Susan N. Pusek

Hepatic gene expression during treatment with peginterferon and ribavirin: Identifying molecular pathways for treatment response.

The reasons for hepatitis C treatment failure remain unknown but may be related to different host responses to therapy. In this study, we compared hepatic gene expression in patients prior to and during peginterferon and ribavirin therapy. In the on‐treatment group, patients received either ribavirin for 72 hours prior to peginterferon alpha‐2a injection or peginterferon alpha‐2a for 24 hours, prior to biopsy. The patients were grouped into rapid responders (RRs) with a greater than 2‐log drop and slow responders (SRs) with a less than 2‐log drop in hepatitis C virus RNA by week 4. Pretreatment biopsy specimens were obtained from a matched control group. The pretreatment patients were grouped as RRs or SRs on the basis of the subsequent treatment response. Gene expression profiling was performed with Affymetrix microarray technology. Known interferon‐stimulated genes (ISGs) were induced in treated patients. In the pretreatment group, future SRs had higher pretreatment ISG expression than RRs. On treatment, RRs and SRs had similar absolute ISG expression, but when it was corrected for the baseline expression with the pretreatment group, RRs showed a greater fold change in ISGs, whereas SRs showed a greater change in interferon (IFN)‐inhibitory pathways. The patients pretreated with ribavirin had heightened induction of IFN‐related genes and down‐regulation of genes involved in IFN inhibition and hepatic stellate cell activation. Conclusion: These data suggest that ISG inducibility is important for the treatment response and that ribavirin may improve outcomes by enhancing hepatic gene responses to peginterferon. Collectively, these mechanisms may provide a molecular basis for the improved efficacy of combination therapy. (HEPATOLOGY 2007.)

Variation in oral clearance of saquinavir is predicted by CYP3A5*1 genotype but not by enterocyte content of cytochrome P450 3A5

Saquinavir, a widely prescribed human immunodeficiency virus 1 protease inhibitor, has a low and variable oral bioavailability that has been attributed to extensive first‐pass extraction mediated by hepatic or intestinal cytochrome P450 (CYP) 3A4 and intestinal P‐glycoprotein (P‐gp). The polymorphic CYP3A5 has also been shown to influence the saquinavir metabolite/parent urinary ratio, suggesting a role for CYP3A5.

Infection Risk Factors in Febrile, Neutropenic Children and Adolescents

We studied 276 fever episodes with an absolute neutrophil count (ANC) < 500/mm3 to determine patient characteristics predicting serious infection. Infections occurred in 38% of patients. Blood cultures were positive in 58% of documented infections. There was no difference in the rates of infection or positive blood culture when ANC was < 200/mm3 compared with a higher ANC. However, certain high risk infections were more common with an ANC < 200/ mm3. Leukemia patients had more infections compared with other groups. Serious infections were more common during induction therapy or relapse. Infection incidence varied significantly with patient age and onset of fever in the inpatients. Less than one fifth of febrile neutropenic episodes had no risk features for serious infection. We conclude that several clinical characteristics correlate with serious infection in febrile, neutropenic children and adolescents receiving modern supportive care. Despite improvements in supportive care measures, most febrile, neutropenic patients need close observation and empiric intravenous antibiotic therapy.

Launching a new fellowship for medical students: the first years of the Doris Duke Clinical Research Fellowship Program.

As part of its commitment to increasing the pipeline of physicians pursuing careers in clinical research, the Doris Duke Charitable Foundation launched the Doris Duke Clinical Research Fellowship (CRF) Program for medical students in 2000. The program, which is based at 10 US medical schools, provides medical students from any US medical school with the opportunity to spend 1 year obtaining both didactic and “hands-on” mentored clinical research experience. This article describes the program and summarizes the early outcomes collected during the first 3.5 years of the program. Interest in the program among medical students has been robust and widespread, with 35% of CRF program fellows matriculated at non-CRF schools. Exit surveys of the first three classes of fellows totaling 174 fellows indicated that (1) 97% of the fellows felt that participating in the fellowship was a good decision; (2) commitment to a career in clinical research was increased among the 44% of fellows reporting that they were unsure about pursuing a clinical research career when they began their fellowship; (3) there was no difference in satisfaction level between the fellows who remained at the medical schools in which they were matriculated and those who completed their fellowship at a medical school in which they were not matriculated; and (4) the majority of fellows responded that the didactic component of their fellowship was useful.

The influence of CYP3A5 expression on the extent of hepatic CYP3A inhibition is substrate-dependent: an in vitro-in vivo evaluation.

