Bridge percolation: electrical connectivity of discontinued conducting slabs by metallic nanowires

The properties of nanostructured networks of conductive materials have been extensively studied under the lens of percolation theory. In this work, we introduce a novel type of local percolation phenomenon used to investigate the conduction properties of a new hybrid material that combines sparse metallic nanowire networks and fractured conducting thin films on flexible substrates. This original concept could potentially lead to the design of a novel composite transparent conducting material. Using a complementary approach including formal analytical derivations, Monte Carlo simulations and electrical circuit representation for the modelling of bridged-percolating nanowire networks, we unveil the key relations between linear crack density, nanowire length and network areal mass density that ensure electrical percolation through the hybrid. The proposed theoretical model provides key insights into the conduction mechanism associated with the original concept of bridge percolation in random nanowire networks.

Cortical reactivations predict future sensory responses

Many theories of offline memory consolidation posit that the pattern of neurons activated during a salient sensory experience will be faithfully reactivated, thereby stabilizing the pattern1,2. However, sensory-evoked patterns are not stable but, instead, drift across repeated experiences3-6. Here, to investigate the relationship between reactivations and the drift of sensory representations, we imaged the calcium activity of thousands of excitatory neurons in the mouse lateral visual cortex. During the minute after a visual stimulus, we observed transient, stimulus-specific reactivations, often coupled with hippocampal sharp-wave ripples. Stimulus-specific reactivations were abolished by local cortical silencing during the preceding stimulus. Reactivations early in a session systematically differed from the pattern evoked by the previous stimulus-they were more similar to future stimulus response patterns, thereby predicting both within-day and across-day representational drift. In particular, neurons that participated proportionally more or less in early stimulus reactivations than in stimulus response patterns gradually increased or decreased their future stimulus responses, respectively. Indeed, we could accurately predict future changes in stimulus responses and the separation of responses to distinct stimuli using only the rate and content of reactivations. Thus, reactivations may contribute to a gradual drift and separation in sensory cortical response patterns, thereby enhancing sensory discrimination7.

In vitro analysis of iron oxide (Fe3O4) nanoparticle mediated degradation of polycyclic aromatic hydrocarbons (PAHs) and their antimicrobial activity

To degrade anthracene, magnetite nanoparticles were produced using a simple co-precipitation process. The fabricated nanoparticles have been analyzed for structural and optical properties. XRD examination revealed that the produced Fe3O4 nanoparticles were cubic phase, having a mean crystallite dimension of 18.84 nm. DLS determined the hydrodynamic diameter of Fe3O4 nanoparticles to be 182 nm. UV-Vis research revealed that Fe3O4 nanoparticles absorb at 390 nm. A peak at 895 cm-1 in the FT-IR study indicated the metal-oxygen connection. The synthesized Fe3O4 nanoparticles demonstrated an effective photocatalytic performance towards anthracene degradation and was found to be 86.55%. Furthermore, Fe3O4 nanoparticles showed the highest antimicrobial activity against Bacillus subtilis was 19.43 mm. The present study is the first and foremost study determining the dual role of Fe3O4 nanoparticles towards bioremediation and biomedical applications.

Inequity in National Institutes of Health Predoctoral Fellowships, 2001-2020

This cross-sectional study examines trends in number of awards and funding of general and diversity F31 predoctoral fellowships from 2001 to 2020.

Differential encoding in prefrontal cortex projection neuron classes across cognitive tasks

Single-cell transcriptomics has been widely applied to classify neurons in the mammalian brain, while systems neuroscience has historically analyzed the encoding properties of cortical neurons without considering cell types. Here we examine how specific transcriptomic types of mouse prefrontal cortex (PFC) projection neurons relate to axonal projections and encoding properties across multiple cognitive tasks. We found that most types projected to multiple targets, and most targets received projections from multiple types, except PFC→PAG (periaqueductal gray). By comparing Ca2+ activity of the molecularly homogeneous PFC→PAG type against two heterogeneous classes in several two-alternative choice tasks in freely moving mice, we found that all task-related signals assayed were qualitatively present in all examined classes. However, PAG-projecting neurons most potently encoded choice in cued tasks, whereas contralateral PFC-projecting neurons most potently encoded reward context in an uncued task. Thus, task signals are organized redundantly, but with clear quantitative biases across cells of specific molecular-anatomical characteristics.

Educational Case: Mantle Cell Lymphoma

The following fictional case is intended as a learning tool within the Pathology Competencies for Medical Education (PCME), a set of national standards for teaching pathology. These are divided into three basic competencies: Disease Mechanisms and Processes, Organ System Pathology, and Diagnostic Medicine and Therapeutic Pathology. For additional information, and a full list of learning objectives for all three competencies, see http://journals.sagepub.com/doi/10.1177/2374289517715040.¹.

Educational Case: Systemic Mastocytosis with an Associated Hematological Neoplasm

The following fictional case is intended as a learning tool within the Pathology Competencies for Medical Education (PCME), a set of national standards for teaching pathology. These are divided into three basic competencies: Disease Mechanisms and Processes, Organ System Pathology, and Diagnostic Medicine and Therapeutic Pathology. For additional information, and a full list of learning objectives for all three competencies, seehttp://journals.sagepub.com/doi/10.1177/2374289517715040.¹

M2 Macrophages in Crystal Storing Histiocytosis Associated with Plasma Cell Myeloma

Crystal Storing Histiocytosis (CSH) is a rare entity occurring in association with underlying lymphoproliferative disorders and plasma cell neoplasms. It denotes accumulation of immunoglobulin crystals in the histiocyte cytoplasm. In this study, we report a patient with plasma cell myeloma who presented with bilateral comminuted femur fractures. Histological examination of fracture tissue revealed hypercellular (~100%) marrow with extensive involvement by sheets of histiocytes with abundant eosinophilic cytoplasm admixed with scattered plasma cells. Intracytoplasmic diamond and rhomboid crystals within histiocytes were demonstrated by electron microscopy. Immunohistochemistry highlighted monotypic plasma cells with kappa restriction, representing 20-30% of marrow cellularity; however, non-polarizable cytoplasmic striations in histiocytes were negative for light chain expression. A diagnosis of crystal-storing histiocytosis associated with plasma cell myeloma was rendered. Further evaluation of these macrophages is positive for CD163 and COX2 and shows pSTAT3 with variable nuclear staining in some histiocytes. This case demonstrates that numerous M2 macrophages are present as crystal storing histiocytosis; and this knowledge might convey prognostic and therapeutic significance for the patients with crystal storing histiocytosis.

Shared Cortex-Cerebellum Dynamics in the Execution and Learning of a Motor Task

Throughout mammalian neocortex, layer 5 pyramidal (L5) cells project via the pons to a vast number of cerebellar granule cells (GrCs), forming a fundamental pathway. Yet, it is unknown how neuronal dynamics are transformed through the L5→GrC pathway. Here, by directly comparing premotor L5 and GrC activity during a forelimb movement task using dual-site two-photon Ca2+ imaging, we found that in expert mice, L5 and GrC dynamics were highly similar. L5 cells and GrCs shared a common set of task-encoding activity patterns, possessed similar diversity of responses, and exhibited high correlations comparable to local correlations among L5 cells. Chronic imaging revealed that these dynamics co-emerged in cortex and cerebellum over learning: as behavioral performance improved, initially dissimilar L5 cells and GrCs converged onto a shared, low-dimensional, task-encoding set of neural activity patterns. Thus, a key function of cortico-cerebellar communication is the propagation of shared dynamics that emerge during learning.

