Checkpoint blockade toxicities: Insights into autoimmunity and treatment.

Checkpoint blockade has transformed not only the way cancers are treated, but also highlighted the importance of mounting a proper immune response against tumors. Despite advances in the field of immunotherapy, many patients develop a range of inflammatory toxicities that limit the efficacy of these therapies. These toxicities range from barrier site injury, such as colitis, to endocrine organ dysfunction, such as diabetes. In order to properly treat patients with cancer and avoid checkpoint blockade induced toxicities, we must gain a deeper understanding of the underlying mechanisms generating these adverse events. Cytotoxic and tissue-resident T cells likely play an important role in mediating some toxicities, though high levels of cytokines and the generation of auto-antibodies in other toxicities demonstrates these mechanisms are not all shared. Certain risk factors for specific toxicities may be able to predict who might benefit most from alternative therapies given the risk-benefit associated with checkpoint blockade. As the targets of checkpoint inhibitors have important functions in the prevention of autoimmunity, insights into risk factors and causes of toxicities will further our knowledge of fundamental immunology and enable the development of novel therapeutics.

The Study of the Epidemiology of Pediatric Hypertension Registry (SUPERHERO): Rationale and Methods.

Despite increasing prevalence of hypertension in youth and high adult cardiovascular mortality rates, the long-term consequences of youth-onset hypertension remain unknown. This is due to limitations of prior research such as small sample sizes, reliance on manual record review, and limited analytic methods that did not address major biases. The Study of the Epidemiology of Pediatric Hypertension (SUPERHERO) is a multisite retrospective Registry of youth evaluated by subspecialists for hypertension disorders. Sites obtain harmonized electronic health record data using standardized biomedical informatics scripts validated with randomized manual record review. Inclusion criteria are index visit for International Classification of Diseases Diagnostic Codes, 10th Revision (ICD-10 code)-defined hypertension disorder ≥January 1, 2015 and age <19 years. We exclude patients with ICD-10 code-defined pregnancy, kidney failure on dialysis, or kidney transplantation. Data include demographics, anthropomorphics, U.S. Census Bureau tract, histories, blood pressure, ICD-10 codes, medications, laboratory and imaging results, and ambulatory blood pressure. SUPERHERO leverages expertise in epidemiology, statistics, clinical care, and biomedical informatics to create the largest and most diverse registry of youth with newly diagnosed hypertension disorders. SUPERHERO's goals are to (i) reduce CVD burden across the life course and (ii) establish gold-standard biomedical informatics methods for youth with hypertension disorders.

Metacognitive accuracy predicts self-reported quality of life following traumatic brain injury.

OBJECTIVE: Metacognition and quality of life (QoL) are both adversely affected by traumatic brain injury (TBI), but the relation between them is not fully understood. As such, the purpose of this study was to determine the degree to which metacognitive accuracy predicts QoL in individuals with TBI. METHODS: Eighteen participants with moderate-to-severe TBI completed a stimulus-response task requiring the discrimination of emotions depicted in pictures of faces and then provided a retrospective confidence judgment after each response. Metacognitive accuracy was calculated using participants' response accuracy and confidence judgment accuracy. Participants also completed the Quality of Life After Brain Injury (QOLIBRI) questionnaire to assess QoL in various areas of functioning. RESULTS: Performance of a linear regression analysis revealed that higher metacognitive accuracy significantly predicted lower overall QoL. Additionally, higher metacognitive accuracy significantly predicted lower QoL related to cognition and physical limitations. CONCLUSION: The study results provide evidence of an inverse relation between metacognitive performance and QoL following TBI. Metacognitive changes associated with TBI and their relation to QoL have several clinical implications for TBI rehabilitation.

Risk Factors and Outcomes Associated with Gaps in Care in Children with Congenital Heart Disease.

