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1.
PLoS One ; 15(10): e0239259, 2020.
Article in English | MEDLINE | ID: mdl-33027271

ABSTRACT

Recent studies have documented a shift from moderate political attitudes to more extreme attitudes at the ends of the political spectrum. This can be seen in Political Correctness (PC) on the left, and white identitarian (WI) attitudes on the 'Alt-Right' (AR). While highly covered in mainstream media, limited academic research has investigated their possible antecedents and psychological correlates. The current study investigated the prevalence and psychological predictors of these attitudes. Utilising a quota-based sample of 512 U.S. participants, we found that extreme political attitudes were associated with various personality traits, social media use, and upbringing. PC attitudes were associated with agreeableness, black-white thinking, social-media use, and perceived overprotective parenting. WI attitudes were associated with low agreeableness and openness, and high black-white thinking. Our results show that extreme left and right attitudes are separated by individual differences, and that authoritarianism can be seen on both the left and the right.


Subject(s)
Politics , Adolescent , Adult , Aged , Aged, 80 and over , Authoritarianism , Ethnicity , Female , Humans , Male , Middle Aged , Personality , Resilience, Psychological , Surveys and Questionnaires , Young Adult
2.
Heliyon ; 6(7): e04453, 2020 Jul.
Article in English | MEDLINE | ID: mdl-32715130

ABSTRACT

It is well established that mainstream personality traits are associated with moderate, traditional political attitudes. However, very little is known regarding trait predictors of extreme political attitudes. In the current study (N = 511 U.S. residents), we examined the relationships between the Dark Triad traits, Entitlement and three extreme political attitudes that are highly covered in mainstream media: White Identitarianism ('Alt-Right'), Political Correctness-Authoritarianism, and Political Correctness-Liberalism. We found that Dark Triad traits and Entitlement had incremental validity in the prediction of these 3 attitudes over demographic factors. The Dark Triad traits and Entitlement explained a substantial portion of variance in White Identitarianism and Political Correctness-Authoritarianism, and only a small portion of variance in Political Correctness-Liberalism. Across all attitudes, Psychopathy and Entitlement were the most consistent, strongest predictors. Results indicate that, from a Dark Triad perspective, Authoritarian PC advocates have more in common with extreme right advocates than those holding PC views related to compassion.

3.
Front Psychol ; 10: 1116, 2019.
Article in English | MEDLINE | ID: mdl-31191383

ABSTRACT

Emotional Intelligence (EI) emerged in the 1990s as an ability based construct analogous to general Intelligence. However, over the past 3 decades two further, conceptually distinct forms of EI have emerged (often termed "trait EI" and "mixed model EI") along with a large number of psychometric tools designed to measure these forms. Currently more than 30 different widely-used measures of EI have been developed. Although there is some clarity within the EI field regarding the types of EI and their respective measures, those external to the field are faced with a seemingly complex EI literature, overlapping terminology, and multiple published measures. In this paper we seek to provide guidance to researchers and practitioners seeking to utilize EI in their work. We first provide an overview of the different conceptualizations of EI. We then provide a set of recommendations for practitioners and researchers regarding the most appropriate measures of EI for a range of different purposes. We provide guidance both on how to select and use different measures of EI. We conclude with a comprehensive review of the major measures of EI in terms of factor structure, reliability, and validity.

4.
Psychol Bull ; 143(1): 91-106, 2017 01.
Article in English | MEDLINE | ID: mdl-27893219

ABSTRACT

Over the last 40 years or more the personality literature has been dominated by trait models based on the Big Five (B5). Trait-based models describe personality at the between-person level but cannot explain the within-person mental mechanisms responsible for personality. Nor can they adequately account for variations in emotion and behavior experienced by individuals across different situations and over time. An alternative, yet understated, approach to personality architecture can be found in neurobiological theories of personality, most notably reinforcement sensitivity theory (RST). In contrast to static trait-based personality models like the B5, RST provides a more plausible basis for a personality process model, namely, one that explains how emotions and behavior arise from the dynamic interaction between contextual factors and within-person mental mechanisms. In this article, the authors review the evolution of a neurobiologically based personality process model based on RST, the response modulation model and the context-appropriate balanced attention model. They argue that by integrating this complex literature, and by incorporating evidence from personality neuroscience, one can meaningfully explain personality at both the within- and between-person levels. This approach achieves a domain-general architecture based on RST and self-regulation that can be used to align within-person mental mechanisms, neurobiological systems and between-person measurement models. (PsycINFO Database Record


