Hepatocellular proliferation and hepatocarcinogen bioactivation in mice with diet-induced fatty liver and obesity

Human liver cancer is in part associated with obesity and related metabolic diseases. The present study was undertaken in a mouse model of diet-induced obesity (DIO) and hepatic steatosis, conditions which can be associated with hepatic neoplasia, to determine whether the rates of cell proliferation or hepatocarcinogen bioactivation were altered in ways which could facilitate hepatocarcinogenesis. DIO mice were generated by feeding C57BL/6 (B6) male mice a high-fat diet beginning at 4 weeks of age; age-matched conventional lean (LEAN) B6 mice fed a low fat diet (10% Kcal from fat) were used for comparison. Groups of 28 week old DIO and LEAN mice were dosed with the bioactivation-dependent DNA-reactive hepatocarcinogen 2-acetylaminofluorene (AAF), at 2.24 or 22.4 mg/kg, given by gavage 3 times per week for 31 days, or received no treatment (DIO and LEAN control groups). Compared with the LEAN control group, the DIO control group had a higher mean body weight (16.5 g), higher mean absolute (1.4 g) and mean relative (25.5%) liver weights, higher (394%) liver triglyceride concentrations, and an increased incidence and severity of hepatocellular steatosis at the end of the dosing phase. The DIO control group also had a higher mean hepatocellular replicating fraction (31% increase, determined by proliferating cell nuclear antigen immunohistochemistry). Hepatocarcinogen bioactivation, based on formation of AAF DNA adducts as measured by nucleotide (32)P-postlabeling, was similar in both DIO and LEAN AAF-dosed groups. Thus, hepatocellular proliferation, but not hepatocarcinogen bioactivation, was identified as an alteration in livers of DIO mice which could contribute to their susceptibility to hepatocarcinogenesis.

Mobilization of host stem cells enables long-term liver transplant acceptance in a strongly rejecting rat strain combination

Careful examination of liver, kidney and heart transplants in human recipients has revealed small numbers of host bone marrow derived stem cells in the graft. If the limited recipient repopulation of a donor graft that is currently observed could be facilitated, it is possible that conversion to a predominantly host phenotype would permit long-term graft function without immunosuppression. We proposed to "engineer" repopulation after transplant in a strain combination (dark agouti [DA] to Lewis green fluorescent protein+[LEW GFP+]) which rejects liver grafts strongly, a model that more closely resembles the situation in humans. Treatment on days 0, 1, 2, 3 and 7 after transplantation with low-dose (0.1 mg/kg) tacrolimus (T) designed to blunt rejection combined with plerixafor (P) to mobilize host stem cells resulted in greater than 180 days graft survival with extensive albeit spotty conversion of a small (50%) DA graft to the recipient LEW GFP+ genotype. Subsequent skin grafting revealed donor-specific graft prolongation. The T plus P treatment resulted in higher levels of Lin-Thy1+CD34+CD133+ stem cells and Foxp3+ regulatory T cells in the blood and liver at day 7. Thus, pharmacological mobilization of host stem cells sustains liver allografts by two mechanisms: repopulation of injured donor cells and regulation of the immune response.

Inner dynein arm defects causing primary ciliary dyskinesia: repeat testing required

Primary ciliary dyskinesia (PCD) results in chronic nasal symptoms and chest disease leading to bronchiectasis. We noted a number of patients referred for diagnostic testing whose initial results suggested PCD due to an inner dynein arm or radial spoke defect but in whom no abnormality was found on retesting. The present study was an audit of all patients referred for PCD diagnostic testing over a 3-yr period whose initial electron microscopy (EM) and beat pattern analysis suggested an inner dynein arm or radial spoke defect. 21 patients referred for diagnostic testing for PCD suspected of an inner dynein arm defect and six suspected of a radial spoke defect on initial EM and beat pattern analysis had repeat testing performed. On repeat testing, five patients initially suspected of an inner dynein arm defect and one with a radial spoke defect had normal EM and beat pattern, leading to the initial diagnosis being questioned. Patients suspected of PCD due to an inner dynein arm defect or radial spoke defect should have the diagnosis reassessed if it has been based on only one diagnostic sample.

