Best Practice Alert to Promote Screening for Primary Aldosteronism Among People With Apparent Treatment-Resistant Hypertension

OBJECTIVE

Guidelines recommend screening all individuals with resistant hypertension for primary aldosteronism (PA) but less than 2% are screened. We aimed to develop a noninterruptive Best Practice Alert (BPA) to assess if its implementation in the electronic health record improved PA screening rates among individuals with apparent treatment-resistant hypertension (aTRH).

METHODS

We implemented a noninterruptive BPA on 9/17/2022 at our ambulatory primary care, endocrinology, nephrology, and cardiology clinics. We assessed clinical parameters of people with aTRH before (9/17/2021-9/16/2022) and after (9/17/2022-9/16/2023) the BPA was implemented. The noninterruptive BPA embedded with an order set identified people with aTRH and recommended screening for PA if it was not previously performed.

RESULTS

There were 10 944 and 11 463 people with aTRH who attended office visits during the 12 months before and after the BPA implementation, respectively. There were no statistically significant differences in median age (P = .096), sex (P = .577), race (P = .753), and ethnicity (P = .472) between the pre- and post-BPA implementation groups. There was a significant increase in PA screening orders placed (227 [2.1%] vs 476 [4.2%], P < .001) and PA screening labs performed (169 [1.5%] vs 382 [3.3, P < .001) after BPA implementation. PA screening tests were positive in 26% (44/169) and 23% (88/382) of people in the pre- and post-BPA groups, respectively (P = .447).

CONCLUSION

Implementation of a real-time electronic health record BPA doubled the screening rate for PA among people with aTRH; however, the overall screening rate was low.

Naturalistic reinforcement learning

Humans possess a remarkable ability to make decisions within real-world environments that are expansive, complex, and multidimensional. Human cognitive computational neuroscience has sought to exploit reinforcement learning (RL) as a framework within which to explain human decision-making, often focusing on constrained, artificial experimental tasks. In this article, we review recent efforts that use naturalistic approaches to determine how humans make decisions in complex environments that better approximate the real world, providing a clearer picture of how humans navigate the challenges posed by real-world decisions. These studies purposely embed elements of naturalistic complexity within experimental paradigms, rather than focusing on simplification, generating insights into the processes that likely underpin humans' ability to navigate complex, multidimensional real-world environments so successfully.

Affect-congruent attention modulates generalized reward expectations

Positive and negative affective states are respectively associated with optimistic and pessimistic expectations regarding future reward. One mechanism that might underlie these affect-related expectation biases is attention to positive- versus negative-valence features (e.g., attending to the positive reviews of a restaurant versus its expensive price). Here we tested the effects of experimentally induced positive and negative affect on feature-based attention in 120 participants completing a compound-generalization task with eye-tracking. We found that participants' reward expectations for novel compound stimuli were modulated in an affect-congruent way: positive affect induction increased reward expectations for compounds, whereas negative affect induction decreased reward expectations. Computational modelling and eye-tracking analyses each revealed that these effects were driven by affect-congruent changes in participants' allocation of attention to high- versus low-value features of compounds. These results provide mechanistic insight into a process by which affect produces biases in generalized reward expectations.

The Impact of Multicultural Interfacility Video Case Conference: A Novel Education Model After the COVID Pandemic

Context

The COVID-19 pandemic challenged undertaking gradual educational activities for residency and fellowship trainees. However, recent technological advances have enabled broadening active learning opportunities through international online conferences.

Objective

The format of our international online endocrine case conference, launched during the pandemic, is introduced. The objective impact of this program on trainees is described.

Methods

Four academic facilities developed a semiannual international collaborative endocrinology case conference. Experts were invited as commentators to facilitate in-depth discussion. Six conferences were held between 2020 and 2022. After the fourth and sixth conferences, anonymous multiple-choice online surveys were administered to all attendees.

Results

Participants included trainees and faculty. At each conference, 3 to 5 cases of rare endocrine diseases from up to 4 institutions were presented, mainly by trainees. Sixty-two percent of attendees reported 4 facilities as the appropriate size for the collaboration to maintain active learning in case conferences. Eighty-two percent of attendees preferred a semiannual conference. The survey also revealed the positive impact on trainees' learning regarding diversity of medical practice, academic career development, and confidence in honing of presentation skills.

Conclusion

We present an example of our successful virtual global case conference to enhance learning about rare endocrine cases. For the success of the collaborative case conference, we suggest smaller cross-country institutional collaborations. Preferably, they would be international, semiannually based, and with recognized experts as commentators. Since our conference has engendered multiple positive effects on trainees and faculty, continuation of virtual education should be considered even after the pandemic era.

PMON81 A Case of Hypophysitis Associated With SARS-CoV2 Vaccination

Objective

Although SARS-CoV2 vaccines have been developed with multiple novel technologies and rapidly disseminated worldwide, the full profile of adverse effects has not been known. Recently, there are sporadic but increasing reports of endocrinopathies in relation to SARS-CoV2 vaccination. Here, we report a rare case of hypophysitis with acute onset of diabetes insipidus after SARS-CoV2 vaccination.

