Publications

OBJECTIVE

Nevirapine is an important component of highly active antiretroviral therapy used in the treatment of HIV infection. There is a considerable variation in the pharmacokinetics of nevirapine and this variation can impact the efficacy and toxicity of nevirapine. Although some of this variation can be attributed to environmental factors, the degree to which heritability influences nevirapine pharmacokinetics is unknown. This study aims to estimate how much variation in nevirapine pharmacokinetics is due to genetic factors and to investigate the contribution of selected polymorphisms to this variability.

METHODS

Two doses of immediate-release nevirapine were administered to European (n=11) and African American (n=6) participants recruited from the Research in Access to Care in the Homeless cohort. A repeated drug administration method was then used to determine the relative genetic contribution (r(GC)) to variability in nevirapine AUC(0-6 h). Nevirapine plasma levels were quantified using LC/MS/MS. Patients were also genotyped for selected polymorphisms in candidate genes that may influence nevirapine pharmacokinetics.

RESULTS

A significant r(GC) for nevirapine AUC(0-6 h) was found in Europeans (P=0.02) and African Americans (P=0.01). A trend toward higher nevirapine AUC(0-6 h) for the CYP2B6 516TT (rs3745274; Q172H) genotype was observed in European Americans (P=0.19).

CONCLUSION

This study demonstrates that there is a significant genetic component to variability in nevirapine pharmacokinetics. Although genetic variants such as CYP2B6 polymorphisms attributed to some of this variation, these data suggest that there may be additional genetic factors that influence nevirapine pharmacokinetics.

Air pollution has been found to cause significant global mortality, with 6.8 million excess deaths attributed to air pollution each year, and similarly large numbers of exacerbations of asthma, chronic obstructive pulmonary disease, and cardiovascular diseases. Epidemiological research has identified associations, and experimental human exposure has provided critical information on dose-response relationships of adverse effects caused by controlled human exposure to individual pollutants. Human exposures further enable examination of the relationship of adverse effects such as symptoms and pulmonary function changes to presumed mechanisms of disease revealed through analysis of bronchoalveolar lavage fluid obtained from the lower respiratory tract. In this Perspective, we analyze the ethics of human exposure, the importance of the information gained, and the risks of such exposure. We find that these studies appear to have been done with proper approval of institutional review boards, were done with informed consent from the participants, and have rarely been associated with serious adverse events.

BACKGROUND

Efforts to curb healthcare spending have included interventions that target frequently hospitalized individuals. It is unclear the extent to which the most frequently hospitalized individuals also represent the costliest individuals.

OBJECTIVE

To examine the relationship between 2 types of "high users" commonly targeted in cost-containment interventions-those incurring the highest hospital costs ("high cost") and those incurring the highest number of hospitalizations ("high admit").

DESIGN, SETTING, AND PATIENTS

Cross-sectional study of 2566 individuals with a primary care physician and at least 1 hospitalization within an academic health system from 2010 to 2011.

MEASUREMENTS

Overlap between the population constituting the top decile of hospital costs and the population constituting the top decile of hospitalizations; characteristics of the 3 resulting high user subgroups.

RESULTS

Only 48% of individuals who were high cost (>$65,000) were also high admit (≥ 3 hospitalizations). Compared to hospitalizations incurred by high cost-high admit individuals (n = 605), hospitalizations incurred by high cost-low admit individuals (n = 206) were more likely to be for surgical procedures (58 vs 22%, P < 0.001), had a higher cost ($68,000 vs $28,000, P < 0.001), longer length of stay (10 vs 5 days, P < 0.001), and were less likely to be a 30-day readmission (17 vs 47%, P < 0.001).

CONCLUSIONS

Stratifying high admit individuals by costs and high cost individuals by hospitalizations yields 3 distinct high user subgroups with important differences in clinical characteristics and utilization patterns. Consideration of these distinct subgroups may lead to better-tailored interventions and achieve greater cost savings.

BACKGROUND

Current knowledge of racial disparities in healthcare utilization and disease outcomes for ulcerative colitis (UC) is limited. We sought to investigate these differences among Caucasian, African American, Asian, and Hispanic patients with ulcerative colitis in Kaiser Permanente, a large integrated health-care system in Northern California.

METHODS

This retrospective cohort study used computerized clinical data from 5,196 Caucasians, 387 African-Americans, 550 Asians, and 801 Hispanics with prevalent UC identified between 1996 and 2007. Healthcare utilization and outcomes were compared at one and five-year follow-up by use of multivariate logistic regression analysis.

RESULTS

Compared with whites, the male-to-female ratio differed for African-Americans (0.68 vs. 0.91, p < 0.01) and Asians (1.3 vs. 0.91, p < 0.01). Asians had fewer co-morbid conditions (p < 0.01) than whites, whereas more African-Americans had hypertension and asthma (p < 0.01). Use of immunomodulators did not differ significantly among race and/or ethnic groups. Among Asians, 5-ASA use was highest (p < 0.05) and the incidence of surgery was lowest (p < 0.01). Prolonged steroid exposure was more common among Hispanics (p < 0.05 at 1-year) who also had more UC-related surgery (p < 0.01 at 5-year) and hospitalization (<0.05 at 5-year), although these differences were not significant in multivariate analysis.

CONCLUSIONS

In this population of UC patients with good access to care, overall health-care utilization patterns and clinical outcomes were similar across races and ethnicity. Asians may have milder disease than other races whereas Hispanics had a trend toward more aggressive disease, although the differences we observed were modest. These differences may be related to biological factors or different treatment preferences.

The SecA2 proteins are a special class of transport-associated ATPases that are related to the SecA component of the general Sec system, and are found in an increasingly large number of Gram-positive bacterial species. The SecA2 substrates are typically linked to the cell wall, but may be lipid-linked, peptidoglycan-linked, or non-covalently associated S-layer proteins. These substrates can have a significant impact on virulence of pathogenic organisms, but may also aid colonization by commensals. The SecA2 orthologues range from being highly similar to their SecA paralogues, to being distinctly different in apparent structure and function. Two broad classes of SecA2 are evident. One transports multiple substrates, and may interact with the general Sec system, or with an as yet unidentified transmembrane channel. The second type transports a single substrate, and is a component of the accessory Sec system, which includes the SecY paralogue SecY2 along with the accessory Sec proteins Asp1-3. Recent studies indicate that the latter three proteins may have a unique role in coordinating post-translational modification of the substrate with transport by SecA2. Comparative functional and phylogenetic analyses suggest that each SecA2 may be uniquely adapted for a specific type of substrate. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey.