bluuebunny/crossref_metadata_2025 huggingface dataset:
The Transition from Stiff to Compliant Materials in Squid Beaks
Authors: Miserez Ali , Schneberk Todd , Sun Chengjun , Zok Frank W. , Waite J. Herbert
Published: March 2008

The beak of the Humboldt squid
Dosidicus gigas
represents one of the hardest and stiffest wholly organic materials known. As it is deeply embedded within the soft buccal envelope, the manner in which impact forces are transmitted between beak and envelope is a matter of considerable scientific interest. Here, we show that the hydrated beak exhibits a large stiffness gradient, spanning two orders of magnitude from the tip to the base. This gradient is correlated with a chemical gradient involving mixtures of chitin, water, and His-rich proteins that contain 3,4-dihydroxyphenyl-
l
-alanine (dopa) and undergo extensive stabilization by histidyl-dopa cross-link formation. These findings may serve as a foundation for identifying design principles for attaching mechanically mismatched materials in engineering and biological applications.
The Eukaryotic Genome as an RNA Machine
Authors: Amaral Paulo P. , Dinger Marcel E. , Mercer Tim R. , Mattick John S.
Published: March 2008

The past few years have revealed that the genomes of all studied eukaryotes are almost entirely transcribed, generating an enormous number of non–protein-coding RNAs (ncRNAs). In parallel, it is increasingly evident that many of these RNAs have regulatory functions. Here, we highlight recent advances that illustrate the diversity of ncRNA control of genome dynamics, cell biology, and developmental programming.
Identification of the First VIM Metallo-β-Lactamase-Producing Multiresistant
Aeromonas hydrophila
Strain
Authors: Libisch Balázs , Giske Christian G. , Kovács Bogáta , Tóth Tamás G. , Füzi Miklós
Published: March 2008

A VIM metallo-β-lactamase-producing
Aeromonas hydrophila
strain carrying an integron-borne
bla
VIM-4
gene was isolated from a cirrhotic patient's fecal sample in a Budapest hospital. The variable region of this integron is identical with that of a previously characterized integron from
Pseudomonas aeruginosa
clinical isolates in Pécs in southern Hungary.
Evaluation of Rubella Virus Immunoglobulin G (IgG) and IgM Assays with the New Vidia Instrument
Authors: Medici Maria Cristina , Martinelli Monica , Albonetti Valeria , Chezzi Carlo , Dettori Giuseppe
Published: March 2008

For rubella virus immunoglobulin G (IgG) and IgM detection, Vidia assays were compared to Vidas, AxSYM, and Liaison assays with 419 serum samples. Only Vidia produced a sensitivity of 100% for IgG and IgM. Vidia specificities were 98.4% for IgG and 99.8% for IgM, versus Vidas specificities of 100 and 99.3%. Vidia IgG and IgM assays performed equally well.
Repetitive-Sequence-Based PCR Using the DiversiLab System for Identification of
Aspergillus
Species
Authors: Hansen Dewey , Healy Mimi , Reece Kristy , Smith Cheryl , Woods Gail L.
Published: March 2008

Repetitive-sequence-based PCR (rep-PCR) using the DiversiLab system was investigated for identification of
Aspergillus
. Ninety-five clinical isolates, identified by conventional methods, and five ATCC strains were tested. Sequencing of the internal transcribed spacer (ITS) region (ITS1-5.8S-ITS2) was performed on 2 isolates with discrepant rep-PCR and conventional results and 15 randomly selected outlier isolates. One isolate not identified by sequencing was excluded from analysis. After resolving discrepancies, all but one
A. glaucus
strain had ≥85% similarity to one or more strains of the same
Aspergillus
species in the mold database, thereby providing accurate identification. No isolate was misidentified.
Detection of Pathogenic
Leptospira
Bacteria in Pinniped Populations via PCR and Identification of a Source of Transmission for Zoonotic Leptospirosis in the Marine Environment
Authors: Cameron Caroline E. , Zuerner Richard L. , Raverty Stephen , Colegrove Kathleen M. , Norman Stephanie A. , Lambourn Dyanna M. , Jeffries Steven J. , Gulland Frances M.
Published: March 2008