Adults with congenital heart disease (CHD) benefit from cardiology follow-up at recommended intervals of ≤ 2 years. However, benefit for children is less clear given limited studies and unclear current guidelines. We hypothesize there are identifiable risks for gaps in cardiology follow-up in children with CHD and that gaps in follow-up are associated with differences in healthcare utilization. Our cohort included children < 10 years old with CHD and a healthcare encounter from 2008 to 2013 at one of four North Carolina (NC) hospitals. We assessed associations between cardiology follow-up and demographics, lesion severity, healthcare access, and educational isolation (EI). We compared healthcare utilization based on follow-up. Overall, 60.4% of 6,969 children received cardiology follow-up within 2 years of initial encounter, including 53.1%, 58.1%, and 79.0% of those with valve, shunt, and severe lesions, respectively. Factors associated with gaps in care included increased drive time to a cardiology clinic (Hazard Ratio (HR) 0.92/15-min increase), EI (HR 0.94/0.2-unit increase), lesion severity (HR 0.48 for shunt/valve vs severe), and older age (HR 0.95/month if < 1 year old and 0.94/year if > 1 year old; p < 0.05). Children with a care gap subsequently had more emergency department (ED) visits (Rate Ratio (RR) 1.59) and fewer inpatient encounters and procedures (RR 0.51, 0.35; p < 0.05). We found novel factors associated with gaps in care for cardiology follow-up in children with CHD and altered health care utilization with a gap. Our findings demonstrate a need to mitigate healthcare barriers and generate clear cardiology follow-up guidelines for children with CHD.

Third-Grade Academic Performance and Episodes of Cardiac Care Among Children with Congenital Heart Defects.

Children with congenital heart defects (CHDs) are at risk for poor academic performance. The degree to which receipt of health care services is associated with adverse academic outcomes is not known. We examined the association between episodes of cardiac care and third-grade performance in children with CHD. We identified subjects between 1/1/2008 and 4/30/2012 among 5 centers in North Carolina. We classified children by CHD type and linked subjects to the state educational records. Any inpatient or outpatient cardiac encounter on a date of service was considered an encounter. We calculated the number of encounters by adding the number of inpatient or outpatient cardiac visits prior to the date of the end-of-grade (EOG) tests. We estimated the odds of failing third-grade reading or math EOG tests by episodes of care stratified at the 50th percentile, controlling for CHD type, maternal education, sex, race/ethnicity, birth weight, and gestational age. A total of 184 children had third-grade EOG scores linked to health care records. The median number of episodes of care was 4 (range: 1-60). Those with visits ˃ 50th percentile (> 4 encounters/year over the 4.3 year observation period) had 2.09 (95% CI 1.04, 4.21) greater odds of failing the math EOG compared to those ≤ 50th percentile (1-4 encounters). The third-grade math score declined by 1.5 points (P < 0.008) for every 10 episodes of care. There was no association of episodes of care on third-grade reading performance. Children with CHD with > 4 episodes of cardiac care/year may be at risk for delays in third-grade academic performance. Strategies to minimize school absenteeism may improve academic success in this population.

Impact of Prenatal Diagnosis of Critical Congenital Heart Disease on Preoperative and Postoperative Outcomes.

The objective of this study was to assess the relationship of prenatal diagnosis of critical congenital heart disease (CHD) to preoperative and postoperative patient findings. Retrospective analysis of neonates with critical CHD who underwent cardiothoracic surgery at one of four centers in North Carolina between 2008 and 2013. Surgical data collected by sites for submission to the Society of Thoracic Surgeons Congenital Heart Surgery Database (STS-CHSD) and the North Carolina CHD Lifespan Database were queried. There were 715 patients with STS records; 558 linked to the NC-CHD database. Patients with prenatal diagnosis had a lower incidence of preoperative risk factors, including need for mechanical ventilation and presence of shock. However, prenatally diagnosed patients had worse short-term outcomes, including higher operative mortality, higher incidence of select postoperative complications, and longer LOS. There was no difference in one-year mortality. Our findings are consistent with current literature which suggests that prenatal diagnosis of critical CHD is associated with a more optimized preoperative clinical status. However, we found that patients with prenatal diagnoses had less favorable postoperative outcomes. This needs to be investigated further, but may be secondary to patient-specific factors, such as CHD disease severity.