Howell-Jolly Body-Like Inclusions in Neutrophils of Patients With Myelodysplastic Syndrome: A Novel Correlation

CONTEXT.—

Howell-Jolly body-like inclusions have been previously associated with patients who are human immunodeficiency virus (HIV) infected, taking antiviral medications, and immunosuppressed. These inclusions appear in neutrophils and resemble Howell-Jolly bodies of normoblasts in abnormal erythropoiesis. In granulocytes, they are thought to represent detached nuclear fragments produced from dysplastic granulopoiesis. To the best of our knowledge, no association of Howell-Jolly body-like inclusions and myelodysplastic syndrome (MDS) has been reported previously.

OBJECTIVE.—

To establish an unprecedented correlation of Howell-Jolly body-like inclusions in patients with MDS.

DESIGN.—

Eleven bone marrow cases from patients diagnosed with MDS and 20 bone marrow cases with no significant pathologic alterations were retrospectively reviewed. Detailed medical record review was performed to ensure none of the patients had a history of HIV, or was taking immunosuppressants and/or antiviral medications.

RESULTS.—

Eight of 11 cases (72%) from the study group show detached intracytoplasmic inclusions in a minority (<5%) of mature neutrophils consistent with Howell-Jolly body-like inclusions. No Howell-Jolly body-like inclusions were identified in the control group. Notably, none of the selected patients had a history of HIV or was taking immunosuppressants and antiviral medications.

CONCLUSIONS.—

In review of the literature, Howell-Jolly body-like inclusions seem to correlate with immunosuppression and antiviral therapies with nucleoside analogs. We propose that the formation of Howell-Jolly body-like inclusions is the consequence of dysplasia, and hence its correlation not only with the abovementioned conditions, but also with MDS. The inclusions are, however, seen in only a minority of white cells (<5%), which is probably why they were not brought to practicing pathologists' awareness in the past. This study aims to raise awareness and correlate the presence of Howell-Jolly body-like inclusions in MDS.

ARIC Hemostasis Study-IV. Intraindividual Variability and Reliability of Hemostatic Factors

We have recently reported the short-term intraindividual variability of several coagulation factors and inhibitors included in the ARIC study (Chambless et al. Ann Epidemiol 1992; 2:723). In this paper, we reported the intraindividual variability results of additional hemostatic factors. Blood samples were collected for hemostatic assays three times at 1-2-week intervals from 39 subjects recruited from 4 ARIC field centers. The contributions of within-person, processing and assay (designated “method”) and between-person variances to the total variance were estimated and from them the reliability coefficient, R, was computed as the proportion of total variance in the between-person component. The R value was high for (β-thromboglobulin and tissue- plasminogen activator: 0.83 and 0.81, respectively; and intermediate for D-dimer and plasminogen activator inhibitor-1: 0.73 and 0.72, respectively. Protein S (total and free) and platelet factor 4 had low repeatability (R<0.50) derived mostly from “method” variability while low R value (0.03) for fibrinopeptide A was attributed to high “method” and “within-person” variability. Gender, age and the level of hemostatic factors did not influence the intraindividual variability.

Effects of the Use of a Mallet during Bone Marrow Biopsy Collection on Specimen Quality: A Quality Improvement Project

CONTEXT

Avoiding procedure-related morphologic distortion such as fragmentation and crush artifact is critical in bone marrow diagnosis. Use of a hammer or mallet, although infrequent, is a known technique of advancing the biopsy needle during specimen collection.

OBJECTIVES

We performed a double-blinded, retrospective review of bone marrow biopsies collected by the Interventional Radiology department at our institution in order to assess specimen quality by using this technique.

DESIGN

We reviewed 93 bone marrow biopsy specimens collected at our hospitals, between January 2015 and June 2015. Routine bone marrow core biopsy slides were reviewed. The presence of crush artifact, specimen fragmentation, and aspiration artifact, as well as the presence of osteopenia and an overall grade of specimen adequacy, was recorded for each specimen.

RESULTS

A sterile mallet was used during the bone marrow biopsy procedure in 29 cases. Use of a mallet was significantly associated with the presence of suboptimal or inadequate specimen quality of bone marrow core biopsy (p<0.005) and was independently associated with severe specimen fragmentation (2+) (p<0.0001). There was no statistically significant association between length of the core and use of a mallet.

CONCLUSIONS

Use of a mallet during bone marrow core biopsy collection is significantly associated with morphologic distortion in the form of severe specimen fragmentation and negatively affects specimen adequacy. There is no difference in length of core biopsy as previously thought by using a mallet to advance the needle during the procedure. We recommend that the use of this technique should be avoided during specimen collection.

Evidence for prevalent Z = 6 magic number in neutron-rich carbon isotopes

The nuclear shell structure, which originates in the nearly independent motion of nucleons in an average potential, provides an important guide for our understanding of nuclear structure and the underlying nuclear forces. Its most remarkable fingerprint is the existence of the so-called magic numbers of protons and neutrons associated with extra stability. Although the introduction of a phenomenological spin-orbit (SO) coupling force in 1949 helped in explaining the magic numbers, its origins are still open questions. Here, we present experimental evidence for the smallest SO-originated magic number (subshell closure) at the proton number six in 13-20C obtained from systematic analysis of point-proton distribution radii, electromagnetic transition rates and atomic masses of light nuclei. Performing ab initio calculations on 14,15C, we show that the observed proton distribution radii and subshell closure can be explained by the state-of-the-art nuclear theory with chiral nucleon-nucleon and three-nucleon forces, which are rooted in the quantum chromodynamics.

Phylogeographic and genome-wide investigations of Vietnam ethnic groups reveal signatures of complex historical demographic movements

The territory of present-day Vietnam was the cradle of one of the world’s earliest civilizations, and one of the first world regions to develop agriculture. We analyzed the mitochondrial DNA (mtDNA) complete control region of six ethnic groups and the mitogenomes from Vietnamese in The 1000 Genomes Project (1000G). Genome-wide data from 1000G (~55k SNPs) were also investigated to explore different demographic scenarios. All Vietnamese carry South East Asian (SEA) haplotypes, which show a moderate geographic and ethnic stratification, with the Mong constituting the most distinctive group. Two new mtDNA clades (M7b1a1f1 and F1f1) point to historical gene flow between the Vietnamese and other neighboring countries. Bayesian-based inferences indicate a time-deep and continuous population growth of Vietnamese, although with some exceptions. The dramatic population decrease experienced by the Cham 700 years ago (ya) fits well with the Nam tiến (“southern expansion”) southwards from their original heartland in the Red River Delta. Autosomal SNPs consistently point to important historical gene flow within mainland SEA, and add support to a main admixture event occurring between Chinese and a southern Asian ancestral composite (mainly represented by the Malay). This admixture event occurred ~800 ya, again coinciding with the Nam tiến.

Myeloid Sarcoma in a Patient with Myelodysplastic Syndrome Associated with del(5q-): Case Report and Literature Review

OBJECTIVE

Myeloid sarcoma (MS) is defined in the World Health Organization classification as a tumor mass consisting of myeloblasts with or without maturation and involving any anatomic site other than the bone marrow. We present a case of MS developing in a patient with 5q- myelodysplastic syndrome (MDS) and review the relevant literature.