Leptospirosis, caused by the spirochete
Leptospira
, is a geographically widespread disease that affects a broad range of mammals, including marine mammals. Among pinniped populations, periodic epizootics of leptospirosis are responsible for significant die-offs. Along the west coast of North America, the most recent leptospirosis epizootic occurred in 2004, during which samples were collected from cases ranging from California to British Columbia. The primary objective of this study was to use this well-defined sample set to determine the feasibility of using PCR techniques to diagnose
Leptospira
infection among pinniped populations in comparison with diagnostic methodologies commonly used for marine mammals. Successful amplification was achieved from a variety of samples, including freshly collected urine, urine stored at −80°C for less than 6 months, and kidney (freshly collected, frozen, and decomposed), as well as feces- and urine-contaminated sand collected in the vicinity of a live-stranded animal. Pathological examination of tissue collected from
Leptospira
-infected animals revealed the presence of leptospiral antigen in the kidneys. The use of species-specific primer pairs revealed a pattern of host specificity for
Leptospira interrogans
in sea lions and
Leptospira kirschneri
in elephant seals. These studies indicate PCR is a sensitive and specific diagnostic tool for the detection of
Leptospira
infection in pinnipeds and reveal a potential source for epizootic, enzootic, and zoonotic spread of leptospirosis in a marine environment.
Dynamic Transmission of NumerousAnaplasma phagocytophilumGenotypes among Lambs in an Infected Sheep Flock in an Area of Anaplasmosis Endemicity
Authors: Ladbury Georgia A. F. , Stuen Snorre , Thomas Rachael , Bown Kevin J. , Woldehiwet Zerai , Granquist Erik G. , Bergström Karin , Birtles Richard J.
Published: March 2008

The transmission dynamics ofAnaplasma phagocytophilumstrains circulating within juvenile members of a sheep flock grazing on anIxodes ricinus-infested pasture in southern Norway were monitored. PCR-based detection of the bacterialp44fragments in the blood of 16 lambs sampled weekly for 16 weeks following their release into pasture revealed rickettsemia in all animals, with an increasing proportion of infected animals as the survey progressed. Comparison of partialmsp4sequences obtained from infected blood samples revealed 24 distinct genotypes, some of which were repeatedly encountered, occurring in up to six sheep over a 14-week period, whereas others were observed only once. Individual sheep were infected by up to five distinct genotypes, with a specific genotype being encountered for between one and three consecutive weeks, and in some sheep, genotypes detected early in the study were also present in later samples. In general, detection ofA. phagocytophilumby PCR correlated well with the observation of infected neutrophils in blood smears. Together these results reveal a previously unrecognized diversity ofA. phagocytophilumstrains simultaneously circulating within an infected population in an area of endemicity and are consistent with a remarkably dynamic transmission of strains among infected animals.
Comparison of Stool Antigen Detection Kits to PCR for Diagnosis of Amebiasis
Authors: Stark D. , van Hal S. , Fotedar R. , Butcher A. , Marriott D. , Ellis J. , Harkness J.
Published: March 2008

