Exposures in early life: associations with DNA promoter methylation in breast tumors.

There is evidence that epigenetic changes occur early in breast carcinogenesis. We hypothesized that early-life exposures associated with breast cancer would be associated with epigenetic alterations in breast tumors. In particular, we examined DNA methylation patterns in breast tumors in association with several early-life exposures in a population-based case-control study. Promoter methylation of E-cadherin, p16 and RAR-ß2 genes was assessed in archived tumor blocks from 803 cases with real-time methylation-specific PCR. Unconditional logistic regression was used for case-case comparisons of those with and without promoter methylation. We found no differences in the prevalence of DNA methylation of the individual genes by age at menarche, age at first live birth and weight at age 20. In case-case comparisons of premenopausal breast cancer, lower birth weight was associated with increased likelihood of E-cadherin promoter methylation (OR = 2.79, 95% CI, 1.15-6.82, for ⩽2.5 v. 2.6-2.9 kg); higher adult height with RAR-ß2 methylation (OR = 3.34, 95% CI, 1.19-9.39, for ⩾1.65 v. <1.60 m); and not having been breastfed with p16 methylation (OR = 2.75, 95% CI, 1.14-6.62). Among postmenopausal breast cancers, birth order was associated with increased likelihood of p16 promoter methylation. Being other than first in the birth order was inversely associated with likelihood of ⩾1 of the three genes being methylated for premenopausal breast cancers, but positively associated with methylation in postmenopausal women. These results suggest that there may be alterations in methylation associated with early-life exposures that persist into adulthood and affect breast cancer risk.

Familial and racial determinants of tumour suppressor genes promoter hypermethylation in breast tissues from healthy women.

To determine the hypermethylation status of the promoter regions of tumour suppressor genes in breast tissues from healthy women and identify the determinants of these epigenetic changes. Questionnaires and breast tissues were collected from healthy women without a history of cancer and undergoing reduction mammoplasty (N= 141). Methylation for p16(INK4), BRCA1, ERalpha and RAR-beta promoter regions from breast tissues were determined by methylation specific PCR. Associations were examined with chi-square and Fisher's exact test as well as logistic regression. All statistical tests were two-sided. p16(INK4), BRCA1, ERalpha and RAR-beta hypermethylation were identified in 31%, 17%, 9% and 0% of the women, respectively. Women with BRCA1 hypermethylation had an eight-fold increase in the risk of ERalpha hypermethylation (P= 0.007). p16(INK4) hypermethylation was present in 28% of African-Americans, but 65% in European-Americans (P= 0.02). There was an increased likelihood of p16(INK4) or BRCA1 hypermethylation for women with family history of cancer (OR 2.3; 95%CI: 1.05-4.85 and OR 5.0; 95%CI: 1.55-15.81, respectively). ERalpha hypermethylation was associated with family history of breast cancer (OR 6.6; 95%CI: 1.58-27.71). After stratification by race, p16(INK4) in European-Americans and BRCA1 hypermethylation in African-Americans were associated with family history of cancer (OR 3.8; 95%CI: 1.21-12.03 and OR 6.5; 95%CI: 1.33-31.32, respectively). Gene promoter hypermethylation was commonly found in healthy breast tissues from women without cancer, indicating that these events are frequent and early lesions. Race and family history of cancer increase the likelihood of these early events.

Detection of Escherichia coli O157:H7 and Salmonella typhimurium using filtration followed by Fourier-transform infrared spectroscopy.

