Effects from filtration, capping agents, and presence/absence of food on the toxicity of silver nanoparticles to Daphnia magna

Relatively little is known about the behavior and toxicity of nanoparticles in the environment. Objectives of work presented here include establishing the toxicity of a variety of silver nanoparticles (AgNPs) to Daphnia magna neonates, assessing the applicability of a commonly used bioassay for testing AgNPs, and determining the advantages and disadvantages of multiple characterization techniques for AgNPs in simple aquatic systems. Daphnia magna were exposed to a silver nitrate solution and AgNPs suspensions including commercially available AgNPs (uncoated and coated), and laboratory-synthesized AgNPs (coated with coffee or citrate). The nanoparticle suspensions were analyzed for silver concentration (microwave acid digestions), size (dynamic light scattering and electron microscopy), shape (electron microscopy), surface charge (zeta potentiometer), and chemical speciation (X-ray absorption spectroscopy, X-ray diffraction). Toxicities of filtered (100 nm) versus unfiltered suspensions were compared. Additionally, effects from addition of food were examined. Stock suspensions were prepared by adding AgNPs to moderately hard reconstituted water, which were then diluted and used straight or after filtration with 100-nm filters. All nanoparticle exposure suspensions, at every time interval, were digested via microwave digester and analyzed by inductively coupled argon plasma-optical emission spectroscopy or graphite furnace-atomic absorption spectroscopy. Dose-response curves were generated and median lethal concentration (LC50) values calculated. The LC50 values for the unfiltered particles were (in μg/L): 1.1 ± 0.1-AgNO(3) ; 1.0 ± 0.1-coffee coated; 1.1 ± 0.2-citrate coated; 16.7 ± 2.4 Sigma Aldrich Ag-nanoparticles (SA) uncoated; 31.5 ± 8.1 SA coated. LC50 values for the filtered particles were (in μg/L): 0.7 ± 0.1-AgNO(3) ; 1.4 ± 0.1-SA uncoated; 4.4 ± 1.4-SA coated. The LC50 resulting from the addition of food was 176.4 ± 25.5-SA coated. Recommendations presented in this study include AgNP handling methods, effects from sample preparation, and advantages/disadvantages of different nanoparticle characterization techniques.     

Genetic Covariation Between the Author Recognition Test and Reading and Verbal Abilities: What Can We Learn from the Analysis of High Performance?

The Author Recognition Test (ART) measures print exposure and is a unique predictor of phonological and orthographic processes in reading. In a sample of adolescent and young adult twins and siblings (216 MZ/430 DZ pairs, 307 singletons; aged 11–29 years) ART scores were moderately heritable (67%) and correlated with reading and verbal abilities, with genes largely accounting for the covariance. We also examine whether high (and low) (i.e. 1SD above the mean) represents a quantitative extreme of the normal distribution. Heritability for high ART was of similar magnitude to the full sample, but, a specific genetic factor, independent from both low ART performance and high reading ability, accounted for 53–58% of the variance. This suggests a distinct genetic etiology for high ART ability and we speculate that the specific genetic influence is on orthographical processing, a critical factor in developing word recognition skills. Edited by Robert Plomin.     

Pain with no gain: allodynia following neural stem cell transplantation in spinal cord injury

Transplantation of neural stem cells (NSCs) in the injured spinal cord has been shown to improve functional outcome; however, recent evidence has demonstrated forelimb allodynia following transplantation of embryonic NSCs. The aim of this study was to investigate whether transplantation of murine C17.2 NSCs alone or transfected with glial-derived neurotrophic factor (C17.2/GDNF) would induce allodynia in transplanted spinal cord-injured animals. One week after a T8-level spinal cord injury (SCI), C17.2, C17.2/GDNF or normal saline was injected at the injury site. Locomotor function and sensory recovery to thermal and mechanical stimuli were then measured. Spinal cords were processed immunohistochemically at the injury/transplantation site for characterization of NSC survival and differentiation; and at the cervicothoracic level for calcitonin gene-related peptide (CGRP), a neuropeptide expressed in dorsal horn nocioceptive neurons, and growth-associated protein-43 (GAP43), a marker of neuronal sprouting. Locomotor function was not significantly improved following NSC transplantation at any time (P >0.05). Significant forelimb thermal and mechanical allodynia were observed following transplantation with both NSC populations (P <0.05). The C17.2 and C17.2/GDNF NSCs survived and differentiated into a predominately astrocytic population. Calcitonin gene-related peptide and GAP43 immunoreactivity significantly increased and co-localized in cervicothoracic dorsal horn laminae I-III following C17.2 and C17.2/GDNF transplantation. This study demonstrated that murine C17.2 NSCs differentiated primarily into astrocytes when transplanted into the injured spinal cord, and resulted in thermal and mechanical forelimb allodynia. Sprouting of nocioceptive afferents occurred rostral to the injury/transplantation site only in allodynic animals, suggesting a principal role in this aberrant pain state. Further, a difference in the degree of allodynia was noted between C17.2- and C17.2/GDNF transplant-treated groups; this difference correlated with the level of CGRP/GAP43 immunoreactivity and sprouting observed in the cervicothoracic dorsal horns. Both allodynia- and CGRP/GAP43-positive afferent sprouting were less in the C17.2/GDNF group compared to the C17.2 group, suggesting a possible protective or analgesic effect of GDNF on post-injury neuropathic pain.     