The present study was conducted to compare two stool antigen detection kits with PCR for the diagnosis of
Entamoeba histolytica
infections by using fecal specimens submitted to the Department of Microbiology at St. Vincent's Hospital, Sydney, and the Institute of Medical and Veterinary Science, Adelaide, Australia. A total of 279 stool samples containing the E complex (
E. histolytica
,
Entamoeba dispar
, and
Entamoeba moshkovskii
) were included in this study. The stool specimens were tested by using two commercially produced enzyme immunoassays (the Entamoeba CELISA PATH and TechLab
E. histolytica
II kits) to detect antigens of
E. histolytica
. DNA was extracted from all of the samples with a Qiagen DNA stool mini kit (Qiagen, Hilden, Germany), and a PCR targeting the small-subunit ribosomal DNA was performed on all of the samples. When PCR was used as a reference standard, the CELISA PATH kit showed 28% sensitivity and 100% specificity. The TechLab ELISA (enzyme-linked immunosorbent assay) kit did not prove to be useful in detecting
E. histolytica
, as it failed to identify any of the
E. histolytica
samples which were positive by PCR. With the TechLab kit, cross-reactivity was observed for three specimens, one of which was positive for both
E. dispar
and
E. moshkovskii
while the other two samples contained
E. moshkovskii
. Quantitative assessment of the PCR and ELISA results obtained showed that the ELISA kits were 1,000 to 10,000 times less sensitive, and our results show that the CELISA PATH kit and the TechLab ELISA are not useful for the detection of
E. histolytica
in stool samples from patients in geographical regions where this parasite is not endemic.
Persistent Replication of Severe Acute Respiratory Syndrome Coronavirus in Human Tubular Kidney Cells Selects for Adaptive Mutations in the Membrane Protein
Authors: Pacciarini Filippo , Ghezzi Silvia , Canducci Filippo , Sims Amy , Sampaolo Michela , Ferioli Elena , Clementi Massimo , Poli Guido , Conaldi Pier Giulio , Baric Ralph , Vicenzi Elisa
Published: March 2008

Severe acute respiratory syndrome (SARS) is a systemic disease characterized by both lung pathology and widespread extrapulmonary virus dissemination causing multiple organ injuries. In this regard, renal dysfunction is an ominous sign in patients with SARS. Indeed, clusters of SARS coronavirus (SARS-CoV) particles have been detected in the cytoplasm of renal tubular epithelial cells in postmortem studies, explaining the presence of infectious virus in the urine of SARS patients. In order to investigate the potential SARS-CoV kidney tropism, we have evaluated the susceptibility of human renal cells of tubular and glomerular origin to in vitro SARS-CoV infection. Immortalized cultures of differentiated proximal tubular epithelial cells (PTEC), glomerular mesangial cells (MC), and glomerular epithelial cells (podocytes) were found to express the SARS-CoV receptor angiotensin-converting enzyme 2 on their surface. Productive infection, however, occurred only in PTEC but not in glomerular cells. A transient infection with poor virus production was observed in MC, whereas podocytes were not permissive to SARS-CoV infection. In contrast to the cytopathic infection of the Vero E6 cell line, SARS-CoV did not cause overt cytopathic effects in PTEC or MC. Of interest, PTEC, but not MC, maintained stable levels of SARS-CoV production in serial subcultures, suggesting a persistent state of infection. In this regard, a SARS-CoV variant with increased replication capacity in PTEC was selected after four serial subculture passages. This SARS-CoV variant acquired a single nonconservative amino acid change from glutamic acid (E) to alanine (A) at position 11 in the viral membrane (M) protein. The E11A point mutation was sufficient for enhanced SARS-CoV replication and persistence in PTEC when introduced in a SARS-CoV recombinant infectious clone. These findings indicate that human PTEC may represent a site of SARS-CoV productive and persistent replication favoring the emergence of viral variants with increased replication capacity, at least in these kidney cells.
Epstein-Barr Virus Latent Membrane Protein 1 Induces Expression of the Epidermal Growth Factor Receptor through Effects on Bcl-3 and STAT3
Authors: Kung Che-Pei , Raab-Traub Nancy
Published: March 2008

Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) activates multiple signaling pathways. Two regions, C-terminal-activating region 1 (CTAR1) and CTAR2, have been identified within the cytoplasmic carboxy terminal domain that activates NF-κB. CTAR2 activates the canonical NF-κB pathway, which includes p50/p65 complexes. CTAR1 can activate both the canonical and noncanonical pathways to produce multiple distinct NF-κB dimers, including p52/p50, p52/p65, and p50/p50. CTAR1 also uniquely upregulates the epidermal growth factor receptor (EGFR) in epithelial cells. Increased p50-Bcl-3 complexes have been detected by chromatin precipitation on the NF-κB consensus motifs within theegfrpromoter in CTAR1-expressing epithelial cells and nasopharyngeal carcinoma cells. In this study, the mechanism responsible for the increase in Bcl-3 has been further investigated. The data indicate that LMP1-CTAR1 induces Bcl-3 mRNA and increases the nuclear translocation of both Bcl-3 and p50. LMP1-CTAR1 constitutively activates STAT3, and this activation was not due to the induction of interleukin 6 (IL-6). In LMP1-CTAR1-expressing cells, increased levels of activated STAT3 were detected by chromatin immunoprecipitation on STAT-binding sites located within both the promoter and the second intron of Bcl-3. A STAT3 inhibitor significantly reduced the activation of STAT3, as well as the CTAR1-mediated upregulation of Bcl-3 and EGFR. These data suggest that LMP1 activates distinct forms of NF-κB through multiple pathways. In addition to activating the canonical and noncanonical pathways, LMP1-CTAR1 constitutively activates STAT3 and increases Bcl-3. The increased nuclear Bcl-3 and p50 homodimer complexes positively regulate EGFR expression. These results indicate that LMP1 likely regulates distinct cellular genes by activating specific NF-κB pathways.
Subdominant CD8 T-Cell Epitopes Account for Protection against Cytomegalovirus Independent of Immunodomination
Authors: Holtappels Rafaela , Simon Christian O. , Munks Michael W. , Thomas Doris , Deegen Petra , Kühnapfel Birgit , Däubner Torsten , Emde Simone F. , Podlech Jürgen , Grzimek Natascha K. A. , Oehrlein-Karpi Silke A. , Hill Ann B. , Reddehase Matthias J.
Published: March 2008

Cytomegalovirus (CMV) infection continues to be a complication in recipients of hematopoietic stem cell transplantation (HSCT). Preexisting donor immunity is recognized as a favorable prognostic factor for the reconstitution of protective antiviral immunity mediated primarily by CD8 T cells. Furthermore, adoptive transfer of CMV-specific memory CD8 T (CD8-TM) cells is a therapeutic option for preventing CMV disease in HSCT recipients. Given the different CMV infection histories of donor and recipient, a problem may arise from an antigenic mismatch between the CMV variant that has primed donor immunity and the CMV variant acquired by the recipient. Here, we have used the BALB/c mouse model of CMV infection in the immunocompromised host to evaluate the importance of donor-recipient CMV matching in immundominant epitopes (IDEs). For this, we generated the murine CMV (mCMV) recombinant virus mCMV-ΔIDE, in which the two memory repertoire IDEs, the IE1-derived peptide 168-YPHFMPTNL-176 presented by the major histocompatibility complex class I (MHC-I) molecule Ldand the m164-derived peptide 257-AGPPRYSRI-265 presented by the MHC-I molecule Dd, are both functionally deleted. Upon adoptive transfer, polyclonal donor CD8-TMcells primed by mCMV-ΔIDE and the corresponding revertant virus mCMV-revΔIDE controlled infection of immunocompromised recipients with comparable efficacy and regardless of whether or not IDEs were presented in the recipients. Importantly, CD8-TMcells primed under conditions of immunodomination by IDEs protected recipients in which IDEs were absent. This shows that protection does not depend on compensatory expansion of non-IDE-specific CD8-TMcells liberated from immunodomination by the deletion of IDEs. We conclude that protection is, rather, based on the collective antiviral potential of non-IDEs independent of the presence or absence of IDE-mediated immunodomination.
Restriction of Foamy Viruses by Primate Trim5α
Authors: Yap Melvyn W. , Lindemann Dirk , Stanke Nicole , Reh Juliane , Westphal Dana , Hanenberg Helmut , Ohkura Sadayuki , Stoye Jonathan P.
Published: March 2008