Fourier-transform infrared spectroscopy has been successfully used as a nondestructive method for identifying, distinguishing, and classifying pathogens. In this study, a less time-consuming Fourier-transform infrared procedure was developed to identify Escherichia coli O157:H7 and Salmonella Typhimurium. Samples containing 10(9) CFU/ml were prepared in tryptic soy broth and then serially diluted (up to eight times) to obtain bacterial solutions of 10(9) to 10 CFU/ml. These dilutions were incubated at 37 degrees C for 6 h, samples were filtered through a Metricel filter hourly (for 0 to 6 h), and spectra were obtained using a ZnSe contact attenuated total reflectance accessory on a Continu mum infrared microscope. Midinfrared spectra (4,000 to 700 cm(-1)) of Salmonella Typhimurium and E. coli O157:H7 were generated, and peak areas in the region of 1,589 to 1,493 cm(-1) were used to detect the pathogens. Initially, detection limits were between 10(6) and 10(7) CFU/ml without preenrichment, and samples starting with 500 CFU/ml were detectable following incubation for 6 h, when counts reached at least 10(6) CFU/ ml. Compared with results of previously published studies in which Fourier-transform infrared spectroscopy was used to identify select pathogens, this method is more rapid and less expensive for practical large-scale sample analysis.

Smoking increases carcinogenic polycyclic aromatic hydrocarbons in human lung tissue.

Tobacco smoke is a major source of human exposure to polycyclic aromatic hydrocarbons (PAHs). The concentration of PAHs in lung tissue would reflect an individual's dose, and its variation could perhaps reflect cancer risk. Eleven PAHs were measured in 70 lung tissue samples from cancer-free autopsy donors by gas chromatography-mass spectrometry. There were 37 smokers and 33 nonsmokers as estimated by serum cotinine concentration. The sum of PAH concentrations was higher in smokers (P = 0.01), and there was a dose-response relationship for greater smoking (P < 0.01). Smoking increased the concentration of five PAHs including benzo(a)pyrene, which increased approximately 2-fold. The risk for increasing carcinogenic PAHs (odds ratio, 8.20; 95% confidence interval, 2.39-28.09) was 3-fold compared with noncarcinogenic PAHs (odds ratio, 2.61; 95% confidence interval, 0.75-9.12). A higher concentration of PAHs was detected in the lung tissue of males, although the estimated smoking was similar in males and females. Race was not associated with PAH concentrations overall, but PAH concentrations appeared to be higher in African-American males than in any other group. Age was weakly correlated with an increase in fluoranthene and pyrene. The measurement of PAHs in human lung tissue can be used to estimate the actual dose to the target organ.

Electrocardiographic prediction of hyperinflation in children.

The mean frontal P wave axis in an electrocardiogram (ECG), which reflects the atrial orientation in the thorax, is altered by the relationship between atria and the diaphragm and, therefore, by hyperinflation. To examine this relationship, 102 children (ages 6-18) with asthma were prospectively studied. Lung volumes were estimated by plethysmography and a standard ECG obtained before and after bronchodilator. The mean thoracic gas volume (TGV) was 120.7 +/- 2.1% of predicted and the mean P axis was 54.9 +/- 1.5 degrees. Sixty-two subjects (61%) had a "vertical" P axis (> or = 60 degrees). Of 27 subjects with moderate or severe hyperinflation (TGV > or = 130% predicted), 23 (85%) had a vertical P axis. As a measure of significant hyperinflation, a vertical P axis had a sensitivity of 85%, specificity of 49%, positive predictive value of 38% and a negative predictive value of 90%. After nebulized albuterol, the mean TGV decreased to 96.4 +/- 1.3% predicted and the mean P axis decreased by 7.1 +/-1.6 degrees. Sixty-two of 76 subjects (82%) with > or = 15% decrease in TGV also had a decrease in P axis, and 62/67 subjects (93%) with a decrease in P axis also had > or = 15% decrease in TGV. The sensitivity was 82%, specificity 81%, and positive predictive value 93% for a decrease in P axis as a measure of decrease in TGV. A vertical P axis combined with a decrease in P axis after bronchodilator is highly sensitive and predictive for hyperinflation in children.

Atypical dyskeratosis congenita.

Dyskeratosis congenita is a syndrome characterised mainly by pigmentation and atrophy of skin, nail dystrophy and oral leucoplakia. We report a patient who had features consistent with this syndrome including skin atrophy and pigmentation, oral leucoplakia, oesophageal stricture, but with normal finger and toe nails. Even though many variants have been described in the literature sparing of the nails as in our patient is extremely uncommon.

The value and limitation of dual-energy X-ray absorptiometry.