InNxSb1−x Light Emitting Diodes Grown by MBE

We present the first reported MBE growth of light emitting diodes (LED's) with active regions made up of InSb/ InNxSbl−x (O<x<0.02) superlattices, grown onto InSb(100) substrates. Such dilute alloys of nitrogen in other III-V materials have been shown to exhibit very large bandgap bowing parameters due to differences in atomic size and the electro-negativity of nitrogen. Novel growth techniques have been developed to enable epitaxy of high quality InNxSbl−x, using an electron cyclotron resonance (ECR) plasma source. Material characterisation was performed by double crystal x-ray diffraction (DXRD) and transmission electron microscopy (TEM), and nitrogen composition has been determined using DXRD and secondary ion mass spectrometry (SIMS). To determine the effect of nitrogen on bandgap, the structures have been fabricated into LED's with InSb/InNxSbl−x superlattice active regions with period ∼1100A. For a nitrogen content of ∼0.3%, the peak emission of the diodes shifts from ∼6pm to >71µm at room temperature.

The antecedents of non-affective psychosis in a birth-cohort, with a focus on measures related to cognitive ability, attentional dysfunction and speech problems

OBJECTIVE

Adults with non-affective psychosis show subtle deviations in a range of developmental trajectories as children and adolescents.

METHOD

Based on a birth-cohort (n = 3801), we examined the Peabody Picture Vocabulary Test (PPTV) at age 5, and Raven's Standard Progressive Matrices (RSPM) and Wide Range Achievement Test reading scale (WRAT-R) at age 14. Items related to speech problems and attentional dysfunction were available from maternal- or self-report. At age 21, we identified 60 cohort members who were screen-positive for non-affective psychosis (SP-NAP).

RESULTS

Impaired performance on the PPVT and RSPM (but not WRAT-R) predicted SP-NAP for males only. Male cohort members in the highest quartile for attentional dysfunction at ages 5 and 14 were about 5-8 times more likely to develop SP-NAP. SP-NAP in males was significantly associated with speech problems at age 14.

CONCLUSION

Males who develop non-affective psychoses have subtle impairments in cognitive capacity prior to the development of their psychotic disorder.

Social factors associated with the decision to relinquish a baby for adoption

Little is known about the characteristics, social circumstances and mental health of women who give a child up for adoption. This paper reports data from a longitudinal study of 8556 women interviewed initially at their first obstetrical visit. In total, 7668 proceeded to give birth to a live singleton baby, of which 64 then relinquished the baby for adoption. Relinquishing mothers were predominantly 18 years of age or younger, in the lowest family income group, single, having an unplanned and/or unwanted baby and reported that they were not living with a partner. These women were somewhat more likely to manifest symptoms of anxiety and depression both prior, and subsequent to, the adoption, but the majority of relinquishing mothers were of 'normal' mental health. The decision to relinquish a baby appears to be a consequence of an unwanted pregnancy experienced by an economically deprived single mother rather than the result of emotional or psychological/psychiatric considerations. These findings document a particular dimension of the impact of poverty on health.

Longitudinal correlates of the persistence of irregular eating from age 5 to 14 years

AIM

To report the stability of parent-perceived child irregular eating from 6 months to 14 years of age and to investigate a predictive model inclusive of child and parent factors.

METHODS

Of the 7223 singleton children in a birth cohort, 5122 children were re-interviewed at 5 years and 4554 for the 14-year analysis. Information was obtained from structured interviews including questions answered by parents of the child at birth, 6 months, 5 years and 14 years; and by teenagers at age 14 years and from physical measures of the child. The mother's perception that the child was an irregular eater at age 14 years was the major outcome variable of interest.

RESULTS

Approximately 40% of irregular eaters at age 5 will still be irregular eaters at age 14 years. This was not related to maternal education or socio-economic class. Significant at multivariate analysis were infant feeding problems and the children's ability to regulate their sleep and mood. Significant maternal factors were greater age, not feeling positive about the baby and persistent maternal anxiety during the child's early years.

CONCLUSION

Irregular eating behaviour displays considerable continuity from childhood to mid-adolescence. Independent contributions to this behavioural phenotype include child biological and psychological factors and maternal anxiety during the child's early years.

Childhood dairy and calcium intake and cardiovascular mortality in adulthood: 65-year follow-up of the Boyd Orr cohort

BACKGROUND

Dairy consumption in childhood may have long-term effects on cardiovascular mortality through influencing the development of risk factors or programming effects.