Subject(s)
Attention/physiology , Models, Psychological , Personality/physiology , Reinforcement, Psychology , Humans
5.
J Adv Nurs ; 70(11): 2577-87, 2014 Nov.
Article in English | MEDLINE | ID: mdl-24720449

ABSTRACT

AIM: To identify key predictors and moderators of mental health 'help-seeking behavior' in adolescents. BACKGROUND: Mental illness is highly prevalent in adolescents and young adults; however, individuals in this demographic group are among the least likely to seek help for such illnesses. Very little quantitative research has examined predictors of help-seeking behaviour in this demographic group. DESIGN: A cross-sectional design was used. METHODS: A group of 180 volunteers between the ages of 17-25 completed a survey designed to measure hypothesized predictors and moderators of help-seeking behaviour. Predictors included a range of health beliefs, personality traits and attitudes. Data were collected in August 2010 and were analysed using two standard and three hierarchical multiple regression analyses. FINDINGS: The standard multiple regression analyses revealed that extraversion, perceived benefits of seeking help, perceived barriers to seeking help and social support were direct predictors of help-seeking behaviour. Tests of moderated relationships (using hierarchical multiple regression analyses) indicated that perceived benefits were more important than barriers in predicting help-seeking behaviour. In addition, perceived susceptibility did not predict help-seeking behaviour unless individuals were health conscious to begin with or they believed that they would benefit from help. CONCLUSION: A range of personality traits, attitudes and health beliefs can predict help-seeking behaviour for mental health problems in adolescents. The variable 'Perceived Benefits' is of particular importance as it is: (1) a strong and robust predictor of help-seeking behaviour; and (2) a factor that can theoretically be modified based on health promotion programmes.


Subject(s)
Mental Disorders/therapy , Patient Acceptance of Health Care , Adolescent , Adult , Cross-Sectional Studies , Humans , Models, Psychological , New South Wales , Young Adult
6.
J Pers ; 76(4): 733-52, 2008 Jul.
Article in English | MEDLINE | ID: mdl-18482358

ABSTRACT

Recently, a model of learning has been proposed that argues that Sensation Seeking indirectly predicts functional and dysfunctional behaviors through Mastery Orientation. Central components of the model were tested across two studies. Study 1 tested the proposed indirect effect in the prediction of functional behavior using an objective learning task. Study 2 tested the proposed indirect effects in the prediction of functional and dysfunctional self-report behavior across two very different samples. Regression analyses in both studies generally supported the proposed model.


Subject(s)
Exploratory Behavior , Impulsive Behavior , Personality , Adult , Female , Humans , Interpersonal Relations , Male , Models, Psychological , Sensation
7.
Accid Anal Prev ; 38(6): 1081-6, 2006 Nov.
Article in English | MEDLINE | ID: mdl-16756930

ABSTRACT

Road crashes involving occupants of light passenger vehicles are the leading cause of traumatic spinal cord injury (SCI). Confirming the results of an earlier study, this study showed that: in single vehicle car crashes in the country, the odds of SCI were nearly five times higher (4.7) for occupants of non-sedan type light passenger vehicles compared with sedans; in single vehicle rollover crashes in the country, the odds of SCI were nearly three times higher (2.8) in non-sedans compared with sedans; the odds of SCI were nearly five times higher (4.8) for sports utility vehicles (SUVs) compared with sedans. When the data from the earlier study was included in order to increase statistical power, it was found that when compared to sedans that did not roll, occupants of all types of light passenger vehicles had a statistically significant substantially higher likelihood of SCI when involved in rollover (sedans 7.5 times, SUVs 5.9 times and others 8.4 times). In addition, SUVs had a higher likelihood of SCI even when not involved in rollover (5.4 times). Vehicle designers and regulators need to give more attention to the prevention of vehicle rollover and the means to improve occupant protection in the event of rollover. This study should be extended nationally to gain a larger case series so that the SCI risk of particular vehicle configurations, considering other crash factors, can be more precisely quantified and characteristics for low occurrence of SCI identified.


