence linking these viruses with human cancer occurrence, while adjusting for possible confounders, including workplace chemical carcinogens. We obtained interviews for 339 lung cancer deaths and 457 controls, selected from our combined cohorts of 30,411 poultry plant workers and 16,405 non-poultry workers, belonging to United Food & Commercial Workers unions. Data was analyzed by both logistic regression and Cox regression, adjusting for smoking and other confounders. Lung cancer risk was independently associated with tasks or work areas indicative of exposure to both poultry oncogenic viruses and to workplace chemical carcinogens. The study provides an incremental piece of evidence (epidemiologic), indirectly linking the oncogenic viruses of poultry with the occurrence of cancer in humans, and thus may have public health implications, but the limitations highlighted must be considered. Confirmatory studies, particularly molecular studies providing definitive proof of poultry oncogenic retrovirus integration in human DNA are needed, before the findings observed in this study can be put into proper perspective.

The Association between SNPs and a Quantitative Trait: Power Calculation

A power calculation for a study with a quantitative outcome requires information on the outcome distribution under the alternative hypothesis. Researchers face challenges when they concisely specify alternative distributions in genetic studies because power depends on genotype frequencies and the average effect of each genotype. In GWAS, investigators evaluate hundreds of thousands of associations; therefore it is unrealistic to specify gene frequencies and gene effects for each test and some simplification is needed. Software packages are available to calculate power, but many of them have limited flexibility and / or may have a steep learning curve. In this review, we describe to researchers and graduate students the essentials of a power calculation for testing for an association between a quantitative trait and genotypes. In addition, we provide them with the codes of the different available software packages—free and commercial—to calculate this power. The calculations can be carried out using virtually any computer language that computes the cumulative distribution function of a non-central F-distribution.

Community Team-Based Care for Hypertension Management: A Public-Private Partnership in Rural Arkansas

Hypertension is a major public health problem in Arkansas. Team-based care (TBC), delivered by health care professionals such as a nurse, dietician, social worker, or community health worker rather than a physician alone, has been shown to improve blood pressure control.

The Effect of Metformin Use on Left Ventricular Ejection Fraction and Mortality Post-Myocardial Infarction

BACKGROUND

Animal studies showed that the use of metformin after myocardial infarction (MI) resulted in a protective effect on cardiac myocytes. In this study, we examined the effect of metformin in patients with diabetes mellitus (DM) on left ventricular ejection fraction (LVEF) and post-MI mortality.

METHODS

We reviewed charts of patients with MI admitted to the UAMS medical center. Baseline characteristics and 12-month follow up data were collected. Patients were classified into three groups: Control group- no DM (n = 464), Metformin group- DM + MI (n = 88) and No-Metformin group- DM + MI (n = 168). First, we compared Metformin and No-Metformin groups to the Control group. Second, we performed propensity-score matching in patients with DM, and compared Metformin to No-Metformin groups.

RESULTS

All-cause 30-day and 12-month mortality was significantly higher in the No-Metformin group compared to controls (13.5 vs 9.3% p = 0.03 at 30 days, 23.7 vs 15.9 % p = 0.03 at 12 months). However, all-cause 30-day and 12-month mortality were similar in the Controls and Metformin group (9.3 vs 6.8 % p = 0.93 at 30 days, 15.9 vs 11.4 % p = 0.97 at 12 months). Mean LVEF on presentation (45 % in the three groups) and at follow up (47.84, 46.38 and 43.62 % in Control, Metformin, and No-Metformin groups, respectively) were not statistically different. There were no significant differences in regard to re-hospitalization, re-intervention, new stroke, CHF development, new MI, or identifiable arrhythmias. Metformin was an independent predictor of lower 30-day and 12-month all-cause mortality in patients with DM (HR 0.25, p = 0.02 and HR 0.32, p = 0.01, respectively). In the matched analysis, 30-day all-cause mortality was significantly higher in the No-Metformin compared to the Metformin group (21.1 vs 8.8 %, p = 0.05). However the difference in 12-month all-cause mortality did not reach statistical significance (24.6 vs 15.8 %, p = 0.15).

CONCLUSION

This proof-of-concept study shows that use of metformin in patients with DM is associated with lower 30-day all-cause mortality and tendency for a lower 12-month all-cause mortality following MI without discernible improvement in LVEF.

