Rainfall and sea level drove the expansion of seasonally flooded habitats and associated bird populations across Amazonia.

Spatial arrangement of distinct Amazonian environments through time and its effect on specialized biota remain poorly known, fueling long-lasting debates about drivers of biotic diversification. We address the late Quaternary sediment deposition that assembled the world's largest seasonally flooded ecosystems. Genome sequencing was used to reconstruct the demographic history of bird species specialized in either early successional vegetation or mature floodplain forests. Sediment deposition that built seasonally flooded habitats accelerated throughout the Holocene (last 11,700 years) under sea level highstand and intensification of the South American Monsoon, at the same time as global increases in atmospheric methane concentration. Bird populations adapted to seasonally flooded habitats expanded due to enlargement of Amazonian river floodplains and archipelagos. Our findings suggest that the diversification of the biota specialized in seasonally flooded habitats is coupled to sedimentary budget changes of large rivers, which rely on combined effects of sea level and rainfall variations.

CYP2E1 expression in human lymphocytes from various ethnic populations.

BACKGROUND: Monitoring CYP2E1 levels in alcoholic individuals holds inherent appeal because such determinations might indicate individuals at increased risk for alcoholic liver disease. We previously demonstrated that lymphocyte CYP2E1 expression reflects in vivo activity of the hepatic enzyme. METHODS: To further validate this approach, the current investigation compared lymphocyte CYP2E1 content and chlorzoxazone pharmacokinetics in 51 alcoholic and nonalcoholic White, Navajo, and Mexican American subjects. After an oral dose of chlorzoxazone, blood samples were collected and lymphocytes isolated. RESULTS: Alcoholics exhibited a 2-fold elevation in lymphocyte CYP2E1 messenger ribonucleic acid (mRNA) and protein compared to nonalcoholics. Chlorzoxazone clearance rates were 1.9-fold higher and area under the concentration curve (AUC) values 1.8-fold lower in alcoholic individuals compared to nonalcoholics. Furthermore, chlorzoxazone clearance rates correlated (r = 0.55, p < 0.01, n = 38) with lymphocyte CYP2E1 mRNA content, and transcript levels further correlated (r = 0.52, p < 0.001, n = 38) with CYP2E1 protein content. To compare phenotype with genotype, restriction fragment length polymorphism analyses on deoxyribonucleic acid samples were performed to identify polymorphisms in the CYP2E1 gene. No subjects were homozygous for rare alleles c2 or C. Nonetheless, 27% of the Navajos and 15% of the Mexican Americans were heterozygous for the c2 allele. Two White subjects appeared heterozygous (c1/c2) when RsaI was used to characterize CYP2E1 genotype but homozygous (c1/c1) at the PstI locus. Fifteen percent of Mexican American subjects, 20% of Navajo subjects, and 6% of White subjects were heterozygous for the C allele. Neither CD nor cl/c2 genotypes were associated with alcoholism. CONCLUSIONS: Human lymphocyte CYP2E1 mRNA levels may be useful predictors of alcohol-mediated alterations in hepatic CYP2E1 activity. Moreover, ethnicity does not appear to play a major role in the levels of expression of lymphocyte CYP2E1.

Academic advising from a nursing theory perspective.

Academic advising is an important faculty role; it not only assists students in selecting appropriate courses, but it also helps them make choices about personal and career goals. Using a theoretical framework to guide the advising process can make advising sessions more efficient and effective. One nursing theory, modeling and role-modeling, is presented here as a framework for student advising. Modeling and role-modeling theory can guide the advisor to establish a caring interpersonal relationship with the student and plan individualized strategies to meet educational goals.

Ethanol-mediated transplacental induction of CYP2E1 in fetal rat liver.