Subject(s)
Accidents, Traffic/statistics & numerical data , Spinal Cord Injuries/epidemiology , Adolescent , Adult , Aged , Automobiles , Female , Humans , Male , Middle Aged , Risk , Victoria/epidemiology
8.
Cancer Epidemiol Biomarkers Prev ; 15(4): 740-3, 2006 Apr.
Article in English | MEDLINE | ID: mdl-16614117

ABSTRACT

Schistosoma haematobium-infected patients are more likely to develop bladder cancer and be more exposed to carcinogenic N-nitroso compounds than uninfected patients. As N7-methylguanine is a marker of exposure to methylating agents of this type, we have measured N7-methyldeoxyguanosine 3'-monophosphate (N7-MedGp) by (32)P postlabeling. DNA was isolated from 42 paired normal and tumor tissue of Egyptians with bladder cancer. N7-MedGp was detected in DNA from 93% of the tumors and 74% of the normal bladder tissue samples. Adduct levels were highly variable and ranged from 0.04 to 6.4 and from 0.02 to 0.72 micromol/mol deoxyguanosine 3'-monophosphate (dGp) in tumor and normal DNA, respectively. N7-MedGp levels in normal and tumor DNA were highly correlated with one another (P = 0.007). The mean difference (95% confidence interval) in adduct levels between tumor and normal DNA was 0.21 (0.13-0.32) micromol/mol dGp and this was statistically significant (P < 0.001). The adduct ratio (tumor DNA/normal DNA) varied between 0.2 and 136 (median, 4.6). N7-MedGp levels were not associated with gender, age, or the presence of schistosomiasis. However, lower N7-MedGp levels were found in normal DNA from individuals lacking the GSTM1 gene (P = 0.03) but not the GSTT1 gene or in subjects with the Ile105Val GSTP1 polymorphism. These results show that exposure to methylating agents is widespread and suggest that such exposure may play a role both in tumor initiation and progression.


Subject(s)
DNA Adducts/analysis , DNA Methylation , Epithelium/chemistry , Guanine/analogs & derivatives , Urinary Bladder Neoplasms/genetics , Urinary Bladder/chemistry , Bacterial Infections/complications , Egypt , Female , Guanine/analysis , Humans , Male , Middle Aged , Schistosomiasis haematobia/complications , Urinary Bladder Neoplasms/pathology
9.
Accid Anal Prev ; 38(4): 737-41, 2006 Jul.
Article in English | MEDLINE | ID: mdl-16490178

ABSTRACT

All maritime fatalities investigated by Coroners that occurred in Australia from 1992 to 1998 inclusive have been collated, coded and recorded in the Australian Boating Injury Database: Fatal Injury (ABID:FI). This article focuses on the work-related maritime fatalities recorded in the database. Over the period 1992-1998 there were 74 fatalities involving people who were working for income at the time of the incident: 46 commercial fishermen, 12 seamen involved in the transport of cargo and 16 miscellaneous workers. The fatality rate of commercial fishermen has declined substantially in Australia over recent years. The main contributing factors were: hazardous conditions; an error of judgement; unsafe work practices; and failure to wear a personal flotation device (PFD) in circumstances where, in the opinion of the Coroners, it would have saved life. Hazardous conditions were much more of a factor in fishermen deaths than in other maritime deaths. Most vessels involved had an insufficient number of PFDs for the number of crew on board. The Australian fatal injury database should be updated with the details of recent fatalities in order to further monitor safety performance, causal factors and prevention measures in the maritime industry in Australia. Attention should be focused on reducing alcohol use and increasing PFD availability and usage. In order to continue to improve safety, it is essential that a constructive dialogue is maintained with industry sources, informed by independent research and up-to-date information.