The Role of Neuroinflammation in Neuropsychiatric Disorders Following Traumatic Brain Injury: A Systematic Review.

BACKGROUND: Neuropsychiatric symptoms are common following traumatic brain injury (TBI), but their etiological onset remains unclear. Mental health research implicates neuroinflammation in the development of psychiatric disorders. The presence of neuroinflammatory responses after TBI thus prompts an investigation of their involvement in the emergence of neuropsychiatric disorders postinjury. OBJECTIVE: Review the literature surrounding the role of neuroinflammation and immune response post-TBI in the development of neuropsychiatric disorders. METHODS: A search of scientific databases was conducted for original, empirical studies in human subjects. Key words such as "neuroinflammation," "TBI," and "depression" were used to identify psychopathology as an outcome TBI and the relation to neuroinflammatory response. RESULTS: Study results provide evidence of neuroinflammation mediated post-TBI neuropsychiatric disorders including anxiety, trauma/stress, and depression. Inflammatory processes and stress response dysregulation can lead to secondary cell damage, which promote the development and maintenance of neuropsychiatric disorders postinjury. CONCLUSION: This review identifies both theoretical and empirical support for neuroinflammatory response as feasible mechanisms underlying neuropsychiatric disorders after TBI. Further understanding of these processes in this context has significant clinical implications for guiding the development of novel treatments to reduce psychiatric symptoms postinjury. Future directions to address current limitations in the literature are discussed.

Dose rate versus gantry speed performance evaluation for slow gantry speeds using DICOM RT plans.

PURPOSE: Varian provides a DICOM RT Plan file that users can deliver to the electronic portal imaging device (EPID) panel to confirm the linear accelerator delivers consistent dose output across several regions of interest for varying dose rates and gantry speeds (DRGS). This work investigates if (a) the vendor-provided DRGS DICOM RT Plan is valid within the gantry speed range of stereotactic body radiation therapy (SBRT) treatments, and (b) if output constancy is maintained at those gantry speeds on a TrueBeam. METHODS: Python code was written to iterate through all control points in the DICOM RT Plan files for 21 SBRT patients and the MU per degree values were calculated for each control point. A histogram was generated to illustrate how MU per degree was distributed among the control points from the patient plans. Then, the total number of MUs was increased in the vendor-provided DRGS DICOM file to make a "modified DRGS DICOM RT Plan," which surpasses the maximum MU per degree value found in the patient plans, forcing the gantry to travel at slow speeds and deliver more MU per degree over the same arc length (representative of those during SBRT treatment delivery). The modified DRGS DICOM RT Plan file was then delivered on a TrueBeam to acquire EPID images of the dose distribution. The EPID images were analyzed with Pylinac, a Python library that analyzes DICOM RT images acquired during routine linac QA. RESULTS: Over 83% of patient DICOM RT Plan control points had MU per degree values greater than the MU per degree values in the vendor-provided DRGS DICOM file. The Pylinac analysis of the EPID-acquired images found a maximum deviation of 0.4% from machine baselines. CONCLUSIONS: The modified DRGS DICOM file can be used to determine if a TrueBeam linac is operating within specifications even when very low gantry speeds are reached.

Causes of Death in Infants and Children with Congenital Heart Disease.