METHODS

A 77-year-old woman with recent diagnosis of MDS associated with del(5q) presented with symptoms and signs attributable to a mass involving the T8 vertebra. Biopsy of the spinal mass was performed and the specimen was analyzed using routine hematoxylin-eosin stain, immunohistochemical methods, and fluorescence in situ hybridization (FISH).

RESULTS

Microscopic examination revealed an infiltrate of intermediate-large cells with basophilic cytoplasm and nuclei containing occasional prominent nucleoli. Immunohistochemical analysis showed that the neoplastic cells were positive for CD4, CD43, CD45, CD68, and CD117, and negative for B- and T-cell antigens supporting the diagnosis of MS. Fluorescence in situ hybridization of the spinal mass showed del(5q) in the neoplastic cells.

CONCLUSION

Although the 5q- syndrome is a clinically indolent form of MDS, a small subset of patients may develop MS as illustrated in this patient. The relevant literature is also reviewed.

Post-transplant Lymphoproliferative Disorder Presented in a Form of Primary Effusion Lymphoma with t (8; 14)

Post-transplant lymphoproliferative disorders (PTLD) are emergent complications of organ transplantation occurring in 2% to 10% of transplanted patients. Epstein-Barr virus (EBV) infections are considered the most important factors for the development of these heterogeneous disorders. Primary effusion lymphoma (PEL) is a lymphoproliferative disorder predominantly described in patients with advanced AIDS and it is almost universally associated with human herpesvirus 8 (HHV8). In rare case, PEL also occurs in HHV8-negative patient, in the setting of hepatitis B and C virus infection. However, all these cases showed pan B-cell markers to be positive. Here, we report a case of PTLD presented as HHV8-negative and HIV-negative primary effusion lymphoma lacking near all lymphoid markers except PAX5 on immunohistochemistry, which created a diagnostic challenge. The diagnosis requires multiple approaches including molecular and genetic tests.

Morphoproteomics Identifies SIRT1 and EZH2 Pathways as Commonalities in B-cell Acute Lymphoblastic Leukemia: Pathogenetic Implications and Opportunities for Therapeutic Intervention

B-cell acute lymphoblastic leukemia (ALL) represents a malignant process in which bone marrow-derived lymphoblasts retain their undifferentiated state. Genetic testing has revealed either no identifiable cytogenetic and genomic abnormalities in such patients or a wide range of aberrations that may or may not contribute to the block in differentiation and the associated proliferation of the malignant lymphoblasts in cases of B-cell ALL. In this study, we applied morphoproteomics to a representative spectrum of cases of newly diagnosed B-cell ALL in order to identify pathways that are known to be associated with the maintenance of the undifferentiated state while promoting proliferation. Our results showed nuclear expression in a majority of the lymphoblasts from bone marrow clot preparations of each of the study cases for both silent mating type information regulation 2 homolog 1 (SIRT1), an NAD+ histone deacetylase and enhancer of Zeste homolog 2 (EZH2), a histone methyltransferase. These represent pathogenetic pathways capable of blocking differentiation and promoting proliferation of the B-cell ALL lymphoblasts. Data mining of the National Library of Medicine's MEDLINE Database and Ingenuity Pathway analysis revealed agents of relatively low toxicity-melatonin, metformin, curcumin and sulforaphane-that are capable of inhibiting directly or pharmacogenomically one or both of the SIRT1 and EZH2 pathways and should, in a combinatorial fashion, remove the block in differentiation and decrease the proliferation of the B-cell ALL lymphoblasts.

Platelet aggregometry cannot identify uremic platelet dysfunction in heart failure patients prior to cardiac surgery

BACKGROUND

Patients with heart failure often have concomitant renal disease which can result in uremic platelet dysfunction. Determining whether uremia has affected platelets by platelet aggregometry can be challenging in these patients since they are often on antiplatelet medications. This study was undertaken to determine if platelet aggregation studies could identify heart failure patients at risk for uremic bleeding prior to cardiac surgery.

METHODS

Platelet aggregation studies from three groups were studied and compared: 17 heart failure patients with mild to moderate renal impairment, 17 heart failure patients without renal abnormalities and 17 healthy volunteers.

RESULTS

Platelet aggregation was severely impaired in both heart failure groups with and without renal abnormalities compared to healthy controls, and there were no significant differences in platelet aggregation in response to any of the agonists. There was a pan-decrease in platelet aggregation to all agonists in all heart failure patients.

CONCLUSION

Platelet aggregometry does not appear to be useful in measuring platelet dysfunction in heart failure patients with mild to moderate renal impairment.

Polar interface phonons in ionic toroidal systems

We use the dielectric continuum model to obtain the polar (Fuchs-Kliewer like) interface vibration modes of toroids made of ionic materials either embedded in a different material or in vacuum, with applications to nanotoroids specially in mind. We report the frequencies of these modes and describe the electric potential they produce. We establish the quantum-mechanical Hamiltonian appropriate for their interaction with electric charges. This Hamiltonian can be used to describe the effect of this interaction on different types of charged particles either inside or outside the torus.

Expression of Sirt1 and FoxP3 in classical Hodgkin lymphoma and tumor infiltrating lymphocytes: Implications for immune dysregulation, prognosis and potential therapeutic targeting

BACKGROUND

Hodgkin Reed-Sternberg (HRS) cells may promote differentiation of CD4+ naïve T cells toward both FoxP3+ T regulatory (Treg) cells and TIA-1+ cytotoxic T lymphocytes (CTL). Previous studies suggest that an overabundance of cytotoxic TIA-1+ cells in relation to FoxP3+ T reg cells portends unfavorable outcomes in classical Hodgkin lymphoma (cHL), raising the possibility that its pathogenesis may be related to immune dysregulation. Sirt1 deacetylates FoxP3 and leads to decreased Treg functionality. Our objective was to compare Sirt1 and FoxP3 expressions in Hodgkin lymphoma infiltrating lymphocytes (HLIL) and confirm Sirt1 expression in HRS cells.

DESIGN

Immunohistochemical staining of paraffin-embedded tissue with antibodies to Sirt1, FoxP3, TIA-1, and CD8 was performed. Expression of Sirt1 was assessed in both the HRS cells and in the HLILs in twenty-four cases. Adequate tissue was available in 13 cHL cases to permit the enumeration of FoxP3, TIA-1 and CD8 by giving their percent staining of HLILs.

RESULTS

In HLILs, nuclear expression of Sirt1 was 32-88% (mean 67%); FoxP3 expression was 9-40% (mean 23.9%); TIA-1 expression was 15-87% (mean 32%); and CD8 expression was 10-45% (mean = 31%). Sirt1 to FoxP3 ratio was 0.96-5.5 (mean 3.2). TIA-1 to FoxP3 ratio was 0.6-5.1 (mean 1.6). CD8 to FoxP3 ratio was 0.43-3.7 (mean 1.5). There was a difference of Sirt1 to FoxP3 ratios between remission and recurrence groups, being significantly higher in the recurrence group (P = 0.005). Sirt1 demonstrated high nuclear expression in the HRS cells of 21 out of 24 (88%) cases analyzed.