Foamy viruses (FVs) are unconventional retroviruses with a replication strategy that is significantly different from orthoretroviruses and bears some homology to that of hepadnaviruses. Although some cellular proteins, such as APOBEC3, have been reported to block FVs, no restriction by Trim5α has been described to date. The sensitivity of three FV isolates of human-chimpanzee or prototypic (PFV), macaque (SFVmac), and feline (FFV) origin to a variety of primate Trim5αs was therefore tested. PFV and SFVmac were restricted by Trim5αs from most New World monkeys, but not from other primates, whereas FFV-based vectors were restricted by Trim5αs from the great apes gorilla and orangutan. Trim5αs from Old World monkeys did not restrict any FV isolate tested. Capuchin Trim5α was unique, as it restricted SFVmac and FFV but not PFV. Trim5α specificity for FVs was determined by the B30.2 domain, interestingly involving, in some instances, the same residues of the variable regions previously implicated as major determinants for human immunodeficiency virus type 1 restriction. FVs with chimeric Gags were made to map the viral determinants of sensitivity to restriction. The N-terminal half of the Gag molecule was found to contain the regions that control susceptibility. This region most likely corresponds to the capsid of conventional retroviruses. Due to their unique replication strategy, FVs should provide a valuable new system to examine the mechanism of retroviral restriction by Trim5α.
Critical Role of Virion-Associated Cholesterol and Sphingolipid in Hepatitis C Virus Infection
Authors: Aizaki Hideki , Morikawa Kenichi , Fukasawa Masayoshi , Hara Hiromichi , Inoue Yasushi , Tani Hideki , Saito Kyoko , Nishijima Masahiro , Hanada Kentaro , Matsuura Yoshiharu , Lai Michael M. C. , Miyamura Tatsuo , Wakita Takaji , Suzuki Tetsuro
Published: March 2008

In this study, we establish that cholesterol and sphingolipid associated with hepatitis C virus (HCV) particles are important for virion maturation and infectivity. In a recently developed culture system enabling study of the complete life cycle of HCV, mature virions were enriched with cholesterol as assessed by the molar ratio of cholesterol to phospholipid in virion and cell membranes. Depletion of cholesterol from the virus or hydrolysis of virion-associated sphingomyelin almost completely abolished HCV infectivity. Supplementation of cholesterol-depleted virus with exogenous cholesterol enhanced infectivity to a level equivalent to that of the untreated control. Cholesterol-depleted or sphingomyelin-hydrolyzed virus had markedly defective internalization, but no influence on cell attachment was observed. Significant portions of HCV structural proteins partitioned into cellular detergent-resistant, lipid-raft-like membranes. Combined with the observation that inhibitors of the sphingolipid biosynthetic pathway block virion production, but not RNA accumulation, in a JFH-1 isolate, our findings suggest that alteration of the lipid composition of HCV particles might be a useful approach in the design of anti-HCV therapy.
Microevolution of Dengue Viruses Circulating among Primary School Children in Kamphaeng Phet, Thailand
Authors: Jarman Richard G. , Holmes Edward C. , Rodpradit Prinyada , Klungthong Chonticha , Gibbons Robert V. , Nisalak Ananda , Rothman Alan L. , Libraty Daniel H. , Ennis Francis A. , Mammen Mammen P. , Endy Timothy P.
Published: March 2008

To determine the extent and structure of genetic variation in dengue viruses (DENV) on a restricted spatial and temporal scale, we sequenced the E (envelope) genes of DENV-1, -2, and -3 isolates collected in 2001 from children enrolled in a prospective school-based study in Kamphaeng Phet, Thailand, and diagnosed with dengue disease. Our analysis revealed substantial viral genetic variation in both time and space, with multiple viral lineages circulating within individual schools, suggesting the frequent gene flow of DENV into this microenvironment. More-detailed analyses of DENV-2 samples revealed strong clustering of viral isolates within individual schools and evidence of more-frequent viral gene flow among schools closely related in space. Conversely, we observed little evolutionary change in those viral isolates sampled over multiple time points within individual schools, indicating a low rate of mutation fixation. These results suggest that frequent viral migration into Kamphaeng Phet, coupled with population (school) subdivision, shapes the genetic diversity of DENV on a local scale, more so than in situ evolution within school catchment areas.
Neuropsychiatric complications of commonly used palliative care drugs
Authors: Jackson N , Doherty J , Coulter S
Published: March 2008

