Abstract P1-04-01: Significance of circulating tumor cells in metastatic triple negative breast cancer: Results of an open label, randomized, phase II trial of nanoparticle albumin-bound paclitaxel with or without the anti-death receptor 5 tigatuzumab (TBCRC 019)

Background: Circulating Tumor cells (CTCs) are prognostic at baseline and first follow-up in patients with metastatic breast cancer (MBC). Using the most commonly used assay (CellSearch®), we have previously reported the ability to detect apoptotic vs. non-apoptotic CTCs in patients with MBC. However, there has been concern regarding the performance of the CellSearch® assay in patients with triple negative (TN) MBC. We hypothesized that CellSearch® is an effective assay in patients with TN MBC, and that CTC-apoptosis might further separate prognosis. Therefore, we studied CTCs in patients with TN MBC who participated in a prospective randomized phase II trial testing for activity of tigatuzumab (TIG) in combination with nanoparticle albumin-bound paclitaxel (nab-PAC) conducted by the Translational Breast Cancer Research Consortium (overall results reported by Forero A., et al, ASCO 2013).

Methods: Whole blood (WB) was drawn into a CellSave tube at baseline, day 15, and day 29 and CTC counts were determined using the CXC CellSearch® kit. Apoptosis was characterized by staining with a monoclonal antibody that detects a neo-epitope on fragmented cytokeratin (M-30) and independently by visual inspection (nucleic condensation and/or fragmentation, as well as granular cytokeratin). Association between levels of CTCs and CTC-apoptosis with the overall response rate (ORR) and progression free survival (PFS) at baseline, day 15, and day 29 was assessed using logistic regression, Kaplan Meier curves, and Cox proportional hazards modeling.

Results: Of the 60 patients entered into the trial, 52 were evaluable for CTCs. Of these, 19/52 (36.5%), 14/52 (26.9%), and 13/49 (26.5%) had elevated CTCs (≥5CTC/7.5 ml WB) at baseline, day 15, and day 29, respectively. Patients with elevated CTCs at each time point had worse PFS than patients with low or no CTCs. Hazard rates (HR) at baseline, day 15, and day 29 were 2.38 (95% CI: 1.27-4.45, p = 0.007), 2.87 (95% CI: 1.46-5.66, p = 0.002), and 3.40 (95% CI: 1.68-6.89, p = 0.001), respectively. The odds of overall response for those who had elevated CTCs compared to those who did not at baseline, day 15, and day 29, were 0.25 (95% CI: 0.073-0.81, p = 0.024), 0.18 (95% CI: 0.04-0.67, p = 0.014), and 0.06 (95% CI: 0.01-0.28, p = 0.001), respectively. There was no apparent prognostic effect comparing the degree of CTC-apoptosis vs. non-apoptosis.

Conclusions: Similar to observations in other intrinsic subgroups, CTCs were detected in a large fraction of TN MBC patients at baseline using CellSearch® assay, and reductions in CTC levels reflected response. In these homogenously prospectively enrolled TN MBC patients, regardless of treatment, CTCs are prognostic at baseline, day 15, and day 29. It does not appear that analysis of CTC-apoptosis is prognostic.

Supported by Susan G. Komen for the Cure, Veridex, LLC, Fashion Footwear Charitable Foundation of New York/QVC Presents Shoes on Sale™ (DFH), Associazione Sandro Pitigliani and by a studentship from FIRC (CP), Triple Negative Breast Cancer Foundation, The AVON Foundation, and The Breast Cancer Research Foundation.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-04-01.

Abstract PD6-4: Heterogeneity of expression of estrogen receptor by circulating tumor cells suggests diverse mechanisms of resistance to fulvestrant in metastatic breast cancer patients

Introduction: Fulvestrant is a selective estrogen receptor down-regulator (SERD). Recent studies have shown that the efficacy of fulvestrant is dose-related. However, at the higher dose (500 mg/month) most cancers develop resistance and progress. We previously reported expression of several markers, including estrogen receptor (ER) and BCL-2, on breast cancer circulating tumor cells (CTC) using CellSearch®. We now report pilot data showing inter-patient heterogeneity of these markers on CTC in patients with known ER positive breast cancer whose disease is progressing on fulvestrant.