With improved surgical outcomes, infants and children with congenital heart disease (CHD) may die from other causes of death (COD) other than CHD. We sought to describe the COD in youth with CHD in North Carolina (NC). Patients from birth to 20 years of age with a healthcare encounter between 2008 and 2013 in NC were identified by ICD-9 code. Patients who could be linked to a NC death certificate between 2008 and 2016 were included. Patients were divided by CHD subtypes (severe, shunt, valve, other). COD was compared between groups. Records of 35,542 patients < 20 years old were evaluated. There were 15,277 infants with an annual mortality rate of 3.5 deaths per 100 live births. The most frequent COD in infants (age < 1 year) were CHD (31.7%), lung disease (16.1%), and infection (11.4%). In 20,265 children (age 1 to < 20 years), there was annual mortality rate of 9.7 deaths per 1000 at risk. The most frequent COD in children were CHD (34.2%), neurologic disease (10.2%), and infection (9.5%). In the severe subtype, CHD was the most common COD. In infants with shunt-type CHD disease, lung disease (19.5%) was the most common COD. The mortality rate in infants was three times higher when compared to children. CHD is the most common underlying COD, but in those with shunt-type lesions, extra-cardiac COD is more common. A multidisciplinary approach in CHD patients, where development of best practice models regarding comorbid conditions such as lung disease and neurologic disease could improve outcomes in this patient population.

Primary Open Abductor Reconstruction: A 5 to 10-Year Study.

BACKGROUND: Gluteal tears are recognized as the source of pain over the greater trochanter. We investigated the outcome of primary open abductor tendon reconstruction with a 5-10 year follow-up. METHODS: One hundred sixty-five consecutive hips underwent an open abductor tendon reconstruction, with all tears confirmed preoperatively by magnetic resonance imaging. Oxford Hip Scores (OHS) were assessed at the initial visit, and at 5-10 years. RESULTS: The average preoperative OHS was 22 (range 7-34) and average postoperative OHS was 40 a difference of 18 (P < .0001). CONCLUSION: Surgical reconstruction of degenerate abductor tendons should be considered in the presence of a magnetic resonance imaging confirmed separation where clinical findings are consistent with the known tendon disruption. Open transosseous reconstruction reliably results in good pain relief at 5-10 years.

A Mechanism for Symmetry Breaking and Shape Control in Single-Crystal Gold Nanorods.

The phenomenon of symmetry breaking-in which the order of symmetry of a system is reduced despite manifest higher-order symmetry in the underlying fundamental laws-is pervasive throughout science and nature, playing a critical role in fields ranging from particle physics and quantum theory to cosmology and general relativity. For the growth of crystals, symmetry breaking is the crucial step required to generate a macroscopic shape that has fewer symmetry elements than the unit cell and/or seed crystal from which it grew. Advances in colloid synthesis have enabled a wide variety of nanocrystal morphologies to be achieved, albeit empirically. Of the various nanoparticle morphologies synthesized, gold nanorods have perhaps been the most intensely studied, thanks largely to their unique morphology-dependent optical properties and exciting application potential. However, despite intense research efforts, an understanding of the mechanism by which a single crystal breaks symmetry and grows anisotropically has remained elusive, with many reports presenting seemingly conflicting data and theories. A fundamental understanding of the symmetry breaking process is needed to provide a rational framework upon which future synthetic approaches can be built. Inspired by recent experimental results and drawing upon the wider literature, we present a mechanism for gold nanorod growth from the moments prior to symmetry breaking to the final product. In particular, we describe the steps by which a cuboctahedral seed particle breaks symmetry and undergoes anisotropic growth to form a nanorod. With an emphasis on the evolving crystal structure, we highlight the key geometrical and chemical drivers behind the symmetry breaking process and factors that govern the formation and growth of nanorods, including control over the crystal width, length, and surface faceting. We propose that symmetry breaking is induced by an initial formation of a new surface structure that is stabilized by the deposition of silver, thus preserving this facet in the embryonic nanorod. These new surfaces initially form stochastically as truncations that remove high-energy edge atoms at the intersection of existing {111} facets and represent the beginnings of a {011}-type surface. Crucially, the finely tuned [HAuCl4]:[AgNO3] ratio and reduction potential of the system mean that silver deposition can occur on the more atomically open surface but not on the pre-existing lower-index facets. The stabilized surfaces develop into side facets of the nascent nanorod, while the largely unpassivated {111} facets are the predominant site of Au atom deposition. Growth in the width direction is tightly controlled by a self-sustaining cycle of galvanic replacement and silver deposition. It is the [HAuCl4]:[AgNO3] ratio that directly determines the particle size at which the more open atomic surfaces can be stabilized by silver and the rate of growth in the width direction following symmetry breaking, thus explaining the known aspect ratio control with Ag ion concentration. We describe the evolving surface faceting of the nanorod and the emergence of higher-index facets. Collectively, these observations allow us to identify facet-size and edge-atom effects as a simple fundamental driver of symmetry breaking and the subsequent development of new surfaces in the presence of adsorbates.