For those facing progressive life limiting disease, symptoms across a range of systems can be problematic. Clinicians may find themselves prescribing from several classes of drugs to alleviate distressing problems and to maximise quality of life for patients. Many drugs used for symptom control in palliative care give rise to neuropsychiatric side effects as they affect the central nervous system either directly or indirectly. The common unwanted effects of these drugs are well known, but there are some important neuropsychiatric effects that physicians are less aware of. If unrecognised, these effects can generate considerable distress and unnecessary harm to patients. We aim to highlight some of the adverse neuropsychiatric effects which occur with commonly used drugs in palliative care. Antiemetics such as metoclopramide and haloperidol can cause significant levels of neuropsychiatric toxicity, as can opiates, antidepressants, anxiolytics and antipsychotics. The syndromes or entities that will be considered are delirium, drug induced parkinsonism, akathisia, serotonin syndrome and neuroleptic malignant syndrome. The intention is to alert clinicians to the iatrogenic complications which may ensue on prescribing drugs commonly used in the palliative care setting.
Incremental predictive value of vascular assessments combined with the Framingham Risk Score for prediction of coronary events in subjects of low–intermediate risk
Authors: Lau K-K , Chan Y-H , Yiu K-H , Tam S , Li S-W , Lau C-P , Tse H-F
Published: March 2008

Background

In patients with low–intermediate risk, the use of the Framingham Risk Score (FRS) may not allow accurate prediction of the occurrence of coronary events.

Objective

To determine whether non-invasive vascular sonographic assessments add value to the FRS for prediction of coronary events.

Methods

Brachial artery flow-mediated dilatation (FMD), carotid intima–media thickness (IMT) and the presence of carotid plaque in 70 male subjects (mean (SD) age 62 (9) years) with a low–intermediate FRS who presented with a recent coronary event were evaluated and compared with those in 35 male controls matched for age (mean age 60 (9) years).

Results

Patients with a recent coronary event had a significantly higher FRS than controls. They had a significantly lower FMD (3.56 (2.41)% vs 5.18 (2.69)%, p = 0.003) and significantly higher prevalence of carotid plaque (67% vs 40%, p = 0.008), but there was no significant difference in mean maximum IMT between the two groups (1.01 (0.28) vs 0.96 (0.14) mm, p = 0.32). Multivariate analysis revealed that FMD ⩽4.75% was an independent predictor of an acute coronary event. Of the three vascular markers, FMD ⩽4.75% and presence of carotid plaque provided the best diagnostic accuracy for a coronary event, with area under the curve (AUC) of 0.70 and 0.64 (p = 0.001 and p = 0.033), respectively, based on receiver operating characteristic curve analysis. Furthermore, incorporating carotid plaque or FMD ⩽4.75% into the FRS (AUC = 0.72 and AUC = 0.78) provided incremental benefit in risk stratification over FRS alone (AUC = 0.66) (p = 0.008 and p = 0.007, for comparison of difference in two receiver operating characteristic curves).