OBJECTIVE

To investigate whether dairy and calcium consumption in childhood is associated with adult mortality due to coronary heart disease (CHD), stroke and all causes.

METHODS

In 1937-9, 4999 children in England and Scotland participated in a study of family food consumption, assessed from 7-day household food inventories. Cause of death was ascertained between 1948 and 2005 in 4374 traced cohort members with complete data. Per capita household intake estimates for dairy products and calcium were used as proxies for individual intake.

RESULTS

No strong evidence that a family diet in childhood high in dairy products was associated with CHD or stroke mortality was found. However, childhood calcium intake was inversely associated with stroke mortality (multivariable adjusted hazard ratio (HR) for highest versus lowest calcium group: 0.41; 95% confidence interval (CI) 0.16 to 1.05; p for trend = 0.04), but not CHD mortality. All-cause mortality was lowest in those with the highest family dairy (HR = 0.77; 95% CI 0.61 to 0.98; p for trend = 0.04) and calcium intake (HR = 0.77, 95% CI 0.60 to 0.98; p for trend = 0.05).

CONCLUSIONS

Children whose family diet in the 1930s was high in calcium were at reduced risk of death from stroke. Furthermore, childhood diets rich in dairy or calcium were associated with lower all-cause mortality in adulthood. Replication in other study populations is needed to determine whether residual confounding explains part of these findings.

Maternal smoking during and after pregnancy and lung function in early adulthood: a prospective study

BACKGROUND AND AIMS

There is a paucity of evidence about whether exposure to antenatal smoking impacts on offspring's lung function in early adulthood. This study aimed to examine whether (1) in utero exposure to maternal smoking is related to poorer respiratory functioning in early adulthood; (2) the impact of prenatal smoking is independent of postnatal maternal smoking; and (3) the link between prenatal smoking and a young adult's lung function is explained by the child's birth weight, smoking or history of asthma.

METHODS

Data were from a 21-year follow-up of mothers and their children recruited into the Mater-University of Queensland Study of Pregnancy, a longitudinal prebirth cohort. The study is based on 2409 young adults (1185 males and 1224 females) who had prospective data available on respiratory function at 21 years and maternal smoking during and after pregnancy. A Spirobank G spirometer system was used to measure forced vital capacity (FVC), forced expiratory volume in 1 s (FEV(1)) and forced expiratory flow between 25% and 75% of FVC (FEF(25-75)).

RESULTS

In utero exposure to maternal smoking was associated with a reduction in FEV(1) and FEF(25-75) in males (regression coefficient, -0.16; 95% CI, -0.30 to -0.02), after accounting for maternal smoking after pregnancy. At least part of the effect of in utero smoking on young adults' lung function was explained by the child's birth weight and subsequent asthma.

CONCLUSIONS

Adverse effects of antenatal smoking on development of airway growth may persist into early adulthood. Gender differences noted in this longitudinal cohort need to be explored further.

Aspartame: a safety evaluation based on current use levels, regulations, and toxicological and epidemiological studies

Aspartame is a methyl ester of a dipeptide used as a synthetic nonnutritive sweetener in over 90 countries worldwide in over 6000 products. The purpose of this investigation was to review the scientific literature on the absorption and metabolism, the current consumption levels worldwide, the toxicology, and recent epidemiological studies on aspartame. Current use levels of aspartame, even by high users in special subgroups, remains well below the U.S. Food and Drug Administration and European Food Safety Authority established acceptable daily intake levels of 50 and 40 mg/kg bw/day, respectively. Consumption of large doses of aspartame in a single bolus dose will have an effect on some biochemical parameters, including plasma amino acid levels and brain neurotransmitter levels. The rise in plasma levels of phenylalanine and aspartic acid following administration of aspartame at doses less than or equal to 50 mg/kg bw do not exceed those observed postprandially. Acute, subacute and chronic toxicity studies with aspartame, and its decomposition products, conducted in mice, rats, hamsters and dogs have consistently found no adverse effect of aspartame with doses up to at least 4000 mg/kg bw/day. Critical review of all carcinogenicity studies conducted on aspartame found no credible evidence that aspartame is carcinogenic. The data from the extensive investigations into the possibility of neurotoxic effects of aspartame, in general, do not support the hypothesis that aspartame in the human diet will affect nervous system function, learning or behavior. Epidemiological studies on aspartame include several case-control studies and one well-conducted prospective epidemiological study with a large cohort, in which the consumption of aspartame was measured. The studies provide no evidence to support an association between aspartame and cancer in any tissue. The weight of existing evidence is that aspartame is safe at current levels of consumption as a nonnutritive sweetener.

