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J McCann

Publications and source records attributed to J McCann.

At least 73 records · Page 4Linked to original sources
PubMed1999

Equine dental disease part 2: a long-term study of 400 cases: disorders of development and eruption and variations in position of the cheek teeth.

Of 400 referred horses with dental disorders, 349 cases suffered from primary disorders of their cheek teeth, ninety of these from disorders of development or eruption, or displacements. These included 20 cases with rostral maxillary and caudal mandibular cheek teeth overgrowths, 16 with diastemata, 15 with grossly enlarged mandibular 'eruption cysts', 4 with grossly enlarged maxillary cheek teeth 'eruption cysts', 10 cases with supernumerary cheek teeth and 23 cases with displaced cheek teeth. These displacements were believed to be developmental in 16 cases and acquired in the remaining 7 cases. Long-term response to treatments, that included removal of overgrowths and extraction of teeth with deep secondary periodontal disease was excellent for most disorders except diastemata.

Animals↗
PubMed1998

The genotoxic potential of electric and magnetic fields: an update.

We review 23 studies on the potential genotoxicity of electric and magnetic fields that have appeared in the published literature since our 1993 review of 55 published studies (McCann et al., Mutat. Res. 297 (1993) 61-95) and six additional studies published prior to 1993, which were not previously reviewed. As in our previous review, internal electric fields present in media (for in vitro experiments) and in the torso (for in vivo experiments) were estimated. Individual experiments are evaluated using basic data quality criteria. The potential for genotoxicity of electric and magnetic fields is discussed in light of the significant body of genotoxicity data that now exists. Three unsuccessful attempts to replicate previously reported positive results have appeared since our previous review. We conclude that, in spite of the 34 studies reviewed in this and our previous publication that report positive genotoxic effects, none satisfy all of three basic conditions: independent reproducibility, consistency with the scientific knowledge base, and completeness according to basic data quality criteria. As we discuss, these criteria are satisfied for several groups of negative studies in several exposure categories (ELF magnetic fields, 150 microT-5 mT, combined ELF electric and ELF magnetic fields, approx. 0.2 mT, 240 mV/m, and static magnetic fields, 1-3.7 T). The evidence reviewed here strengthens the conclusion of our previous review, that the preponderance of evidence suggests that ELF electric or magnetic fields do not have genotoxic potential. Nevertheless, a pool of positive results remains, which have not yet been tested by independent replication. Among the 12 studies reviewed here, which report statistically significant or suggestive positive results, we point particularly to results from five laboratories [J. Miyakoshi, N. Yamagishi, S. Ohtsu, K. Mohri, H. Takebe, Increase in hypoxanthine-guanine phosphoribosyl transferase gene mutations by exposure to high-density 50-Hz magnetic fields, Mutat. Res. 349 (1996) 109-114; J. Miyakoshi, K. Kitagawa, H. Takebe, Mutation induction by high-density, 50-Hz magnetic fields in human MeWo cells exposed in the DNA synthesis phase, Int. J. Radiat. Biol. 71 (1997) 75-79; H. Lai. N.P. Singh, Acute exposure to a 60-Hz magnetic field increases DNA strand breaks in rat brain cells, Bioelectromagnetics, 18 (1997) 156-165; H. Lai, N.P. Singh, Melatonin and N-tert-butyl-alpha-phenylnitrone block 60-Hz magnetic field-induced DNA single and double strand breaks in rat brain cells, J. Pineal Res. 22 (1997) 152-162; T. Koana, M. Ikehata, M. Nakagawa, Estimation of genetic effects of a static magnetic field by a somatic cell test using mutagen-sensitive mutants of Drosophila melanogaster, Bioelectrochem. Bioenergetics 36 (1995) 95-100; F.L. Tabrah, H.F. Mower, S. Batkin, P.B. Greenwood, Enhanced mutagenic effect of a 60-Hz time-varying magnetic field on numbers of azide-induced TA100 revertant colonies, Bioelectromagnetics 15 (1994) 85-93; S. Tofani, A. Ferrara, L. Anglesio, G. Gilli, Evidence for genotoxic effects of resonant ELF magnetic fields, Bioelectrochem. Bioenergetics, 36 (1995) 9-13], which satisfy most basic data quality criteria and may be of interest.

Animals↗
PubMed1998

Breast cancer in East Anglia: the impact of the breast screening programme on stage at diagnosis.

OBJECTIVES: To assess the impact of the National Health Service breast screening programme on overall and stage-specific incidence of breast cancer in East Anglia; also, to predict the magnitude of the screening induced reduction in breast cancer mortality. SETTING: Women resident in East Anglia aged 50-69, diagnosed between 1976 and 1995. METHODS: Comparison of numbers and incidence of breast cancer by age, stage, and mode of detection; investigation of relative contributions of advanced (stages II, III, and IV) cancers to total incidence by detection mode; estimation of the reduction in advanced cancer incidence. RESULTS: There has been a large increase in early stage incidence in the age group 50-64 targeted by the screening programme. By 1995, the estimated decrease in advanced cancer incidence was between 7 and 19%. In 1995, of all breast cancers arising in the age group 50-69 years, 33% were screen detected, 27% were interval cancers, 15% were in non-attenders, 9% were in lapsed attenders, 7% occurred before invitation, and 4% arose in women outside the birth year range for invitation. Of the advanced cancers diagnosed in 1995, 31% were interval cancers, 20% were screen detected, 19% were in non-attenders, 12% were in lapsed attenders, 8% occurred before invitation, and 4% presented in women outside the birth year range for invitation. CONCLUSIONS: Screening has brought about a large increase in detection of early stage cancers. This increase has not yet been fully matched by a corresponding deficit in advanced cancers, possibly because the full effect of screening has not yet been achieved. Reducing the proportion of interval cancers is necessary to increase the effect of screening on mortality.

