Reprint of: Silver and titanium dioxide nanoparticle toxicity in plants: A review of current research

Nanoparticles (NPs) have become widely used in recent years for many manufacturing and medical processes. Recent literature suggests that many metallic nanomaterials including those of silver (Ag) and titanium dioxide (TiO₂) cause significant toxic effects in animal cell culture and animal models, however, toxicity studies using plant species are limited. This review examines current progress in the understanding of the effect of silver and titanium dioxide nanoparticles on plant species. There are many facets to this ongoing environmental problem. This review addresses the effects of NPs on oxidative stress-related gene expression, genotoxicity, seed germination, and root elongation. It is largely accepted that NP exposure results in the cellular generation of reactive oxygen species (ROS), leading to both positive and negative effects on plant growth. However, factors such as NP size, shape, surface coating and concentration vary greatly among studies resulting in conflicting reports of the effect at times. In addition, plant species tend to differ in their reaction to NP exposure, with some showing positive effects of NP augmentation while many others showing detrimental effects. Seed germination studies have shown to be less effective in gauging phytotoxicity, while root elongation studies have shown more promise. Given the large increase in nanomaterial applications in consumer products, agriculture and energy sectors, it is critical to understand their role in the environment and their effects on plant life. A closer look at nanomaterial-driven ecotoxicity is needed. Ecosystem-level studies are required to indicate how these nanomaterials transfer at the critical trophic levels affecting human health and biota.

Silver and titanium dioxide nanoparticle toxicity in plants: A review of current research

Nanoparticles (NPs) have become widely used in recent years for many manufacturing and medical processes. Recent literature suggests that many metallic nanomaterials including those of silver (Ag) and titanium dioxide (TiO2) cause significant toxic effects in animal cell culture and animal models, however, toxicity studies using plant species are limited. This review examines current progress in the understanding of the effect of silver and titanium dioxide nanoparticles on plant species. There are many facets to this ongoing environmental problem. This review addresses the effects of NPs on oxidative stress-related gene expression, genotoxicity, seed germination, and root elongation. It is largely accepted that NP exposure results in the cellular generation of reactive oxygen species (ROS), leading to both positive and negative effects on plant growth. However, factors such as NP size, shape, surface coating and concentration vary greatly among studies resulting in conflicting reports of the effect at times. In addition, plant species tend to differ in their reaction to NP exposure, with some showing positive effects of NP augmentation while many others showing detrimental effects. Seed germination studies have shown to be less effective in gauging phytotoxicity, while root elongation studies have shown more promise. Given the large increase in nanomaterial applications in consumer products, agriculture and energy sectors, it is critical to understand their role in the environment and their effects on plant life. A closer look at nanomaterial-driven ecotoxicity is needed. Ecosystem-level studies are required to indicate how these nanomaterials transfer at the critical trophic levels affecting human health and biota.

Histone deacetylase activity and recurrent bacterial bronchitis in severe eosinophilic asthma

An increase in P13 Kinase activity and an associated reduction in histone deacetylase activity may contribute to both relative steroid insensitivity in patients with severe eosinophilic asthma and impaired macrophage scavenger function and susceptibility to recurrent infective bronchitis that may, in turn, contribute to further steroid insensitivity.

Escherichia coli induces platelet aggregation in an FcγRIIa-dependent manner

BACKGROUND

The discovery of pathogen-recognition receptors such as Toll-like receptors on platelets has led to the emergence of the concept of platelets as important components of the host response to infection. Escherichia coli (E. coli)-mediated sepsis is a serious illness characterized by the occurrence of thrombocytopenia. Whereas there has been a wealth of research on platelet activation by Gram-positive bacteria, little is known about the mechanisms associated with Gram-negative bacteria-induced platelet activation with Gram-negative bacteria.

OBJECTIVES

To determine the mechanisms by which Gram-negative E. coli induces platelet aggregation.

METHODS

Induction of platelet aggregation with E. coli strain O157:H7 was tested in platelet-rich plasma (PRP), washed platelets, and serum depleted of complement factors. Platelet inhibitors (against αII b β3 , glycoprotein Ibα and FcγRIIa) were used. Platelet thromboxane synthesis was analyzed after E. coli stimulation. Cell binding assays were used to assess the ability of E. coli to support platelet adhesion. Trypsinization was used to determine the role of E. coli surface proteins.