Subject(s)
Accidents, Occupational/statistics & numerical data , Accidents, Occupational/mortality , Alcohol Drinking/epidemiology , Australia/epidemiology , Cause of Death , Data Collection , Drowning/epidemiology , Humans , Oceans and Seas , Protective Devices/statistics & numerical data , Safety , Ships
10.
Accid Anal Prev ; 38(1): 71-7, 2006 Jan.
Article in English | MEDLINE | ID: mdl-16111641

ABSTRACT

This study reports on trends in spinal cord injury based on the Australian Spinal Cord Injury Register (ASCIR), which provided full coverage in those aged 15 years and over. The underlying annual rate of change from 1986 to 1997 was calculated for age-specific, crude and age-standardised incidence rates. An appropriate model for this type of data was the Poisson regression model, with a Poisson error distribution, a log link function and the natural log of population treated as an 'offset'. It was found that there was no change in the age-standardised rate of spinal cord injury. However, an assessment of specific rates by age, sex, cause and neurological group revealed some contrasting trends, notably declining rates in young males, transport-related injury and complete tetraplegia, and increasing rates in elderly males, fall-related injury and incomplete tetraplegia and complete paraplegia. These changes are considered to reflect the impact of a raft of public health measures directed at transport-related injury but a paucity of prevention programs directed at fall-related spinal cord injury. More research is required to determine the causes of the increasing rate of elderly male fall-related spinal cord injury. There is also more that can be done to prevent transport-related spinal cord injury. Sport utility vehicles pose an increased concern. In order to reinvigorate the debate about the need for a vehicle rollover resistance rating in Australia, the spinal cord injury risk of different models of SUV should be measured. This has already been implemented in the United States, providing the public with information to assist purchasing based on safety considerations.


Subject(s)
Spinal Cord Injuries/epidemiology , Accidental Falls/prevention & control , Accidental Falls/statistics & numerical data , Accidents, Traffic/prevention & control , Accidents, Traffic/statistics & numerical data , Adolescent , Adult , Age Distribution , Aged , Australia/epidemiology , Female , Humans , Incidence , Male , Middle Aged , Morbidity/trends , Multivariate Analysis , Paralysis/epidemiology , Paralysis/etiology , Regression Analysis , Sex Distribution , Spinal Cord Injuries/etiology , Spinal Cord Injuries/prevention & control
11.
Accid Anal Prev ; 37(4): 689-98, 2005 Jul.
Article in English | MEDLINE | ID: mdl-15949461

ABSTRACT

The aim of this study was to investigate the causes and prevention of the 333 boating deaths that occurred in Australia over the period 1992-1998. It involved: assessment of the Coroner's findings; review of witness statements, police reports, autopsy findings, search and rescue reports, weather maps and reports; analysis of forensic and scientific data; assessment of photographic evidence; review of other related information. The data were coded according to a recently developed national data standard. It was found that nearly half of the vessels involved had an insufficient number of personal flotation devices for the number of people on board; of all people killed only 9% were wearing them, and survivors were more than two times more likely to have been wearing them. If usage could be increased to 75%, five lives could be saved each year with a cost saving to the Australian community of nearly $8 million. The contribution of alcohol to boating deaths (28% in excess of 0.05g/100ml) was similar to its contribution to road deaths. The sequence of events resulting in a boating death was initiated most often by capsize (36%). Capsize was more likely to involve overloading or improper loading, hazardous wind or sea conditions, and dinghies. Twenty-five percent of the vessels involved in fatalities were dinghies and they were more likely to be overloaded, involve capsize, alcohol, and failure to wear a personal flotation device. Fatalities involving personal watercraft were mainly caused by human factors. Boating causes a significant level of harm to the Australian community measured in terms of mortality. This can be reduced by a concerted effort to address the identified hazards and protective factors.