Case Report

A 48-year-old female who had been in her usual state of health until she received the first SARS-CoV2 vaccine. Two days after the vaccination, she started to have flu-like symptoms including severe headache and myalgia as well as persistent headache, polydipsia and polyuria. On presentation, her vital signs were stable, with her pulse being 81 bpm, BP: 122/84 mm Hg, temperature: 98.6F. Her physical examination was unremarkable. Laboratory evaluation revealed normal values of the basic metabolic panel including sodium level of 142 mmol/L and normal complete blood count. Due to her prolonged and worsening headache, she underwent a brain MRI which revealed a 4 mm round shape of thickening pituitary stalk and partial empty sella. The polydipsia, polyuria, and the thickening of the pituitary stalk led to further pituitary work-up. She underwent the overnight water deprivation test followed by the desmopressin challenge test. Her overnight water deprivation test revealed hypernatremia (Na 147 mmol/L), elevated serum osmolarity (309 mmol/kg), and low urinary osmolarity (83 mmol/kg) which were compatible with diabetes insipidus. Her IGF1 level revealed low normal range (66 ng/mL). Her 250 mcg cosyntropin test showed appropriate response without adrenal insufficiency. DDAVP was started. 3 months after the vaccination, her symptoms have partially improved, and on repeating the MRI brain she has persistent pituitary stalk thickening.

Discussion

We report a rare case of diabetes insipidus from hypophysitis associated with SARS-CoV2 vaccine. Mechanisms of SARS-CoV2 vaccination-associated endocrinopathy is unknown. From our literature search, we found increasing numbers of the cases of endocrinopathy reported after the SARS- CoV2 vaccination. The thyroid seems the most frequently reported endocrine organ (83%), followed by the pituitary (11%) and adrenal (6%). Average onset is 1-5 days after the vaccinations and reported with all types of SARS-CoV2 vaccines. More mid-age (average age 46) female (78%) cases have been reported. Although associations are not confirmed, endocrinopathies may be underestimated in the post vaccinated population. Further studies are warranted to better understand SARS-CoV2 vaccinations and potential associations of endocrinopathy.

Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

ODP358 The effect of multi-cultural inter-facility endocrine video case conferencing – A novel model of education during the COVID pandemic

Introduction

Coronavirus disease 2019 (COVID-19) pandemic brought not only physical and mental health problems but also negative impacts on social, economic and educational activities. Trainees, including medical students, residents, and clinical fellows had fewer opportunities to see and discuss patients with supervisors in person. In contrast, recent advances in technology have made it possible to review cases with overseas experts through online conferences. We launched a biannual inter-facility endocrine case review meeting in a video conference format during the pandemic of COVID-19. Here we present the format of our inter-facility online case conference and its impact on trainees.

Methods

The conference was organized by clinical faculty members from Japan, USA and Canada. For each conference, each facility prepared one to two cases in English. Four to five cases were presented and discussed with participants and guest commentators. After completion of the 4th conference, an anonymous multiple-choice online survey was administered to all attendees, and data was collected and analyzed by the committee members. Differences in responses before and after attendance were analyzed by paired t-test.

Results

Four conferences were held between July/31/2020, and Dec/10/2021 (CST). The facilities participating was as follows: University of Minnesota, Hokkaido Univ., University of Alberta, and Kobe Univ. Participants included medical students, residents, endocrine fellows, and faculty. Presenters were medical students (n=1), endocrine fellows (n=15), and neurosurgery faculty (n=1). Presented topics included the following: 11 cases with pituitary disorders, 3 cases with neuroendocrine tumors, 2 cases with adrenal disorders and 1 case of thyroid disorder. Sixty-two percent of the attendees stated that 3-4 facilities are an ideal size of the collaborations in inter-facility case conference, and 82% of the attendees felt twice a year is an appropriate frequency of the conference. Ninety-seven percent of the participants indicated their willingness to continue to attend. The survey results also revealed that the conference has a positive impact on trainees’ clinical practice and career development. Furthermore, the confidence in presenting skills in English significantly increased after the conference (p<0. 01).

Conclusion

Under the COVID-19 pandemic, we launched a new format of inter-institutional case review meeting using a video conferencing system that transcends national boundaries. This represents a new educational method for trainees. A small-scale (3-4 facilities) international collaboration in a video format may provide opportunities for learning rare endocrine cases, cultural diversity of endocrine care, enhanced active learning for trainees, and the opportunity for international presentation. This may lead to the development of a novel educational system in the future.

Presentation: No date and time listed

A Case of Hypophysitis Associated With SARS-CoV-2 Vaccination

Background/Objective

Although SARS-CoV-2 vaccines have been developed with multiple novel technologies and rapidly disseminated worldwide, the full profile of adverse effects has not been known. Recently, there are sporadic but increasing reports of endocrinopathy in relation to SARS-CoV-2 vaccination. Here we report a rare case of hypophysitis with acute onset of diabetes insipidus, immediately after SARS-CoV-2 vaccination.

Case Report

A 48-year-old female patient had been in her usual state of health until she received the first SARS-CoV-2 vaccine. Two days after vaccination, she started to have flu-like symptoms, including severe headache and myalgia as well as persistent headache, polydipsia, and polyuria. She was diagnosed with diabetes insipidus, and magnetic resonance imaging revealed thickening of the pituitary stalk. Three months after vaccination, her symptoms had somewhat improved, but she still had pituitary stalk thickening on magnetic resonance imaging.

Discussion

Given the timing of the occurrence of diabetes insipidus, we believe that the patient’s hypophysitis may be associated with SARS-CoV-2 vaccination. We also found 19 cases of endocrinopathy after SARS-CoV-2 vaccination by literature search. The reported endocrine organs were the thyroid, pituitary, and adrenals. Twelve cases of diabetes were also reported. Among 3 pituitary cases, diabetes insipidus was reported only in our case.