RESULTS AND CONCLUSION

E. coli-induced aggregation in PRP was donor-dependent. E. coli O157:H7 induced aggregation with a lag time of 6.9 ± 1.3 min in an αII b β3 -dependent and FcγRIIa-dependent manner. Furthermore, this interaction was enhanced by the presence of complement, and was dependent on thromboxane synthesis. These results show E. coli to be a potent inducer of platelet aggregation.

Bilateral obstruction of bilaterally duplicated collecting systems requiring upper and lower moiety drainage

A 60-year-old woman with a history of breast cancer presented with bilateral obstruction of bilaterally duplicated renal collecting systems secondary to extrinsic compression from metastatic pelvic lymphadenopathy. Bilateral JJ ureteric stents were inserted, resulting in some improvement of renal function but a failure to normalise completely. Repeat computed tomography demonstrated bilateral duplex collecting systems with persisting obstruction of the undrained moieties. Selective puncture was performed to decompress the obstructed renal moieties for bilateral nephrostomy catheter insertion. This allowed renal function to improve sufficiently for the patient to be discharged and commence chemotherapy. This is the first reported case of bilaterally obstructed partially duplicated collecting systems and it illustrates the importance of recognising anatomical variants to tailor treatment appropriately. It also highlights the important relationship between urology and interventional radiology in the management of such complex patients.

Pimavanserin

Pimavanserin (ACP-103) is a selective inverse agonist of the 5-hydroxytryptamine 2A (5-HT2A) receptor intended to treat patients with Parkinson's disease psychosis (PDP). Currently there are no FDA-approved medications in the United States for the treatment of PDP, although on September 2, 2014, the United States Food and Drug Administration granted breakthrough therapy status to pimavanserin, highlighting the unmet need for therapeutics in this class. Most antipsychotic medications worsen motor dysfunction due to dopamine antagonism, and all carry a black box warning for an increased risk of mortality in elderly patients with dementia-related psychosis. Data from phase II and phase III clinical trials suggest that pimavanserin is a safe and effective treatment option for PDP. Trial results indicate a significant reduction in hallucinations and delusions in patients with PDP without worsening motor symptoms. Additional studies are ongoing for the treatment of Alzheimer's psychosis, schizophrenia and insomnia. Such promising outcomes warrant a review of the available literature regarding pimavanserin and its use in the treatment of PDP symptoms.

False-positive hepatitis C virus serology after placement of a ventricular assistance device

BACKGROUND

Ventricular assist devices (VADs) have been associated with immune activation and sensitization. We observed several cases of false-positive (FP) hepatitis C virus (HCV) antibody (Ab) tests in patients being evaluated for orthotopic heart transplant (OHT), prompting us to investigate this further.

METHODS

We reviewed all VAD and OHT cases at Johns Hopkins from 2005 to 2012. FP HCV serology was defined as an equivocal or low-positive HCV Ab, plus either (i) a negative recombinant immunoblot (RIBA) and/or HCV nucleic acid test (NAT), or (ii) an indeterminate RIBA and negative NAT.

RESULTS

In 53 patients with available HCV testing, nearly 40% of patients (21/53: 39.6%) developed FP HCV Ab tests after VAD placement: 4 patients had negative NAT, 12 had negative RIBA, and 5 had an indeterminate RIBA and negative NAT. All patients with indeterminate RIBA tests had isolated reactivity to the same HCV protein, c100p/5-1-1p (NS4b protein). In 3 of 4 VAD patients who had OHT and repeat HCV Ab testing after VAD removal, repeat HCV Ab was negative (699-947 days after OHT); in 1 case, FP HCV serology persisted (5 days after OHT). Thirteen patients had OHT alone and none developed a FP HCV Ab.

CONCLUSIONS

FP HCV Ab results following VAD placement are very common. Reversal of FP serology in several patients after VAD removal is suggestive of a possible association with the VAD hardware. Clinicians should be aware of this phenomenon, as it could lead to delays in determining eligibility for OHT and increased costs.

Process Improvements Positively Impact the Use of Intravesical Mitomycin C after Transurethral Resection of Nonmuscle Invasive Bladder Cancer in a Large, Urban Urology Practice

INTRODUCTION

We assessed the rate of intravesical mitomycin C therapy in patients with nonmuscle invasive bladder cancer who underwent transurethral resection of the bladder, as well as the impact of procedural changes governing its use.