Conclusions

Incorporating a measure of FMD or carotid plaque burden with FRS significantly increases the accuracy of predicting coronary events in subjects of low–intermediate risk and hence should be considered as additional investigations to improve coronary risk assessment.
Pharmacotherapy of Mood Disorders
Authors: Thase Michael E. , Denko Timothey
Published: March 2008

The mood disorders—primarily major depressive disorder and bipolar affective disorder—constitute one of the world's greatest public health problems and are associated with significant reductions in productivity, health, and longevity. In addition, people who suffer from these common illnesses, along with their families and loved ones, experience an incalculable toll on quality of life. Dating to the introduction of the first effective therapies for mood disorders in the late 1950s and 1960s, various types of pharmacotherapy have become a mainstay for the management of mood disorders, particularly more severe, chronic, and recurrent forms of depression and most forms of bipolar disorder. This review examines recent developments in the pharmacotherapy of both forms of mood disorder, comparing the newer antidepressants such as the selective serotonin reuptake inhibitors and serotonin norepinephrine reuptake inhibitors with their predecessors (the monoamine oxidase inhibitors and tricyclic antidepressants) and likewise comparing the older standard for management of bipolar disorder, lithium, with newer classes of medications, such as a selected group of anticonvulsants and the atypical antipsychotics. Although these newer classes of medications have generally improved upon the earlier treatments in terms of better tolerability and safety, there are no universally effective pharmacologic treatments for mood disorders, and careful medical management of these medications is still warranted.
Development of Secondary Lymphoid Organs
Authors: Randall Troy D. , Carragher Damian M. , Rangel-Moreno Javier
Published: March 2008

Secondary lymphoid organs develop during embryogenesis or in the first few weeks after birth according to a highly coordinated series of interactions between newly emerging hematopoietic cells and immature mesenchymal or stromal cells. These interactions are orchestrated by homeostatic chemokines, cytokines, and growth factors that attract hematopoietic cells to sites of future lymphoid organ development and promote their survival and differentiation. In turn, lymphotoxin-expressing hematopoietic cells trigger the differentiation of stromal and endothelial cells that make up the scaffolding of secondary lymphoid organs. Lymphotoxin signaling also maintains the expression of adhesion molecules and chemokines that govern the ultimate structure and function of secondary lymphoid organs. Here we describe the current paradigm of secondary lymphoid organ development and discuss the subtle differences in the timing, molecular interactions, and cell types involved in the development of each secondary lymphoid organ.
The Master Switch: The Role of Mast Cells in Autoimmunity and Tolerance
Authors: Sayed Blayne A. , Christy Alison , Quirion Mary R. , Brown Melissa A.
Published: March 2008

There are many parallels between allergic and autoimmune responses. Both are considered hypersensitivity responses: pathologies that are elicited by an exuberant reaction to antigens that do not pose any inherent danger to the organism. Although mast cells have long been recognized as central players in allergy, only recently has their role in autoimmunity become apparent. Because of the commonalities of these responses, much of what we have learned about the underlying mast cell–dependent mechanisms of inflammatory damage in allergy and asthma can be used to understand autoimmunity. Here we review mast cell biology in the context of autoimmune disease. We discuss the huge diversity in mast cell responses that can exert either proinflammatory or antiinflammatory activity. We also consider the myriad factors that cause one response to predominate over another in a particular immune setting.
Syncoilin is required for generating maximum isometric stress in skeletal muscle but dispensable for muscle cytoarchitecture
Authors: Zhang Jianlin , Bang Marie-Louise , Gokhin David S. , Lu Yingchun , Cui Li , Li Xiaodong , Gu Yusu , Dalton Nancy D. , Scimia Maria Cecilia , Peterson Kirk L. , Lieber Richard L. , Chen Ju
Published: March 2008