Cardiac Angiosarcoma Management and Outcomes: 20-Year Single-institution Experience

Purpose

To identify the clinicopathologic characteristics, treatments, and outcomes of a series of patients with primary cardiac angiosarcoma (AS).

Methods

This retrospective case series was set in a tertiary referral center with a multidisciplinary clinic. Consecutive patients with institutionally confirmed pathologic diagnosis of cardiac AS from January 1990 to May 2011 were reviewed. Main outcome measures included patient demographics, tumor characteristics, management strategies, disease response, and survival.

Results

Data from 18 patients (78?% male) were reviewed. Sixteen patients (89?%) had AS originating in the right atrium. At diagnosis, eight patients (44?%) had localized/locally advanced disease and ten patients (56?%) had metastatic disease. Initial treatment strategies included resection (44?%), chemotherapy (39?%), and radiotherapy (11?%). Of the eight patients with localized/locally advanced AS, two underwent macroscopically complete resection with negative microscopic margins, one underwent macroscopically complete resection with positive microscopic margins, one underwent macroscopically incomplete resection, two received chemotherapy followed by surgery and intraoperative radiotherapy, one received chemotherapy alone, and one died before planned radiotherapy. Median follow-up was 12?months. Median overall survival (OS) was 13?months for the entire cohort; median OS was 19.5?months for those presenting with localized/locally advanced AS and 6?months for those with metastatic disease at presentation (p?=?0.08). Patients who underwent primary tumor resection had improved median OS compared with patients whose tumors remained in situ (17 vs. 5?months, p?=?0.01).

Conclusions

Cardiac AS is associated with poor prognosis. Resection of primary tumor should be attempted when feasible, as OS may be improved. Nevertheless, most patients die of disease progression.     

Innovative surgical strategies: Minimally invasive CABG and off-pump CABG

Minimally invasive coronary artery bypass grafting (CABG) and off-pump coronary artery bypass grafting (OPCAB) have made up a significant facet of the recent attempts of surgical myocardial revascularization to evolve. Driven by an effort to limit the deleterious effects of cardiopulmonary bypass (CPB), along with a response to both the growing interests in performing procedures through smaller incisions and the successes of catheter-based therapies, these therapeutic options have found themselves moving into the future by resurrecting their past. Minimally invasive CABG is the procedure by which coronary grafting is performed through a small anterior thoracotomy, without the use of CPB. Although feasible, the inability to offer a more thorough degree of revascularization has limited the applicability of this procedure and, therefore, accounts for its overall minor contribution to the number of coronary revascularizations performed annually. Conversely, as the technical feasibility of performing complete revascularization without CPB has been achieved with OPCAB, its place as a mode of therapy remains uncertain. Several clinical trials have been performed to date with only a few being done in a prospective, randomized fashion. From this data has come a mix of information regarding either improvements or, at a minimum, no change in the rate of complications between CABG with, and without, CPB, while at the same time maintaining equivalent short-term graft patencies. The question remains, however, to which patient population is this approach to CABG optimal? Our practice has largely reserved OPCAB for those patients in whom manipulation of the aorta is considered not feasible due to severe calcification or in "high-risk" patients who are felt to be unable to tolerate the adverse physiologic effects of CPB. This makes up approximately 15% of our CABG population, roughly equal to the national average, with the remaining patients being revascularized with the assistance of CPB.     

Phlebotomy teams reduce blood-culture contamination rate and save money

OBJECTIVE: To determine the extent of resource utilization due to contaminated blood cultures. DESIGN: Case-control retrospective analysis. Twenty-three patients who had contaminated blood cultures were matched by age, underlying diseases, and discharge diagnoses with 23 patients who had negative blood cultures. SETTING: St Luke's Medical Center, a community teaching hospital in Cleveland, Ohio. The phlebotomy team was eliminated in November 1993 to reduce the costs. RESULTS: Blood cultures drawn by the phlebotomy team had a lower contamination rate compared with those drawn by nonphlebotomists (2.6% vs 5.6%). Patients with contaminated blood cultures were compared to those with negative blood cultures. The following parameters were found to be statistically significant: total hospital length of stay (LOS; 13.9 vs 5.5 days; P = .002), postculture LOS (8.9 vs 4.6; P = .01), postculture number of days on antibiotics (5.9 vs 2.9; P = .03), vancomycin use (9 vs 2 patients; P = .03), postculture cost of antibiotics ($762 vs $121; P = .004), and postculture hospital cost per patient ($10,515 vs $4,213; P = .001). CONCLUSIONS: This study demonstrated a substantial increase in resource utilization in our hospital due to contaminated blood cultures. The reinstitution of a phlebotomy team could be a cost-effective solution with savings between $950,000 and $1.5 million per year for our hospital.     