Aged↗
PubMed1998

Mammographic parenchymal patterns and mode of detection: implications for the breast screening programme.

OBJECTIVES: To assess the effects of mammographic parenchymal patterns on the risk of breast cancer detected at first screen, second screen, and in the interval between these two screens. SETTINGS: A nested case-control study within a screening cohort in East Anglia was designed. The study group comprised 502 patients with cancer at the prevalence screening round, 198 patients with interval cancer, and 175 with cancer at the first incidence screen. These patients were matched with 2601 controls. METHODS: The mammographic parenchymal patterns of breast tissue were assessed according to Wolfe's classification. Statistical analysis was by conditional logistic regression. RESULTS: Overall, 67% of patients and 59% of controls were considered to have high risk pattern (P2 + DY) mammogram. The risk associated with P2 or DY mammographic patterns compared with N1 was higher for interval cancers (odds ratios (ORs) 2.2 and 2.4 respectively) than for screen detected cancers (ORs 1.7 and 1.1 respectively). For interval cancers in the first 18 months after the last negative mammogram, the risk was particularly high (ORs 3.8 for P2 and 4.1 for DY compared with N1). The high risk associated with P2 and DY patterns was concentrated on invasive ductal grade III cancers (ORs 2.7 and 3.8) rather than grade I or II cancers (ORs 1.6 and 1.2). CONCLUSIONS: The study strongly suggests that screening effectiveness is reduced for high risk parenchymal patterns which are associated with high grade cancers. Changes should aim at improving screening sensitivity for dense parenchymal patterns, and the diagnosis of high grade tumours.

Aged↗
PubMed1998

Cancer risk assessment of extremely low frequency electric and magnetic fields: a critical review of methodology.

This review provides a discussion of cancer risk assessment methodology pertinent to developing a strategy for extremely low frequency electric and magnetic fields (EMF). Approaches taken for chemical agents or ionizing radiation in six key topic areas are briefly reviewed, and then those areas are examined from the perspective of EMF, identifying issues to be addressed in developing a risk assessment strategy. The following recommendations are offered: 1) risk assessment should be viewed as an iterative process that informs an overall judgment as to health risk and consists of a complex of related activities incorporating both positive and negative data, tumor and nontumor end points, and human and nonhuman sources of information; 2) a hazard identification resulting in a conclusion of weak or null effects, such as may be associated with EMF, will need to assign significant weight to animal cancer bioassays conducted under defined exposure conditions as well as to human epidemiologic studies; 3) a default factor to account for possible age differences in sensitivity to carcinogenesis should be included in an EMF risk assessment; 4) lack of evidence of dose response and the apparent lack of DNA reactivity of EMF suggest that a safety (or uncertainty) factor or margin of exposure type of risk characterization may be most appropriate; and 5) an EMF risk assessment should permit at least tentative conclusions to be reached as to the limits of carcinogenic risk from exposure to EMF, and should also define an efficient research agenda aimed at clarifying uncertainties appropriate to a more complete assessment.

Animals↗
PubMed1997

Retrospective study of reasons for improved survival in patients with breast cancer in east Anglia: earlier diagnosis or better treatment.

OBJECTIVES: To investigate the recent fall in mortality from breast cancer in England and Wales, and to determine the relative contributions of improvements in treatment and earlier detection of tumours. DESIGN: Retrospective study of all women with breast cancer registered by the East Anglian cancer registry and diagnosed between 1982 and 1989. SUBJECTS: 3965 patients diagnosed 1982-5 compared with 4665 patients diagnosed 1986-9, in three age groups 0-49, 50-64, > or = 65 years, with information on stage at diagnosis and survival. MAIN OUTCOME MEASURES: Three year relative survival rates by time period, age group, and stage; relative hazard ratios for each time period and age group derived from Cox's proportional hazards model, adjusted for single year of age and stage. RESULTS: Survival improved in the later time period, although there was little stage specific improvement. The proportion of early stage tumours increased especially in the 50-64 year age group, and adjustment for stage accounted for over half of the improvement in survival in women aged under 65 years. CONCLUSION: Over half of the drop in mortality in women aged under 65 years seems to be attributable to earlier detection of tumours, which has been observed since the mid-1980s. This could have resulted from an increase in breast awareness predating the start of the breast screening programme.

Adolescent↗
PubMed1997

A validational study of the Structured Interview of Symptoms Associated with Sexual Abuse (SASA) using three samples of sexually abused, allegedly abused, and nonabused boys.

OBJECTIVE: With the rapid rise of sexual abuse allegations, there is a growing need to develop instruments to help clinicians determine the likelihood that sexual abuse has occurred. METHOD: This study evaluated the discriminant validity of a structured parent interview regarding emotional, behavioral, and physical symptoms by comparing results among three subsamples of age matched boys: 22 sexually abused boys whose perpetrator confessed, 47 boys evaluated in a sexual abuse clinic but without a history of perpetrator confession and 52 nonabused boys selected after rigorous screening. RESULTS: In comparison with the nonabused (NA) boys, the sexually abused boys were significantly more likely to demonstrate sudden emotional and behavioral changes, frequent stomach aches, more knowledge about sex and sexual activities than expected for age, unusual aggressiveness toward playmate or toy's private parts, crying easily, difficulty getting to sleep, and a change to poor school performance. The internal reliability of the SASA was determined to be .83 and scoring of an abbreviated 12-item scale demonstrated a sensitivity of 90.9% and a specificity of 88.5%. CONCLUSIONS: The findings suggest that Structured Interview of Symptoms Associated with Sexual Abuse (SASA) is an effective tool which may help in the comprehensive assessment of boys who may have been sexually abused.

Adolescent↗