Assessing the clinical significance of botanical supplementation on human cytochrome P450 3A activity: comparison of a milk thistle and black cohosh product to rifampin and clarithromycin

Phytochemical-mediated modulation of cytochrome P450 enzymes (CYPs) may underlie many herb-drug interactions. This study's purpose was to assess the effects of milk thistle and black cohosh supplementation on CYP3A activity and compare them to a clinically recognized inducer, rifampin, and inhibitor, clarithromycin. Healthy volunteers were randomly assigned to receive a standardized milk thistle (900 mg) or black cohosh (80 mg) supplement for 14 days. Subjects also received rifampin (600 mg) and clarithromycin (1000 mg) for 7 days as positive controls for CYP3A induction and inhibition, respectively. Midazolam was administered orally before and after each supplementation and control period. The effects of milk thistle, black cohosh, rifampin, and clarithromycin on midazolam pharmacokinetics were determined using noncompartmental techniques. Unlike those observed for rifampin and clarithromycin, midazolam pharmacokinetics was unaffected by milk thistle or black cohosh. Milk thistle and black cohosh appear to have no clinically relevant effect on CYP3A activity in vivo.     

Evolution of type-specific immunoassays to evaluate the functional immune response to Gardasil: a vaccine for human papillomavirus types 16, 18, 6 and 11

Epidemiological studies and clinical trials of vaccines depend on the accurate measurement of antibodies within the polyclonal response to infection or vaccination. The assay currently used to measure the antibody response to vaccination with GARDASIL [Quadrivalent Human Papillomavirus (Types 6, 11, 16, 18) Recombinant Vaccine]--a quadrivalent vaccine used against human papillomavirus (HPV) types 6, 11, 16, and 18--is a competitive Luminex assay (cLIA) that uses multiplex technology to detect type-specific neutralizing antibodies against all four HPV types in a single serum sample. Here we describe how the cLIA was developed, as well as how the monoclonal antibodies (mAbs), used as competitors in the assay, were characterized. An enzyme-linked immunosorbent assay (ELISA) was used to screen eight previously-identified mAbs for their ability to bind to HPV virus-like particles (VLPs) in a type-specific and conformation-dependent manner. Four of these mAbs, H6.M48, K11.B2, H16.V5, and H18.J4, met our specifications and were shown to have the potential to neutralize HPV infection in hemagglutination inhibition and pseudovirus neutralization assays. The competitive immunoassay format was able to distinguish type-specific antibodies in the sera of nonhuman primates vaccinated with HPV VLPs, whereas a traditional direct-bind ELISA could not. In addition, the serum antibodies measured by the competitive assay are known to be neutralizing, whereas the ELISA does not distinguish neutralizing and nonneutralizing antibodies in a serum sample. By detecting antibodies to neutralizing epitopes, the competitive assay both demonstrates sero-conversion and provides a potential functional link between sero-conversion and protective immunity in response to vaccination with GARDASIL.     

A comparative study of CYP3A4 polymorphisms in Mexican Amerindian and Mestizo populations

Cytochrome P-450 3A4 (CYP3A4) contributes to the metabolism of approximately half the drugs in clinical use today. The aim of the present study was to determine the frequency of the CYP3A4*1B, *2, *4, *5, and *18 alleles amongst both Tepehuan Amerindians, a native group that has inhabited northern Mexico for thousands of years, and Mestizo Mexicans, and to compare the data with those of other populations. Genotyping experiments revealed that 8.8 and 8.0% of the Mestizo and Tepehuano subjects, respectively, carried the CYP3A4*1B allele. Only one Mestizo subject was heterozygous for the CYP3A4*2 variant, while CYP3A4*4, *5 and *18 allelic variants were not detected in either group. On the other hand, the frequencies of the CYP3A4*1B variant in Mestizos and Tepehuanos were similar to those reported for Caucasians, but different from those observed for African and Asian populations.     

Associations of iron metabolism genes with blood manganese levels: a population-based study with validation data from animal models

Background

Given mounting evidence for adverse effects from excess manganese exposure, it is critical to understand host factors, such as genetics, that affect manganese metabolism.

Methods

Archived blood samples, collected from 332 Mexican women at delivery, were analyzed for manganese. We evaluated associations of manganese with functional variants in three candidate iron metabolism genes: HFE [hemochromatosis], TF [transferrin], and ALAD [δ-aminolevulinic acid dehydratase]. We used a knockout mouse model to parallel our significant results as a novel method of validating the observed associations between genotype and blood manganese in our epidemiologic data.