METHODS

A retrospective review of our bladder cancer database identified patients who underwent transurethral resection of the bladder with mitomycin C therapy during January 2008 to July 2014. Since our mitomycin C protocols were revised during 2013, patients were stratified based on date of service. Patient demographics and data describing mitomycin C use were tabulated.

RESULTS

During January 2008 to May 2013, 276 of 737 (37.5%) ideal patients received mitomycin C (not accounting for patients in whom mitomycin C was contraindicated). Conversely 461 of 737 patients (62.5%) did not receive mitomycin C. Shortages of mitomycin C were responsible for nonuse in 18.4% of cases while no specified reason for nonuse was given in 59%. When cases in which mitomycin C use was contraindicated were taken into account, mitomycin C was used in 51.6% overall. After the implementation of new mitomycin C operating procedures, mitomycin C use increased significantly to 76.0% (p <0.001) (accounting for appropriate nonuse). During this period mitomycin C shortages were not responsible for any case in which mitomycin C was not used.

CONCLUSIONS

During 2008 to 2013 mitomycin C was not used in a significant proportion of patients who underwent transurethral resection of the bladder. The implementation of a revised protocol governing mitomycin C use significantly and positively impacted mitomycin C use. Importantly, pharmacy shortages no longer contribute to the nonuse of mitomycin C in patients with bladder cancer. These data highlight the impact of continual improvement initiatives on standard clinical practice.

Virological failure and development of new resistance mutations according to CD4 count at combination antiretroviral therapy initiation

Objectives

No randomized controlled trials have yet reported an individual patient benefit of initiating combination antiretroviral therapy (cART) at CD4 counts > 350 cells/μL. It is hypothesized that earlier initiation of cART in asymptomatic and otherwise healthy individuals may lead to poorer adherence and subsequently higher rates of resistance development.

Methods

In a large cohort of HIV‐positive individuals, we investigated the emergence of new resistance mutations upon virological treatment failure according to the CD4 count at the initiation of cART.

Results

Of 7918 included individuals, 6514 (82.3%), 996 (12.6%) and 408 (5.2%) started cART with a CD4 count ≤ 350, 351–499 and ≥ 500 cells/μL, respectively. Virological rebound occurred while on cART in 488 (7.5%), 46 (4.6%) and 30 (7.4%) with a baseline CD4 count ≤ 350, 351–499 and ≥ 500 cells/μL, respectively. Only four (13.0%) individuals with a baseline CD4 count > 350 cells/μL in receipt of a resistance test at viral load rebound were found to have developed new resistance mutations. This compared to 107 (41.2%) of those with virological failure who had initiated cART with a CD4 count < 350 cells/μL.

Conclusions

We found no evidence of increased rates of resistance development when cART was initiated at CD4 counts above 350 cells/μL.

Preclinical assessment of a new magnetic resonance-based technique for determining bone quality by characterization of trabecular microarchitecture

The utility of HR-CT to study longitudinal changes in bone microarchitecture is limited by subject radiation exposure. Although MR is not subject to this limitation, it is limited both by patient movement that occurs during prolonged scanning at distal sites, and by the signal-to-noise ratio that is achievable for high-resolution images in a reasonable scan time at proximal sites. Recently, a novel MR-based technique, fine structure analysis (FSA) (Chase et al. Localised one-dimensional magnetic resonance spatial frequency spectroscopy. PCT/US2012/068284 2012, James and Chase Magnetic field gradient structure characteristic assessment using one-dimensional (1D) spatial frequency distribution analysis. 7932720 B2, 2011) has been developed which provides both high-resolution and fast scan times, but which generates at a designated set of spatial positions (voxels) a one-dimensional signal of spatial frequencies. Appendix 1 provides a brief introduction to FSA. This article describes an initial exploration of FSA for the rapid, non-invasive characterization of trabecular microarchitecture in a preclinical setting. For L4 vertebrae of sham and ovariectomized (OVX) rats, we compared FSA-generated metrics with those from CT datasets and from CT-derived histomorphometry parameters, trabecular number (Tb.N), bone volume density (BV/TV), trabecular thickness (Tb.Th) and trabecular separation (Tb.Sp). OVX caused a reduction of the higher frequency structures that correspond to a denser trabecular lattice, while increasing the preponderance of lower frequency structures, which correspond to a more open lattice. As one example measure, the centroid of the FSA spectrum (which we refer to as fSAcB) showed strong correlation in the same region with CT-derived histomorphometry values: Tb.Sp: r -0.63, p < 0.001; Tb.N: r 0.71, p < 0.001; BV/TV: r 0.64, p < 0.001, Tb.Th: r 0.44, p < 0.05. Furthermore, we found a 17.5% reduction in fSAcB in OVX rats (p < 0.0001). In a longitudinal study, FSA showed that the age-related increase in higher frequency structures was abolished in OVX rats, being replaced with a 78-194% increase in lower frequency structures (2.4-2.8 objects/mm range), indicating a more sparse trabecular lattice (p < 0.05). The MR-based fine structure analysis enables high-resolution, radiation-free, rapid quantification of bone structures in one dimension (the specific point and direction being chosen by the clinician) of the spine.