Increasing body mass index from age 5 to 14 years predicts asthma among adolescents: evidence from a birth cohort study

BACKGROUND

Obesity and asthma are common disorders, and the prevalence of both has increased in recent decades. It has been suggested that increases in the prevalence of obesity might in part explain the increase in asthma prevalence. This study aims to examine the prospective association between change in body mass index (BMI) z-score between ages 5 and 14 years and asthma symptoms at 14 years.

METHODS

Data was taken from the Mater University Study of Pregnancy and its outcomes (MUSP), a birth cohort of 7223 mothers and children started in Brisbane (Australia) in 1981. BMI was measured at age 5 and 14 years. Asthma was assessed from maternal reports of symptoms at age 5 and 14 years. In this study analyses were conducted on 2911 participants who had information on BMI and asthma at both ages.

RESULTS

BMI z-score at age 14 and the change in BMI z-score from age 5 to 14-years were positively associated with asthma symptoms at age 14 years, whereas BMI z-score at age 5 was not associated with asthma at age 14. Adjustment for a range of early-life exposures did not substantially alter these findings. The association between change in BMI z-score with asthma symptoms at 14 years appeared stronger for male subjects compared with female subjects but there was no statistical evidence for a sex difference (P=0.36).

CONCLUSIONS

Increase in BMI z-score between age 5 and 14 years is associated with increased risk of asthma symptoms in adolescence.

Ozone modifies associations between temperature and cardiovascular mortality: analysis of the NMMAPS data

OBJECTIVES

Both ambient ozone and temperature are associated with human health. However, few data are available on whether ozone modifies temperature effects. This study aims to explore whether ozone modified associations between maximum temperature and cardiovascular mortality in the USA.

METHODS

The authors obtained data from the US National Morbidity, Mortality, and Air Pollution Study (NMMAPS) website. They used two time-series Poisson regression models (a response surface model and a stratification model) to examine whether ozone modified associations between maximum temperature and cardiovascular mortality (CVM) in 95 large US communities during 1987-2000 in summer (June to September). Bayesian meta-analysis was used to pool estimates in each community.

RESULTS

The response surface model was used to examine the joint effects of temperature and ozone on CVM in summer. Results indicate that ozone positively modified the temperature-CVM associations across the different regions. The stratification model quantified the temperature-CVM associations across different levels of ozone. Results show that in general the higher the ozone concentration, the stronger the temperature-CVM associations across the communities. A 10 degrees C increase in temperature on the same day was associated with an increase in CVM by 1.17% and 8.31% for the lowest and highest level of ozone concentrations in all communities, respectively.

CONCLUSION

Ozone modified temperature effects in different regions in the USA. It is important to evaluate the modifying role of ozone when estimating temperature-related health impacts and to further investigate the reasons behind the regional variability and mechanism for the interaction between temperature and ozone.

A critical review of the data related to the safety of quercetin and lack of evidence of in vivo toxicity, including lack of genotoxic/carcinogenic properties

Quercetin is a naturally-occurring flavonol (a member of the flavonoid family of compounds) that has a long history of consumption as part of the normal human diet. Because a number of biological properties of quercetin may be beneficial to human health, interest in the addition of this flavonol to various traditional food products has been increasing. Prior to the use of quercetin in food applications that would increase intake beyond that from naturally-occurring levels of the flavonol in the typical Western diet, its safety needs to be established or confirmed. This review provides a critical examination of the scientific literature associated with the safety of quercetin. Results of numerous genotoxicity and mutagenicity, short- and long-term animal, and human studies are reviewed in the context of quercetin exposure in vivo. To reconcile results of in vitro studies, which consistently demonstrated quercetin-related mutagenicity to the absence of carcinogenicity in vivo, the mechanisms that lead to the apparent in vitro mutagenicity, and those that ensure absence of quercetin toxicity in vivo are discussed. The weight of the available evidence supports the safety of quercetin for addition to food.

