Impact of GGCX, STX1B and FPGS Polymorphisms on Warfarin Dose Requirements in European-Americans and Egyptians

Genotype-based algorithms that include VKORC1 and CYP2C9 genotypes are less predictive of warfarin dose variability in Africans as opposed to Europeans. Polymorphisms in GGCX, FPGS, or STX1B are associated with warfarin dose requirements in African-Americans. We sought to determine if they influenced warfarin dose in European-Americans, and another African population, specifically Egyptians. We genotyped 529 adults (n = 325 European-Americans, 204 Egyptians) on a stable warfarin dose for GGCX rs12714145 and rs10654848, FPGS rs7856096, and STX1B rs4889606. Rs12714145, rs10654848, and rs7856096 were not associated with warfarin dose, whereas STX1B rs4889606 was a significant determinant in univariate analysis (P < 0.0001) in both cohorts. However, STX1B rs4889606 was in high linkage disequilibrium with VKORC1-1639 G>A, and was no longer significant after including VKORC1-1639 G>A in the regression model. Based on these data, the polymorphisms do not appear to influence, in a clinically important way, warfarin dose requirements in European-Americans and Egyptians.

Repair of sacral fractures using pins and polymethylmethacrylate (six cases)

CASE REPORTS

Sacral fracture repair was accomplished in a cat and five dogs using a composite technique consisting of pins and polymethylmethacrylate (PMMA). In three of the cases, planned traditional iliosacral lag screw fixation was either abandoned or considered inadequate and in the other three, fracture configuration demanded an alternate repair method. All six cases healed uneventfully with no surgery-associated complications. To the author's knowledge, the use of a composite technique has been previously described for vertebral fracture repair, but not in the stabilisation of sacral fractures. Indications for the composite technique include failed iliosacral lag screw repairs, augmentation of a tenuous repair and any sacral fracture configuration not amenable to lag screw fixation.

CONCLUSION

Composite repair is a versatile primary, ancillary or revision technique for sacral fracture fixation.

Abstract 701: A novel class of Ras selective inhibitors

Despite the fact that activating mutations in the various forms of Ras were identified as driving factors in oncogenesis over thirty years ago, there are still no effective therapeutics which act on this target. We recently synthesized and characterized a novel class of compounds that show striking potency and selectivity to inhibit the growth of tumor cells with mutant Ras. Through iterative structure-activity studies, we selected for and optimized Ras selectivity to achieve high potency with IC50 values in the low nanomolar range and selectivity indices of nearly 100-fold. For example, ADT-062 inhibited the growth of human HCT116 colon tumor cells that harbor mutant K-Ras with an IC50 value of 8.4 + 3.6 nM,. In contrast, human HT29 colon tumor cells that have wild type Ras displayed an IC50 value of 521 + 253 nM in response to ADT-062 treatment. When surveying a larger panel of colon tumor cell lines, we observed a direct correlation between potency and Ras activation status. Further, ADT-062 induced cell cycle arrest only in the Ras-mutant cell line. To study the mechanism by which this class of compounds selectively inhibits the growth of tumor cells with mutant K-Ras, we profiled lysates from treated HCT116 and HT29 colon tumor cells using high resolution LC-MS/MS. Over 100 ions were identified that were differentially affected by treatment with ADT-062 at its IC50 value in the respective cell line. Among the ions of interest, a component of the purine biosynthetic pathway, 5′-phosphoribosyl-N-formylglycinamide (FGAR), was found to be induced 200-fold (p = .0031) in K-Ras mutant cells compared with Ras wild type cells. Together, these findings suggest that this compound may cause a Ras selective disruption of purine metabolism and cell cycle progression which contributes to the selectivity by which this novel class of compounds inhibit the growth of tumor cells with mutant Ras. These findings may enable us to develop this compound class as a novel therapeutic which targets Ras driven tumors and tumors which may become resistant to other targeted therapeutics through secondary Ras mutations.