Neighborhood and Acute Myocardial Infarction Mortality as Related to the Driving Time to Percutaneous Coronary Intervention-Capable Hospital

BACKGROUND

Driving time to a percutaneous coronary intervention (PCI)-capable hospital is important in timely treatment of acute myocardial infarction (AMI). Our objective was to determine whether driving time from one's residence to a PCI-capable hospital contributes to AMI deaths. We conducted a cross-sectional study of age- and sex-adjusted mortality in census block groups to evaluate this question.

METHODS AND RESULTS

We studied all (14 027) AMI deaths that occurred during 2008-2012 in Arkansas to assess the relationship between driving time from the population center of a block group (neighborhood) to the nearest PCI-capable hospital. We estimated standardized mortality ratios in block groups that were adjusted for education (population over 25 years of age who did not graduate from high school), poverty (population living below federal poverty level), population density (population per square mile), mobility (population residing at the same address as 1 year ago), black (population that is black), rurality (rural households), geodesic distance, and driving time. The median geodesic distance and driving time were 12.8 miles (interquartile range 3.6-30.1) and 28.3 minutes (interquartile range 9.6-58.7), respectively. Risks in neighborhoods with long driving times (90th percentile) were 26% greater than risks in neighborhoods with short driving times (10th percentile), even after adjusting for education, poverty, population density, rurality, and black race (P<0.0001).

CONCLUSIONS

AMI mortality increases with increasing driving time to the nearest PCI-capable hospital. Improving the healthcare system by reducing time to arrive at a PCI-capable hospital could reduce AMI deaths.

Abstract 209: Driving Time to Percutaneous Coronary Intervention Capable Hospital and Acute Myocardial Infarction Mortality

Objectives: To determine if driving time to the percutaneous coronary intervention (PCI) capable hospital is an important factor in deaths of patients with acute myocardial infarction (AMI).

Methods: We studied the relationship between driving time to the nearest PCI-capable hospital and AMI mortality (2008-2012) in census block groups (BG), N=2147, in the state of Arkansas. Population center of a BG was used as a proxy for an individual’s place of residence. The driving time to the nearest PCI-capable hospital was calculated from the population center of a BG. The risk of AMI death was then calculated using five census measures: poverty (% of population below federal poverty level); population density (population per square mile); education (% of population over 25 years of age that did not graduate from high school); mobility (% of population who resided at the same address 1 year ago) and the percent of non-Hispanic blacks (% of population that is Black); and the calculated driving time to the nearest PCI-capable hospital. Arc GIS was used to calculate the driving time to the nearest PCI-capable hospital. Generalized additive models were used to estimate the variation in AMI mortality among BGs.

Findings: During 2008-2012, there were 14,027 AMI deaths in Arkansas. There was considerable variation in the relative risk between BGs and AMI mortality based on the distance to the PCI hospital. The median distance to the nearest PCI-capable hospital was 12.7 miles (Interquartile range 3.5 - 30.1); and the median driving time to the nearest PCI-capable hospital was 28.3 minutes (Interquartile range 9.6-58.7). However, driving time (Range- 58.7 to 149.3 minutes) among residents in BGs (n=536) that are in the fourth quartile was much higher than the optimal timeframe to receive PCI for AMI. The regression analyses indicated that the driving time to the nearest PCI-capable hospital is a significant predictor of AMI mortality (p < 0.0001) in all BGs, after adjusting for education, poverty, race, and population density.

Conclusions: Our study shows that the driving time to the nearest PCI-capable hospital is an independent predictor of AMI mortality. Improving health care system by reducing time to arrive at a PCI-capable hospital could reduce AMI deaths in underserved communities.

Obesity is associated with visit-to-visit systolic blood pressure variability in the US adults

BACKGROUND

Evidence has accumulated showing that blood pressure variability is associated with cardiovascular disease. A substantial increase in the prevalence of obesity has been documented globally. Our objective was to examine the relation of total and central obesity on visit-to-visit blood pressure variability.

METHODS

We used data collected from the cross-sectional Third National Health and Nutrition Examination Survey, to examine the association of visit-to-visit blood pressure variability with body mass index and waist circumference.

RESULTS

The analysis included 14,988 participants. The participants' mean age was 43.45 years. Visit-to-visit systolic blood pressure variability was associated with a body mass index ≥30 and a large waist circumference (beta coefficients were 0.25 and 0.31, respectively, P-values < 0.01). Neither the bivariate nor the multivariable analyses showed significant relationships between the obesity indicators and diastolic blood pressure variability.

CONCLUSIONS

Obesity is associated with visit-to-visit systolic blood pressure variability. Additional research is required to replicate the reported results in prospective studies and evaluate approaches to reduce blood pressure variability observed in clinical settings among obese persons to reduce its subsequent complications.