A correlative study of ultrasound with serology in an area in China co-endemic for human alveolar and cystic echinococcosis

We correlated ultrasound (US) imaging classifications for human alveolar echinococcosis (AE) and cystic echinococcosis (CE) with serology (ELISA and immunoblotting (IB) incorporating native and recombinant/purified echinococcal antigens) in community surveys (2001-2003) and follow-up (2002 and 2003) of US-confirmed cases in Ningxia, China. One hundred and seventy-one cases (96 with AE, 75 with CE) were identified; of these, US classification and serological data were obtained for 142 and 112 cases, respectively. Seropositive-rates increased in CE patients with highly viable unilocular cyst lesions (Types CL, CE 1 or CE 2) to degenerating primary lesions (CE 3), but then decreased in subjects with inactive (CE 4) or dead (CE 5) cysts. In contrast, there was a constant increase in seropositivity from the early (P1, P2) to the advanced stages (P3, P4) with AE cases. For US-confirmed cases, follow-up by US combined with serology is invaluable for studying the clinical progression of echinococcosis and for detecting recurrent cysts or reinfection post-treatment.

Evaluation of certain food additives and contaminants

This report represents the conclusions of a Joint FAO/WHO Expert Committee convened to evaluate the safety of various food additives, including flavouring agents, with a view to recommending acceptable daily intakes (ADIs) and to preparing specifications for identity and purity. The Committee also evaluated the risk posed by two food contaminants, with the aim of advising on risk management options for the purpose of public health protection. The first part of the report contains a general discussion of the principles governing the toxicological evaluation and assessment of intake of food additives (in particular flavouring agents) and contaminants. A summary follows of the Committee's evaluations of technical, toxicological and intake data for certain food additives (acidified sodium chlorite, asparaginase from Aspergillus oryzae expressed in Aspergillus oryzae, carrageenan and processed Eucheuma seaweed, cyclotetraglucose and cyclotetraglucose syrup, isoamylase from Pseudomonas amyloderamosa, magnesium sulfate, phospholipase A1 from Fusarium venenatum expressed in Aspergillus oryzae, sodium iron(III) ethylenediaminetetraacetic acid (EDTA) and steviol glycosides); eight groups of related flavouring agents (linear and branched-chain aliphatic, unsaturated, unconjugated alcohols, aldehydes, acids and related esters; aliphatic acyclic and alicyclic terpenoid tertiary alcohols and structurally related substances; simple aliphatic and aromatic sulfides and thiols; aliphatic acyclic dials, trials and related substances; aliphatic acetals; sulfur-containing heterocyclic compounds; aliphatic and aromatic amines and amides; and aliphatic alicyclic linear alpha, beta -unsaturated di- and trienals and related alcohols, acids and esters); and two food contaminants (aflatoxin and ochratoxin A). Specifications for the following food additives were revised: maltol and ethyl maltol, nisin preparation, pectins, polyvinyl alcohol, and sucrose esters of fatty acids. Specifications for the following flavouring agents were revised: maltol and ethyl maltol, maltyl isobutyrate, 3-acetyl-2,5-dimethylfuran and 2,4,5-trimethyl-delta-oxazoline (Nos 1482, 1506 and 1559), and monomenthyl glutarate (No. 1414), as well as the method of assay for the sodium salts of certain flavouring agents. Annexed to the report are tables summarizing the Committee's recommendations for intakes and toxicological evaluations of the food additives and contaminants considered.

Approaches to the risk assessment of genotoxic carcinogens in food: A critical appraisal

The present paper examines the particular difficulties presented by low levels of food-borne DNA-reactive genotoxic carcinogens, some of which may be difficult to eliminate completely from the diet, and proposes a structured approach for the evaluation of such compounds. While the ALARA approach is widely applicable to all substances in food that are both carcinogenic and genotoxic, it does not take carcinogenic potency into account and, therefore, does not permit prioritisation based on potential risk or concern. In the absence of carcinogenicity dose-response data, an assessment based on comparison with an appropriate threshold of toxicological concern may be possible. When carcinogenicity data from animal bioassays are available, a useful analysis is achieved by the calculation of margins of exposure (MOEs), which can be used to compare animal potency data with human exposure scenarios. Two reference points on the dose-response relationship that can be used for MOE calculation were examined; the T25 value, which is derived from linear extrapolation, and the BMDL10, which is derived from mathematical modelling of the dose-response data. The above approaches were applied to selected food-borne genotoxic carcinogens. The proposed approach is applicable to all substances in food that are DNA-reactive genotoxic carcinogens and enables the formulation of appropriate semi-quantitative advice to risk managers.