Citation Format: Joshua C. Canzoneri, Xi Chen, Adam B. Keeton, Kevin Lee, Bernard Gary, Ethan B. Butler, William E. Grizzle, Landon Wilson, Stephen Barnes, Michael R. Boyd, Gary A. Piazza. A novel class of Ras selective inhibitors. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 701. doi:10.1158/1538-7445.AM2015-701

Parasite management extension - challenging traditional practice through adoption of a systems approach

The drivers for anthelmintic use today are substantial and anthelmintic use has become an embedded normalised behaviour. The cheapness and easy availability of anthelmintic products has meant that New Zealand farmers have had access to easy "solutions" for dealing with parasites and minimal forward planning or system redesign has been required. Despite 30 years of messaging about the emerging issue of anthelmintic resistance, management to reduce parasitism and the need to change behaviour, farmer practice has largely remained unchanged. Traditional approaches to extension, particularly around parasite management, appear to have been quite ineffective, apart from encouraging change in anthelmintic products and a switch to use of anthelmintics in combination. More effective approaches are required. The evolving nature of anthelmintic resistance and sustainable management of parasitism require attitudes, knowledge and behaviour to change. This is a challenge for all players in the industry; researchers, manufacturers and sellers, advisors and farmers. Looking beyond agriculture to the health sector provides some insight into models of decision making and behaviour change that can inform future strategies. Features in the health belief model including concepts of self-efficacy and cues to action appear to align with the issues, challenges and culture prevailing in farming, and parasite management in particular. Programmes through which farmers have made substantial beneficial behaviour change and the lessons learnt are discussed. Effecting consistent behaviour change around parasite management will involve new approaches by all participants in the process. And the process itself also needs to change. It requires an understanding of whole-farm systems, and the consideration of all the sources of influence on the farmer and the other participants in the process. The process of knowledge sharing involving the farmer should be based on equality; each person in the process brings their own expertise and knowledge and that needs to be valued and integrated into new practices. In effect, a multi-disciplinary team approach is required through which knowledge is shared and developed, confidence and understanding is developed, practice and behaviour is reflected on and positive behaviours are given affirmation.

Peroxiredoxin-2 recycling is inhibited during erythrocyte storage

AIMS

Transfusion with stored red blood cells (RBCs) is associated with increased morbidity and mortality. Peroxiredoxin-2 (Prx-2) is a primary RBC antioxidant that limits hydrogen peroxide (H2O2)-mediated toxicity. Whether Prx-2 activity is altered during RBC storage is not known.

RESULTS

Basal and H2O2-induced Prx-2 activity was measured in RBCs (stored for 7-35 days). Basal Prx-2 thiol oxidation increased with RBC age, whereas H2O2-dependent formation of dimeric Prx-2 was similar. However, reduction of Prx-2 dimers to monomers became progressively slower with RBC storage, which was associated with increased H2O2-induced hemolysis. Surprisingly, no change in the NADPH-dependent thioredoxin (Trx)/Trx-reductase system, which recycles dimeric Prx-2, was observed in stored RBCs. Using mouse RBCs expressing human wild type (β93Cys) or hemoglobin (Hb) in which the conserved β93Cys residue is replaced by Ala (β93Ala), a role for this thiol in modulating Prx-2 reduction was demonstrated. Specifically, Prx-2 recycling was blunted in β93Ala RBC, which was reversed by carbon monoxide-treatment, suggesting that heme autoxidation-derived H2O2 maintains Prx-2 in the oxidized form in these cells. Moreover, assessment of the oxidative state of the β93Cys in RBCs during storage showed that while it remained reduced on intraerythrocytic Hb in stored RBC, it was oxidized to dehydroalanine on hemolyzed or extracellular Hb.

INNOVATION

A novel mechanism for regulated Prx-2 activity in RBC via the β93Cys residue is suggested.

CONCLUSION

These data highlight the potential for slower Prx-2 recycling and β93Cys oxidation in modulating storage-dependent damage of RBCs and in mediating post-transfusion toxicity.