Despite several studies suggesting that CYP3A5 expression can influence the extent of hepatic CYP3A-mediated inhibition, a systematic in vitro-in vivo evaluation of this potential clinically important issue has not been reported. Using representative probes from two distinct CYP3A substrate subgroups (midazolam, erythromycin), the inhibitory potency of fluconazole was evaluated in pooled human liver microsomes (HLM) with a low or high specific CYP3A5 content, in recombinant CYP3A enzymes (rCYP3A), and in healthy volunteers lacking or carrying the CYP3A5*1 allele. Fluconazole was a slightly more potent inhibitor of CYP3A activity in CYP3A5-HLM than in CYP3A5+ HLM with midazolam (Ki of 15 and 25 μM, respectively) but not with erythromycin (IC50 of 70 and 54 μM, respectively). In comparison, fluconazole was a much more potent inhibitor of rCYP3A4 than rCYP3A5 with both midazolam (Ki of 7.7 and 54 μM, respectively) and erythromycin (IC50 of 100 and 350 μM, respectively). As predicted from HLM, with i.v. midazolam, the average (± S.D.) in vivo Ki (Ki,iv) was significantly higher in CYP3A5*1 carriers (24 ± 17 and 17 ± 8 μM for homozygous and heterozygous groups, respectively) than in noncarriers (13 ± 6 μM) (p = 0.02). With the erythromycin breath test, the average Ki,iv was not different between homozygous CYP3A5*1 carriers (30 ± 12 μM) and noncarriers (58 ± 53 μM). In conclusion, the effect of CYP3A5 on hepatic CYP3A-mediated inhibitory drug-drug interactions is substrate-dependent, and HLM, rather than rCYP3A, are the preferred in vitro system for predicting these interactions in vivo.

Clinical and Translational Scientist Career Success: Metrics for Evaluation

Despite the increased emphasis on formal training in clinical and translational research and the growth in the number and scope of training programs over the past decade, the impact of training on research productivity and career success has yet to be fully evaluated at the institutional level. In this article, the Education Evaluation Working Group of the Clinical and Translational Science Award Consortium introduces selected metrics and methods associated with the assessment of key factors that affect research career success. The goals in providing this information are to encourage more consistent data collection across training sites, to foster more rigorous and systematic exploration of factors associated with career success, and to help address previously identified difficulties in program evaluation. Clin Trans Sci 2012; Volume 5: 400–407

The Environmental Polymorphisms Registry: a DNA resource to study genetic susceptibility loci.

The National Institute of Environmental Health Sciences is establishing a DNA repository named the Environmental Polymorphisms Registry (EPR). The goal is to recruit 20,000 subjects from the greater Research Triangle Park region of North Carolina and collect a sample of each subject’s DNA for genetic study. Personal information is obtained from each EPR subject and linked to their sample in coded form. Once individuals with the genotypes of interest are identified, their samples are decoded, and their names and contact information are given to scientists for follow-up studies in which genotype is important. “Recruit-by-genotype” resources such as the EPR require a transparent consent process and rigorous human subjects protection measures. Unlike the EPR, most US DNA resources are anonymous. Once scientists identify potentially significant genetic variants, they must screen new populations to find individuals with the variants of interest to study. The EPR eliminates this time consuming and expensive step. In designing the EPR, consideration was given to achieving high response rates, minimizing attrition and maximizing usefulness for future research studies. Subjects are recruited from outpatient clinics in area medical centers as well as from the general population to ascertain individuals in diverse states of health. Data are collected on race, ethnicity, gender and age, and are monitored for demographic diversity. As of November 2007, 7,788 individuals have been recruited into the EPR and their DNA samples have been used in numerous genetic studies. EPR subjects have also been solicited for several follow-up studies with high response rates (>90%). The success of the EPR based on the number of subjects recruited and genetic studies underway, suggests that it will be a model for future DNA resources.

Factors that influence the timing of spontaneous labor at term.

Objective. Whether pre-term birth culminates as a result of a de novo pathologic process or is more simply early activation of physiologic mechanisms is unknown. Exploration of the onset of labor in term women with classical risk factors for early delivery might provide insights into the mechanisms leading to pre-term birth. This study examines whether sociodemographic factors known to increase the risk of pre-term birth also affect the length of term gestations. Methods. From a large prospective cohort composed of women delivering from 1995–2000, a sample was selected of 441 women from Central North Carolina, US, who delivered singletons after 37 weeks gestation. An algorithm was designed to identify induced labors and gestational age was censored at the time of induction. Gestational age was assigned by sonography and menstrual dating. Data were analysed using the Cox proportional hazards model. The main outcome measure was time to spontaneous labor. Results. Women with ≥12 years of education had longer periods of gestation than women with less than 12 years of education, HR = 0.57 [0.39, 0.84]. Shorter gestational periods were found for women with pre-term premature rupture of membranes (PPROM) in a previous pregnancy, HR = 3.70 [1.60, 8.52], even after adjusting for confounders. Smoking was not associated (p > 0.1) with the timing of labor at term. Conclusions. By studying the timing of spontaneous parturition at term we identified that there is little overlap in risk factors that affect timing of delivery between spontaneous term and pre-term births.

A Model for Developing, Evaluating, and Disseminating Best Practices in Education and Training

With the shift toward team‐based translational science came recognition that existing strategies for training individual investigators and retaining them in the biomedical workforce would be inadequate. To support this shift, it is important to: develop innovative strategies to educate and train diverse members of research teams; evaluate those programs; and disseminate best practices broadly. We have developed a four‐phase model to facilitate the development, evaluation, and widespread dissemination of innovative strategies to train the biomedical research workforce. Phase I (Innovate) involves small scale trials of programs to address perceived training needs or new methods of delivery. Phase II (Incubate) refines and evaluates promising Phase I activities on a larger scale. Phase III (Translate) seeks to replicate initial successes either locally (Phase IIIa) or with other interested institutions (Phase IIIb). Phase IV (Disseminate) assesses whether identified local best practices can have success on a broader scale. We present specific examples from our own experience that demonstrate the utility of this model, and then conclude with opportunities and challenges related to the education and training of this workforce.