Methods: We conducted a pilot trial to determine the analytical validity of measuring expression of markers of endocrine sensitivity (ER, BCL-2) or resistance (HER-2, Ki-67) with fluorescent-labeled antibodies using the CellSearch® system. Patients with ER positive metastatic breast cancer (MBC) whose disease was progressing on any type of therapy were eligible after signed informed consent. This report is limited to the subjects who were progressing on fulvestrant. Whole blood (WB) was characterized for CTC counts and each of the four molecular markers using the CXC CellSearch® kit.

Results: Of 50 enrolled patients, seven were progressing on fulvestrant. Two patients had no detectable CTC, while five patients had an average of ≥5 CTC/7.5 mL WB. Results are shown in a table below:

   CTC-ERCTC-BCL-2Patient #Fulvestrant dose (mg/month)Days since last doseN CTC/7.5 mL of WB% of CTC-ER+N CTC/7.5 mL of WB% of CTC-BCL-2+295002880%110%4550028170%170%2250341010%714%850031812%1735%172507728%367%

These exploratory data suggest widely different mechanisms of resistance to fulvestrant in different patients with ER positive MBC. In two of the patients (29, 45) treated with 500 mg/month, both CTC-ER and CTC-BCL-2 expression were absent, suggesting no signaling through the ER pathway. We hypothesize either that fulvestrant was actively down-regulating ER, but the cancers had adopted other growth and survival pathways, or that ER negative, hormone-independent clones had evolved. In the other three cases, ER was clearly present with evidence of signaling, based on BCL-2 expression. Two of these patients (2, 17) were on the lower dose of fulvestrant, now considered to be less effective. However, the third (8) was on the higher dose and yet still had evidence of ER signaling. This observation suggests that some patients may benefit from even higher doses of SERD therapy.

Conclusions: These pilot results suggest heterogeneous biological or pharmacological mechanisms of resistance to SERD therapy. These data suggest that CTC-ER and CTC-BCL-2 expression could serve as pharmacodynamic monitoring tools for dose escalation of fulvestrant or other SERDs. Further molecular analysis might provide biological bases for resistance to fulvestrant.

Supported by Veridex, LLC, Fashion Footwear Charitable Foundation of New York/QVC Presents Shoes on Sale™ (DFH), Associazione Sandro Pitigliani and by a studentship from FIRC (CP).

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr PD6-4.

Cellular encapsulation enhances cardiac repair

Background

Stem cells for cardiac repair have shown promise in preclinical trials, but lower than expected retention, viability, and efficacy. Encapsulation is one potential strategy to increase viable cell retention while facilitating paracrine effects.

Methods and Results

Human mesenchymal stem cells (hMSC) were encapsulated in alginate and attached to the heart with a hydrogel patch in a rat myocardial infarction (MI) model. Cells were tracked using bioluminescence (BLI) and cardiac function measured by transthoracic echocardiography (TTE) and cardiac magnetic resonance imaging (CMR). Microvasculature was quantified using von Willebrand factor staining and scar measured by Masson's Trichrome. Post‐MI ejection fraction by CMR was greatly improved in encapsulated hMSC‐treated animals (MI: 34±3%, MI+Gel: 35±3%, MI+Gel+hMSC: 39±2%, MI+Gel+encapsulated hMSC: 56±1%; n=4 per group; P<0.01). Data represent mean±SEM. By TTE, encapsulated hMSC‐treated animals had improved fractional shortening. Longitudinal BLI showed greatest hMSC retention when the cells were encapsulated (P<0.05). Scar size at 28 days was significantly reduced in encapsulated hMSC‐treated animals (MI: 12±1%, n=8; MI+Gel: 14±2%, n=7; MI+Gel+hMSC: 14±1%, n=7; MI+Gel+encapsulated hMSC: 7±1%, n=6; P<0.05). There was a large increase in microvascular density in the peri‐infarct area (MI: 121±10, n=7; MI+Gel: 153±26, n=5; MI+Gel+hMSC: 198±18, n=7; MI+Gel+encapsulated hMSC: 828±56 vessels/mm², n=6; P<0.01).