In population studies, in which patients and controls are of comparable size, bone mineral area density (BMD) gives reliable results for mean bone mass data although, with sequential data, BMD may under-estimate the degree of change in bone mass. In children BMD data should be reliable, provided that patients and controls, matched for age and sex, are also of the same size. With disease children may be small for their age so that low bone mass by BMD may be due to small body size and not necessarily to osteopoenia. In these situations the bone mineral content (BMC) index may be more reliable than BMD. To assess bone mass status in individuals, BMC index, as well as BMD, should be used, particularly with adults at the extremes of body size (the very small or very tall).

Studies of incinerator ashes and environmental effects using radioanalytical techniques.

We have studied solid waste incinerator ashes to understand the leaching mechanism and speciation of toxic and other elements in them. Leaching media, such as water and acetate buffer, at various pHs were used. Incinerator ashes generally contain concentrations of many toxic elements, such as Cd, As, Hg, and Se. These elements are leached out rather easily. Many of the elements are leached within the first few minutes to an hour, and the majority of the elements reach peak equilibrium concentrations within 200 h. The pH and nature of the leaching medium are important factors in the leaching of the elements.

Would decreased aluminum ingestion reduce the incidence of Alzheimer's disease?

Although the cause of Alzheimer's disease (AD) remains unknown there is mounting evidence that implicates aluminum as a toxic environmental factor of considerable importance. Four independent lines of evidence--laboratory studies of the effects of intracerebral aluminum on the cognitive and memory performance of animals, biochemical studies, epidemiologic studies and the slowing of the progress of the disease with the use of an agent that removes aluminum from the body--now support the concept that aluminum is one of the pathogenic factors in AD. The evidence warrants serious consideration of reducing human exposure to aluminum. We hypothesize that a public health effort to restrict human ingestion of aluminum would reduce the incidence of this common chronic illness in the elderly.

Studies of cadmium uptake in bone and its environmental distribution.

Rat experiments indicate that oral ingestion of cadmium through drinking water leads to an accumulation of cadmium in bone, in addition to liver and kidney. After five weeks of cadmium intake in drinking water (50 to 100 mg/L), the bone cadmium levels increased in proportion to the intake concentration. Bone and kidney histology showed no signs of bone or kidney damage up to 5 wk of cadmium ingestion. Cadmium accumulation in bone was a primary phenomenon and not secondary to renal failure. In addition, cadmium levels have been estimated in a variety of sources, e.g., foodstuff, fertilizer, and sewage sludge, using neutron and proton activation analyses and atomic absorption spectrophotometry. Cadmium levels of Canadian foods are in the range of 0.002-0.07 mg/kg, and soils are in the range of 0.55 to 1.72 mg/kg. Fertilizers contain cadmium from 0.3 to 1.25 mg/kg, whereas sewage sludge contains up to 122 mg/kg.

Recent developments in in vivo neutron activation analysis facilities.

Two new facilities for in vivo activation analysis of patients have been designed, developed, and constructed at Toronto General Hospital. One of these is for the determination of body calcium for the diagnosis of osteoporosis and other diseases associated with bone loss. The other is for the measurement of total body nitrogen for the determination of protein status. These facilities replace old university facilities and take into account the comfort and management of patients. In addition, in the case of the calcium facility, the precision of the measurements has been improved because of larger detector volume and increased neutron source strength. Both the facilities are now in routine hospital clinical use.

Improved clinical facility for in vivo nitrogen measurement.

The design and construction of a hospital clinical facility for in vivo prompt gamma neutron activation analysis for total body nitrogen (TBN) measurement is described. The use of 252Cf neutron sources gives a better signal-to-background ratio compared with 238Pu-Be sources of equal strength, thus yielding better reproducibility of measurements. By measuring the hydrogen and nitrogen signals separately using appropriate gating circuits, signal-to-background ratio is further improved. Measurements using a urea phantom (5.63 kg nitrogen as urea in 34.53 kg of water) show that 2 x 6 micrograms 252Cf sources gives a nitrogen signal-to-background ratio of 5.6 (compared with 3.4 in the case of a 2 x 10 Ci 238Pu-Be source) and a reproducibility for nitrogen signal of +/- 1.1% (CV) and for hydrogen signal (internal standard) of +/- 2.33% (CV). Approximately 30 minutes of patient's time is required for each TBN measurement with an estimated reproducibility of +/- 3.8% (CV). The radiation dose to the patient is about 0.2 mSv (effective dose equivalent; QF = 10) per 20 min measurement. A report for the clinician is produced within a few minutes after the measurement by a dedicated IBM-PC computer. The entire facility is clean, comfortable and the electronics and computer processing are simple and economical.

