Rapid changes in climate may impose strong selective pressures on organisms. Evolutionary responses to climate change have been observed in natural populations, yet no example has been documented for a metabolic enzyme locus. Furthermore, few studies have linked physiological responses to stress with allozyme genotypic variation. We quantified changes in allele frequency between 1988 and 1996 at three allozyme loci (isocitrate dehydrogenase, Idh; phosphoglucose isomerase, Pgi; and phosphoglucomutase, Pgm) for the leaf beetle Chrysomela aeneicollis in the Bishop Creek region of the Sierra Nevada of California (2900-3300 m). Beetles often experience high daytime (> 32 degrees C) and extremely low nighttime (
BACKGROUND AND METHODS: The purpose of this article was to examine differences in demographics, general health status, and utilization of breast and cervical cancer screening for subgroups of American Indians and Alaska Natives (AIAN) using the 2001 California Health Interview Survey. RESULTS: The statewide distribution of California American Indians, non-California AIANs, and unknown AIANs are 10%, 51%, and 39%, respectively. Significant differences exist among the 3 tribal subgroups. CONCLUSIONS: Overall, AIAN women aged 40+ years are close to the Healthy People 2010 goals for receipt of a mammogram in the past 2 years and for receipt of a Pap test ever and in the past 3 years. Less than 5% of AIAN in California report Indian Health Service coverage.
Most conifer species occur in large continuous populations, but radiata pine, Pinus radiata, occurs only in five disjunctive natural populations in California and Mexico. The Mexican island populations were presumably colonized from the mainland millions of years ago. According to Axelrod (1981), the mainland populations are relicts of an earlier much wider distribution, reduced some 8,000 years ago, whereas according to Millar (1997, 2000), the patchy metapopulation-like structure is typical of the long-term population demography of the species. We used 19 highly polymorphic microsatellite loci to describe population structure and to search for signs of the dynamics of population demography over space and time. Frequencies of null alleles at microsatellite loci were estimated using an approach based on the probability of identity by descent. Microsatellite genetic diversities were high in all populations [expected heterozygosity (H(e)) = 0.68-0.77], but the island populations had significantly lower estimates. Variation between loci in genetic differentiation (F(ST)) was high, but no locus deviated statistically significantly from the rest at an experiment wide level of 0.05. Thus, all loci were included in subsequent analysis. The average differentiation was measured as F(ST) = 0.14 (SD 0.012), comparable with earlier allozyme results. The island populations were more diverged from the other populations and from an inferred common ancestral gene pool than the mainland ones. All populations showed a deficiency of expected heterozygosity given the number of alleles, the mainland populations more so than the island ones. The results thus do not support a recent important contraction in the mainland range of radiata pine.
In the Pacific Basin, the hepatitis B virus is closely associated with hepatocellular carcinoma in its geographic distribution and familial clustering, and its presence in liver tissues. The contribution of aflatoxin to the development of hepatocellular carcinoma in different regions varies from negligible to probably major. Neither the hepatitis B virus nor aflatoxin can account for the varied epidemiology of hepatocarcinogenesis in the Pacific Basin. Many potential carcinogens for the liver have been identified in food, drugs, industrial chemicals, and in the general environment, but their importance in hepatocarcinogenesis remains to be defined.
Two hundred and thirty-six marijuana users who volunteered for a study in which they would use the drug were administered a Drug History and a Marihuana Effects Questionnaires. In addition to obtaining descriptive information of drug experiment volunteers and a factor analysis of the marijuana experience, the relationship between experience and effect variables were studied. The results of the above analysis suggest that the "typical" subject in marijuana experiments is not a "typical" user, that the marijuana experience is verbally definable, and that prior expectancies and histories of effect alter the experience.
Ovarian cysts of several types are common in women of reproductive age. Their etiology is not well understood but is likely related to perturbations in the hypothalamic-pituitary-gonadal axis. The relationship of ovarian cysts to breast cancer risk is not known, although a negative association with polycystic ovarian syndrome has been reported. Incident, invasive female breast cancer cases, population-based controls and unaffected sisters of cases were studied from 3 countries participating in the Breast Cancer Family Registry: Melbourne and Sydney, Australia; the San Francisco Bay Area, USA; and Ontario, Canada. Using the same questionnaire, information was collected on self-reported history of ovarian cysts and other risk factors. Analyses were based on 3,049 cases, 2,344 population controls and 1,934 sister controls from all sites combined. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using both unconditional and conditional logistic regression using an offset term to account for sampling fractions at 2 of the sites. A significantly reduced risk of breast cancer was observed for women reporting a history of ovarian cysts (OR = 0.70, 95% CI 0.59-0.82, among all cases and all controls). This risk estimate was similar regardless of control group used, within all 3 sites and in both premenopausal and postmenopausal women (ORs ranging from 0.68-0.75, all 95% CI excluded 1.00). A self-reported history of ovarian cysts was strongly and consistently associated with a reduced risk of breast cancer. Further study of ovarian cysts may increase our understanding of hormonal and other mechanisms of breast cancer etiology.