Conclusion

We report a rare case of SARS-CoV-2 vaccine-triggered hypophysitis, which led to diabetes insipidus. SARS-CoV-2 vaccine–related endocrinopathy seems, indeed, possible. Endocrinopathy is associated with infrequent complications; however, it may be underestimated in the post–SARS-CoV-2-vaccinated population. Further studies are warranted to better understand SARS-CoV-2 vaccine–related endocrinopathy.

Bifractal structure of chromatin in rat lymphocyte nuclei

The small-angle neutron scattering (SANS) on the rat lymphocyte nuclei demonstrates the bifractal nature of the chromatin structural organization. The scattering intensity from rat lymphocyte nuclei is described by power law Q^{-D} with fractal dimension approximately 2.3 on smaller scales and 3 on larger scales. The crossover between two fractal structures is detected at momentum transfer near 10^{-1}nm^{-1}. The use of contrast variation (D_{2}O-H_{2}O) in SANS measurements reveals clear similarity in the structural organizations of nucleic acids (NA) and proteins. Both chromatin components show bifractal behavior with logarithmic fractal structure on the large scale and volume fractal with slightly smaller than 2.5 structure on the small scale. Scattering intensities from chromatin, protein component, and NA component demonstrate an extremely extensive range of logarithmic fractal behavior (from 10^{-3} to approximately 10^{-1}nm^{-1}). We compare the fractal arrangement of rat lymphocyte nuclei with that of chicken erythrocytes and the immortal HeLa cell line. We conclude that the bifractal nature of the chromatin arrangement is inherent in the nuclei of all these cells. The details of the fractal arrangement-its range and correlation/interaction between nuclear acids and proteins are specific for different cells and is related to their functionality.

Observation of nucleic acid and protein correlation in chromatin of HeLa nuclei using small-angle neutron scattering with D_{2}O-H_{2}O contrast variation

The small-angle neutron scattering (SANS) on HeLa nuclei demonstrates the bifractal nature of the chromatin structural organization. The border line between two fractal structures is detected as a crossover point at Q_{c}≈4×10^{-2}nm^{-1} in the momentum transfer dependence Q^{-D}. The use of contrast variation (D_{2}O-H_{2}O) in SANS measurements reveals clear similarity in the large scale structural organizations of nucleic acids (NA) and proteins. Both NA and protein structures have a mass fractal arrangement with the fractal dimension of D≈2.5 at scales smaller than 150 nm down to 20 nm. Both NA and proteins show a logarithmic fractal behavior with D≈3 at scales larger than 150 nm up to 6000 nm. The combined analysis of the SANS and atomic force microscopy data allows one to conclude that chromatin and its constitutes (DNA and proteins) are characterized as soft, densely packed, logarithmic fractals on the large scale and as rigid, loosely packed, mass fractals on the smaller scale. The comparison of the partial cross sections from NA and proteins with one from chromatin as a whole demonstrates spatial correlation of two chromatin's components in the range up to 900 nm. Thus chromatin in HeLa nuclei is built as the unified structure of the NA and proteins entwined through each other. Correlation between two components is lost upon scale increases toward 6000 nm. The structural features at the large scale, probably, provide nuclei with the flexibility and chromatin-free space to build supercorrelations on the distance of 10^{3} nm resembling cycle cell activity, such as an appearance of nucleoli and a DNA replication.

Human Representation Learning

The central theme of this review is the dynamic interaction between information selection and learning. We pose a fundamental question about this interaction: How do we learn what features of our experiences are worth learning about? In humans, this process depends on attention and memory, two cognitive functions that together constrain representations of the world to features that are relevant for goal attainment. Recent evidence suggests that the representations shaped by attention and memory are themselves inferred from experience with each task. We review this evidence and place it in the context of work that has explicitly characterized representation learning as statistical inference. We discuss how inference can be scaled to real-world decisions by approximating beliefs based on a small number of experiences. Finally, we highlight some implications of this inference process for human decision-making in social environments.

Phase behavior of ultrasoft spheres show stable bcc lattices

The phase behavior of supersoft spheres is explored using solutions of ultralow cross-linked poly(N-isopropylacrylamide)-based microgels as a model system. For these microgels, the effects of the electric charges on their surfaces can be neglected and therefore only the role of softness on the phase behavior is investigated. The samples show a liquid-to-crystal transition at higher volume fraction with respect to both hard spheres and stiffer microgels. Furthermore, stable body centered cubic (bcc) crystals are observed in addition to the expected face centered cubic (fcc) crystals. Small-angle x-ray and neutron scattering with contrast variation allow the characterization of both the microgel-to-microgel distance and the architecture of single microgels in crowded solutions. The measurements reveal that the stable bcc crystals depend on the interplay between the collapse and the interpenetration of the external shell of the ultralow cross-linked microgels.

Switch of fractal properties of DNA in chicken erythrocytes nuclei by mechanical stress

The small-angle neutron scattering (SANS) on the chicken erythrocyte nuclei demonstrates the bifractal nature of the chromatin structural organization. Use of the contrast variation (D_{2}O-H_{2}O) in SANS measurements reveals the differences in the DNA and protein arrangements inside the chromatin substance. It is the DNA that serves as a framework that constitutes the bifractal behavior showing the mass fractal properties with D=2.22 at a smaller scale and the logarithmic fractal behavior with D≈3 at a larger scale. The protein spatial organization shows the mass fractal properties with D≈2.34 throughout the whole nucleus. The borderline between two fractal levels can be significantly shifted toward smaller scales by centrifugation of the nuclei disposed on the dry substrate, since nuclei suffer from mechanical stress transforming them to a disklike shape. The height of this disk measured by atomic force microscopy (AFM) coincides closely with the fractal borderline, thus characterizing two types of the chromatin with the soft (at larger scale) and rigid (at smaller scale) properties. The combined SANS and AFM measurements demonstrate the stress induced switch of the DNA fractal properties from the rigid, but loosely packed, mass fractal to the soft, but densely packed, logarithmic fractal.