Hospital and community surveys reveal the severe public health problem and socio-economic impact of human echinococcosis in Ningxia Hui Autonomous Region, China

A comprehensive study of human echinococcosis (caused by Echinococcus granulosus or E. multilocularis), including assessment of hospital records, community surveys and patient follow-up, was conducted in Ningxia Hui Autonomous Region (NHAR), China. In contrast to hospital records that showed 96% of echinococcosis cases were caused by cystic echinococcosis (CE), 56% of cases detected in active community surveys were caused by alveolar echinococcosis (AE). The AE and CE cases co-existed frequently in the same village, even occurring in the same patient. A serious public health problem caused by echinococcosis was evident in southern NHAR, typified by: a long diagnostic history for both AE and CE (7.5 years) compared with a shorter treatment history (4.7 years); a significant mortality rate (39%) caused by AE in one surveyed village, where patients had no previous access to treatment; family aggregation of CE and AE cases; a high proportion of both AE (62.5%) and CE (58%) in females; a high rate of recurrent surgery (30%) for CE demonstrated by surgical records; and frequent symptomatic recurrences (51%) because of discontinuous or sporadic access to chemotherapy for AE. The disease burden for both human AE and CE is thus very severe among these rural communities in NHAR, and this study provides the first attempt to determine the costs of morbidity and surgical intervention of human CE and AE cases both at the hospital and community level in this setting. This information may be useful for assessing the cost effectiveness of designing effective public health programs to control echinococcosis in this and other endemic areas in China and elsewhere.

Assessment of chronic toxicity and carcinogenicity in an accelerated cancer bioassay in rats of Nifurtimox, an antitrypanosomiasis drug

The chronic toxicity and carcinogenicity of Nifurtimox (NFX), a 5-nitrofuran derivative used in the treatment of American trypanosomiasis, were studied in male and female Wistar rats in an accelerated cancer bioassay (ACB). The ACB is a mechanistic initiation/promotion chronic toxicity and carcinogenicity bioassay designed to assess potential carcinogenic activity of a test substance in critical organs and tissues of rodents in which human carcinogens are active. The organs studied were liver, lungs, urinary bladder (UB), mammary gland (MG), bone marrow, spleen, kidneys, colon, stomach and any grossly observed lesions. NFX is a genotoxin which has been reported previously to exert a variable degree of carcinogenic activity in rat liver, kidney, UB and MG. The present study was undertaken to assess whether NFX has initiating activity in these four named target sites. In the initiation phase, groups of 20 Wistar rats were given NFX daily in the diet at 0.2% for the first 12 weeks of the study to assess initiating activity, followed by promoters (PROs) for four organs for an additional 24 weeks. NFX was compared to the following known initiators (INs) for each of these four tissues: diethylnitrosamine (DEN) for liver and kidney, N-butyl-N(4-hydroxybutyl)nitrosamine (BBN) for UB and 7,12-dimethylbenz(a)anthracene (DMBA) for MG. PROs included phenobarbital (PB) for liver and kidney, nitrilotriacetic acid (NTA) for UB, and diethylstilbestrol (DES) for MG. NFX was also administered continuously without PROs for 40 weeks. At the end of dosing (40 weeks) and at the end of recovery (52 weeks), animals were sacrificed and subjected to complete gross and histopathological examinations, along with evaluations of body weight gain over time and terminal body weights. Mortality was highest with DEN+PB (group 6) (40%), followed by BBN+NTA (group 7) (15%) and NFX+DES (group 5) and DMBA+DES (group 8) (10% each). The same groups also showed significant reductions in body weight gain over time and terminal body weights at sacrifice. In these groups, the expected preneoplastic, neoplastic and metastatic neoplastic lesions were produced, demonstrating the sensitivity of the model. In groups given NFX+PROs (groups 3-5), either no neoplasms occurred (group 4) or only single neoplasms (groups 3 and 5). In contrast, the PROs all elicited tumors in groups given INs (groups 6-8). Also, NFX given alone for 40 weeks did not produce any chronic toxicity, preneoplastic or neoplastic lesions. Thus, in this study, NFX did not demonstrate chronic toxicity or carcinogenicity. Moreover, in four target sites, i.e., liver, kidney, UB and MG, it exhibited no neoplastic initiating activity manifested by PROs for these four target sites.