Conclusions

Alginate encapsulation improved retention of hMSCs and facilitated paracrine effects such as increased peri‐infarct microvasculature and decreased scar. Encapsulation of MSCs improved cardiac function post‐MI and represents a new, translatable strategy for optimization of regenerative therapies for cardiovascular diseases.

Delivery of Nox2-NADPH oxidase siRNA with polyketal nanoparticles for improving cardiac function following myocardial infarction

Myocardial infarction (MI) is the most common cause of heart failure (HF), the leading cause of death in the developed world. Oxidative stress due to excessive production of reactive oxygen species (ROS) plays a key role in the pathogenesis of cardiac remodeling leading to HF. NADPH oxidase with Nox2 as the catalytic subunit is a major source for cardiac ROS production. Nox2-NADPH expression is significantly increased in the infarcted myocardium, primarily in neutrophils, macrophages and myocytes. Moreover, mice lacking the Nox2 gene are protected from ischemic injury, implicating Nox2 as a potential therapeutic target. RNAi-mediated gene silencing holds great promise as a therapeutic owing to its high specificity and potency. However, in vivo delivery hurdles have limited its effective clinical use. Here, we demonstrate acid-degradable polyketal particles as delivery vehicles for Nox2-siRNA to the post-MI heart. In vitro, Nox2-siRNA particles are effectively taken up by macrophages and significantly knockdown Nox2 expression and activity. Following in vivo intramyocardial injection in experimental mice models of MI, Nox2-siRNA particles prevent upregulation of Nox2 and significantly recovered cardiac function. This study highlights the potential of polyketals as siRNA delivery vehicles to the MI heart and represents a viable therapeutic approach for targeting oxidative stress.

Acute preconditioning of cardiac progenitor cells with hydrogen peroxide enhances angiogenic pathways following ischemia-reperfusion injury

There are a limited number of therapies available to prevent heart failure following myocardial infarction. One novel therapy that is currently being pursued is the implantation of cardiac progenitor cells (CPCs); however, their responses to oxidative stress during differentiation have yet to be elucidated. The objective of this study was to determine the effect of hydrogen peroxide (H2O2) treatment on CPC differentiation in vitro, as well as the effect of H2O2 preconditioning before implantation following ischemia-reperfusion (I/R) injury. CPCs were isolated and cloned from adult rat hearts, and then cultured in the absence or presence of H2O2 for 2 or 5 days. CPC survival was assessed with Annexin V, and cellular differentiation was evaluated through mRNA expression for cardiogenic genes. We found that 100 μM H2O2 decreased serum withdrawal-induced apoptosis by at least 45% following both 2 and 5 days of treatment. Moreover, 100 μM H2O2 treatment for 2 days significantly increased endothelial and smooth muscle markers compared to time-matched untreated CPCs. However, continued H2O2 treatment significantly decreased these markers. Left ventricular cardiac function was assessed 28 days after I/R and I/R with the implantation of Luciferase/GFP(+) CPCs, which were preconditioned with 100 μM H2O2 for 2 days. Hearts implanted with Luciferase/GFP(+) CPCs had significant improvement in both positive and negative dP/dT over I/R. Furthermore, cardiac fibrosis was significantly decreased in the preconditioned cells versus both I/R alone and I/R with control cells. We also observed a significant increase in endothelial cell density in the preconditioned CPC hearts compared to untreated CPC hearts, which also coincided with a higher density of Luciferase(+) vessels. These findings suggest that preconditioning of CPCs with H2O2 for 2 days stimulates neoangiogenesis in the peri-infarct area following I/R injury and could be a viable therapeutic option to prevent heart failure.