Cold and distant: structural features of the nucleoprotein complex of a cold-adapted influenza A virus strain

Two influenza A nucleoprotein variants (wild-type: G102R; and mutant: G102R and E292G) were studied with regard to macro-molecular interactions in oligomeric form (24-mers). The E292G mutation has been previously shown to provide cold adaptation. Molecular dynamics simulations of these complexes and trajectory analysis showed that the most significant difference between the obtained models was distance between nucleoprotein complex strands. The isolated complexes of two ribonucleoprotein variants were characterized by transmission electron microscopy and differential scanning fluorimetry (DSF). Presence of the E292G substitution was shown by DSF to affect nucleoprotein complex melting temperature. In the filament interface peptide model, it was shown that the peptide corresponding in primary structure to the wild-type NP (SGYDFEREGYS) is prone to temperature-dependent self-association, unlike the peptide corresponding to E292G substitution (SGYDFGREGYS). It was also shown that the SGYDFEREGYS peptide is capable of interacting with a monomeric nucleoprotein (wild type); this interaction's equilibrium dissociation constant is five orders of magnitude lower than for the SGYDFGREGYS peptide. Using small-angle neutron scattering (SANS), the supramolecular structures of isolated complexes of these proteins were studied at temperatures of 15, 32, and 37 °C. SANS data show that the structures of the studied complexes at elevated temperature differ from the rod-like particle model and react differently to temperature changes. The data suggest that the mechanism behind cold adaptation with E292G is associated with a weakening of the interaction between strands of the ribonucleoprotein complex and, as a result, the appearance of inter-chain interface flexibility necessary for complex function at low temperature.Communicated by Ramaswamy H. Sarma.

Thyroid nodules over 4 cm do not have higher malignancy or benign cytology false-negative rates

PURPOSE

Whether thyroid nodules 4 cm or larger with benign cytology carry a higher risk of malignancy, and should be managed differently than smaller nodules remains controversial. We aimed to evaluate the malignancy rate and benign cytology false-negative rate in thyroid nodules ≥4 cm compared with those <4 cm.

METHODS

All thyroidectomies between January 2010 and December 2014 were reviewed. Patient demographics, preoperative sonographic nodule size, fine needle aspiration cytology (FNAC), and final surgical pathology results were compared for index nodules ≥4 vs. <4 cm.

RESULTS

A total of 490 index nodules with preoperative FNAC were identified. A total of 137 nodules were ≥4 cm and 353 nodules were <4 cm. The prevalence of carcinoma was lower (23 vs. 53%) in nodules ≥4 vs. <4 cm (p < 0.0001). The false-negative rate of benign FNAC for ≥4 and <4 cm index nodule was 5.2% and 5.9%, respectively (p = 1.000).

CONCLUSIONS

This study shows that thyroid nodules ≥4 cm do not have a higher malignancy rate at surgery nor higher benign cytology false-negative rate than smaller nodules. Thyroid nodules over 4 cm do not require resection, to rule out malignancy, based on size alone.

State representation in mental illness

Reinforcement learning theory provides a powerful set of computational ideas for modeling human learning and decision making. Reinforcement learning algorithms rely on state representations that enable efficient behavior by focusing only on aspects relevant to the task at hand. Forming such representations often requires selective attention to the sensory environment, and recalling memories of relevant past experiences. A striking range of psychiatric disorders, including bipolar disorder and schizophrenia, involve changes in these cognitive processes. We review and discuss evidence that these changes can be cast as altered state representation, with the goal of providing a useful transdiagnostic dimension along which mental disorders can be understood and compared.

Direct Assessment of Tube Dilation in Entangled Polymers

A key ingredient within theories focusing on the rheology of entangled polymers is the way how the topological constraints of an entangled chain are lifted by unconstrained segments, i.e., how the constraining tube is dilated. This important question has been addressed by directly measuring the tube diameter d at the scale of the tube by neutron spin echo spectroscopy. The tube diameter d and plateau modulus G_{N}^{0} of highly entangled polyethylene oxide (PEO) chains of volume fraction c that are diluted by low molecular PEO show a concentration dependence d∝c^{a/2} and G_{N}^{0}∝c^{1+a} with an exponent a close to 4/3. This result allows the clear discrimination between different theoretical models that predict 4/3 or other values between 1 and 2 and provides an important ingredient to tube model theories.

Holistic Reinforcement Learning: The Role of Structure and Attention

Compact representations of the environment allow humans to behave efficiently in a complex world. Reinforcement learning models capture many behavioral and neural effects but do not explain recent findings showing that structure in the environment influences learning. In parallel, Bayesian cognitive models predict how humans learn structured knowledge but do not have a clear neurobiological implementation. We propose an integration of these two model classes in which structured knowledge learned via approximate Bayesian inference acts as a source of selective attention. In turn, selective attention biases reinforcement learning towards relevant dimensions of the environment. An understanding of structure learning will help to resolve the fundamental challenge in decision science: explaining why people make the decisions they do.