Results

Percentage of participants carrying at least one copy of HFE C282Y, HFE H63D, TF P570S, and ALAD K59N variant alleles was 2.4%, 17.7%, 20.1%, and 6.4%, respectively. Percentage carrying at least one copy of either C282Y or H63D allele in HFE gene was 19.6%. Geometric mean (geometric standard deviation) manganese concentrations were 17.0 (1.5) μg/l. Women with any HFE variant allele had 12% lower blood manganese concentrations than women with no variant alleles (β = -0.12 [95% CI = -0.23 to -0.01]). TF and ALAD variants were not significant predictors of blood manganese. In animal models, Hfe^-/- mice displayed a significant reduction in blood manganese compared with Hfe^+/+ mice, replicating the altered manganese metabolism found in our human research.

Conclusions

Our study suggests that genetic variants in iron metabolism genes may contribute to variability in manganese exposure by affecting manganese absorption, distribution, or excretion. Genetic background may be critical to consider in studies that rely on environmental manganese measurements.

     

Impact of breastfeeding on the mobilization of lead from bone

To evaluate the hypothesis that lactation stimulates lead release from bone to blood, the authors analyzed breastfeeding patterns and bone lead concentrations as determinants of blood lead levels among 425 lactating women in Mexico City for 7 months after delivery (1994-1995). The authors measured in vivo patella and tibia lead concentrations at 1 month postpartum using K x-ray fluorescence. Maternal blood samples and questionnaire information were collected at delivery and at 1, 4, and 7 months postpartum. Blood lead was analyzed using graphite furnace atomic absorption spectroscopy. Mean blood lead level at delivery was 8.4 microg/dl (range: 1.8--23.4). Mean cortical and trabecular lead levels were 10.6 microg/g (range: nondetectable to 76.5) and 15.3 microg/g (range: nondetectable to 85.9), respectively, reflecting a population with elevated and diverse past and current lead exposure. The association of bone lead and breastfeeding with blood lead was estimated using generalized estimating equations. Breastfeeding practices and maternal bone lead were important predictors of blood lead level. After adjustment for bone lead and environmental exposure, women who exclusively breastfed their infants had blood lead levels that were increased by 1.4 microg/dl and women who practiced mixed feeding had levels increased by 1.0 microg/dl, in relation to those who had stopped lactation. These results support the hypothesis that lactation is directly related to the amount of lead released from bone.     

Childhood cancer and agricultural pesticide use: an ecologic study in California

We analyzed population-based childhood cancer incidence rates throughout California in relation to agricultural pesticide use. During 1988-1994, a total of 7,143 cases of invasive cancer were diagnosed among children under 15 years of age in California. Building on the availability of high-quality population-based cancer incidence information from the California Cancer Registry, population data from the U.S. Census, and uniquely comprehensive agricultural pesticide use information from California's Department of Pesticide Regulation, we used a geographic information system to assign summary population, exposure, and outcome attributes at the block group level. We used Poisson regression to estimate rate ratios (RRs) by pesticide use density adjusted for race/ethnicity, age, and sex for all types of childhood cancer combined and separately for the leukemias and central nervous system cancers. We generally found no association between pesticide use density and childhood cancer incidence rates. The RR for all cancers was 0.95 [95% confidence interval (CI), 0.80-1.13] for block groups in the 90th percentile and above for use of pesticides classified as probable carcinogens, compared to the block groups with use of < 1 lb/mi(2). The RRs were similar for leukemia and central nervous system cancers. Childhood leukemia rates were significantly elevated (RR = 1.48; 95% CI, 1.03-2.13) in block groups with the highest use of propargite, although we saw no dose-response trend with increasing exposure categories. Results were unchanged by further adjustment for socioeconomic status and urbanization.     