Does being against euthanasia legislation equate to being anti-euthanasia?

This study investigated issues raised in qualitative data from our previous studies of health professionals and community members, which suggested that being opposed to euthanasia legislation did not necessarily equate to being anti-euthanasia per se. A postal survey of 1002 medical practitioners, 1000 nurses and 1200 community members was undertaken. In addition to a direct question on changing the law to allow active voluntary euthanasia (AVE), four statements assessed attitudes to euthanasia with or without a change in legislation. Responses were received from 405 doctors (43%), 429 nurses (45%) and 405 community members (38%). Compared with previous studies there was a slight increase in support for a change in the law from medical practitioners, a slight decrease in support from community members and almost no change among nurses. Different interpretations of the results of the four attitude questions are possible, depending on the perspective of the interpreter.

Tooth whitening products and the risk of oral cancer

Tooth whitening products (TWP) containing hydrogen peroxide (HPO) or carbamide peroxide (CPO) were evaluated in relation to potential oral cancer risk from their use. HPO is genotoxic in vitro, but such activity is not expressed in vivo. The genotoxic risk of HPO exposure of the oral mucosa encountered from TWP use is likely therefore to be vanishingly small. Available animal data on the carcinogenicity of HPO are of limited relevance to risk assessment of oral hazard of HPO exposure from TWP, and where relevant, do not indicate that there is an increased oral cancer risk for people using TWP. Clinical data on HPO-containing TWP only show evidence of mild, transient gingival irritation and tooth sensitivity, with no evidence for the development of preneoplastic or neoplastic oral lesions. Exposures to HPO received by the oral cavity, including areas commonly associated with oral cancer, are exceedingly low and do not plausibly pose a risk for the promotion of initiated cells or for induction of co-carcinogenic effects in conjunction with cigarette smoke or alcohol. The use of TWP was concluded not to pose an increased risk for oral cancer in alcohol abusers and/or heavy cigarette smokers. Furthermore, TWP were concluded to be safe for use by all members of the population, including potential accidental use by children.

Testing strategies in mutagenicity and genetic toxicology: An appraisal of the guidelines of the European Scientific Committee for Cosmetics and Non-Food Products for the evaluation of hair dyes

The European Scientific Committee on Cosmetics and Non-Food Products (SCCNFP) guideline for testing of hair dyes for genotoxic/mutagenic/carcinogenic potential has been reviewed. The battery of six in vitro tests recommended therein differs substantially from the batteries of two or three in vitro tests recommended in other guidelines. Our evaluation of the chemical types used in hair dyes and comparison with other guidelines for testing a wide range of chemical substances, lead to the conclusion that potential genotoxic activity may effectively be determined by the application of a limited number of well-validated test systems that are capable of detecting induced gene mutations and structural and numerical chromosomal changes. We conclude that highly effective screening for genotoxicity of hair dyes can be achieved by the use of three assays, namely the bacterial gene mutation assay, the mammalian cell gene mutation assay (mouse lymphoma tk assay preferred) and the in vitro micronucleus assay. These need to be combined with metabolic activation systems optimised for the individual chemical types. Recent published evidence [D. Kirkland, M. Aardema, L. Henderson, L. Müller, Evaluation of the ability of a battery of three in vitro genotoxicity tests to discriminate rodent carcinogens and non-carcinogens. I. Sensitivity, specificity and relative predictivity, Mutat. Res. 584 (2005) 1-256] suggests that our recommended three tests will detect all known genotoxic carcinogens, and that increasing the number of in vitro assays further would merely reduce specificity (increase false positives). Of course there may be occasions when standard tests need to be modified to take account of special situations such as a specific pathway of biotransformation, but this should be considered as part of routine testing. It is clear that individual dyes and any other novel ingredients should be tested in this three-test battery. However, new products are formed on the scalp by reaction between the chemicals present in hair-dye formulations. Ideally, these should also be tested for genotoxicity, but at present such experiences are very limited. There is also the possibility that one component could mask the genotoxicity of another (e.g. by being more toxic), and so it is not practical at this time to recommend routine testing of complete hair-dye formulations as well. The most sensible approach would be to establish whether any reaction products within the hair-dye formulation penetrate the skin under normal conditions of use and test only those that penetrate at toxicologically relevant levels in the three-test in vitro battery. Recently published data [D. Kirkland, M. Aardema, L. Henderson, L. Müller, Evaluation of the ability of a battery of three in vitro genotoxicity tests to discriminate rodent carcinogens and non-carcinogens. I. Sensitivity, specificity and relative predictivity, Mutat. Res. 584 (2005) 1-256] suggest the three-test battery will produce a significant number of false as well as real positives. Whilst we are aware of the desire to reduce animal experiments, determining the relevance of positive results in any of the three recommended in vitro assays will most likely have to be determined by use of in vivo assays. The bone marrow micronucleus test using routes of administration such as oral or intraperitoneal may be used where the objective is extended hazard identification. If negative results are obtained in this test, then a second in vivo test should be conducted. This could be an in vivo UDS in rat liver or a Comet assay in a relevant tissue. However, for hazard characterisation, tests using topical application with measurement of genotoxicity in the skin would be more appropriate. Such specific site-of-contact in vivo tests would minimise animal toxicity burden and invasiveness, and, especially for hair dyes, be more relevant to human routes of exposure, but there are not sufficient scientific data available to allow recommendations to be made. The generation of such data is encouraged.