CONCLUSION

The relative overexpression of Sirt1 to FoxP3 in HLILs may be considered possible targets for immune modulation. Histone deacetylase inhibitors may increase the efficacy of existing treatment regimens by downregulating SIRT1 gene mRNA/Sirt1 protein function and together with rapamycin could expand the T regulatory/FoxP3 population and functionality and improve prognosis for remission in cHL. Targeting Sirt1 in the HRS cells may facilitate their ability to promote naïve T cell differentiation toward Treg cells over CTL.

Accelerated bone loss and increased post-fracture mortality in elderly women and men

Bone loss, a fracture risk factor, may play a role in post-fracture mortality. We found accelerated bone loss (≥1.31 % bone loss/year for women and ≥1.35 % bone loss/year for men) associated with 44-77 % increased mortality. It remains unclear whether bone loss is a marker or plays a role in mortality.

INTRODUCTION

Osteoporotic fractures are associated with increased mortality although the cause is unknown. Bone loss, a risk factor for osteoporotic fracture is also associated with increased mortality, but its role in mortality risk post-fracture is unclear. This study aimed to examine post-fracture mortality risk according to levels of bone loss.

METHODS

Community-dwelling participants aged 60+ from Dubbo Osteoporosis Epidemiology Study with incident fractures were followed from 1989 to 2011. Kaplan-Meier survival curves were constructed according to bone loss quartiles. Cox proportional hazard models were used to determine the effect of bone loss on mortality.

RESULTS

There were 341 women and 106 men with ≥2 BMD measurements. The rate of bone loss was similar for women and men (women mean -0.79 %/year, highest bone loss quartile -1.31 %/year; men mean -0.74 %/year, highest quartile -1.35 %/year). Survival was lowest for the highest quartile of bone loss for women (p < 0.005) and men (p = 0.05). When analysed by fracture type, the association of bone loss with mortality was observed for vertebral (highest vs lower 3 quartiles of bone loss, women p = 0.03 and men p = 0.02) and non-hip non-vertebral fractures in women (p < 0.0001). Bone loss did not play an additional role in mortality risk following hip fractures. Importantly, overall, rapid bone loss was associated with 44-77 % increased mortality risk after multiple variable adjustment.

CONCLUSION

Rapid bone loss was an independent predictor of post-fracture mortality risk in both women and men. The association of bone loss and post-fracture mortality was predominantly observed following vertebral fracture in both women and men and non-hip non-vertebral fracture in women. It remains to be determined whether bone loss is a marker or plays a role in the mortality associated with fractures.

Morphoproteomics identifies constitutive activation of the mTORC2/Akt and NF-κB pathways and expressions of IGF-1R, Sirt1, COX-2, and FASN in peripheral T-cell lymphomas: pathogenetic implications and therapeutic options

BACKGROUND

Gaining a better understanding of the molecular circuitries and pathways implicated in the malignant growth and biological behavior of T cell lymphomas may identify potential cellular targets with clinical therapeutic potential. The immunohistochemical characterization of key cellular proteins participating in these pathways can provide surrogate markers of biological activity. The mammalian target of rapamycin complex (mTORC) signaling pathway has been implicated in T-cell lymphopoiesis. The mTORC2 pathway involves downstream activation of nuclear factor (NF)-κB and p-Akt (Ser 473). Fatty acid synthase (FASN) and insulin-like growth factor-1 receptor (IGF-1R) are expressed upstream of the mTORC and NF-κB signaling pathways. Cyclooxygenase (COX)-2 products influence these pathways. Our goal was to use morphoproteomics to characterize the expression patterns of the proteins in various peripheral T-cell lymphomas.

DESIGN

Ten cases of peripheral T-cell lymphoma (PTCL) were examined for expression of proteins along the mTORC, Akt and NF-κB pathways and affiliated tumorigenic molecules. These included two angioimmunoblastic PTCL, one natural killer/PTCL, one anaplastic large PTCL, and six PTCL not otherwise specified. Immunostaining for phosphorylated (p) mTOR (Ser 2448), p-Akt (Ser 473), p-NF-κBp65 (Ser 536), IGF-1R (Tyr1165/1166), silent mating type information regulation 2 homolog 1 (Sirt1), COX-2 and FASN was performed on paraffin-embedded tissue for each case. Percent expression was scored using bright-field microscopy with high expression designated as more than 50% of the cells with positive stain in the appropriate subcellular compartment.

RESULTS

All ten cases demonstrated nuclear staining for p-mTOR (Ser 2448) corresponding to mTORC 2, and all cases showed strong, diffuse nuclear staining for p-NF-κBp65 (Ser 536). All ten also showed nuclear and cytoplasmic staining for p-Akt (Ser 473) and cytoplasmic staining for IGF-1R. High expressions for nuclear Sirt1, and cytoplasmic COX-2 and FASN were detected in 7, 9, and 8 out of 10 cases, respectively. Six out of 10 cases demonstrated high expression of all the mentioned markers.

CONCLUSION

The constitutive activation of mTORC2, NF-κB, p-Akt and the concomitant expression of IGF-1R suggests convergence of these molecular pathways in T-cell lymphoma. The results of this study also suggest that mTORC2 may be a common denominator among this heterogeneous group of lymphomas. Interference of key nodes of this pathway may carry a clinical therapeutic benefit. Agents that may be considered based on existing data include: bortezomib to inhibit NF-κB pathway activation; metformin to inhibit both NF-κB and mTORC2 and histone deacteylase inhibitors to inhibit mTORC2 pathway signaling. Furthermore, panobinostat inhibits Sirt1 pathway when present, and celecoxib inhibits NF-κB pathway activation independent of COX2.

Metallic nanowire networks: effects of thermal annealing on electrical resistance

Metallic nanowire networks have huge potential in devices requiring transparent electrodes. This article describes how the electrical resistance of metal nanowire networks evolve under thermal annealing. Understanding the behavior of such films is crucial for the optimization of transparent electrodes which find many applications. An in-depth investigation of silver nanowire networks under different annealing conditions provides a case study demonstrating that several mechanisms, namely local sintering and desorption of organic residues, are responsible for the reduction of the systems electrical resistance. Optimization of the annealing led to specimens with transmittance of 90% (at 550 nm) and sheet resistance of 9.5 Ω sq(-1). Quantized steps in resistance were observed and a model is proposed which provides good agreement with the experimental results. In terms of thermal behavior, we demonstrate that there is a maximum thermal budget that these electrodes can tolerate due to spheroidization of the nanowires. This budget is determined by two main factors: the thermal loading and the wire diameter. This result enables the fabrication and optimization of transparent metal nanowire electrodes for solar cells, organic electronics and flexible displays.

Association between hypertension and fragility fracture: a longitudinal study

Hypertension is an independent risk factor for osteoporosis and osteoporotic fracture in postmenopausal women.

INTRODUCTION

Although hypertension has been suggested to be associated with increased fracture risk, it is not clear whether the association is independent of bone mineral density (BMD). The present study sought to examine the interrelationships between hypertension, BMD, and fracture risk.

METHODS

The study included 1,032 men and 1,701 women aged 50 years and older who were participants in the Dubbo Osteoporosis Epidemiology Study. BMD at the femoral neck and lumbar spine was measured by dual energy X-ray absorptiometry (GE-LUNAR Corp., Madison, WI, USA). The presence of hypertension was ascertained by direct interview and verification through clinical history. The incidence of fragility fractures was ascertained by X-ray report during the follow-up period (1989-2008). The Cox proportional hazards model was used to assess the association between hypertension and fracture risk.