All-DNA System Close to the Percolation Threshold

We characterize via small-angle neutron scattering the structural properties of a mixture of all-DNA particles with functionalities 4 (A) and 2 (B) constrained by design to reside close to the percolation threshold. DNA base sequences are selected such that A particles can only bind with B ones and that at the studied temperature (10 °C) all AB bonds are formed and long-lived, originating highly polydisperse persistent equilibrium clusters. The concentration dependence of the scattered intensity and its wavevector dependence is exploited to determine the fractal dimension and the size distribution of the clusters, which are found to be consistent with the critical exponents of the 3-D percolation universality class. The value of DNA nanoparticles as nanometric patchy colloids with well-defined functionality, bonding selectivity, and exquisite control of the interaction strength is demonstrated.

Association of Biotin Ingestion With Performance of Hormone and Nonhormone Assays in Healthy Adults

IMPORTANCE

Biotinylated antibodies and analogues, with their strong binding to streptavidin, are used in many clinical laboratory tests. Excess biotin in blood due to supplemental biotin ingestion may affect biotin-streptavidin binding, leading to potential clinical misinterpretation. However, the degree of interference remains undefined in healthy adults.

OBJECTIVE

To assess performance of specific biotinylated immunoassays after 7 days of ingesting 10 mg/d of biotin, a dose common in over-the-counter supplements for healthy adults.

DESIGN, SETTING, AND PARTICIPANTS

Nonrandomized crossover trial involving 6 healthy adults who were treated at an academic medical center research laboratory.

EXPOSURE

Administration of 10 mg/d of biotin supplementation for 7 days.

MAIN OUTCOMES AND MEASURES

Analyte concentrations were compared with baseline (day 0) measures on the seventh day of biotin treatment and 7 days after treatment had stopped (day 14). The 11 analytes included 9 hormones (ie, thyroid-stimulating hormone, total thyroxine, total triiodothyronine, free thyroxine, free triiodothyronine, parathyroid hormone, prolactin, N-terminal pro-brain natriuretic peptide, 25-hydroxyvitamin D) and 2 nonhormones (prostate-specific antigen and ferritin). A total of 37 immunoassays for the 11 analytes were evaluated on 4 diagnostic systems, including 23 assays that incorporated biotin and streptavidin components and 14 assays that did not include biotin and streptavidin components and served as negative controls.

RESULTS

Among the 2 women and 4 men (mean age, 38 years [range, 31-45 years]) who took 10 mg/d of biotin for 7 days, biotin ingestion-associated interference was found in 9 of the 23 (39%) biotinylated assays compared with none of the 14 nonbiotinylated assays (P = .007). Results from 5 of 8 biotinylated (63%) competitive immunoassays tested falsely high and results from 4 out of 15 (27%) biotinylated sandwich immunoassays tested falsely low.

CONCLUSIONS AND RELEVANCE

In this preliminary study of 6 healthy adult participants and 11 hormone and nonhormone analytes measured by 37 immunoassays, ingesting 10 mg/d of biotin for 1 week was associated with potentially clinically important assay interference in some but not all biotinylated assays studied. These findings should be considered for patients taking biotin supplements before ordering blood tests or when interpreting results.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT03034707.

Polymer Chain Conformation and Dynamical Confinement in a Model One-Component Nanocomposite

We report a neutron-scattering investigation on the structure and dynamics of a single-component nanocomposite based on SiO_{2} particles that were grafted with polyisoprene chains at the entanglement limit. By skillful labeling, we access both the monomer density in the corona as well as the conformation of the grafted chains. While the corona profile follows a r^{-1} power law, the conformation of a grafted chain is identical to that of a chain in a reference melt, implying a high mutual penetration of the coronas from different particles. The brush crowding leads to topological confinement of the chain dynamics: (i) At local scales, the segmental dynamics is unchanged compared to the reference melt, while (ii) at the scale of the chain, the dynamics appears to be slowed down; (iii) by performing a mode analysis in terms of end-fixed Rouse chains, the slower dynamics is tracked to topological confinement within the cone spanned by the adjacent grafts; (iv) by adding 50% matrix chains, the topological confinement sensed by the grafted chain is lifted partially and the apparent chain motion is accelerated. We observe a crossover from pure Rouse motion at short times to topological confined motion beyond the time when the segmental mean squared displacement has reached the distance to the next graft.

The role of the binding salt sodium salicylate in semidilute ionic cetylpyridinium chloride micellar solutions: a rheological and scattering study

The viscosity varies as a consequence of binding, first, and screening, later, action of the penetrating salt.

The effects of aging on the interaction between reinforcement learning and attention

Reinforcement learning (RL) in complex environments relies on selective attention to uncover those aspects of the environment that are most predictive of reward. Whereas previous work has focused on age-related changes in RL, it is not known whether older adults learn differently from younger adults when selective attention is required. In 2 experiments, we examined how aging affects the interaction between RL and selective attention. Younger and older adults performed a learning task in which only 1 stimulus dimension was relevant to predicting reward, and within it, 1 "target" feature was the most rewarding. Participants had to discover this target feature through trial and error. In Experiment 1, stimuli varied on 1 or 3 dimensions and participants received hints that revealed the target feature, the relevant dimension, or gave no information. Group-related differences in accuracy and RTs differed systematically as a function of the number of dimensions and the type of hint available. In Experiment 2 we used trial-by-trial computational modeling of the learning process to test for age-related differences in learning strategies. Behavior of both young and older adults was explained well by a reinforcement-learning model that uses selective attention to constrain learning. However, the model suggested that older adults restricted their learning to fewer features, employing more focused attention than younger adults. Furthermore, this difference in strategy predicted age-related deficits in accuracy. We discuss these results suggesting that a narrower filter of attention may reflect an adaptation to the reduced capabilities of the reinforcement learning system. (PsycINFO Database Record

Correlation Between Histological Diagnosis and Mutational Panel Testing of Thyroid Nodules: A Two-Year Institutional Experience

BACKGROUND

Indeterminate thyroid fine-needle aspiration (FNA) cytology, including atypia of undetermined significance (AUS/FLUS) and suspicious for follicular neoplasm (SFN), continues to generate uncertainty about the presence of malignancy, resulting in repeated follow-up, repeat FNA, or diagnostic surgery. Mutational panel testing may improve the malignancy risk prediction in indeterminate nodules, but the general application of such testing has not been investigated extensively.