Risk assessment of DNA-reactive carcinogens in food

Risk assessment of DNA-reactive carcinogens in food requires knowledge of the extent of DNA damage in the target organ which results from the competition between DNA adduct formation and repair. Estimates of DNA adduct levels can be made by direct measurement or indirectly as a consequence of their presence, for example, by tumor formation in animal models or exposed populations epidemiologically. Food-borne DNA-reactive carcinogens are present from a variety of sources. They are generally not intrinsically DNA-reactive but require bioactivation to DNA-reactive metabolites a process which may be modulated by the compound itself or the presence of other xenobiotics. A single DNA reactant may form several distinct DNA adducts each undergoing different rates of repair. Some DNA reactants may be photochemically activated or produce reactive oxygen species and thus indirect oxidative DNA damage. The levels of DNA adducts arising from exposures influenced by variations in the doses, the frequency with which an individual is exposed, and rates of DNA repair for specific adducts. Each adduct has a characteristic efficiency with which it induces mutations. Based on experience with the well-studied DNA-reactive food carcinogen aflatoxin B(1) (AFB(1)), a limit of 20 ppb or approximately 30 microg/day has been set and is considered a tolerable daily intake (TDI). Since AFB(1) is considered a potent carcinogen, doses of <1.5 microg of unknown compounds are considered TDIs. Most DNA-reactants, including acrylamide, heterocyclic amines, and alpha,beta-unsaturated carbonyl are below this value. Above that value, measurement of actual DNA adducts levels in either experimental animals with a risk assessment, or, when this occurs, exposed humans are needed. A number of approaches to undertake this are described including immunological, mass spectrometric and (32)P-postlabeling or the use of surrogates such as hemoglobin adducts, together with approaches to evaluate the results. A discussion of approaches to estimating possible threshold effects for DNA-reactive carcinogens is made.

Is being overweight associated with behavioural problems in childhood and adolescence? Findings from the Mater-University study of pregnancy and its outcomes

AIMS

To examine the associations between being overweight and behavioural problems at ages 5 and 14.

METHODS

Birth cohort study of 2875 individuals who were born in Brisbane between 1981 and 1984 and who were followed up at ages 5 and 14 years. Behavioural problems were defined as scoring above the 90th centile on Achenbach's child behavioural checklist.

RESULTS

In cross-sectional analyses there was no association between being overweight and behavioural problems in either females at age 5. At age 14 females who were overweight were more likely than those who were normal weight to experience behavioural problems. However, there was no association between being overweight and behavioural problems at age 14 among males. The prevalence of behavioural problems increased linearly across the distribution of body mass index in females at age 14. In prospective analyses, among participants who had no behavioural problems at age 5, there was no association between being overweight at age 5 and behavioural problems at age 14 in either sex. Females who were overweight at age 5 and normal weight at age 14 had reduced odds of behavioural problems at age 14.

CONCLUSIONS

Among adolescent females there is a positive linear association between body size and behavioural problems. However, no such association was found in adolescent males, or in either sex at age 5 years, and in prospective analyses being overweight at age 5 was not associated with behavioural problems in either sex at age 14.