RESULTS

Women with hypertension had lower BMD at the femoral neck (0.79 versus 0.82 g/cm(2), P = 0.02) than those without the disease. After adjusting for BMD and covariates, hypertension was an independent risk factor for fragility fracture [hazard ratio (HR), 1.49; 95% CI, 1.13-1.96]. In men, hypertension was associated with higher femoral neck BMD (0.94 versus 0.92 g/cm(2), P = 0.02), but the association between hypertension and fracture risk did not reach statistical significance.

CONCLUSION

Hypertension is associated with increased fracture risk in women, and the association is independent of BMD.

Emergency department triage of low acuity patients to a Federally Qualified Health Center

Many emergency departments (ED) are experiencing ever increasing volumes as they serve as a safety net for patients without established access to primary care. Impending physician shortages, our aging population, and recent changes in national healthcare policy are expected to further exacerbate this situation and worsen ED overcrowding. These conditions could result in a dilution of ED resources and significantly impact the ability of emergency personnel to provide quality care for patients with serious illnesses. Previous studies have demonstrated that low acuity patients without emergencies can be safely and legally identified in triage and can be sent away from the ED for further outpatient treatment and evaluation. However, without a specific designated clinic follow up, these patients often fail to get the appropriate care required. In this study, we couple the ED medical screening exam process with a timely medical referral system to a local Federally Qualified Healthcare Clinic (FQHC). These referred patients were monitored for subsequent success in satisfaction with their primary care needs and their rate of recidivism to the ED. Most of the non-emergent patients who were judged to be appropriate to refer to the FQHC were satisfied with their medical screening process (89%) and most elected to attend the same day clinic appointment at the FQHC (85%). Only 17% of these patients who were referred out of our ED returned to be seen in our ED within the three-month interval. We concluded that referring low acuity patients out of the emergency department to a primary care clinic setting provided an opportunity for these patients to establish a medical home for future access to non-emergent health care.

Quantitative ultrasound and fracture risk prediction in non-osteoporotic men and women as defined by WHO criteria

This study sought to determine the association between calcaneal quantitative ultrasound (QUS) and fracture risk in individuals without osteoporosis according to the World Health Organization criteria (i.e., BMD T-score > -2.5). We found that calcaneal QUS is an independent predictor of fracture risk in women with non-osteoporotic bone mineral density (BMD).

INTRODUCTION

More than 50 % of women and 70 % of men who sustain a fragility fracture have BMD above the osteoporotic threshold (T-score > -2.5). Calcaneal QUS is associated with fracture risk. This study aimed to test the hypothesis that low calcaneal QUS is associated with increased fracture risk in individuals with non-osteoporotic BMD.

METHODS

We included 312 women and 390 men aged 62-90 years with BMD T-score > -2.5 at femoral neck. QUS was measured in broadband ultrasound attenuation (BUA) at the calcaneus using a CUBA sonometer. BMD was measured at the femoral neck (FNBMD) by dual energy X-ray absorptiometry using GE Lunar DPX-L densitometer. The incidences of any fragility fracture were ascertained by X-ray reports during the follow-up period from 1994 to 2011.

RESULTS

Of the 702 participants, 26 % of women (n = 80/312) and 14 % of men (n = 53/390) experienced at least one fragility fracture during the follow-up period. In women, after adjusting for covariates, increased risk of any fracture was significantly associated with decreased BUA (HR = 1.50; 95 % CI, 1.13-1.99). Compared with that of FNBMD, the models with BUA, in women, had greater AUC (0.71, 0.85, 0.71 for any, hip and vertebral fracture, respectively), and yielded a net reclassification improvement of 16.4 % (P = 0.009) when combined with FNBMD. In men, BUA was not significantly associated with fracture risk before and after adjustment.

CONCLUSION

These results suggest that calcaneal BUA is an independent predictor of fracture risk in women with non-osteoporotic BMD.

Vitamin D status and parathyroid hormone in a urban population in Vietnam

In this cross-sectional study in Vietnam, the prevalence of vitamin D insufficiency was 46% in adult women and 20% in adult men. There was a linear inverse relationship between serum 25(OH)D and PTH concentrations, but there was no threshold of 25(OH)D at which PTH levels plateaued.

INTRODUCTION

Vitamin D insufficiency is adversely associated with health outcomes. Vitamin D status in Asian populations is not well documented. This study sought to assess vitamin D status and its relationship to parathyroid hormone in a Vietnamese population.

METHODS

This cross-sectional study involved 205 men and 432 women aged 18-87 years, who were randomly sampled from various districts in Ho Chi Minh City (Vietnam) according to a proportional sampling scheme. Serum concentration of 25(OH)D and PTH were measured by the Electrochemiluminescence immunoassay on the Roche Elecsys 10100/201 system (Roche Diagnosis Elecsys). Vitamin D insufficiency was quantified as serum 25(OH)D levels below 30 ng/ml (75 nmol/L).

RESULTS

The average age for men and women was 43.8 ± 18.4 years (mean ± SD) and 47.7 ± 17.1 years, respectively. The mean 25(OH)D concentration in men (36.8 ± 10.2 ng/mL) was significantly higher than in women (30.1 ± 5.9; P < 0.0001). The prevalence of vitamin D insufficiency in men was 20% (41/205) which was significantly lower than in women (46%, 199/432). Age, height and weight were independent predictors of 25(OH)D concentrations, and the three factors explained 15% and 5% of variance in 25(OH)D in men and women, respectively. There was a linear inverse relationship between serum 25(OH)D and PTH concentrations, but there was no threshold of 25(OH)D at which PTH levels plateaued.

CONCLUSIONS

These data show that vitamin D insufficiency is common even in tropical region, and that women had a greater risk of vitamin D insufficiency than men. These data suggest that an elevation in PTH cannot be used as a marker for vitamin D deficiency.

Identification of undiagnosed type 2 diabetes by systolic blood pressure and waist-to-hip ratio

AIMS/HYPOTHESIS

We estimated the current prevalence of type 2 diabetes in the Vietnamese population and developed simple diagnostic models for identifying individuals at high risk of undiagnosed type 2 diabetes.

METHODS

The study was designed as a cross-sectional investigation with 721 men and 1,421 women, who were aged between 30 and 72 years and were randomly sampled from Ho Chi Minh City (formerly Saigon) in Vietnam. A 75 g oral glucose tolerance test to assess fasting and 2 h plasma glucose concentrations were determined for each individual. The ADA diagnostic criteria were used to determine the prevalence of type 2 diabetes. WHR and blood pressure were also measured in all individuals.

RESULTS

The prevalence of type 2 diabetes was 10.8% in men and 11.7% in women. Higher WHR and blood pressure were independently associated with a greater risk of type 2 diabetes. Compared with participants without central obesity and hypertension, the odds of diabetes was increased by 6.4-fold (95% CI 3.2-13.0) in men and 4.1-fold (2.2-7.6) in women with central obesity and hypertension. Two nomograms were developed that help identify men and women at high risk of type 2 diabetes.