Subject(s)
Accident Prevention/statistics & numerical data , Accidents/mortality , Ships/statistics & numerical data , Australia/epidemiology , Causality , Drowning/mortality , Environment , Humans , Incidence , Ships/classification , Ships/standards , Substance-Related Disorders/epidemiology
12.
Med J Aust ; 182(12): 617-20, 2005 Jun 20.
Article in English | MEDLINE | ID: mdl-15963017

ABSTRACT

OBJECTIVE: To evaluate the effectiveness of a community-based and GP-based intervention in reducing unnecessary antibiotic prescribing for upper respiratory tract infections (URTIs) including sore throats, sinusitis and otitis media. DESIGN: Analysis of pharmacy dispensing data in June to October before (2000) and after (2001) the intervention, which commenced on 25 June 2001. SETTING AND PARTICIPANTS: Local consumers, health professionals, the Adelaide Southern Division of General Practice, the South Australian Government, and the local media in a rural region of South Australia, covering about 2000 square kilometres, with a population of over 20 000. INTERVENTION: Community dissemination of consumer information on antibiotic use for URTIs (including a local media campaign) and education of health professionals (including sessions with general practitioners at the four practices in the study area) on current Australian therapeutic guidelines for antibiotics, and a validated clinical scoring system for decision making in managing sore throat. MAIN OUTCOME MEASURES: Total dispensing data from local pharmacies for the months of June to October in 2000 and 2001, covering the six antibiotics considered most likely to be used for URTIs (amoxycillin, amoxycillin/clavulanic acid, cefaclor, doxycycline, erythromycin and roxithromycin). RESULTS: The dispensing of the six antibiotics reduced by 32% overall, from 77.1 to 52.9 defined daily doses per 1000 population per day, with statistically significant reductions in the range of 31%-70% for individual antibiotics; there was no reduction for amoxycillin with or without clavulanic acid. CONCLUSION: The intervention was associated with reduced dispensing of unnecessary antibiotics for URTIs.


Subject(s)
Anti-Bacterial Agents/therapeutic use , Drug Utilization/statistics & numerical data , Physicians, Family , Respiratory Tract Infections/drug therapy , Adolescent , Adult , Aged , Australia , Child , Child, Preschool , Female , Humans , Infant , Infant, Newborn , Male , Middle Aged , Otitis Media/drug therapy , Pharmacies , Practice Patterns, Physicians' , Quality Assurance, Health Care , Rural Health Services , Rural Population
13.
Traffic Inj Prev ; 6(1): 60-6, 2005 Mar.
Article in English | MEDLINE | ID: mdl-15823877

ABSTRACT

The objective of this study was to assess the role of helmets and helmet type in relation to injury to the cervical spinal cord. It was based on a consecutive series of 110 motorcyclists with neurological damage to the spinal cord admitted alive (referred to as acute survivors) to a specialist spinal cord injuries unit at an Australian hospital. Cases were those with injury to the cervical spinal cord and controls were those with injury to the cord of other segments of the spine. The study showed that there was no significant difference in the odds of cervical spinal cord injury among unhelmeted and helmeted motorcyclist acute survivors. In addition, it confirmed the findings of a recently published Australian fatality study demonstrating no difference in the odds of cervical spinal cord injury among full-face and open-face helmet wearers. These results contrasted with the findings of earlier studies. In consideration of the limitations of existing research on the role of helmets in spinal cord injury, further study is required based on a larger series or a series having a higher proportion of non-wearers and open-face helmet wearers, including both survivors and those killed, and including assessment of cord and non-cord spinal injuries separately, helmet type, head impact, and helmet retention.


Subject(s)
Head Protective Devices/statistics & numerical data , Motorcycles , Spinal Cord Injuries/epidemiology , Adult , Australia/epidemiology , Case-Control Studies , Cervical Vertebrae/injuries , Equipment Design , Humans , Interviews as Topic , Paraplegia/epidemiology , Quadriplegia/epidemiology
14.
Arch Phys Med Rehabil ; 86(1): 37-47, 2005 Jan.
Article in English | MEDLINE | ID: mdl-15640987