Polar methane accumulation and rainstorms on Titan from simulations of the methane cycle

Titan has a methane cycle akin to Earth's water cycle. It has lakes in polar regions, preferentially in the north; dry low latitudes with fluvial features and occasional rainstorms; and tropospheric clouds mainly (so far) in southern middle latitudes and polar regions. Previous models have explained the low-latitude dryness as a result of atmospheric methane transport into middle and high latitudes. Hitherto, no model has explained why lakes are found only in polar regions and preferentially in the north; how low-latitude rainstorms arise; or why clouds cluster in southern middle and high latitudes. Here we report simulations with a three-dimensional atmospheric model coupled to a dynamic surface reservoir of methane. We find that methane is cold-trapped and accumulates in polar regions, preferentially in the north because the northern summer, at aphelion, is longer and has greater net precipitation than the southern summer. The net precipitation in polar regions is balanced in the annual mean by slow along-surface methane transport towards mid-latitudes, and subsequent evaporation. In low latitudes, rare but intense storms occur around the equinoxes, producing enough precipitation to carve surface features. Tropospheric clouds form primarily in middle and high latitudes of the summer hemisphere, which until recently has been the southern hemisphere. We predict that in the northern polar region, prominent clouds will form within about two (Earth) years and lake levels will rise over the next fifteen years.

P4-07-16: Development of Circulating Tumor Cell-Endocrine Therapy Index in Metastatic Breast Cancer Patients

Introduction: Only ∼ 50% of patients (pts) with estrogen receptor (ER) positive metastatic breast cancer (MBC) benefit from endocrine therapy (ET). Currently only clinical judgment can be used to identify pts with endocrine-refractory MBC, who are better palliated with chemotherapy. Circulating Tumor Cells (CTC) are reliably enumerated using an automated immunomagnetic system (CellSearch®; Veridex LLC). High CTC levels predict rapid progression in pts with MBC. We have developed a multi-parameter assay, the CTC-Endocrine Therapy Index (CTC-ETI) using CellSearch® that may identify pts with ER positive MBC who are unlikely to benefit from ET and may be better served with chemotherapy. CTC-ETI scores are assigned based on CTC levels coupled with the relative percent and degree of marker positivity on the CTC. We report preliminary results from a pilot single institutional study.

Methods: CellSearch® has 4 fluorescence channels. Three distinguish CTC from WBC (DAPI, anti-cytokeratin, anti-CD45). The 4th “empty” channel was used to measure ER, BCL-2, HER-2, and Ki-67 expression with fluorescent-labeled antibodies. These 4 markers reflect sensitivity (ER, BCL-2) or resistance (HER-2, Ki-67) to ET. Forty ml of blood was drawn into 4 CellSave® tubes from pts with progressive MBC. Whole blood from 4 tubes was pooled and divided into 4 different 7.5 ml aliquots of blood, which were processed and characterized for CTC counts and each of the four molecular markers using the CXC CellSearch® kit.

Results: 21 pts have been accrued to the feasibility study. One patient was ineligible. Five of 20 pts had low CTC counts (&lt;5 CTC/7.5ml whole blood), and are expected to have a relatively favorable prognosis. CTC-ETI was successfully determined in 10 pts (50%): 2 pts had low, while 3 had intermediate, and 5 had high CTC-ETI. Technical difficulties precluded accurate CTC-ETI in the remaining 5 patients. Of note, expression of the biomarkers among CTC in single patients was heterogeneous, suggesting that future iterations of the CTC-ETI will have to consider expression variability. Further exploratory results regarding associations between CTC-ETI and outcomes will be presented.

Conclusions: ER, BCL-2, HER-2, and Ki-67 can be accurately determined on CTC using the 4th channel in the CellSearch® system to calculate CTC-ETI. We predict that lower CTC-ETI scores (low or no CTC, or CTC with high CTC ER and BCL-2 and low CTC HER-2 and Ki-67) could be associated with favorable response to ET. Successful completion of the feasibility study will lead to a prospective trial to determine if high CTC-ETI at baseline predicts resistance and rapid progression on ET in women starting a new endocrine therapy for MBC.

Supported by Veridex, LLC, Fashion Footwear Charitable Foundation of New York/QVC Presents Shoes on Sale ™ (DFH), Associazione Sandro Pitigliani and by a studentship from FIRC (CP).