The Neighborhood Where You Live Is a Risk Factor for Stroke

Background—

The excess stroke mortality in the southeastern states of the United States (stroke-belt states) is well known; however, the factors associated with this pattern have not been fully elucidated. We measured the contribution of several demographic factors by analyzing stroke mortality data (2005–2009) at the census block group (BG) level in the state of Arkansas.

Methods and Results—

Census BGs were used as proxies for neighborhoods. BGs were stratified using 5 census measures: poverty (percent of population below federal poverty level), population density (population per square mile), education (percent of population aged >25 years who did not graduate from high school), population mobility (percent of population who resided at the same address 1 year ago), and the percent of non-Hispanic blacks (percent of population that is black). Generalized additive models were used to estimate the variation in stroke mortality among BGs and to assess the impact of different demographic variables. From 2005 to 2009, there were 8930 stroke deaths in Arkansas. There was considerable variation in the relative risk even between adjacent BGs within a single county. The geographically weighted regression analyses indicated that 4.5% to 9% of deviance in stroke mortality among BGs could be explained by poverty, education, population density, and population mobility. Race/ethnicity (non-Hispanic blacks) explains <2% of the deviance in stroke mortality among BGs.

Conclusions—

Our study shows that primordial risk factors such as poverty and education drive disparities in stroke mortality among neighborhoods in Arkansas.

Comparison of Basal gene expression in cultured primary rat hepatocytes and freshly isolated rat hepatocytes

Cultured primary hepatocytes are one of the most suitable in vitro models for hepatic toxicological studies. Unfortunately, there is a temporal loss of liver-specific function in culture that limits their utility for some applications. Plating hepatocytes on a substratum has been shown to stabilize the differentiated phenotype for short-term culture. In order to identify the substratum that best supports in vivo basal hepatocyte gene expression profiles in vitro, the gene expression profiles of primary rat hepatocytes plated on collagen I in hepatocyte maintenance medium (HMM) or hepatocyte culture medium (HCM), or on matrigel in HMM medium for 2 h, 16 h, or 72 h were compared to the expression profiles of freshly isolated rat hepatocytes using the Atlas rat stress array. After 16 h in culture, there were differences in gene expression between cultured primary hepatocytes and freshly isolated hepatocytes, but no apparent substratum effects. At 72 h, the expression of 9 genes was altered in hepatocytes plated on either substratum compared to expression in freshly isolated hepatocytes. However, there were an additional 13 genes with increased expression in hepatocytes plated on collagen I that were expressed at low or non-detectable levels in freshly isolated hepatocytes or primary hepatocytes plated on matrigel. In summary, after 72 h, primary hepatocytes plated on matrigel had basal gene expression patterns more similar to patterns in freshly isolated hepatocytes than did hepatocytes cultured on collagen. In addition, culture on matrigel suppressed the expression of atypical genes in culture. These preliminary studies suggest that culture on matrigel may be preferable for longer-term in vitro toxicological studies.

A method for computing the overall statistical significance of a treatment effect among a group of genes

BACKGROUND

In studies that use DNA arrays to assess changes in gene expression, our goal is to evaluate the statistical significance of treatments on sets of genes. Genes can be grouped by a molecular function, a biological process, or a cellular component, e.g., gene ontology (GO) terms. The meaning of an affected GO group is often clearer than interpretations arising from a list of the statistically significant genes.

RESULTS

Computer simulations demonstrated that correlations among genes invalidate many statistical methods that are commonly used to assign significance to GO terms. Ignoring these correlations overstates the statistical significance. Meta-analysis methods for combining p-values were modified to adjust for correlation. One of these methods is elaborated in the context of a comparison between two treatments. The form of the correlation adjustment depends upon the alternative hypothesis.

CONCLUSION

Reliable corrections for the effect of correlations among genes on the significance level of a GO term can be constructed for an alternative hypothesis where all transcripts in the GO term increase (decrease) in response to treatment. For general alternatives, which allow some transcripts to increase and others to decrease, the bias of naïve significance calculations can be greatly decreased although not eliminated.

