Chemoprevention of dibenzo[a,l]pyrene transplacental carcinogenesis in mice born to mothers administered green tea: primary role of caffeine.

Our laboratory recently developed a mouse model of transplacental induction of lymphoma, lung and liver cancer by the polycyclic aromatic hydrocarbon, dibenzo[a,l]pyrene (DBP). Pregnant B6129SF1 females, bred to 129S1/SvIm males, were treated on day 17 of gestation with an oral dose of 15 mg/kg DBP. Beginning on day 0 of gestation, dams were given (ad lib) buffered water, 0.5% green tea, 0.5% decaffeinated green tea, caffeine or epigallocatechin-3-gallate (EGCG) (both at equivalent concentrations found in tea). The concentration of the teas (and corresponding caffeine and EGCG) was increased to 1.0% upon entering the second trimester, 1.5% at onset of the third trimester and continued at 1.5% until pups were weaned at 21 days of age. Offspring were raised with normal drinking water and AIN93G diet. Beginning at 2 months of age, offspring experienced significant mortalities due to an aggressive T-cell lymphoma as seen in our previous studies. Ingestion of caffeinated, but not decaffeinated, green tea provided modest but significant protection (P = 0.03) against mortality. Caffeine provided a more robust (P = 0.006) protection, but EGCG was without effect. Offspring also developed DBP-dependent lung adenomas. All treatments significantly reduced lung tumor multiplicity relative to controls (P < 0.02). EGCG was most effective at decreasing tumor burden (P = 0.005) by on average over 40% compared with controls. Induction of Cytochrome P450 (Cyp)1b1 in maternal liver may reduce bioavailability of DBP to the fetus as a mechanism of chemoprevention. This is the first demonstration that maternal ingestion of green tea, during pregnancy and nursing, provides protection against transplacental carcinogenesis.

Frequency of appropriate and inappropriate presentation and analysis methods of ordered categorical data in the veterinary dermatology literature from January 2003 to June 2006.

Clinical outcomes that are difficult to measure directly are often graded with ordinal scales in the veterinary dermatology literature to approximate objective evaluation. Ordered categorical scales require statistical presentation and analysis methods consistent with the structure of the data. The objective of this study was to determine the frequency of inappropriate presentation and analysis methods of ordered categorical data in the recent veterinary dermatology literature. A total of 62 articles published between 1 January 2003 and 30 June 2006 in 16 journals reported categorical scales and were included in the study. The presentation and analysis methods of ordered categorical data were classified as appropriate or inappropriate based on published recommendations. Forty articles (64.5%) utilized a median of four ordinal scales (range 1-13). Inappropriate presentation methods of ordered categorical data were identified in 23 of 40 articles (57.5%). These included reporting inappropriate summary statistics (n = 17) and summation of ad hoc numerical rating scales (n = 15). Inappropriate analytical methods were used in nine of 40 articles (22.5%). These included inappropriate use of t-tests (n = 3) and analysis of variance (anova, n = 6). The frequency of inappropriate presentation and analysis methods of ordered categorical data in the veterinary dermatology literature is similar to that reported for several fields in the human medical literature. In order to reduce the likelihood of making unwarranted implications or conclusions regarding ordinal data, authors should follow established guidelines for methods of presentation and analysis of ordered categorical scales.