METHODS

A retrospective review was performed of all patients undergoing thyroidectomy at a tertiary care facility over a two-year period. Mutational panel test results, when present, were analyzed relative to FNA cytologic result and surgical histopathologic diagnosis. Malignancy rates, sensitivity, specificity, positive predictive values (PPV), negative predictive values (NPV) and positive and negative likelihood ratios (LR) were calculated.

RESULTS

A total of 261 operated thyroid nodules had the following initial FNA cytology results: 2% non-diagnostic, 23% benign, 28% AUS/FLUS, 11% SFN, 9% suspicious for malignancy (SUSP), and 27% malignant. The histopathologic malignancy rate was 48%, subcategorized by cytology into benign 7%, AUS/FLUS 30%, SFN 38%, and SUSP 83%. Mutations were more frequent in indeterminate nodules that were histologically malignant versus benign (p < 0.0001) or versus adenoma (p = 0.001). Mutational analysis in 44 AUS/FLUS nodules resulted in a malignancy detection sensitivity of 85%, a specificity of 65%, a PPV of 50%, a NPV of 91%, and a positive LR of 2.4. In 12 SFN nodules analyzed with ThyroSeq(®) testing, sensitivity was 100%, specificity 57%, PPV 63%, NPV 100%, and LR 2.3. Performance of the seven-gene mutational panel was not significantly different from the ThyroSeq(®) panel in the AUS/FLUS group. The malignancy yield, comparing the mutation positive AUS/FLUS group with the untested AUS/FLUS surgical cohort, did not reach statistical significance (p = 0.17).

CONCLUSIONS

In a surgical cohort, a similar NPV but a lower PPV was found with the use of mutational panel testing compared to the published literature. Following the identification of a mutation, the prevalence of malignancy in the AUS/FLUS or SFN category was increased by nearly 15% to 45% and 53%, respectively. Further study is needed to confirm these results and to analyze clinical outcome subcategories relative to the utility of mutational testing.

DYT1 dystonia increases risk taking in humans

It has been difficult to link synaptic modification to overt behavioral changes. Rodent models of DYT1 dystonia, a motor disorder caused by a single gene mutation, demonstrate increased long-term potentiation and decreased long-term depression in corticostriatal synapses. Computationally, such asymmetric learning predicts risk taking in probabilistic tasks. Here we demonstrate abnormal risk taking in DYT1 dystonia patients, which is correlated with disease severity, thereby supporting striatal plasticity in shaping choice behavior in humans.

DOI:http://dx.doi.org/10.7554/eLife.14155.001

We learn to choose better options and avoid worse ones through trial and error, but exactly how this happens is still unclear. One idea is that we learn 'values' for options: whenever we choose an option and get more reward than originally expected (for example, if an unappetizing-looking food turns out to be very tasty), the value of that option increases. Likewise, if we get less reward than expected, the chosen option’s value decreases.

This learning process is hypothesized to work via the strengthening and weakening of connections between neurons in two parts of the brain: the cortex and the striatum. In this model, the activity of the neurons in the cortex represents the options, and the value of these options is represented by the activity of neurons in the striatum. Strengthening the connections is thought to increase the value of the stimulus, but this theory has been difficult to test.

In humans, a single genetic mutation causes a movement disorder called DYT1 dystonia, in which muscles contract involuntarily. In rodents, the same mutation causes the connections between the neurons in the cortex and the striatum to become too strong. If the theory about value learning is true, this strengthening should affect the decisions of patients that have DYT1 dystonia.

Arkadir et al. got healthy people and people with DYT1 dystonia to play a game where they had to choose between a 'sure' option and a 'risky' option. Picking the sure option guaranteed the player would receive a small amount of money, whereas the risky option gave either double this amount or nothing. The theory predicts that the double rewards should cause the patients to learn abnormally high values, which would lure them into making risky choices. Indeed, Arkadir et al. found that players with DYT1 dystonia were more likely to choose the risky option, with the people who had more severe symptoms of dystonia having a greater tendency towards taking risks.

Arkadir et al. showed that these results correspond with a model that suggests that people with DYT1 dystonia learn excessively from unexpected wins but show weakened learning after losses, causing them to over-estimate the value of risky choices. This imbalance mirrors the previous results that showed an inappropriate strengthening of the connections between neurons in rodents, and so suggests that similar changes occur in the brains of humans. Thus it appears that the changes in the strength of the connections between neurons translate into changes in behavior.

This pattern of results might also mean that the movement problems seen in people with DYT1 dystonia may be because they over-learn movements that previously led to a desired outcome and cannot sufficiently suppress movements that are no longer useful. Testing this idea will require further experiments.