Selecting optimal features from Fourier transform infrared spectroscopy for discrete-frequency imaging.

Tissue histology utilizing chemical and immunohistochemical labels plays an important role in biomedicine and disease diagnosis. Recent research suggests that mid-infrared (IR) spectroscopic imaging may augment histology by providing quantitative molecular information. One of the major barriers to this approach is long acquisition time using Fourier-transform infrared (FTIR) spectroscopy. Recent advances in discrete frequency sources, particularly quantum cascade lasers (QCLs), may mitigate this problem by allowing selective sampling of the absorption spectrum. However, DFIR imaging only provides a significant advantage when the number of spectral samples is minimized, requiring a priori knowledge of important spectral features. In this paper, we demonstrate the use of a GPU-based genetic algorithm (GA) using linear discriminant analysis (LDA) for DFIR feature selection. Our proposed method relies on pre-acquired broadband FTIR images for feature selection. Based on user-selected criteria for classification accuracy, our algorithm provides a minimal set of features that can be used with DFIR in a time-frame more practical for clinical diagnosis.

TRAF1 Coordinates Polyubiquitin Signaling to Enhance Epstein-Barr Virus LMP1-Mediated Growth and Survival Pathway Activation.

The Epstein-Barr virus (EBV) encoded oncoprotein Latent Membrane Protein 1 (LMP1) signals through two C-terminal tail domains to drive cell growth, survival and transformation. The LMP1 membrane-proximal TES1/CTAR1 domain recruits TRAFs to activate MAP kinase, non-canonical and canonical NF-kB pathways, and is critical for EBV-mediated B-cell transformation. TRAF1 is amongst the most highly TES1-induced target genes and is abundantly expressed in EBV-associated lymphoproliferative disorders. We found that TRAF1 expression enhanced LMP1 TES1 domain-mediated activation of the p38, JNK, ERK and canonical NF-kB pathways, but not non-canonical NF-kB pathway activity. To gain insights into how TRAF1 amplifies LMP1 TES1 MAP kinase and canonical NF-kB pathways, we performed proteomic analysis of TRAF1 complexes immuno-purified from cells uninduced or induced for LMP1 TES1 signaling. Unexpectedly, we found that LMP1 TES1 domain signaling induced an association between TRAF1 and the linear ubiquitin chain assembly complex (LUBAC), and stimulated linear (M1)-linked polyubiquitin chain attachment to TRAF1 complexes. LMP1 or TRAF1 complexes isolated from EBV-transformed lymphoblastoid B cell lines (LCLs) were highly modified by M1-linked polyubiqutin chains. The M1-ubiquitin binding proteins IKK-gamma/NEMO, A20 and ABIN1 each associate with TRAF1 in cells that express LMP1. TRAF2, but not the cIAP1 or cIAP2 ubiquitin ligases, plays a key role in LUBAC recruitment and M1-chain attachment to TRAF1 complexes, implicating the TRAF1:TRAF2 heterotrimer in LMP1 TES1-dependent LUBAC activation. Depletion of either TRAF1, or the LUBAC ubiquitin E3 ligase subunit HOIP, markedly impaired LCL growth. Likewise, LMP1 or TRAF1 complexes purified from LCLs were decorated by lysine 63 (K63)-linked polyubiqutin chains. LMP1 TES1 signaling induced K63-polyubiquitin chain attachment to TRAF1 complexes, and TRAF2 was identified as K63-Ub chain target. Co-localization of M1- and K63-linked polyubiquitin chains on LMP1 complexes may facilitate downstream canonical NF-kB pathway activation. Our results highlight LUBAC as a novel potential therapeutic target in EBV-associated lymphoproliferative disorders.