CONCLUSIONS/INTERPRETATION

The current prevalence of type 2 diabetes in the Vietnamese population is high. Simple field measurements such as waist-to-hip ratio and systolic blood pressure can identify individuals at high risk of undiagnosed type 2 diabetes.

Prognosis of fracture: evaluation of predictive accuracy of the FRAX algorithm and Garvan nomogram

We evaluated the prognostic accuracy of fracture risk assessment tool (FRAX) and Garvan algorithms in an independent Australian cohort. The results suggest comparable performance in women but relatively poor fracture risk discrimination in men by FRAX. These data emphasize the importance of external validation before widespread clinical implementation of prognostic tools in different cohorts.

INTRODUCTION

Absolute risk assessment is now recognized as a preferred approach to guide treatment decision. The present study sought to evaluate accuracy of the FRAX and Garvan algorithms for predicting absolute risk of osteoporotic fracture (hip, spine, humerus, or wrist), defined as major in FRAX, in a clinical setting in Australia.

METHODS

A retrospective validation study was conducted in 144 women (69 fractures and 75 controls) and 56 men (31 fractures and 25 controls) aged between 60 and 90 years. Relevant clinical data prior to fracture event were ascertained. Based on these variables, predicted 10-year probabilities of major fracture were calculated from the Garvan and FRAX algorithms, using US (FRAX-US) and UK databases (FRAX-UK). Area under the receiver operating characteristic curves (AUC) was computed for each model.

RESULTS

In women, the average 10-year probability of major fracture was consistently higher in the fracture than in the nonfracture group: Garvan (0.33 vs. 0.15), FRAX-US (0.30 vs. 0.19), and FRAX-UK (0.17 vs. 0.10). In men, although the Garvan model yielded higher average probability of major fracture in the fracture group (0.32 vs. 0.14), the FRAX algorithm did not: FRAX-US (0.17 vs. 0.19) and FRAX-UK (0.09 vs. 0.12). In women, AUC for the Garvan, FRAX-US, and FRAX-UK algorithms were 0.84, 0.77, and 0.78, respectively, vs. 0.76, 0.54, and 0.57, respectively, in men.

CONCLUSION

In this analysis, although both approaches were reasonably accurate in women, FRAX discriminated fracture risk poorly in men. These data support the concept that all algorithms need external validation before clinical implementation.

Anaplastic large cell lymphoma in leukemic phase: extraordinarily high white blood cell count

Anaplastic large cell lymphoma (ALCL) is a distinct type of T/null-cell non-Hodgkin lymphoma that commonly involves nodal and extranodal sites. The World Health Organization of lymphoid neoplasms recognizes two types: anaplastic lymphoma kinase (ALK) positive or ALK negative, the former as a result of abnormalities involving the ALK gene at chromosome 2p23. Patients with ALCL rarely develop a leukemic phase of disease, either at the time of initial presentation or during the clinical course. Described herein is a patient with ALK+ ALCL, small cell variant, associated with the t(2;5)(p23;q35), who initially presented with leukemic involvement and an extraordinarily high leukocyte count of 529 x 10(9)/L, which subsequently peaked at 587 x 10(9)/L. Despite chemotherapy the patient died 2(1/2) months after diagnosis. In the literature review 20 well-documented cases are identified of ALCL in leukemic phase reported previously, with a WBC ranging from 15 to 151 x 10(9)/L. Leukemic phase of ALCL occurs almost exclusively in patients with ALK+ ALCL, most often associated with the small cell variant and the t(2;5)(p23;q35), similar to the present case. Patients with leukemic phase ALK+ ALCL appear to have a poorer prognosis than most patients with ALK+ ALCL.

Development of prognostic nomograms for individualizing 5-year and 10-year fracture risks

We have developed clinical nomograms for predicting 5-year and 10-year fracture risks for any elderly man or woman. The nomograms used age and information concerning fracture history, fall history, and BMD T-score or body weight.

INTRODUCTION

Although many fracture risk factors have been identified, the translation of these risk factors into a prognostic model that can be used in primary care setting has not been well realized. The present study sought to develop a nomogram that incorporates non-invasive risk factors to predict 5-year and 10-year absolute fracture risks for an individual man and woman.

METHODS

The Dubbo Osteoporosis Epidemiology Study was designed as a community-based prospective study, with 1358 women and 858 men aged 60+ years as at 1989. Baseline measurements included femoral neck bone mineral density (FNBMD), prior fracture, a history of falls and body weight. Between 1989 and 2004, 426 women and 149 men had sustained a low-trauma fracture (not including morphometric vertebral fractures). Two prognostic models based on the Cox's proportional hazards analysis were considered: model I included age, BMD, prior fracture and falls; and model II included age, weight, prior fracture and fall.

RESULTS

Analysis of the area under the receiver operating characteristic curve (AUC) suggested that model I (AUC = 0.75 for both sexes) performed better than model II (AUC = 0.72 for women and 0.74 for men). Using the models' estimates, we constructed various nomograms for individualizing the risk of fracture for men and women. If the 5-year risk of 10% or greater is considered "high risk", then virtually all 80-year-old men with BMD T-scores < -1.0 or 80-year-old women with T-scores < -2.0 were predicted to be in the high risk group. A 60-year-old woman's risk was considered high risk only if her BMD T-scores < or = -2.5 and with a prior fracture; however, no 60-year-old men would be in the high risk regardless of their BMD and risk profile.

CONCLUSION

These data suggest that the assessment of fracture risk for an individual cannot be based on BMD alone, since there are clearly various combinations of factors that could substantially elevate an individual's risk of fracture. The nomograms presented here can be useful for individualizing the short- and intermediate-term risk of fracture and identifying high-risk individuals for intervention to reduce the burden of fracture in the general population.

Discordance of longitudinal changes in bone density between densitometers

This study examined the concordance in BMD measurement and longitudinal change in BMD between the GE Lunar Prodigy and GE Lunar DPX. Even though a high concordance between the densitometers was observed on a single measurement occasion, a significant discordance in longitudinal changes in BMD was observed.

INTRODUCTION

Measurement of bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA) technology plays an important role in the diagnosis and management of osteoporosis. The present study examined the concordance in BMD measurement and longitudinal change in BMD between GE Lunar Prodigy and DPX.

METHODS

BMD at the lumbar spine and femoral neck was measured in 135 individuals (47 men and 88 women, mean age 73+/-9 years) using both GE Lunar DPX and Prodigy densitometers at baseline. In this group, 56 individuals (22 men and 34 women) had repeated BMD measurements using the DPX and Prodigy during a subsequent follow-up visit (average duration: 2.2 years).

RESULTS

For a single BMD measurement, the coefficient of concordance between the Prodigy and DPX was greater than 0.98 at the lumbar spine and 0.96 at the femoral neck, with the slope of linear regression being approximately 1.0. During the period of follow-up, the lumbar spine BMD decreased by -0.5% (S.D. 1.8%) when measured by DPX, which was significantly different (p=0.002) from the change measured by Prodigy (mean change=0, S.D. 2.0%). However, there was no significant difference (p=0.95) in the rate of change in femoral neck BMD measured by DPX (mean=-1.6%, S.D.=2.9) and Prodigy (mean=-1%, S.D.=1.8%). The correlation in rates of BMD change between Prodigy and DPX was 0.63 at the lumbar spine and 0.52 at the femoral neck. Simulation analysis showed that the theoretical maximum correlation in rates of BMD change between Prodigy and DPX was 0.71.