Investigation of factors which lead to the background in the measurement of nitrogen by IVNAA.

A major problem in the measurement of nitrogen in the body by in vivo neutron activation analysis is the size of the background. Investigations show that random summing of gamma rays in the range 4-7 MeV is a major contributor. By direct comparison, 252Cf is shown to be a better neutron source than Pu-Be in this regard. Data are presented on the contribution to the background of water and chloride in the body.

Aluminium and calcium in soil and food from Guam, Palau and Jamaica: Implications for amyotrophic lateral sclerosis and parkinsonism-dementia syndromes of Guam.

Low calcium and high aluminium concentrations in the soils, waters and native foods have been hypothesised as environmental factors contributing to the unusually high incidence of amyotrophic lateral sclerosis and parkinsonism with dementia (ALS-PD) found on the island of Guam. The amounts of elemental aluminium and calcium were measured in foods of the native diet of the Chamorro people of Guam. The amount of aluminium eluted from topsoil by water at pH 7 at 22 °C was also measured. For comparison, food, water and soil samples were collected from two islands which have not reported a high incidence of ALS-PD syndromes: Palau and Jamaica.Compared with agricultural soils of Jamaica or Palau, the agricultural soils of Guam averaged 42-fold higher yield of elutable aluminium. The food data, however, do not indicate a differentially high exposure to elemental aluminium or low calcium intake in the diet of any one population. While this study did not detect an unusually high dietary aluminium or low dietary calcium content, the soils and possibly the dusts of Guam may be a major source of aluminium entering the body of the native people, particularly through the respiratory epithelium. Since iipid soluble organic ligands of aluminium more readily penetrate epithelial membranes, further study of soil aluminium ligands is required.

Aluminum toxicity to the brain.

The association between elevated brain aluminum levels and Alzheimer's disease (AD) is examined and critically reviewed. We found elevated aluminum levels in the brains of patients with AD (greater than 4 micrograms/g dry wt.) compared with normal subjects (approximately 1.5 micrograms/g dry wt.). Nine laboratories from different geographical regions have confirmed this finding. Two laboratories did not find any differences between AD and control brains. This discrepancy is traced to differences in sample sizes used for the aluminum assay and the sample selection criteria. It is found that it is essential to use small sizes (approximately 10 mg dry wt.) and to ensure that control brains do not contain neurofibrillary tangles (NFT) and that AD brains do. The exact pathogenic role of aluminum in AD is, as yet, unclear. It is the only element (other than calcium, which non-specifically accumulates at all degenerating tissue sites) that is found in elevated concentrations in NFTs. It is found elevated at four loci in the brain, i.e. the DNA-containing structures of the nucleus, the protein moities of NFTs, the amyloid cores of senile plaques and cerebral ferritin. The evidence thus far indicates that aluminum is toxic to the brain and it is probable that it has a pathogenic role in Alzheimer's disease.

Waste water treatment for heavy metal toxins using plant and hair as adsorbents.

The adsorption of cadmium, mercury and lead by Cattails (Typha Plant) and human hair has been investigated to assess their possible use as adsorbents in the treatment of industrial wastewater. Capacity experiments were performed, and it was found that significant amounts of cadmium, mercury and lead were adsorbed by Cattails, while only mercury was adsorbed by hair. Depending upon the concentration, adsorption capacities varied from 1 to 27 mg of metal per gram of adsorbent. The relatively fast uptake of cadmium and lead by Cattail leaves suggests that a continuous process is viable. The results are similar in the case of hair and mercury.