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-07-16.

Professional values and pharmacy practice: Keywords and concepts

A range of factors was established, such as knowledge and ethics, which underlay the practice of six groups of health professionals: pharmacists, dentists, doctors, nurses, optometrists and radiographers. These factors have been identified as “concepts”. The method used was content analysis of official documents of the professions, such as codes of ethics and guidance documents. Postal questionnaires were also used to collect data. Nine principal concepts were identified. A “collective professional consciousness” was evident, in which knowledge, patient welfare and ethics were important concepts for the highest quality of practice. The perceived importance of these and other concepts was broadly similar across the professions.

Professional values and pharmacy practice: implications of a predominantly female Register of Pharmaceutical Chemists

It is expected that the Register of Pharmaceutical Chemists of Great Britain will comprise a majority of female practitioners by about the year 2000. It is, therefore, pertinent to compare the opinions of male and female practitioners (pharmacists, doctors, dentists, nurses, optometrists and radiographers) about their practice. This study uses methodology published in an earlier paper to identify those opinions. Male and female practitioners had similar views in three areas: the concepts they considered important for the highest quality of practice, their valuation of patient safety, and the prevalence of conflict between National Health Service policies and professional ideas. There were three concepts which female practitioners considered more important than did males. One was confidentiality. Another was law (and, indeed, more male, than female, pharmacists were both investigated by the Royal Pharmaceutical Society's Statutory Committee and removed from the Register). The third was “health care art”: a new balance between the artistic and scientific sides of pharmacy is predicted when the majority of pharmacists are female. The one concept which male practitioners considered more important was independence. This may be related to the lower proportion of females than males who have risen to positions of authority.

Temporal effects of catalase overexpression on healing after myocardial infarction

BACKGROUND

Reactive oxygen species, such as hydrogen peroxide (H(2)O(2)), contribute to progression of dysfunction after myocardial infarction (MI). However, chronic overexpression studies do not agree with acute protein delivery studies. The purpose of the present study was to assess the temporal role of cardiomyocyte-derived H(2)O(2) scavenging on cardiac function after infarction using an inducible system.

METHODS AND RESULTS

We developed a tamoxifen-inducible, cardiomyocyte-specific, catalase-overexpressing mouse. Catalase overexpression was induced either 5 days before or after MI. Mice exhibited a 3-fold increase in cardiac catalase activity that was associated with a significant decrease in H(2)O(2) levels at both 7 and 21 days. However, cardiac function improved only at the later time point. Proinflammatory and fibrotic genes were acutely upregulated after MI, but catalase overexpression abolished the increase despite no acute change in function. This led to reduced overall scar formation, with lower levels of Collagen 1A and increased contractile Collagen 3A expression at 21 days.

CONCLUSIONS

In contrast to prior studies, there were no acute functional improvements with physiological catalase overexpression before MI. Scavenging of H(2)O(2), however, reduced proinflammatory cytokines and altered cardiac collagen isoforms, associated with an improvement in cardiac function after 21 days. Our results suggest that sustained H(2)O(2) levels rather than acute levels immediately after MI may be critical in directing remodeling and cardiac function at later time points.

Protein Binding to Peptide-Imprinted Porous Silica Scaffolds

Of the many types of biomolecules used for molecular imprinting applications, proteins are some of the most useful, yet challenging, templates to work with. One method, termed the 'epitope approach', involves imprinting a short peptide fragment of the protein into the polymer to promote specific adsorption of the entire protein, similar to the way an antigen binds to an antibody via the epitope. Whole lysozyme or the 16 residue lysozyme C peptide was imprinted into porous silica scaffolds using sol-gel processing. After removing template, scaffolds were exposed to lysozyme and/or RNase A, which was used as a competitor molecule of comparable size. When comparing protein- to peptide-imprinted scaffolds, similar amounts of lysozyme and RNase were bound from single protein solutions. However, while whole lysozyme-imprinted scaffolds showed about 4:1 preferential binding of lysozyme to RNase, peptide-imprinted scaffolds failed to show statistical significance, even though a slight preferential binding trend was present. These initial studies suggest there is potential for using peptide-imprinting to create specific protein-binding sites on porous inorganic surfaces, although further development of the materials is needed.