Improved high sensitivity analysis of polyphenols and their metabolites by nano-liquid chromatography-mass spectrometry

This study was conducted to assess the value of a high resolution, high mass accuracy time-of-flight analyzer in combination with nanoliquid chromatography for the analysis of polyphenols and their metabolites. The goal was to create a method that utilizes small volumes of biological fluids and provides a significant improvement in sensitivity compared with existing methods. Accordingly, nanoLC-MS and nanoLC-pseudo-multiple reaction monitoring (MRM) methods were developed that had a lower limit of quantification of 0.5 nM for several polyphenols and were linear over 2-3 orders of magnitude (R(2)>0.999). Using urine samples, the ability to observe and quantify polyphenols in such a complex biological fluid depended on much narrower mass windows (0.050 amu or less) on a TOF analyzer than those used on a quadrupole analyzer (0.7 amu). Although a greater selectivity was possible with the low mass resolution of a triple quadrupole instrument using the MRM approach, for the daidzein metabolite O-DMA, a chromatographically resolvable second peak could only be substantially reduced by using a 0.01 amu mass window. The advantage of a TOF analyzer for product ion data is that the whole MSMS spectrum is collected at high mass accuracy and MRM experiments are conducted in silico after the analysis.

Predicting utility scores for prostate cancer: mapping the Prostate Cancer Index to the Patient-Oriented Prostate Utility Scale (PORPUS)

BACKGROUND

The Prostate Cancer Index (PCI) is a health profile instrument that measures health-related quality of life with six subscales: urinary, sexual, and bowel function and bother. The Patient-Oriented Prostate Utility Scale (PORPUS-U) measures utility (0=dead and 1=full health). Utility is a preference-based approach to measure health-related quality of life, required for decision analyses and cost-effectiveness analyses. We developed a function to estimate PORPUS-U utilities from PCI scores.

METHODS

The development data set included 676 community-dwelling prostate cancer (PC) survivors who completed the PCI and PORPUS-U by mail. We fit three linear regression models: one used original PORPUS-U scores and two used log-transformed PORPUS-U scores, one with a hierarchy constraint and one without. The model selection was performed using stepwise selection and fivefold cross validation. The validation data included 248 PC outpatients with three assessments on the PCI and PORPUS-U. Scores were retransformed for validation, with Duan's smearing estimator applied to correct potential bias. The predictive ability of the models was assessed with R(2), root mean square error (RMSE) and by comparing predicted and observed utilities.

RESULTS

The best-fitting model used the log-transformed PORPUS-U with no hierarchy constraint. The R(2) was 0.72. The RMSE ranged from 0.040 to 0.061 for the three validation data sets. Differences between predicted and observed utilities ranged from 0.000 to 0.006 but predicted utilities overestimated the lowest 5% of observed PORPUS-U scores and underestimated the highest observed scores.

CONCLUSIONS

Our algorithm can calculate PORPUS-U utility scores from PCI scores, thus supplementing descriptive quality of life measures with utility scores in PC patients. Utilities derived from mapping algorithms are useful for assigning utility to groups of patients but are less accurate at predicting utility of individual patients. We are exploring statistical methods to improve the mapping of utilities from descriptive instruments.

Immunogenicity of quadrivalent human papillomavirus vaccine in organ transplant recipients

Solid organ transplant recipients are at risk of morbidity from human papillomavirus (HPV)-related diseases. Quadrivalent HPV vaccine is recommended for posttransplant patients but there are no data on vaccine immunogenicity. We determined the immunogenicity of HPV vaccine in a cohort of young adult transplant patients. Patients were immunized with three doses of quadrivalent HPV vaccine containing viral types 6, 11, 16 and 18. Immunogenicity was determined by type-specific viral-like protein ELISA. Four weeks after the last dose of vaccine, a vaccine response was seen in 63.2%, 68.4%, 63.2% and 52.6% for HPV 6, 11, 16 and 18, respectively. Factors that led to reduced immunogenicity were vaccination early after transplant (p = 0.019), having a lung transplant (p = 0.007) and having higher tacrolimus levels (p = 0.048). At 12 months, there were significant declines in antibody titer for all HPV types although the number of patients who remained seropositive did not significantly differ. The vaccine was safe and well tolerated. We show suboptimal immunogenicity of HPV vaccine in transplant patients. This is important for counseling patients who choose to receive this vaccine. Further studies are needed to determine an optimal HPV vaccine type and schedule for this population.