The EM structure of the TRAPPIII complex leads to the identification of a requirement for COPII vesicles on the macroautophagy pathway

The transport protein particle (TRAPP) III complex, comprising the TRAPPI complex and additional subunit Trs85, is an autophagy-specific guanine nucleotide exchange factor for the Rab GTPase Ypt1 that is recruited to the phagophore assembly site when macroautophagy is induced. We present the single-particle electron microscopy structure of TRAPPIII, which reveals that the dome-shaped Trs85 subunit associates primarily with the Trs20 subunit of TRAPPI. We further demonstrate that TRAPPIII binds the coat protein complex (COP) II coat subunit Sec23. The COPII coat facilitates the budding and targeting of ER-derived vesicles with their acceptor compartment. We provide evidence that COPII-coated vesicles and the ER-Golgi fusion machinery are needed for macroautophagy. Our results imply that TRAPPIII binds to COPII vesicles at the phagophore assembly site and that COPII vesicles may provide one of the membrane sources used in autophagosome formation. These events are conserved in yeast to mammals.Macroautophagy is a highly conserved catabolic process that uses a specialized membrane trafficking pathway to target proteins and organelles for degradation (1). Defects in this process have been linked to a variety of human diseases, including neurodegenerative diseases such as Parkinson’s disease (2). Macroautophagy is induced by a variety of physiological stresses and begins with the expansion of a cup-shaped nucleating membrane called the phagophore, or isolation membrane. As the phagophore expands, it engulfs intracellular proteins and membranes that are marked for degradation. This expanding membrane eventually closes to become an autophagosome, a double-membrane structure that seals its contents from the cytosol and delivers it to the lysosome or vacuole for degradation. A central unanswered question in the autophagy field is the mechanism by which the phagophore forms and matures into an autophagosome. Although it was once thought that the phagophore assembles de novo, recent evidence suggests it forms from a preexisting compartment. Compartments on the secretory pathway, including the endoplasmatic reticulum (ER) and Golgi complex, have been invoked in phagophore assembly (3, 4).A collection of ATG (autophagy-related) genes, the products of which regulate autophagy, were identified in the yeast Saccharomyces cerevisiae (1). Many of the Atg proteins needed for macroautophagy in yeast are shared with the biosynthetic cytoplasm to vacuole targeting (Cvt) pathway that transports certain hydrolases into the vacuole. Both pathways require the sequestration of cargo within a double-membrane structure; however, only the macroautophagy pathway is conserved in higher eukaryotes (5). When autophagy is induced, ATG gene products assemble at the phagophore assembly site (PAS) in a hierarchical manner. The scaffold protein complex that organizes this site is the Atg17 complex (6, 7).Previous studies have shown that the transport protein particle (TRAPP) III complex, an autophagy-specic guanine nucleotide exchange factor (GEF) for the Rab GTPase Ypt1, is recruited to the PAS (8) by Atg17 (9). At the PAS, TRAPPIII activates Ypt1 (8), which then recruits its downstream effector, the serine/threonine Atg1 kinase, to the PAS (9). TRAPPIII is one of three multimeric GEFs, called TRAPPI, TRAPPII, and TRAPPIII, that activate Ypt1 on different trafficking pathways (10). TRAPPI, an elongated complex ∼18 nm in length (11, 12), binds to ER-derived COPII-coated vesicles via an interaction between the TRAPPI subunit Bet3 and the coat subunit Sec23 (11, 13). The TRAPPIII complex contains the same six subunits present in TRAPPI plus one unique subunit, Trs85, that targets this complex to the PAS (8, 9). Here, we describe the single-particle electron microscopy (EM) structure of TRAPPIII from S. cerevisiae. TRAPPIII (23 nm) is longer than TRAPPI with Trs85 capping one end of the complex. As in TRAPPI, the two Bet3 subunits in TRAPPIII are solvent accessible and are available for interaction with Sec23. This observation suggests that TRAPPIII may play a role in tethering COPII-coated vesicles at the PAS. Consistent with this proposal, we find that COPII vesicles accumulate at the PAS when autophagy is blocked. Additionally, we show that mutations in components of the ER-Golgi trafficking machinery, which mediate COPII vesicle fusion, disrupt autophagy. Finally, we find that COPII vesicles accumulate at or near ER-mitochondria contact sites when COS-7 cells are starved. ER-mitochondria contact sites are where autophagosomes form in mammalian cells (14).