Counseling Practices for Fetal Hypoplastic Left Heart Syndrome.

While counseling parents of a fetus diagnosed with hypoplastic left heart syndrome (HLHS), pediatric cardiologists play a critical role in shaping a family's expectations for the months and years to come. However, techniques for the most effective counseling practices have not been studied, and significant variation among physicians is likely present. Web-based survey of pediatric cardiologists that perform fetal echocardiography using snowball sampling. 201 physicians responded (61% male, 81% from academic centers, and 95% from the U.S.), with an average experience of 12 years. The majority of respondents (73%) typically received initial referrals for HLHS between 20 and 24 weeks of gestation. Most physicians counsel families alone (54%), while others counsel with a nurse (35%), social worker (12%), and/or maternal-fetal medicine colleague (15%). Termination of pregnancy was discussed by 79% of respondents, although 15% did not know their state's legal limit for termination. While initial counseling sessions routinely described the typical earlier ramifications of HLHS, many long-term sequelae of the disease were not commonly discussed. Content of counseling was affected by region of the country, but not by practice setting, experience, or fetal volume. Respondents identified multiple barriers that limited their counseling practices. Our data suggest that current counseling practices often fail to cover important information. Perceived barriers to a full discourse on long-term sequelae of HLHS are common and may lead to a disconnect between reality and a family's understanding of the natural history of palliated HLHS. Opportunities to improve counseling practices exist, and there may be benefits to gain from more formal training.

Accounting for tissue heterogeneity in infrared spectroscopic imaging for accurate diagnosis of thyroid carcinoma subtypes.

Fourier transform infrared (FT-IR) microscopy was used to image tissue samples from twenty patients diagnosed with thyroid carcinoma. The spectral data were then used to differentiate between follicular thyroid carcinoma and follicular variant of papillary thyroid carcinoma using principle component analysis coupled with linear discriminant analysis and a Naïve Bayesian classifier operating on a set of computed spectral metrics. Classification of patients' disease type was accomplished by using average spectra from a wide region containing follicular cells, colloid, and fibrosis; however, classification of disease state at the pixel level was only possible when the extracted spectra were limited to follicular epithelial cells in the samples, excluding the relatively uninformative areas of fibrosis. The results demonstrate the potential of FT-IR microscopy as a tool to assist in the difficult diagnosis of these subtypes of thyroid cancer, and also highlights the importance of selectively and separately analyzing spectral information from different features of a tissue of interest.

A label-free approach by infrared spectroscopic imaging for interrogating the biochemistry of diabetic nephropathy progression.

Routine histology, the current gold standard, involves staining for specific biomolecules. However, untapped biochemical information in tissue can be gathered using biochemical imaging. Infrared spectroscopy is an emerging modality that allows label-free chemical imaging to derive biochemical information (such as protein, lipids, DNA, collagen) from tissues. Here we employed this technology in order to better predict the development of diabetic nephropathy. Using human primary kidney biopsies or nephrectomies, we obtained tissue from 4 histologically normal kidneys, 4 histologically normal kidneys from diabetic subjects, and 5 kidneys with evidence of diabetic nephropathy. A biochemical signature of diabetic nephropathy was derived that enabled prediction of nephropathy based on the ratio of only 2 spectral frequencies. Nonetheless, using the entire spectrum of biochemical information, we were able to detect renal disease with near-perfect accuracy. Additionally, study of sequential protocol biopsies from 3 transplanted kidneys showed biochemical changes even prior to clinical manifestation of diabetic nephropathy. Thus, infrared imaging can identify critical biochemical alterations that precede morphologic changes, potentially allowing for earlier intervention.

