Efficacy of a Nonpathogenic Acidovorax citrulli Strain as a Biocontrol Seed Treatment for Bacterial Fruit Blotch of Cucurbits

Bacterial fruit blotch (BFB), caused by the seedborne, gram-negative bacterium Acidovorax citrulli, is a serious threat to cucurbit seed and fruit production worldwide. Because of the lack of effective management strategies, we investigated the efficacy of a nonpathogenic A. citrulli strain as a biological control seed treatment for BFB. For this study, we generated a type III secretion system mutant of A. citrulli, AAC00-1ΔhrcC, that was nonpathogenic on watermelon but retained its ability to colonize germinating watermelon seed. With watermelon seed naturally infested with A. citrulli, AAC00-1ΔhrcC reduced BFB seedling transmission by 81.8% relative to control seed. In comparison, another A. citrulli antagonist, A. avenae strain AAA 99-2, reduced BFB seedling transmission by 74.6% for seed samples from the same lot. Additionally, when female watermelon blossoms were protected with AAC00-ΔhrcC and subsequently challenged with AAC00-1, the resulting seedlots displayed 8% BFB seedling transmission. This was not significantly different than seed from blossoms protected with AAA 99-2 (4%) but significantly less than those from blossoms protected with 0.1 M phosphate-buffered saline (36%). These results suggest that nonpathogenic A. citrulli has potential as a biological control seed treatment component in a comprehensive BFB management program.

Cancer antigen 125 in ovarian cancer surveillance: a decision analysis model

We used decision analysis techniques with Markov cohort modeling to examine the role of cancer antigen 125 (CA-125) in follow-up surveillance strategies among patients with advanced ovarian cancer. Utilities were derived from a societal perspective.

Using quality-adjusted life years (qalys) as the outcome variable, the value of CA-125 monitoring for asymptomatic women with ovarian cancer was found to be reduced as compared with a strategy that includes CA-125 testing. Decisions to include CA-125 in surveillance strategies for ovarian cancer patients should be made after discussion with full disclosure of the preference-sensitive nature of CA-125. The model demonstrates that preferences and perspective can influence decisions in cancer care.

A Computational Fluid Dynamic (CFD) Tool for Optimization and Guided Implantation of Biomedical Devices

We are developing computational tools to perform virtual surgeries under physiological conditions with patient-specific anatomies. Virtual surgery can revolutionize the biomedical device (BMD) design and implantation by: enabling the optimization of BMD on the specific patient's anatomy and flow conditions, which has already been shown to significantly affect the hemodynamics; and facilitating surgical planning to select the best location/orientation for BMD implantation. As shown by past research the difference in the implantation, for example, of a bileaflet mechanical heart valve (BMHV) can affect the performance and hemodynamics of the valve. We have developed a powerful CFD tool that can simulate the blood flow through biomedical devices with moving boundaries and the fluid-structure interaction (FSI) under physiologic conditions. This tool has been tested in different applications with complex anatomic configurations, such as aneurysm hemodynamics, Fontan surgeries, and BMHV flows. The FSI simulations of a BMHV flow was validated against in vitro experiments and could capture all the flow features with great accuracy. We have recently carried out FSI simulations of a BMHV implanted in a anatomically realistic aorta in which the left ventricle (LV) was replaced by a pulsatile inflow waveform. In this work, we propose to extend our method to simulate the flow through a BMHV driven by the actual LV motion. The anatomy of the heart is obtained from MRI scan of unhealthy volunteer (St. Jude Hospital) and the left ventricle and the aorta geometry are extracted. The first step is to simulate the flow through a stationary LV with an implanted BMHV to test the capabilities of FSI-CFD tool in real anatomical setting. The second step is to impose theoretical kinematics for LV motion and test the interaction of the BMHV with the flow. The last step is to extract the real patient-specific LV wall motions from MRI data and specify it into the simulation. The shear stress and other parameters will be calculated in the flow field and the cardiovascular walls to identify the locations with high chance of blood cell damage. This work is supported by NIH Grant RO1-HL-07262 and the Minnesota Supercomputing Institute.