Policies and opportunities for physical activity in middle school environments

BACKGROUND: This study examined physical activity opportunities and barriers at 36 geographically diverse middle schools participating in the Trial of Activity for Adolescent Girls. METHODS: Principals, physical education and health education department heads, and program leaders were interviewed to assess policies and instructional practices that support physical activity. RESULTS: Schools provided approximately 110 hours per year in physical education instruction. Approximately 20% of students walked or bicycled to school. Eighty-three percent of schools offered interscholastic sports and 69% offered intramural sports. Most schools offered programs for girls, but on average, only 24 girls ( approximately 5%) in the schools attended any programs. Only 25% of schools allowed after school free play. An overall score created to assess school environmental support for physical activity indicated that, on average, schools met 6.7 items of 10 items. Free/reduced lunch program participation versus not (p = .04), perceived priority of physical education instruction over coaching (p = .02), and safety for walking/bicycling to school (p = .02) predicted environmental support score. CONCLUSIONS: Schools have policies and practices that support physical activity, although unfavorable practices exist. Schools must work with community partners and officials to provide environments that optimally support physical activity, especially schools that serve low-income students.     

Promising outcomes in teen mothers enrolled in a school-based parent support program and child care center

BACKGROUND: This study described a cohort of teen mothers and their children attending an urban high school with a parent support program and school-based child care center. Specific aims of the study were to describe maternal characteristics and outcomes, and child developmental and health outcomes. METHODS: A volunteer sample of 65 adolescent mothers enrolled in the parent support program and their children were interviewed, surveyed, and assessed. Fifty-three mothers had children enrolled in the school-based child care center and 12 mothers had their children cared for by family members. Maternal characteristics assessed included self-esteem and depressive symptoms, social stressors and support, self-perceived parental competence, parent-child teaching interactions, and subsequent childbearing and maternal educational outcomes. Child outcomes included child developmental assessments and health outcomes. RESULTS: About 33% of teen mothers were mildly to moderately depressed and 39% of the sample had experienced transitional homelessness. Social support networks were small; in the past 12 months, mothers experienced a mean number of 13.2 +/- 11.9 negative life events. Maternal self-report measures and mother-child observation measures indicated positive levels of parental competence. Maternal educational outcomes were positive, and only 6% of mothers had subsequent childbirths within 2 years. The mean scores on developmental assessments of children fell within the normal range, although there were 7 children identified with developmental delays. CONCLUSIONS: For at-risk teen mothers, this parent support program and school-based child care setting appears to offer promising opportunities to help young mothers with parenting, avoid rapid subsequent pregnancies, and stay engaged with school, while their children are cared for in a close and safe environment.     

Comparison of gestational age classifications: date of last menstrual period vs. clinical estimate

PURPOSE: The purpose was to compare the two different measures of gestational age currently used on birth certificates (the duration of pregnancy based on the date of last menstrual period [LMP] and the clinical estimate [CE] as related to health status indicators. We contrasted these measures by race/ethnicity. METHODS: NCHS natality files for 2000-2002 were used, selecting cases of single live birth to U.S. resident mothers with both LMP and CE gestational age information. RESULTS: Approximately 75% of the records had valid LMP and CE values and for approximately one-half of these, the LMP and CE values did not exactly agree. Overall and for each race and ethnic group, the LMP measures resulted in higher proportions of very preterm, preterm, postterm and SGA births. CE value provided preterm rates of 7.9% and for LMP, 9.9%. The odds ratio of preterm birth for African-Americans using the CE measure was 1.78 [95% Cl 1.77-1.79]. The odds ratio using LMP was 1.93 [95% Cl 1.92-1.94]. Whites were the referent population. CONCLUSIONS: Different measures of gestational age result in different overall and race-specific rates of very preterm, preterm, postterm, and SGA births. These findings indicate that substituting or combining these measures may have consequences.     

Use of Enthalpy and Gibbs Free Energy to Evaluate the Risk of Amorphous Formation

The control of crystalline and amorphous phases is important during the development of a new drug candidate. Our approach begins with an understanding of the thermodynamics of these two phases. We have developed a quantitative yet practical work flow consisting of three steps towards the analysis of the risk of amorphous material formation. First, we derive the thermodynamic equations to calculate the enthalpy, Gibbs free energy, and the solubility of each phase and their differences as a function of temperature. The enthalpy for each crystalline drug substance at its melting point is selected as the reference state to enable a consistent approach for all analysis. Second, we use data from DSC measurements and the derived thermodynamic equations to construct the enthalpy, Gibbs free energy and solubility diagrams so as to compare the characteristics of these two phases. Finally, we use the results of these calculations to evaluate the potential risk of crystalline-to-amorphous phase conversion during processing of either the drug substance or the drug product. In addition, the impact of amorphous formation on solubility is evaluated. Two drug candidates are used to illustrate this workflow for risk analysis. © 2010 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:4096–4105, 2010