Examining the photoprotection hypothesis for adaxial foliar anthocyanin accumulation by revisiting comparisons of green- and red-leafed varieties of coleus (Solenostemon scutellarioides).

Although plants rely on light to drive energy production via photosynthesis, excess light can be harmful. Plants have evolved photoprotective mechanisms to mitigate this threat, including thermal energy dissipation, the most common form of which involves de-epoxidized constituents of the xanthophyll cycle facilitating the conversion of excess excitation energy to heat. A role in photoprotection has also been proposed for red anthocyanins when they accumulate near the adaxial leaf surface. Here, we compared the response to experimental light stress of a red-leafed (anthocyanin rich) and a green-leafed variety of coleus [Solenostemon scutellarioides (L.) Codd], examining chlorophyll fluorescence emission and pigment composition. After experimentally imposed intense white light, red- and green-leafed coleus exhibited manifestations of light stress (decreased photosystem II quantum efficiency) of a similar magnitude. This, considered alone, could be interpreted as evidence that anthocyanins do not serve a photoprotective role. However, during excess light exposure, the green-leafed variety employed a greater level of thermal energy dissipation and possessed correspondingly higher xanthophyll cycle pool sizes and de-epoxidation states. During exposure to red light, which anthocyanins absorb very poorly, levels of thermal energy dissipation did not differ between coleus varieties. Taken together, our findings suggest that adaxial anthocyanins minimize stress associated with excess light absorption and that the green-leafed variety of coleus compensated for its much lower levels of adaxial anthocyanins by invoking higher levels of energy dissipation. Thus, anthocyanin accumulation should be considered alongside the suite of photoprotective mechanisms employed by photosynthetic tissues.

Cysteine Enhances Bioavailability of Copper to Marine Phytoplankton.

Emiliania huxleyi, a ubiquitous marine algae, was cultured under replete and Cu-limiting conditions to investigate Cu uptake strategies involving thiols and associated redox reactions; comparisons to a model diatom, Thalassiosira pseudonana, were also drawn. Cu-limitation increased rates of cell surface reduction of Cu(II) to Cu(I) in E. huxleyi but not in T. pseudonana. Furthermore, Cu-limited E. huxleyi cells took up more Cu when cysteine was present compared to when no ligand was added, although a dependence on cysteine concentration was not observed. In contrast, Cu uptake by replete cells was dependent upon the relative abundance of inorganic species [Cu(I)']. We also show that cysteine can increase the bioavailability of Cu to Cu-limited cells, of both species, through the reductive release of Cu(I) from fairly strong Cu(II) ligands such as EDTA. Finally, support for a mechanism involving uptake of a Cys-Cu complex in E. huxleyi is drawn from the observation that Cu-limitation significantly enhances cysteine uptake by transporters that exhibit Michaelis-Menten kinetics. These Cu uptake strategies help explain the presence and distribution of dissolved thiols in surface seawater and have implications for the biogeochemical cycling of Cu in low Cu environments.

High-resolution Fourier-transform infrared chemical imaging with multiple synchrotron beams.

Conventional Fourier-transform infrared (FTIR) microspectroscopic systems are limited by an inevitable trade-off between spatial resolution, acquisition time, signal-to-noise ratio (SNR) and sample coverage. We present an FTIR imaging approach that substantially extends current capabilities by combining multiple synchrotron beams with wide-field detection. This advance allows truly diffraction-limited high-resolution imaging over the entire mid-infrared spectrum with high chemical sensitivity and fast acquisition speed while maintaining high-quality SNR.