CONCLUSIONS

Despite both densitometers being highly concordant in a single BMD measurement, discordance in the assessment of BMD changes between the Prodigy and DPX densitometers was observed. These findings have implications regarding the assessment of response to therapy in a multi-centre setting when different densitometers are used.

Development of a nomogram for individualizing hip fracture risk in men and women

Until now there has been no published prognostic tool available for predicting of hip fracture to primary care settings. We have developed a nomogram for predicting the absolute risk of hip fracture for any individual by using clinical factors, including age, prior fracture and fall, in addition to BMD that was based on a 15-year follow-up cohort study.

INTRODUCTION

Bone mineral density or clinical risk factors alone are useful but limited tools for the identification of individuals with high-risk of hip fracture. It is hypothesized that the combination of clinical risk factors and BMD can improve the accuracy of fracture prediction. This study was aimed at developing a nomogram which combines these factors for predicting 5-year and 10-year risk of hip fracture for an individual.

METHODS

The study, designed as a epidemiologic, community-based prospective study, included 1,208 women and 740 men aged 60+ years with median duration of follow-up of 13 years (inter-quartile range, IQR: 6-14) for both women and men, yielding 10,523 and 7,586 person-years of observation, respectively. Main outcome measures were incidence of hip fractures and risk factors were femoral neck bone mineral density (FNBMD), prior fracture, history of fall, postural sway and quadriceps strength. Femoral neck BMD was measured by DXA (GE-LUNAR Corp, Madison, Wisconsin, USA). Cox's proportional hazards model was used to estimate the risk of fracture for individuals, and a nomogram was constructed for predicting hip fracture risk.

RESULTS

Between 1989 and 2004, 127 individuals (96 women) sustained a hip fracture. Advancing age, low femoral neck BMD, prior fracture and history of falls were independent predictors of hip fracture. The area under the receiver operating characteristic curve for the model was 0.85 for both sexes. A nomogram was constructed for predicting hip fracture risk for an individual. Among those aged 75 or older with BMD T-scores < or = -2.5, the risk of hip fracture in men was comparable to or higher than in women; however, in younger age groups, the risk was higher in women than in men.

CONCLUSION

The combination of BMD and non-invasive clinical risk factors in a nomogram could be useful for identifying high-risk individuals for intervention to reduce the risk of hip fracture.

Iron status of young Vietnamese children in Australia

OBJECTIVE

The aim of this study was to estimate the prevalence of iron deficiency in Vietnamese children living in Australia and to identify risk factors associated with iron deficiency.

METHODS

A cohort of healthy term Vietnamese infants, were followed from birth (n = 210) to 18 months (n = 174) with anthropometry, dietary intake and feeding practices measured at seven time points. Socio-demographic data were collected from the parents at the first home visit. At 18 months iron status was examined by full blood count and plasma ferritin concentration in 129/152 (85%) of the eligible children. Iron depletion was defined as a plasma ferritin level < 10 microg/L. Iron deficiency without anaemia was defined as iron depletion plus MCV < 70fl and iron deficiency anaemia was defined as iron deficiency anaemia plus Hb < 110 g/L.

RESULTS

The prevalence of iron deficiency was iron depletion 19.4% (95% CI: 13.0%, 27.3%), iron deficiency without anaemia 3.1% (95% CI: 0.9%, 7.8%) and iron deficiency anaemia 3.9% (95% CI: 1.3%, 8.8%). Multiple regression analysis showed three significant predictors of iron deficiency: cows milk intake (negative effect), meat, fish or poultry intake (positive effect) and weight gain (negative effect). A cows milk intake > or = 650 mL/day was a risk factor for iron deficiency.

CONCLUSION

Prevalence of iron deficiency at 18 months was high despite appropriate infant feeding practices during the first year. Modification of the diet in the second year of life may decrease the risk of iron deficiency in Vietnamese children.

Growth and feeding practices of Vietnamese infants in Australia

OBJECTIVE

To investigate the growth and feeding practices in first-generation Vietnamese infants living in Australia.

DESIGN

Cohort study.

SETTING

The study was conducted between 1999 and 2002 in Sydney.

SUBJECTS

A total of 239 Vietnamese women were recruited randomly from antenatal clinics, and of these 210 were initially seen. During the first year, 20 cases (9.5%) were lost to follow-up. Data were collected at 0.5, 2, 4, 6, 9 and 12 months.

RESULTS

Vietnamese infants were significantly longer and heavier than reference data (both P<0.0001). The Vietnamese infants had a significant decline in weight growth with age compared with reference data (P<0.001). The Vietnamese infants had marginally higher s.d. score for ideal weight for length than reference data (P=0.044). There was a significant decline in ideal weight for length with age compared with reference data (P=0.0065). Both parents were significantly shorter (mean s.d. height scores: -1.5+/-0.8 (mother) and -1.8+/-0.8 (father)) than reference data (P<0.001). The incidence of breast feeding was 79%, but half of the breast feeding women had stopped breast feeding by 3 months. A total of 162 (79.8%) infants were given infant formula within the first week, of whom 131 (80.1%) were fed infant formula within the first 24 h after birth.

CONCLUSIONS

Vietnamese infants in this study had growth comparable with reference data despite their parents being shorter than reference data. Breast feeding duration was short with infant formula being introduced early.

Molecular cloning and functional characterization of a novel delayed rectifier potassium channel from channel catfish (Ictalurus punctatus): expression in taste buds

The gustatory system of channel catfish is widely studied for its sensitivity to amino acids. As a first step in identifying the molecular components that play a role in taste transduction in catfish, we cloned the full-length cDNA for Kv2-catfish, a novel K(+) channel that is expressed in taste buds. The deduced amino acid sequence is 816 residues, and shares a 56-59% sequence identity with Kv2.1 and Kv2.2, the other members of the vertebrate Kv2 subfamily of voltage-gated K(+) channels. The Kv2-catfish RNA was expressed in taste buds, brain, skeletal muscle, kidney, intestine and gills, and its gene is represented as a single copy in the catfish genome. Recombinant channels expressed in Xenopus oocytes were selective for K(+), and were inhibited by tetraethylammonium applied to the extracellular side of the membrane during two-electrode voltage clamp analysis with a 50% inhibitory constant of 6.1 mM. The channels showed voltage-dependent activation, and did not inactivate within 200 ms. Functionally, Kv2-catfish is a voltage-gated, delayed rectifier K(+) channel, and its primary structure is the most divergent sequence identified among the vertebrate members of the Kv2 subfamily of K(+) channels, being related equally well to Kv2.1 and Kv2.2.