DOI:http://dx.doi.org/10.7554/eLife.14155.002

A Combined SAXS/SANS Study for the in Situ Characterization of Ligand Shells on Small Nanoparticles: The Case of ZnO

ZnO nanoparticles (NPs) have great potential for their use in, e.g., thin film solar cells due to their electro-optical properties adjustable on the nanoscale. Therefore, the production of well-defined NPs is of major interest. For a targeted production process, the knowledge of the stabilization layer of the NPs during and after their formation is of particular importance. For the study of the stabilizer layer of ZnO NPs prepared in a wet chemical synthesis from zinc acetate, only ex situ studies have been performed so far. An acetate layer bound to the surface of the dried NPs was found; however, an in situ study which addresses the stabilizing layer surrounding the NPs in a native dispersion was missing. By the combination of small angle scattering with neutrons and X-rays (SANS and SAXS) for the same sample, we are now able to observe the acetate shell in situ for the first time. In addition, the changes of this shell could be followed during the ripening process for different temperatures. With increasing size of the ZnO core (d(core)) the surrounding shell (d(shell)) becomes larger, and the acetate concentration within the shell is reduced. For all samples, the shell thickness was found to be larger than the maximum extension of an acetate molecule with acetate concentrations within the shell below 50 vol %. Thus, there is not a monolayer of acetate molecules that covers the NPs but rather a swollen shell of acetate ions. This shell is assumed to hinder the growth of the NPs to larger macrostructures. In addition, we found that the partition coefficient μ between acetate in the shell surrounding the NPs and the total amount of acetate in the solution is about 10% which is in good agreement with ex situ data determined by thermogravimetric analysis.

Statistical computations underlying the dynamics of memory updating

Psychophysical and neurophysiological studies have suggested that memory is not simply a carbon copy of our experience: Memories are modified or new memories are formed depending on the dynamic structure of our experience, and specifically, on how gradually or abruptly the world changes. We present a statistical theory of memory formation in a dynamic environment, based on a nonparametric generalization of the switching Kalman filter. We show that this theory can qualitatively account for several psychophysical and neural phenomena, and present results of a new visual memory experiment aimed at testing the theory directly. Our experimental findings suggest that humans can use temporal discontinuities in the structure of the environment to determine when to form new memory traces. The statistical perspective we offer provides a coherent account of the conditions under which new experience is integrated into an old memory versus forming a new memory, and shows that memory formation depends on inferences about the underlying structure of our experience.

When do we modify old memories, and when do we create new ones? We suggest that this question can be answered statistically: The parsing of experience into distinct memory traces corresponds to inferences about the underlying structure of the environment. When sensory data change gradually over time, the brain infers that the environment has slowly been evolving, and the current representation of the environment (an existing memory trace) is updated. In contrast, abrupt changes indicate transitions between different structures, leading to the formation of new memories. While these ideas fall naturally out of statistical models of learning, they have not yet been directly tested in the domain of human memory. In this paper, we describe a model of statistical inference that instantiates these ideas, and test the model by asking human participants to reconstruct previously seen visual objects that have since changed gradually or abruptly. The results of this experiment support our theory of how the statistical structure of sensory experiences shapes memory formation.

A free-choice premium in the basal ganglia

Apparently, the act of free choice confers value: when selecting between an item that you had previously chosen and an identical item that you had been forced to take, the former is often preferred. What could be the neural underpinnings of this free-choice bias in decision making? An elegant study recently published in Neuron suggests that enhanced reward learning in the basal ganglia may be the culprit.

Left renal cyst - left duplex kidney with compromised superior renal unit and ectopic ureteral orifice in the prostatic urethra

The urinary abnormalities are an important health problem. If they are not recognized in due time, they usually lead to the loss of the renal unit function. In many cases, the diagnosis is late and incidental.

CASE PRESENTATION

We present the case of M.I., a 74-year-old male admitted in our surgical unit with diffuse left lumbar pain, low urinary tract symptoms and slow increase in abdomen volume in the past 4 years. Computer tomography scan and ecography showed a large left lumbar cyst like mass with a dilated supernumerary ureter with ectopic ureteral orifice in the prostatic urethra and apparently normal anatomic inferior renal unit. The goal was the excision of the "cyst like" mass (superior left renal unit) but because of the anatomical particularities (extensive fibrosis and local topographical changes) total nephrectomy was performed.

CONCLUSIONS

Given a normal contralateral kidney, the discovery of a urinary abnormality can be a real challenge, their evolution being a silent one. This type of disease can be suspected only with the development of clinical symptoms. The anatomic particularities (duplex kidney) together with the long evolution of the disease changed the local topography making the preservation of the inferior left renal unit a difficult, almost impossible task for the surgeon.

Microscopic dynamics of polyethylene glycol chains interacting with silica nanoparticles

We present high resolution neutron spectroscopic investigations of polyethylene glycol matrices interacting attractively with neat SiO2 nanoparticles. We observe a very rich dynamical picture that significantly contradicts earlier conclusions on such systems. Investigating a short chain matrix we realized that a fraction of chains is attached at the nanoparticle surface suppressing completely its translational diffusion. Nevertheless these attached chains undergo an unchanged segmental dynamics seemingly forming a micellelike corona of chains attached with their OH end groups. Changing to methyl-terminated chains the picture changes drastically, now showing a tightly adsorbed layer that however is not glassy as often assumed but undergoes fast picosecond local dynamics. With the singular importance of end groups, mean field approaches are not applicable and future simulations should be redirected to model such unexpected phenomena.

Effect of nanoconfinement on polymer dynamics: surface layers and interphases

We present neutron spin echo experiments that address the much debated topic of dynamic phenomena in polymer melts that are induced by interacting with a confining surface. We find an anchored surface layer that internally is highly mobile and not glassy as heavily promoted in the literature. The polymer dynamics in confinement is, rather, determined by two phases, one fully equal to the bulk polymer and another that is partly anchored at the surface. By strong topological interaction, this phase confines further chains with no direct contact to the surface. These form the often invoked interphase, where the full chain relaxation is impeded through the interaction with the anchored chains.