ABSTRACT

OBJECTIVE: To assess survival after spinal cord injury (SCI) in Australia. DESIGN: Cohort study of incident cases from 1986 to 1997, with follow-up to the end of 1998. SETTING: Cases registered by 6 Australian treatment centers for the acute care and rehabilitation of SCI patients. PARTICIPANTS: Subjects (N=2892), age 15 years and older, from a national population-based SCI register. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Cumulative and relative survival proportions and hazard ratios. RESULTS: The all-cases cumulative survival proportion was 94% at 1 year and 86% at 10 years; the relative survival proportions were 95% and 92%, respectively. Significant predictors of survival were: age at injury, sex, neurologic level, and extent of lesion. Cox regression modeling revealed a statistically significant reduction in the 2-month (36% reduction, P=.01) and 1-year (27% reduction, P=.04) hazard ratio from 1986 to 1991 to 1992 to 1997. Benchmarking analysis revealed no statistically significant difference in survival experience between the 6 spinal treatment units. CONCLUSIONS: Further improvement in survival rates can be achieved through better understanding of the predictors, temporal patterns, and causes of death, and by benchmarking. Early deaths have an important impact on overall survival rates, and warrant further study. International standardization of methods is strongly recommended.


Subject(s)
Spinal Cord Injuries/mortality , Adolescent , Adult , Age Distribution , Aged , Australia/epidemiology , Cohort Studies , Female , Humans , Male , Middle Aged , Risk Factors , Sex Distribution , Survival Analysis , Survival Rate/trends , Trauma Severity Indices
15.
Arch Phys Med Rehabil ; 86(1): 48-51, 2005 Jan.
Article in English | MEDLINE | ID: mdl-15640988

ABSTRACT

OBJECTIVES: To forecast annual numbers of cases of spinal cord injury (SCI) and to assess the effect on case mix. DESIGN: Cohort of incident cases from 1986 to 1997, with forecasting to 2021. SETTING: Australian cases registered by treatment centers for the acute care and rehabilitation of SCI patients. PARTICIPANTS: A total of 2959 SCI patients, aged 15 years and over, identified through the Australian Spinal Cord Register. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Incidence and case mix. RESULTS: If the recent trends in SCI continue (ie, a 6.21% per annum rate increase in elderly men and a 2.8% per annum rate decrease in young men), the annual number of cases will increase from 253 in 1997 to 464 in 2021. In addition, the case mix would change substantially and the number and proportion of elderly persons with SCI would increase from 32 cases per annum in 1997 (13% of cases) to 233 per annum in 2021 (47% of cases). In addition, there would be a 143% increase in the number of cases of incomplete tetraplegia, from 88 cases per annum in 1997 to 214 cases per annum in 2021. Substantial increases would occur even if the age-specific rates of SCI were stable over the period. CONCLUSIONS: Population growth, and aging, plus increasing rates of SCI in the elderly will have profound effects on the expected number of SCI patients and their case mix. Treatment centers in Australia will need to plan for these changes. At the same time, there should be increased efforts to prevent SCI in order to ameliorate the problem.


Subject(s)
Spinal Cord Injuries/epidemiology , Adolescent , Adult , Age Factors , Aged , Australia/epidemiology , Diagnosis-Related Groups/trends , Female , Forecasting , Humans , Male , Middle Aged , Models, Statistical , Morbidity/trends , Population Dynamics
16.
Cancer Res ; 63(22): 7699-703, 2003 Nov 15.
Article in English | MEDLINE | ID: mdl-14633693

ABSTRACT

Ethenobases are promutagenic DNA adducts formed by some environmental carcinogens and products of endogenous lipid peroxidation. Mutation spectra in tumors induced in mice by urethane or its metabolite vinyl carbamate (Vcar) are compatible with 1,N(6)-ethenoadenine (epsilonA) being an initiating lesion in the development of these tumors. As alkylpurine-DNA-N-glycosylase (APNG) releases epsilonA from DNA in vitro, wild-type and APNG-/- C57Bl/6J mice were treated with Vcar and levels of epsilonA and 3,N(4)-ethenocytosine (epsilonC), which is not a substrate of APNG, were analyzed in liver and lung DNA. At 6 h after the last dose, levels of epsilonA were 1.6-fold higher in DNA from APNG-/- mice and subsequently persisted at higher levels for longer than in DNA from wild-type animals, confirming that epsilonA is released by APNG in vivo. In contrast, approximately 14-fold lower levels of epsilonC were induced by Vcar, and the kinetics of formation and persistence of epsilonC was similar in the two mouse strains. The carcinogenicity of Vcar was compared in APNG-/- and wild-type suckling mice given a single dose of Vcar (30 or 150 nmol/g). After 1 year, only mice in the high-dose group developed hepatocellular carcinoma; however, the incidence was not higher in APNG-/- mice. Although higher levels and increased persistence of epsilonA was observed in hepatic DNA from APNG-/- mice at 150 nmol/g Vcar, apoptosis and cell proliferation levels were similar in both strains of mice. This may explain why differences in epsilonA formation/persistence observed here did not result in higher susceptibility of APNG-/- mice to hepatocarcinogenesis.