No oceans on Titan from the absence of a near-infrared specular reflection

With its substantial atmosphere of nitrogen, hydrocarbons and nitriles, Saturn's moon Titan is a unique planetary satellite. Photochemical processing of the gaseous constituents produces an extended haze that obscures the surface. Soon after the Voyager fly-bys in 1980 and 1981 photochemical models led to the conclusion that there should be enough liquid methane/ethane/nitrogen to cover the surface to a depth of several hundred metres. Recent Earth-based radar echoes imply that surface liquid may be present at a significant fraction of the locations sampled. Here we present ground-based observations (at near-infrared wavelengths) and calculations showing that there is no evidence thus far for surface liquid. Combined with the specular signatures from radar observations, we infer mechanisms that produce very flat solid surfaces, involving a substance that was liquid in the past but is not in liquid form at the locations we studied.

A low-density M-type asteroid in the main belt

The orbital parameters of a satellite revolving around 22 Kalliope indicate that the bulk density of this main-belt asteroid is 2.37 +/- 0.4 grams per cubic centimeter. M-type asteroids such as Kalliope are thought to be the disrupted metallic cores of differentiated bodies. The low-density indicates that Kalliope cannot be predominantly composed of metal and may be composed of chondritic material with approximately 30% porosity. The satellite orbit is circular, suggesting that Kalliope and its satellite have different internal structures and tidal dissipation rates. The satellite may be an aggregate of impact ejecta from an earlier collision with Kalliope.

Therapeutically effective antibodies against amyloid-beta peptide target amyloid-beta residues 4-10 and inhibit cytotoxicity and fibrillogenesis

Immunization of transgenic mouse models of Alzheimer disease using amyloid-beta peptide (Abeta) reduces both the Alzheimer disease-like neuropathology and the spatial memory impairments of these mice. However, a therapeutic trial of immunization with Abeta42 in humans was discontinued because a few patients developed significant meningo-encephalitic cellular inflammatory reactions. Here we show that beneficial effects in mice arise from antibodies selectively directed against residues 4-10 of Abeta42, and that these antibodies inhibit both Abeta fibrillogenesis and cytotoxicity without eliciting an inflammatory response. These findings provide the basis for improved immunization antigens as well as attempts to design small-molecule mimics as alternative therapies.

Rhabdoviruses and the cellular ubiquitin-proteasome system: a budding interaction

The matrix (M) proteins of vesicular stomatitis virus (VSV) and rabies virus (RV) play a key role in both assembly and budding of progeny virions. A PPPY motif (PY motif or late-budding domain) is conserved in the M proteins of VSV and RV. These PY motifs are important for virus budding and for mediating interactions with specific cellular proteins containing WW domains. The PY motif and flanking sequences of the M protein of VSV were used as bait to screen a mouse embryo cDNA library for cellular interactors. The mouse Nedd4 protein, a membrane-localized ubiquitin ligase containing multiple WW domains, was identified from this screen. Ubiquitin ligase Rsp5, the yeast homolog of Nedd4, was able to interact both physically and functionally with full-length VSV M protein in a PY-dependent manner. Indeed, the VSV M protein was multiubiquitinated by Rsp5 in an in vitro ubiquitination assay. To demonstrate further that ubiquitin may be involved in the budding process of rhabdoviruses, proteasome inhibitors (e.g., MG132) were used to decrease the level of free ubiquitin in VSV- and RV-infected cells. Viral titers measured from MG132-treated cells were reproducibly 10- to 20-fold lower than those measured from untreated control cells, suggesting that free ubiquitin is important for efficient virus budding. Last, release of a VSV PY mutant was not inhibited in the presence of MG132, signifying that the functional L domain of VSV is required for the inhibitory effect exhibited by MG132. These data suggest that the cellular ubiquitin-proteasome machinery is involved in the budding process of VSV and RV.