A regulatory domain (R1-R2) in the amino terminus of the N-methyl-D-aspartate receptor: effects of spermine, protons, and ifenprodil, and structural similarity to bacterial leucine/isoleucine/valine binding protein

There are complex interactions between spermine, protons, and ifenprodil at N-methyl-D-aspartate receptors. Spermine stimulation may involve relief of proton inhibition, whereas ifenprodil inhibition may involve an increase in proton inhibition. We studied mutations at acidic residues in the NR1 subunit using voltage-clamp recording of NR1/NR2B receptors expressed in Xenopus oocytes. Mutations at residues near the site of the exon-5 insert, including E181 and E185, reduced spermine stimulation and proton inhibition. Mutation NR1(D130N) reduced sensitivity to ifenprodil by more than 500-fold, but had little effect on sensitivity to spermine and pH. Mutations at six other residues in this region of the NR1 subunit reduced the potency and, in some cases, the maximum effect of ifenprodil. These mutants did not affect sensitivity to pH, glutamate, glycine, or other hallmark properties of N-methyl-D-aspartate channels such as Mg2+ block and Ba2+ permeability. Residues in this region presumably form part of the ifenprodil-binding site. To model this region of NR1 we compared the predicted secondary structure of NR1 (residues 19-400) with the known structures of 1,400 proteins. This region of NR1 is most similar to bacterial leucine/isoleucine/valine binding protein, a globular amino acid binding protein containing two lobes, similar to the downstream S1-S2 region of glutamate receptors. We propose that the tertiary structure of NR1(22-375) is similar to leucine/isoleucine/valine binding protein, containing two "regulatory" domains, which we term R1 and R2. This region, which contains the binding sites for spermine and ifenprodil, may influence the downstream S1 and S2 domains that constitute the glycine binding pocket.

The selectivity filter of the N-methyl-D-aspartate receptor: a tryptophan residue controls block and permeation of Mg2+

A hallmark feature of N-methyl-D-aspartate (NMDA) receptors is their voltage-dependent block by extracellular Mg2+. The structural basis for Mg2+ block is not fully understood. Although asparagine residues in the pore-forming M2 regions of NR1 and NR2 subunits influence Mg2+ block, it has been speculated that additional residues are likely to be involved. Here, we report the unexpected finding that a tryptophan residue in the M2 region of NR2 subunits controls Mg2+ block. An NR2B(W607L) mutation abolished block and greatly increased permeation of extracellular Mg2+. A similar effect was seen with a mutation at the equivalent residue in NR2A but not with mutations at the equivalent residue or adjacent residues in NR1. In NR2B, mutations that changed NR2B(W607) to asparagine (W607N) or alanine (W607A) also greatly reduced Mg2+ block, whereas mutations that changed W607 to the aromatic residues tyrosine (W607Y) or phenylalanine (W607F) had little or no effect on Mg2+ block. Furthermore, the W607L, W607N, and W607A mutants, but not the W607Y and W607F mutants, decreased Ba2+ permeability of NMDA channels. Thus, residue NR2B(W607) may be involved in binding of divalent cations, in particular Mg2+, through a cation-pi interaction with the electron-rich aromatic ring of the tryptophan. We previously suggested that NR2B(W607) may contribute to the narrow constriction of the NMDA channel. A model is now proposed in which the M2 loop of NR2B is folded in such a way that NR2B(W607) is positioned at the narrow constriction, at a level similar to NR2B(N616) and NR1(N616), with these three residues forming a binding site for Mg2+.

Neuroendocrine stress hormones do not recreate the postoperative hypercoagulable state

Surgery causes changes in hemostasis, leading to a hypercoagulable state that has been linked to both arterial and venous thrombotic complications. The etiology of this state is unknown, but many investigators have hypothesized that perioperative neuroendocrine changes are responsible. We have previously demonstrated minimal increases in hemostatic function with a stress hormone infusion. This study was undertaken to further examine the relationship between neuroendocrine hormones and hemostatic function. Seventeen healthy volunteers were administered a stress hormone cocktail i.v. (epinephrine, cortisol, glucagon, angiotensin II, and vasopressin) for 24 h in a blind, placebo-controlled, cross-over design in our clinical research center. Venous blood samples were obtained for measurement of hemostatic function before the infusion and at 2, 8, and 24 h. There were no demonstrable increases in any measure of hypercoagulability. Alternatively, there was an increase in tissue plasminogen activator and protein C activity. These changes are consistent with an inhibition of coagulation and improved fibrinolysis. These data suggest that this combination of neuroendocrine hormones is not responsible for the postoperative hypercoagulable state.

IMPLICATIONS

Infusion of five stress hormones (epinephrine, cortisol, glucagon, vasopressin, and angiotensin II) to normal volunteers does not cause increases in procoagulant proteins and platelet reactivity or decreases in fibrinolytic proteins. Alternatively, these five hormones caused increased levels of fibrinolytic proteins (tissue plasminogen activator) and endogenous anticoagulants (protein C antigen and activity).

Femoral neck fractures in the elderly patient: a preventable injury

There is growing evidence that many fractures of the femoral neck in the elderly occur spontaneously because of stresses imposed on osteoporotic bone, rather than because of the trauma of the fall. A case of a spontaneous femoral neck fracture (Garden type IV) in an elderly woman with osteoporosis is presented. Early detection and medical management of osteoporosis complemented with assistive technology could have prevented this common injury.

Corrosion of stainless steel pipes in a hydrotherapy pool by a silver-copper disinfection system

The silver-copper disinfection system has been shown to be effective for water purification. It emits silver ions that combine with bacteria, causing their death. While disinfecting the water, these silver ions exhibit adverse effects on the stainless steel pipes in hydrotherapy pools. In an oxidation-reduction reaction the silver ions are converted into solid silver that is deposited on stainless steel, causing a corrosion reaction. The corroded steel has a black deposit that readily adheres to the burned patient's skin.

ARIC hemostasis study--IV. Intraindividual variability and reliability of hemostatic factors. The Atherosclerosis Risk in Communities (ARIC)

We have recently reported the short-term intraindividual variability of several coagulation factors and inhibitors included in the ARIC study (Chambless et al. Ann Epidemiol 1992; 2:723). In this paper, we reported the intraindividual variability results of additional hemostatic factors. Blood samples were collected for hemostatic assays three times at 1-2-week intervals from 39 subjects recruited from 4 ARIC field centers. The contributions of within-person, processing and assay (designated "method") and between-person variances to the total variance were estimated and from them the reliability coefficient, R, was computed as the proportion of total variance in the between-person component. The R value was high for beta-thromboglobulin and tissue-plasminogen activator: 0.83 and 0.81, respectively; and intermediate for D-dimer and plasminogen activator inhibitor-1: 0.73 and 0.72, respectively. Protein S (total and free) and platelet factor 4 had low repeatability (R < 0.50) derived mostly from "method" variability while low R value (0.03) for fibrinopeptide A was attributed to high "method" and "within-person" variability. Gender, age and the level of hemostatic factors did not influence the intraindividual variability.

Bronchiolar wall changes in sudden infant death syndrome: morphometric study of a new observation

Sudden infant death syndrome (SIDS) infants have significantly thicker and more cellular bronchiolar walls than control infants of similar age. A morphometric study of 25 SIDS and 18 control infants was undertaken to measure the bronchiolar wall thickness using a Cue-2 image analysis system. A mathematical formula (relative index) was used to compare the thickness of bronchioles of varying diameter. Data analysis using a nested design two-way analysis of variance and covariance of the measured bronchioles showed a significant difference between the SIDS and control infants with a P value less than .001. Manual counting of the cells in the bronchiolar walls and data analysis using an unpaired two-tailed t test showed that the SIDS infants had a significantly greater number of cells than control infants (P less than .01). Our preliminary results indicate that the cells in the bronchiolar wall are either peripheral nerve-derived (Schwann cells) or Langerhans cells. We postulate that these cells are increased in number in response to chronic hypoxia in SIDS infants.