Mouse lymphoma thymidine kinase gene mutation assay: follow-up meeting of the International Workshop on Genotoxicity Testing--Aberdeen, Scotland, 2003--Assay acceptance criteria, positive controls, and data evaluation

The Mouse Lymphoma Assay (MLA) Workgroup of the International Workshop on Genotoxicity Testing (IWGT), comprised of experts from Japan, Europe, and the United States, met on August 29, 2003, in Aberdeen, Scotland, United Kingdom. This meeting of the MLA Workgroup was devoted to reaching a consensus on the appropriate approach to data evaluation and on acceptance criteria for both the positive and negative/vehicle controls. The Workgroup reached consensus on the acceptance criteria for both the agar and microwell versions of the MLA. Recommendations include acceptable ranges for mutant frequency, cloning efficiency, and suspension growth of the negative/vehicle controls and on criteria to define an acceptable positive control response. The recommendation for the determination of a positive/negative test chemical response includes both the requirement that the response exceeds a defined value [the global evaluation factor (GEF)] and that there also be a positive dose-response (evaluated by an appropriate statistical method).

Mouse Lymphoma Thymidine Kinase Gene Mutation Assay: International Workshop on Genotoxicity Tests Workgroup Report—Plymouth, UK 2002

The Mouse Lymphoma Assay (MLA) Workgroup of the International Workshop on Genotoxicity Tests (IWGT) met on June 28th and 29th, 2002, in Plymouth, England. This meeting of the MLA group was devoted to discussing the criteria for assay acceptance and appropriate approaches to data evaluation. Prior to the meeting, the group conducted an extensive analysis of data from both the microwell and soft agar versions of the assay. For the establishment of criteria for assay acceptance, 10 laboratories (6 using the microwell method and 4 using soft agar) provided data on their background mutant frequencies, plating efficiencies of the negative/vehicle control, cell suspension growth, and positive control mutant frequencies. Using the distribution curves generated from this data, the Workgroup reached consensus on the range of values that should be used to determine whether an individual experiment is acceptable. In order to establish appropriate approaches for data evaluation, the group used a number of statistical methods to evaluate approximately 400 experimental data sets from 10 laboratories entered into a database created for the earlier MLA Workshop held in New Orleans [Environ. Mol. Mutagen. 40 (2002) 292]. While the Workgroup could not, during this meeting, make a final recommendation for the evaluation of data, a general strategy was developed and the Workgroup members agreed to evaluate this new proposed approach using their own laboratory data. This evaluation should lead to a consensus global approach for data evaluation in the near future.

Effects of the ADH3, CYP2E1, and GSTP1 genetic polymorphisms on their expressions in Caucasian lung tissue

Individual differences in lung cancer susceptibility should be considered for effective lung cancer prevention. We investigated the CYP2E1, ADH3, and GSTP1 genetic polymorphisms that biotransform xenobiotic carcinogens, and variations of their enzyme activity in Caucasian lung tissues (N=28), and found a variant distribution in pulmonary ADH and CYP2E1 activity. The ADH3*1/*1 subjects (N=8) showed significantly higher ADH activity than ADH3*2/*2 (N=3) subjects (P<0.01). On the other hand, we found a 5-fold variation in the pulmonary CYP2E1 activity using a sensitive HLPC/EC based technique. A subject with the CYP2E1-c/t allele showed 2-fold higher CYP2E1 activity than subjects with the c/c allele (N=14). GSTP1 expression comprised 83% of the total pulmonary GSTs. However, neither the GSTP1 polymorphism, nor other lifestyle factors, such as age, gender, smoking status, were found to be associated with pulmonary GST expression. In conclusion, subjects with the ADH3*1 allele showed higher ADH activity and acetaldehyde-DNA adducts in lung than other subjects; thus, the ADH3*1 allele could be considered a risk factor for lung cancer.

Detection of stable chromosome aberrations by FISH in A-bomb survivors: comparison with previous solid Giemsa staining data on the same 230 individuals

PURPOSE

To evaluate the relative abilities of the solid Giemsa staining (conventional) and fluorescence in situ hybridization (FISH) methods in the detection of stable chromosome aberrations in the peripheral blood lymphocytes of A-bomb survivors.

MATERIALS AND METHODS

Lymphocytes from a total of 230 A-bomb survivors for whom prior chromosome aberration data had been obtained by the conventional method were recently examined afresh using FISH in which chromosomes 1, 2 and 4 were painted with composite probes.

RESULTS

It was found that the early use of the solid Giemsa staining method had allowed the detection of translocations with a mean frequency of 73% of the value for the genome-equivalent translocation frequency (F(G)) that was now obtained using FISH. The disparity may at least in part be due to the reciprocal exchange of seemingly identical amount of chromosome material; such exchanges can escape detection by the conventional method but can be readily identified using FISH.

CONCLUSION

It has previously been established that the conventional method can detect about 20% of radiation-induced translocations as abnormal monocentric chromosomes. Present results indicate that an additional 50% can be detected if proper karyotyping is conducted and the remaining 30% are not likely to be detected unless FISH or banding methods are used. Thus, solid Giemsa staining accompanied by karyotyping may not be quite as unsuitable as is generally assumed for retrospective biodosimetry analyses, which deal mainly with stable aberrations.