Comparison of echocardiography and electron beam tomography in differentiating the etiology of heart failure

BACKGROUND

The clinical manifestations in patients with ischemic cardiomyopathy are often indistinguishable from those in patients with primary dilated cardiomyopathy (DCM). Clinicians often base work-up of patients with heart failure on echocardiographic wall motion abnormalities; however misclassification can lead to unnecessary coronary angiography.

HYPOTHESIS

The study was undertaken to evaluate the diagnostic ability of echocardiography and electron beam tomography (EBT) to differentiate between ischemic and nonischemic cardiomyopathy.

METHODS

The accuracy of EBT and echocardiography was compared in 111 patients undergoing coronary angiography for the evaluation of heart failure. The presence of coronary calcification (CC) by EBT or segmental wall motion abnormalities by echocardiography was used as evidence of coronary-induced cardiomyopathy.

RESULTS

Of 63 patients, 61 (97%) with obstructive coronary artery disease had CC by EBT. This sensitivity was significantly higher compared with 43 of 63 patients (68%) with segmental wall motion abnormalities by echocardiography (p < 0.001). Of 48 patients without obstructive coronary artery disease by angiography, 39 (81%) had no CC by EBT and 35 (73%) had no segmental wall motion (global hypokinesis) by echocardiography (p = 0.33). The overall accuracy of EBT to differentiate ischemic from nonischemic cardiomyopathy was 90%, significantly higher than echocardiography (70%, p < 0.001).

CONCLUSION

This double-blind study demonstrates that the presence of CC by EBT is superior to that of segmental wall motion abnormalities by echocardiography to distinguish ischemic from nonischemic cardiomyopathy. This modality may prove to be an important diagnostic tool when the etiology of the cardiomyopathy is not clinically evident.

Reduced amelogenin-MMP20 interactions in amelogenesis imperfecta

Amelogenin with a proline 41 to threonine mutation (P41T) is hydrolyzed at a lower rate by matrix metalloproteinase 20 (MMP20), resulting in an inherited tooth enamel defect, amelogenesis imperfecta (AI). The aim of this study was to elucidate the effect of P41T on the interactions between amelogenin and MMP20, which may contribute to the formation of this type of AI. The interactions of a recombinant wild-type human amelogenin and its P41T mutant with recombinant human MMP20 were compared by substrate competition assay, pull-down assay, and surface plasmon resonance (SPR). The results showed that the binding of the P41T mutant amelogenin for MMP20 was significantly lower than that of wild-type amelogenin. Our study supports a model in which the P41T mutation reduces the interactions between amelogenin and MMP20, leading to decreased degradation of amelogenin by MMP20, and resulting in AI.

Prospective evaluation of weekly topotecan in recurrent platinum-resistant epithelial ovarian cancer

Topotecan administered on a weekly basis has been reported to possess antineoplastic activities with lower toxicities than the standard 5-day regimen every 3 weeks. We studied the activity of weekly topotecan regimen in recurrent platinum-resistant epithelial ovarian cancer patients. Ovarian cancer patients with documented platinum-resistant recurrences were treated with weekly intravenous topotecan (4 mg/m2) on days 1, 8, and 15 on a 28-day cycle. Prospective data collection included patients' demographics together with disease- and treatment-related toxicities. Responses were evaluated using Response Evaluation Criteria in Solid Tumors (RECIST) and CA125 criteria. Progression-free survival and overall survival time from commencement of weekly treatment were estimated using the Kaplan–Meier method. All P values less than 0.05 were considered to be statistically significant. Twenty-two patients were treated. Weekly topotecan was used most commonly as third-line chemotherapy (range 1–5). A total of 244 weekly treatments were administered, with a median of 12 weekly treatments per patient. Two patients (9%) reported grade 3/4 gastrointestinal and two had grade 3/4 hematologic toxicities respectively. No dose reduction or treatment delay was required. Partial response was observed in two patients (9.1%) and another seven patients (31.8%) showed stable disease. No significant association was observed between best clinical response and patients' initial platinum sensitivity status. The estimated median progression-free survival was 20.9 weeks (95% CI 11.2–30.5) from the start of the weekly regimen. Weekly topotecan is well tolerated in patients with recurrent platinum-resistant ovarian cancer with modest activity.