Experimental determination of resolution function parameters from small-angle neutron scattering data of a colloidal SiO2dispersion

A dilute dispersion of charge-stabilized, monodisperse silica nanoparticles has been used to determine the instrumental resolution function parameters of a conventional small-angle neutron scattering instrument in pinhole geometry over the entire accessible range of momentum transferq. Independent determination of the structure parameters of the colloidal silica dispersion by small-angle X-ray scattering enables refinement of both theq-independent geometric and theq-dependent (wavelength spread or polychromaticity of the neutron beam) contributions to the resolution function. The procedure described is appropriate if no further instrumental characterization is available. It is demonstrated that the sample used for refining the resolution function parameters has to exhibit sharp structural scattering features such as Bragg reflections, form factor maxima and minima, or an inter-particle correlation peak for each instrumental configuration at which the measurements have been performed to cover aqrange of two orders of magnitude (0.03 <q< 3.2 nm−1).

The effect on glucagon, glucagon-like peptide-1, total and acyl-ghrelin of dietary fats ingested with and without potato

INTRODUCTION

We are interested in the metabolic response to ingested macronutrients and the interaction between macronutrients in meals. Recently, we have determined the insulin and glucose response to ingestion of lard, olive oil, or safflower oil, fat sources varying in fatty acid composition and carbohydrate (CHO), in the form of potato.

OBJECTIVE

Our aim was to determine the effect of these dietary fats ingested alone or with potato on glucagon, glucagon-like peptide-1 (GLP-1) (7-37 and 7-36 amide), and total and acyl-ghrelin concentrations.

METHODS

Healthy subjects ingested 25 g fat (lard, olive oil, or safflower oil), 50 g CHO (potato), 25 g fat with 50 g CHO, or water only. Glucagon, GLP-1 (7-37 and 7-36 amide), and total and acyl-ghrelin responses were determined over 4 h.

RESULTS

All fats when ingested alone increased glucagon. Glucagon increases were dramatically attenuated when fats were ingested with the potato. GLP-1 increased after all meals, but was greatest when fats were ingested alone. The fat-stimulated increase was completely negated when fats were ingested with potato. Both acyl and total ghrelin decreased when only fats were ingested, as expected. When potato was ingested with any of the fats, the fat-induced decrease in acyl-ghrelin response also was essentially negated. Paradoxically, ghrelin increased when potato alone was ingested.

CONCLUSIONS

The current data indicate that the glucagon, GLP-1 and ghrelin responses to ingested fats, varying in fatty acid composition, are significantly affected by co-ingestion of CHO. Overall, the interaction between ingested foods in general is likely to be complex.

Direct observation of confined single chain dynamics by neutron scattering

Neutron spin echo has revealed the single chain dynamic structure factor of entangled polymer chains confined in cylindrical nanopores with chain dimensions either much larger or smaller than the lateral pore sizes. In both situations, a slowing down of the dynamics with respect to the bulk behavior is only observed at intermediate times. The results at long times provide a direct microscopic measurement of the entanglement distance under confinement. They constitute the first experimental microscopic evidence of the dilution of the total entanglement density in a polymer melt under strong confinement, a phenomenon that so far was hypothesized on the basis of various macroscopic observations.

The degree of saturation of fatty acids in dietary fats does not affect the metabolic response to ingested carbohydrate

BACKGROUND

We are interested in the metabolic response to ingested macronutrients, and the interaction between macronutrients in meals. Previously, we and others reported that the postprandial rise in serum glucose following ingestion of 50 g carbohydrate, consumed as potato, was markedly attenuated when butter was ingested with the carbohydrate, whereas the serum insulin response was little affected by the combination.

OBJECTIVE

To determine whether a similar response would be observed with three other dietary fats considerably different in fatty acid composition.

DESIGN

Nine healthy subjects received lard, twelve received olive oil and eleven received safflower oil as a test meal. The subjects ingested meals of 25 g fat (lard, olive oil or safflower oil), 50 g CHO (potato), 25 g fat with 50 g CHO or water only. Glucose, C peptide, insulin, triacylglycerols and nonesterified fatty acids were determined.

RESULTS

Ingestion of lard, olive oil or safflower oil with potato did not affect the quantitative glucose and insulin responses to potato alone. However, the responses were delayed, diminished and prolonged. All three fats when ingested alone modestly increased the insulin concentration when compared to ingestion of water alone. When either lard, olive oil or safflower oil was ingested with the potato, there was an accelerated rise in triacylglycerols. This was most dramatic with safflower oil.

CONCLUSIONS

Our data indicate that the glucose and insulin response to butter is unique when compared with the three other fat sources varying in their fatty acid composition.

Aspherical refractive lenses for small-angle neutron scattering

Aspherical neutron lenses are discussed in detail as focusing elements for existing small-angle neutron scattering (SANS) diffractometers. The conceptual design can be obtained by analytical equations, while computer simulations provide the intensity distribution of the primary beam, which is strongly correlated with the instrumental resolution and the minimal momentum transferQ. For large illuminated sample/lens areas of 50 mm diameter the aspherical lens design is essential, while spherical lenses are limited toca20 mm diameter with a 60% spherical aberration for standard SANS experiments. Scattering experiments on different samples proved the applicability and revealed the resolution limits of the two lens types. From theoretical considerations it is proposed that lens cooling can be used to reduce the thermal diffuse scattering.