Relationship between NAT1 genotype and phenotype in a Japanese population

NAT1, which biotransforms many carcinogens, is genetically polymorphic. This polymorphism has been postulated as a mechanism for susceptibility differences in cancer, possibly due to NAT1 activity differences. However, the relationship between NAT1 genotype and phenotype is not clear. In our study of 110 Japanese, the frequency of the NAT1*10 allele (0.53, 95% confidence interval 0.46-0.59) was higher than others have observed in Caucasians (0.16). From genotype frequency studies, 26.4% of the subjects belonged to the NAT1*10/*10 genotype, 53.6% to the NAT1*4/*10 genotype and 20% to the NAT1*4/*4 genotype. Neither NAT1*3 nor NAT1*11 genotype was seen in these subjects. In female subjects, we found higher NAT1 activity in NAT1*4/*10 subjects than in NAT1*4/*4 subjects (n = 49; 2.63 versus 2.16 nmol/min/mg protein). NAT1 activity-difference between NAT1*4/*10 and NAT1*10/*10 was not statistically significant. Thus, not only the presence of NAT1*10 allele, but also other factors are suspected of increasing NAT1 activities. After full sequencing of 10 subjects, five individuals having the highest activities and five individuals having the lowest activities, we found NAT1*18A and NAT1*18B to be in the high activity group and the low activity group, respectively. The genotypes containing these variants were heterozygous, i.e. NAT1*4/*18A and NAT1*4/*18B. Due to rare frequencies of these variants, they cannot be considered as other effective, genetic factors on NAT1 activity. Age and tobacco smoking did not affect the relationship between NAT1 genotype and phenotype.

Distribution and concordance of N-acetyltransferase genotype and phenotype in an American population

Polymorphic arylamine N-acetyltransferase 2 (NAT2) status varies widely between individuals and ethnic groups and has been associated with susceptibility to several cancers. Few studies have reported the distribution of NAT2 status for Caucasian-American populations or evaluated the concordance between methods of assessment for cancer cases and controls. In our study, distribution of NAT2 status was classified by genotype and phenotype measurements in PANCAN, a population-based case-control study of pancreatic cancer, and concordance between measurements was evaluated for 33 cases and 222 controls. Major genotypes and alleles among controls were *5B/*6A, *5B/*5B, *4/*6A, and *5B/*4. One putative new allele was found in a single individual. Genotypes and phenotypes were classified as rapid or slow, according to a bimodal model. Presence of the *4 (wild-type) allele defined a NAT2 genotype as rapid. The NAT2 phenotype was analyzed by the caffeine assay. Ratios of 5-acetylamino-6-formylamino-3-methyluracil to 1-methylxanthine were determined, and individuals with values of > or =0.66 were identified as having a rapid phenotype. In our population, 58.1 and 59.5% of control subjects were classified as slow acetylators by phenotype and genotype, respectively. Concordance of NAT2 genotype and phenotype classification was 97.8% in the bimodal model. A similar analysis was completed for a trimodal model. Concordance of genotype and phenotype was high in cases (90.9%) and similar to controls; genotyping alone provided an efficient, accurate method of analysis for acetylator status. A comparison with two previous reports revealed subtle differences in genotype and allele distribution but exhibited overall similarity with other Caucasian-American populations.

Estimation of minimal size of translocated chromosome segments detectable by fluorescence in situ hybridization

Apparent non-reciprocal translocations are commonly observed using fluorescence in situ hybridization. We hypothesize that these are 'hidden' reciprocals due to one translocated segment being too small to detect. Assuming that the translocation breakpoints distribute randomly, the proportion of reciprocal to non-reciprocal exchanges can be used to estimate the minimal detectable size of translocated segments. To estimate segment size in this study, cytogenetic data for 120 A-bomb survivors were used. Among 2295 aberrant metaphases, 1629 exhibited reciprocal translocations and 666 non-reciprocal. Of the non-reciprocal translocations, 501 showed only a painted chromosome segment, translocated to an unpainted chromosome with centromere, and 165 showed only an unpainted chromosome segment, translocated to a painted chromosome with centromere. On the basis of the above two assumptions, we obtained the most likely estimates for minimal detectable sizes: 11.1 +/- 0.8 Mb for the painted and 14.6 +/- 0.6 Mb for the unpainted chromosomes. The implications of these findings are discussed.