Subject(s)
Carcinogens/toxicity , DNA Glycosylases/deficiency , DNA Repair/physiology , DNA/drug effects , DNA/metabolism , Deoxyadenosines/metabolism , Urethane/analogs & derivatives , Urethane/toxicity , Animals , Apoptosis/drug effects , Cell Cycle/drug effects , Cell Division/drug effects , DNA Damage , DNA Glycosylases/genetics , Deoxyadenosines/biosynthesis , Female , Hepatocytes/cytology , Hepatocytes/drug effects , Liver/drug effects , Liver/metabolism , Lung/drug effects , Lung/metabolism , Male , Mice , Mice, Inbred C57BL , Mice, Knockout
17.
Carcinogenesis ; 24(3): 527-33, 2003 Mar.
Article in English | MEDLINE | ID: mdl-12663514

ABSTRACT

Putative risk factors (DNA damage) and risk modifying factors (DNA repair and cell proliferation) were examined in an experimental mouse model in which treatment with dimethylhydrazine (6.8 mg/kg DMH i.p. once weekly) for up to 20 weeks induces colon tumours in a site specific manner with 0, 43 and 87% of animals having proximal, mid and distal colon tumours respectively at the highest cumulative dose. Levels of the pro-carcinogenic DNA adduct, O(6)-methylguanine (O(6)-MeG), in colonic DNA were found to vary with time after final treatment and with location within the colon but not with total DMH dose. O(6)-MeG levels were generally lowest in proximal colon DNA and highest in distal colon DNA. Steady state O(6)-MeG levels were obtained at the highest cumulative DMH dose with O(6)-MeG levels in mid and distal colon DNA being 5 and 10 times higher those in proximal colon DNA. O(6)-alkylguanine-DNA alkyltransferase (MGMT) activity, and cell proliferation indices in the colon were also found to vary with time after final treatment but not with either location within the colon or total DMH dose. O(6)-MeG levels, MGMT activity and cell proliferation indices at specific time points as well as basal MGMT activity were not associated with differences in tumour yield within the colon. However tumour yield was associated with the cumulative amount of O(6)-MeG present in DNA over the treatment period and with the treatment induced cumulative increase in cell proliferation, particularly within regions of the colon crypt where stem cells reside but not with cumulative changes in MGMT activity. Results are consistent with an increased cancer risk arising from an increased mutation load in the target stem cell population due to increased adduct formation/persistence and cell proliferation but also suggest that other cell specific factors may help to determine tumourigenic response.


Subject(s)
Cell Division , Colon/drug effects , Colonic Neoplasms/metabolism , DNA Repair , DNA/metabolism , 1,2-Dimethylhydrazine , Alkylation , Animals , Autoradiography , Biomarkers, Tumor , Carcinogens , Colon/cytology , Colon/enzymology , Colon/metabolism , Colonic Neoplasms/chemically induced , Colonic Neoplasms/enzymology , Colonic Neoplasms/pathology , Mice , O(6)-Methylguanine-DNA Methyltransferase/metabolism
18.
J Nutr ; 132(11 Suppl): 3518S-3521S, 2002 11.
Article in English | MEDLINE | ID: mdl-12421880