Effects of fluoride on the interactions between amelogenin and apatite crystals

Fluorosed enamel is more porous and less mineralized, possibly related to altered amelogenin-modulated crystal growth. The purpose of this study was to examine the role of fluoride in interactions between amelogenin and apatite crystals. Recombinant human amelogenin (rh174) was bound to carbonated hydroxyapatite containing various amounts of fluoride, and analyzed by protein assay, SDS PAGE, and AFM. Interactions between rh174 and fluoride were assayed by isothermal titration calorimetry (ITC). The initial binding rate of rh174, as well as total amount of rh174 bound to fluoride-containing carbonated hydroxyapatite, was greater than that in the control carbonated hydroxyapatite. Fluoride in solution at physiologic (5.3 micromolar, or 0.1 ppm) concentrations showed no significant effect on binding, but higher fluoride levels significantly decreased protein binding. ITC showed no interactions between fluoride and rh174. These results suggest that fluoride incorporation into the crystal lattice alters the crystal surface to enhance amelogenin binding, with no direct interactions between fluoride and amelogenin.

Ultrashort Laguerre-Gaussian pulses with angular and group velocity dispersion compensation

Coherent optical vortices are generated from ultrashort 6.4 fs pulses. Our results demonstrate angular dispersion compensation of ultrashort 6.4 fs Laguerre-Gaussian (LG) pulses as well as what is believed to be the first direct autocorrelation measurement of 80 fs LG amplified pulses. A reflective-mirror-based 4f-compressor is proposed to compensate the angular and group velocity dispersion of the ultrashort LG pulses.

Targeting FGF19 inhibits tumor growth in colon cancer xenograft and FGF19 transgenic hepatocellular carcinoma models

Although fibroblast growth factor 19 (FGF19) can promote liver carcinogenesis in mice its involvement in human cancer is not well characterized. Here we report that FGF19 and its cognate receptor FGF receptor 4 (FGFR4) are coexpressed in primary human liver, lung and colon tumors and in a subset of human colon cancer cell lines. To test the importance of FGF19 for tumor growth, we developed an anti-FGF19 monoclonal antibody that selectively blocks the interaction of FGF19 with FGFR4. This antibody abolished FGF19-mediated activity in vitro and inhibited growth of colon tumor xenografts in vivo and effectively prevented hepatocellular carcinomas in FGF19 transgenic mice. The efficacy of the antibody in these models was linked to inhibition of FGF19-dependent activation of FGFR4, FRS2, ERK and beta-catenin. These findings suggest that the inactivation of FGF19 could be beneficial for the treatment of colon cancer, liver cancer and other malignancies involving interaction of FGF19 and FGFR4.

The lack of significance of Ca125 response in epithelial ovarian cancer patients treated with neoadjuvant chemotherapy and delayed primary surgical debulking

OBJECTIVES

To examine the prognostic significance of Ca125 response to neoadjuvant chemotherapy and delayed primary surgical debulking in epithelial ovarian cancer patients.

METHODS

Retrospective chart reviews were carried out from 1997 to 2005 to identify ovarian cancer patients treated with neoadjuvant chemotherapy. Ca125 response was defined as being a decrease of at least 50% from baseline assessment. Ca125 response was assessed in two phases: prior to surgical debulking to reflect the response to neoadjuvant chemotherapy and at the end of primary chemotherapy to assess the response to debulking surgery and further chemotherapy. Cox proportional hazard models were built to model progression-free intervals using predictor variables of: age, cancer stage, tumour grade, residual disease, and Ca125 response.

RESULTS

Ninety-one patients were included. About 83% had a positive Ca125 response following three cycles of neoadjuvant chemotherapy preoperatively. Cox regressions revealed two significant predictive variables of prolonged time to first progression: younger age (p=0.002) and microscopic residual disease compared to suboptimal residual disease (p=0.003). Ca125 response to neoadjuvant chemotherapy was not significantly predictive of progression-free survivals. The estimated median survival was 71.42 months (95% CI: 44.34-78.50) in patients with >50% Ca125 decrease from surgery and further chemotherapy whereas in those with no response, the corresponding survival estimate was 44.02 months (95% CI: 33.26-54.79).

CONCLUSION

The lack of Ca125 response from neoadjuvant chemotherapy is not an independent prognostic factor. All patients treated with neoadjuvant chemotherapy should undergo radical debulking surgery.