Laurent M, Cox A. Collaboration on a public health-driven vaccine initiative

Disease surveillance can be used as an opportunity to determine priorities for research and the development of new therapeutics. This is evident in the work underway to develop a new vaccine to combat a serious invasive childhood disease: Haemophilus influenzae serotype a (Hia). Following the introduction of Hib vaccine into the routine childhood immunization schedule in Canada in the early 1990's, the Public Health Agency of Canada (PHAC) began to document the dropping rates of H influenzae serotype b (Hib) infection. However, invasive H. influenzae diseases due to non-Hib strains began to increase and in 2007, surveillance for invasive H. influenzae disease due to all serotypes as well as non-typeable strains was initiated. Current data suggests Hia is a cause of serious invasive disease, particularly in Aboriginal populations. Similar to Hib, Hia causes severe illnesses such as meningitis, sepsis and bacteremic pneumonia in young children under the age of five. Given the emerging threat due to Hia in Aboriginal populations in Canada, PHAC formed a partnership with the National Research Council of Canada (NRC) to investigate the potential of creating a capsular polysaccharide vaccine against Hia. At the present time, candidate vaccine seed strains have been identified and PHAC and the NRC are working with the Northern Ontario School of Medicine, the US Centers for Disease Control and Prevention and others. The goal of this research is to identify and prepare a candidate vaccine against Hia while increasing the understanding of how such a vaccine would improve the health of a vulnerable population.

Abstract 4826: Mobilization of tumor cells into the circulation during radiation therapy for lung cancer

Thousands of patients die annually with distant metastasis after curative-intent or “radical” radiation therapy (RT). Because non-small cell lung cancer (NSCLC), the most common cause of cancer-related mortality, exhibits an especially high rate of distant metastasis after radical RT or chemo-RT for locoregionally-advanced disease, it represents a suitable model to investigate the relationship between RT and metastasis. We hypothesized that disruption of tumour architecture during RT could result in the release of viable tumor cells into the peripheral circulation.

We enumerated circulating tumor cells (CTCs) by fluorescence microscopy of blood samples immunostained with conventional CTC markers. We measured their DNA damage levels using γ-H2AX, a biomarker for radiation-induced DNA double-strand breaks, either by fluorescence-activated sorting (FACS) or by immunofluorescence microscopy. Twenty seven RT-treated NSCLC patients had blood samples analyzed by one or more methods. We identified increased CTC numbers after commencement of RT in 7 of 9 patients treated with palliative RT, and in 4 of 8 patients treated with curative-intent RT. CTCs were also identified, singly and in clumps in large numbers during RT by cytopathologic examination (in all 5 cases studied). Elevated γ-H2AX signal in post-RT blood samples signified the presence of CTCs derived from irradiated tumors. Blood taken after the commencement of RT contained tumor cells that proliferated extensively in vitro (in all 6 cases studied), and first experiments revealed that these cells survive in bloodstream of NOD/SCID mice for several months. CTCs formed γ-H2AX foci in response to ex vivo irradiation providing further evidence of their viability.

Although of concern, these findings could represent an opportunity to monitor and target CTCs during RT. They provide a rationale for the development of strategies to reduce the concentration of viable CTCs by modulating RT fractionation or by co-administering systemic therapies.

Citation Format: Michael MacManus, Robin Anderson, Prudence Russell, Ashley Cox, Agnieszka Swierczak, Judy P. Doherty, Daphne Jacobs, Jai Smith, Shankar Siva, Patricia E. Daly, David L. Ball, Roger F. Martin, Olga A. Martin. Mobilization of tumor cells into the circulation during radiation therapy for lung cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4826. doi:10.1158/1538-7445.AM2014-4826