ABSTRACT

O6-methylguanine (O6-MeG), a procarcinogenic DNA adduct that arises from exposure to methylating agents, has been detected in human colorectal DNA at levels comparable to those that cause adverse effects in model systems. O6-MeG levels vary within the colon, being higher in the cancer-prone regions of the large bowel. In rats and mice, O6-MeG persistence in colon DNA is associated with the induction of colon tumors after treatment with methylating agents. These tumors frequently contain K-ras GC-->AT transition mutations, which is consistent with the mutagenic properties of O6-MeG: such mutations are also commonly found in human colorectal cancers. O6-Alkylguanine adducts are removed by the DNA repair protein, O6-alkylguanine DNA-alkyltransferase (MGMT). MGMT overexpression in transgenic mice reduces the formation of K-ras GC-->AT mutations and tumors induced by methylating agents. Interindividual variations in human colon MGMT activity are large and large bowel tumors can occur in regions of low activity. Low MGMT activity in normal mucosa has been associated with the occurrence of K-ras GC-->AT mutations, whereas reduced MGMT expression and an increased frequency of K-ras GC-->AT mutations in colorectal cancers have been linked to MGMT promoter methylation. MGMT activity is also lower in adenomas than in adjacent normal tissue but only in those adenomas with this specific mutation. These results are entirely consistent with the hypothesis that GC-->AT mutations in the K-ras oncogene result from the formation and persistence of O6-alkylguanine lesions in colorectal DNA. Human exposure to endogenous or exogenous alkylating agents may thus be an environmental determinant of colorectal cancer risk.


Subject(s)
DNA Damage , DNA Repair , Intestine, Large/metabolism , 1,2-Dimethylhydrazine , Alkylation , Animals , Carcinogens , Colon/metabolism , Colonic Neoplasms/chemically induced , Colonic Neoplasms/metabolism , Colorectal Neoplasms/genetics , Humans , Rectum/metabolism
19.
FEBS Lett ; 519(1-3): 205-9, 2002 May 22.
Article in English | MEDLINE | ID: mdl-12023046

ABSTRACT

Extracts of the adult worms of both Schistosoma mansoni and Schistosoma haematobium can metabolise some typical P450 substrates but to differing degrees. S. mansoni worm extracts displayed a approximately 12-fold higher specific activity for an aminopyrine substrate than rat liver microsomes. At 4 mM substrate concentration the demethylation reaction with N-nitrosodimethylamine (NDMA) (5 nmol HCHO/mg protein/min) was only half that of rat liver microsomes, whereas in extracts of S. haematobium, no detectable activity was found towards NDMA. Using ethylmorphine as substrate the demethylation activity of S. mansoni extracts (1.82 nmol HCHO/mg protein/min) was 5.5-fold lower than that of rat liver microsomes. Benzphetamine demethylase activity was also readily detectable in S. mansoni worm extracts at 6.79 nmol HCHO/mg protein/min compared with 10.20 nmol HCHO/mg protein/min in the case of rat liver microsomes. When aniline was used as substrate, surprisingly, no activity was found in worm extracts of either S. mansoni or S. haematobium, whereas rat liver microsomes showed high activity towards this amine. The anti-P450 2E1 and 2B1/2 cross-reacted with both worm homogenates and gave a specific band corresponding to a protein of molecular weight of approximately 50.0 kDa. A study with anti-P450 IVA antibody revealed that while this protein was strongly expressed in S. haematobium worm extracts, no immunoreactivity was observed with extracts of S. mansoni. Immunoblotting analyses with anti-P450 IIIA and P450 1A1 did not detect immunoreactive protein in either S. mansoni or S. haematobium.


Subject(s)
Cytochrome P-450 Enzyme System/metabolism , Schistosoma haematobium/enzymology , Schistosoma mansoni/enzymology , Aminopyrine/pharmacology , Aniline Compounds/pharmacology , Animals , Benzphetamine/pharmacology , Cricetinae , Cytochrome P-450 Enzyme System/chemistry , Dimethylnitrosamine/pharmacology , Enzyme Activation/drug effects , Ethylmorphine/pharmacology , Female , Formaldehyde/analysis , Formaldehyde/metabolism , Immunoblotting , Male , Mice , Microsomes, Liver/drug effects , Microsomes, Liver/enzymology , NADPH-Ferrihemoprotein Reductase/metabolism , Oxazines/pharmacology , Rats , Schistosoma haematobium/chemistry , Schistosoma mansoni/chemistry , Substrate Specificity
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