Vaccinia virus-free recovery of vesicular stomatitis virus

The advent of reverse-genetics represents a powerful new approach to elucidate aspects of negative-sense RNA virus replication. The reverse-genetics system established previously for vesicular stomatitis virus (VSV) required four plasmids encoding the nucleoprotein (N), phosphoprotein (P), polymerase (L), and the full-length, anti-genomic RNA. Transcription to yield the antigenomic RNA as well as the N, P, and L, mRNAs was initiated by bacteriophage T7 polymerase expressed from a recombinant Vaccinia virus. In this report, we describe the successful recovery of infectious VSV in the absence of Vaccinia virus. The N, P, and L genes of VSV were inserted downstream of both the T7 promoter and an internal ribosomal entry site (IRES element). T7 polymerase was expressed constitutively from BSR-T7/5 cells. RTPCR was used to confirm that the recovered VSV was derived from transfected DNA. Virion protein profile, CPE in tissue culture, and virus titer of the recombinant VSV were indistinguishable from those of parental VSV. Thus, the need for Vaccinia virus is eliminated with this system, making it an attractive, alternative approach for the recovery of infectious VSV from DNA.

Factors affecting phantom scores at annual mammography facility inspections by the U.S. Food and Drug Administration

RATIONALE AND OBJECTIVES

The authors performed this study to evaluate the factors affecting phantom image score at the annual inspection of mammography facilities.

MATERIALS AND METHODS

In 1997, three U.S. Food and Drug Administration (FDA)-trained inspectors performed inspections of all mammography facilities in North Carolina. All federal and state inspection data were collected and evaluated by using linear regression analysis. Factors affecting the American College of Radiology phantom scores were assessed.

RESULTS

Phantom score was affected by inspector identity, view box luminance, and optical density. All of these factors had a statistically significant effect on mass score (P < .05). Inspector identity yielded a statistically significant effect on speck group score, fibril score, and total score. Luminance yielded a statistically significant effect on both speck group score and total score.

CONCLUSION

Phantom scoring should be automated to allow for more consistent interobserver scoring. In addition, radiology facilities can improve the likelihood of receiving a passing phantom score by reducing the ambient light and increasing the view box luminance in the location where the images are evaluated and the phantom is scored routinely. Radiologists should also consider increasing phantom and clinical image optical density to allow for improved phantom testing outcomes.

Infection transmission system models for microbial risk assessment

Chemical risk assessments often focus on measuring exposure as if individuals were subject only to exogenous environmental sources of risk. For infectious diseases, exposure might not only depend on exogenous sources of microbes, but also on the infection status of other individuals in the population. For example, waterborne infections from agents such as Cryptosporidium parvum and Escherichia coli: O157:H7 might be transmitted from contaminated water to humans through drinking water; from interpersonal contact; or from infected individuals to the environment, and back to other susceptible individuals. These multiple pathways and the dependency of exposure on the prevalence of infection in a population suggest that epidemiological models are required to complement standard risk assessments in order to quantify the risk of infection. This paper presents new models of infection transmission systems that are being developed for the US Environmental Protection Agency as part of a project to quantify the risk of microbial infection. The models are designed to help inform water treatment system design decisions.

Do patients use marijuana as an antidepressant?

Several lines of evidence suggest that cannabis may have antidepressant effects. However, methodologic limitations in available studies make the results difficult to interpret. We review this literature and present five cases in which the evidence seems particularly clear that marijuana produced a direct antidepressant effect. If true, these observations argue that many patients may use marijuana to "self-treat" depressive symptoms.

Measuring the physician perspective on quality of care in health plans

Physicians provide one source of information about the quality of care in health plans, but concerns exist that physicians cannot distinguish quality from financial considerations or other underlying attitudes. We examined whether physicians can (a) distinguish different domains of health plan quality and (b) distinguish health plan quality from their underlying attitudes. We analyzed data on 419 generalist physicians from four health plans. Three scales assessed physicians' perceptions of facilitators and barriers to high-quality care in the plans and the clinical capabilities of plan physicians. Structural equation modeling indicated that physicians could distinguish domains of health plan quality. Physicians could also distinguish plan quality from their attitudes toward the plan, but plan quality was more highly correlated with general managed care attitudes than expected. These data suggest that physicians can provide information about health plan quality, but it will be important to validate these measures against patient outcomes.