We examined the potential for the widely consumed xenobiotic ethanol to transplacentally induce fetal rat CYP2E1. Throughout gestation, rat dams were fed a liquid diet containing 5% ethanol or two separate control diets. At 2 days before term, the dams were killed, and maternal and embryonic tissues were collected. Immunoblot analysis of microsomes from fetal liver, placenta and maternal brain revealed a band that comigrated with adult liver CYP2E1. The identity of the immunoreactive protein in placenta, brain and fetal liver was substantiated as CYP2E1 through restriction enzyme digestion of a reverse transcription-polymerase chain reaction product. Quantification of immunoblots containing microsomes from maternal and fetal liver of ethanol-treated dams displayed a 1.4- and 2.4-fold increase in CYP2E1, respectively, compared with microsomes from pair-fed controls. Chlorzoxazone and low substrate concentrations of N-nitrosodimethylamine were used as metabolic probes for CYP2E1. The rate of chlorzoxazone metabolism by maternal hepatic microsomes from dams fed the 5% ethanol diet was 2.6-fold greater than that of controls. Conversely, a negligible increase was observed in the rate of metabolism by hepatic microsomes from ethanol-exposed fetuses compared with pair-fed animals. When N-nitrosodimethylamine demethylation was examined, these same fetal samples exhibited greater rates of activity (1.5-fold) compared with microsomes from control animals. However, this increase was not as great as expected considering the 2.4-fold increase in CYP2E1 protein. Collectively, fetuses exposed to a 5% ethanol diet throughout gestation exhibited transplacental induction of an hepatic CYP2E1 that may possess different catalytic properties from the analogous adult enzyme.

Human lymphocyte cytochrome P450 2E1, a putative marker for alcohol-mediated changes in hepatic chlorzoxazone activity.

Cytochrome P450 (CYP) 2E1 is implicated in a variety of chemically initiated hepatotoxicities, including alcoholic liver disease. These pathological conditions arise from increased production of reactive intermediates caused by elevated enzyme concentrations. Thus, the ability to detect enhanced CYP2E1 levels would aid in identifying individuals at high risk for xenobiotic-promoted liver injury. With this in mind, the present investigation assessed in vivo chlorzoxazone metabolism and compared pharmacokinetic parameters with CYP2E1 expression in blood. Twenty-two subjects were recruited and divided into two groups, control subjects and alcohol abusers, based on responses to two screening questionnaires. Those individuals with higher survey scores, i.e. those who consumed alcohol more frequently, exhibited higher rates of chlorzoxazone metabolism. Indeed, a correlation (r = 0.66, p < 0.01) was obtained when scores were compared with the pharmacokinetic parameter AUC for chlorzoxazone. Lymphocyte microsomes isolated from blood samples obtained from these same individuals were subjected to immunoblot analyses to detect CYP2E1 levels. That lymphocytes contained CYP2E1 was confirmed by reverse transcription-polymerase chain reaction and sequence analysis of the cDNA. Quantification of immunoreactive bands revealed that levels of this P450 were 2.3-fold higher in alcoholics than in control subjects. This increase in lymphocyte CYP2E1 content in alcoholic subjects coincided with a 2.1-fold increase in chlorzoxazone clearance and a 2-fold decrease in the AUC for chlorzoxazone. Importantly, a correlation (r = 0.62, p < 0.01) was observed between CYP2E1 content in lymphocytes and chlorzoxazone clearance rates. Thus, monitoring lymphocyte CYP2E1 expression may provide a substitute for estimating hepatic activity of this P450.

The older adult. A comparative assessment.

Thorough assessment of older men and women is a complex but vital part of their health care. The ability to differentiate the changes owing to normal aging from those resulting from pathologic processes is necessary if their lives are to be as productive and enjoyable as they are prolonged. Each body system and function must be examined or tested with this difference in mind. Because aging occurs in different individuals at differing rates, a variety of functions may all be considered healthy or normal. Assessment findings must be viewed through the focus of the individual person as well as that of the population. The nurse will find opportunities to use assessment skills for older adults in many settings, ranging from independent living arrangements to institutional residential areas. In the community, social meeting places, day-care facilities, meal sites, and shopping areas are but a few of the places where older adults may be found, alone or in groups. Assessment opportunities can be identified or structured in any milieu. The setting itself, as well as the needs of the older adult(s), will help to determine the complexity of the assessment activities. The benefit to nursing of increased and expanded ability to assess the older adult is considerable. The organized concern of science and health care with aging is a relatively recent phenomenon. The older adults of today are unique--there are more of them than ever before, and they are living longer. Although their lives are not without health complications, they are, in a sense, role models for the rest of us: pathfinders in aging who can, if we observe them carefully, give us insight and direction for our own healthy aging processes and those of generations to come. Nursing is uniquely poised to use our caring methodology with the older adult. The elderly are interested in their health and willingly cooperate with those whose assessments are knowledgeable and realistic. Nursing is challenged to develop and implement advanced and specialized ways to identify and meet their needs.