Postpartum Multifocal Avascular Necrosis: What Are the Possible Etiologies?

Avascular necrosis of bone (osteonecrosis) that is atraumatic is most frequently associated with corticosteroid excess or alcoholism and usually involves the femoral head. We report a case of multifocal avascular necrosis in a 38-year-old woman with autoimmune Addison's disease taking corticosteroid replacement therapy. The onset of joint symptoms occurred 6 months after a pregnancy complicated by acute fatty liver and disseminated intravascular coagulation. Although both knees and ankles were involved, an unusual feature is that the hips were spared. As illustrated in this patient, avascular necrosis is frequently misdiagnosed in cases of joint pain of acute onset and may occur in the context of physiologic replacement doses of corticosteroids. Etiologic factors can precede the onset of symptoms and the diagnosis by several months.

Light differentially regulates cell division and the mRNA abundance of pea nucleolin during de-etiolation

The abundance of plant nucleolin mRNA is regulated during de-etiolation by phytochrome. A close correlation between the mRNA abundance of nucleolin and mitosis has also been previously reported. These results raised the question of whether the effects of light on nucleolin mRNA expression were a consequence of light effects on mitosis. To test this we compared the kinetics of light-mediated increases in cell proliferation with that of light-mediated changes in the abundance of nucleolin mRNA using plumules of dark-grown pea (Pisum sativum) seedlings. These experiments show that S-phase increases 9 h after a red light pulse, followed by M-phase increases in the plumule leaves at 12 h post-irradiation, a time course consistent with separately measured kinetics of red light-induced increases in the expression of cell cycle-regulated genes. These increases in cell cycle-regulated genes are photoreversible, implying that the light-induced increases in cell proliferation are, like nucleolin mRNA expression, regulated via phytochrome. Red light stimulates increases in the mRNA for nucleolin at 6 h post-irradiation, prior to any cell proliferation changes and concurrent with the reported timing of phytochrome-mediated increases of rRNA abundance. After a green light pulse, nucleolin mRNA levels increase without increasing S-phase or M-phase. Studies in animals and yeast indicate that nucleolin plays a significant role in ribosome biosynthesis. Consistent with this function, pea nucleolin can rescue nucleolin deletion mutants of yeast that are defective in rRNA synthesis. Our data show that during de-etiolation, the increased expression of nucleolin mRNA is more directly regulated by light than by mitosis.

A PPxY motif within the VP40 protein of Ebola virus interacts physically and functionally with a ubiquitin ligase: implications for filovirus budding

VP40, the putative matrix protein of both Ebola and Marburg viruses, possesses a conserved proline-rich motif (PY motif) at its N terminus. We demonstrate that the VP40 protein can mediate its own release from mammalian cells, and that the PY motif is important for this self-exocytosis (budding) function. In addition, we used Western-ligand blotting to demonstrate that the PY motif of VP40 can mediate interactions with specific cellular proteins that have type I WW-domains, including the mammalian ubiquitin ligase, Nedd4. Single point mutations that disrupted the PY motif of VP40 abolished the PY/WW-domain interactions. Significantly, the full-length VP40 protein was shown to interact both physically and functionally with full-length Rsp5, a ubiquitin ligase of yeast and homolog of Nedd4. The VP40 protein was multiubiquitinated by Rsp5 in a PY-dependent manner in an in vitro ubiquitination assay. These data demonstrate that the VP40 protein of Ebola virus possesses a PY motif that is functionally similar to those described previously for Gag and M proteins of specific retroviruses and rhabdoviruses, respectively. Last, these studies imply that VP40 likely plays an important role in filovirus budding, and that budding of retroviruses, rhabdoviruses, and filoviruses may proceed via analogous mechanisms.