Syncoilin is a striated muscle-specific intermediate filament-like protein, which is part of the dystrophin-associated protein complex (DPC) at the sarcolemma and provides a link between the extracellular matrix and the cytoskeleton through its interaction with α-dystrobrevin and desmin. Its upregulation in various neuromuscular diseases suggests that syncoilin may play a role in human myopathies. To study the functional role of syncoilin in cardiac and skeletal muscle in vivo, we generated syncoilin-deficient ( syncoilin−/−) mice. Our detailed analysis of these mice up to 2 yr of age revealed that syncoilin is entirely dispensable for cardiac and skeletal muscle development and maintenance of cellular structure but is required for efficient lateral force transmission during skeletal muscle contraction. Notably, syncoilin−/− skeletal muscle generates less maximal isometric stress than wild-type (WT) muscle but is as equally susceptible to eccentric contraction-induced injury as WT muscle. This suggests that syncoilin may play a supportive role for desmin in the efficient coupling of mechanical stress between the myofibril and fiber exterior. It is possible that the reduction in isometric stress production may predispose the syncoilin skeletal muscle to a dystrophic condition.
Thrombin mediates mitogenesis and survival of human endothelial cells through distinct mechanisms
Authors: Zania Panagiota , Papaconstantinou Matthew , Flordellis Christodoulos S. , Maragoudakis Michael E. , Tsopanoglou Nikos E.
Published: March 2008

Thrombin has been reported to play a pivotal role in the initiation of angiogenesis by indirectly regulating and organizing a network of angiogenic molecules. In addition, it has been proposed that thrombin can directly activate endothelial cell proliferation. However, in this report it was shown that thrombin is a poor growth factor for human endothelial cells, and its modest mitogenic activity is mediated indirectly by the release of heparin-binding epidermal growth factor, subsequent to proteinase-activated receptor 1 (PAR1) activation. On the other hand, it was demonstrated that thrombin is a potent anti-apoptotic factor for endothelial cells, pointing to a novel role of thrombin in vascular protection. Analysis by annexin V-propidium iodide double staining revealed that thrombin, specifically, promoted survival of serum-starved endothelial cells in a concentration-dependent manner. In contrast to its mitogenic effect, the anti-apoptotic effect of thrombin was largely independent of its catalytic activity and was mediated through interaction with ανβ3 and α5β1 integrins, whereas the involvement of PAR1 was limited. These results provide new insights in understanding the role of thrombin in endothelial cell signaling and vascular biology.
Estrogen and the Ca2+-mobilizing agonist ATP evoke acute NO synthesis via distinct pathways in an individual human vascular endothelium-derived cell
Authors: Sheng Jian-Zhong , Arshad Furqan , Braun Janice E. , Braun Andrew P.
Published: March 2008

In this study, we have systematically evaluated the signaling mechanisms underlying stimulated nitric oxide (NO) synthesis by estrogen (E2) and other vasoactive agents at the level of a single endothelium-derived cell. To do so, we have characterized and contrasted rapid E2-evoked NO synthesis with that of ATP using single-cell microfluorimetry and patch-clamp recordings to monitor stimulated changes in cellular NO synthesis (via 4-amino-5-methylamino-2′,7′-difluorofluorescein), Ca2+ transients (via Fluo-3), and membrane hyperpolarization in cultured human EA.hy926 cells. E2-evoked NO synthesis in single cells (EC50 ∼0.3 nM) was blocked by the E2 receptor antagonist ICI 182,780 and the NO synthase inhibitor Nω-nitro-l-arginine methyl ester. Although both E2 and ATP stimulated comparable Ca2+ transients, E2-induced NO synthesis was insensitive to intracellular BAPTA-AM or removal of external Ca2+. In contrast, ATP-evoked NO production was abolished by either one of these treatments. ATP-evoked hyperpolarizations (∼20 mV) and NO production were both inhibited by the respective small-conductance and intermediate-conductance calcium- activated K+ channel blockers apamin and charybdotoxin. E2 minimally affected membrane potential, and stimulated NO synthesis was insensitive to calcium-activated K+ channel blockers. Exposure to either the phosphatidylinositol 3-kinase inhibitor LY-294001 or the MAP kinase inhibitor PD-98059 abolished the NO response to E2, but not that to ATP. Finally, the NO response evoked by a combined stimulus of E2 plus ATP was similar to that of ATP alone. In conclusion, our data directly demonstrate that an individual human EA.hy926 cell contains at least two distinct mechanisms for stimulated NO synthesis that depend on either calcium or protein kinase signaling events.
Claudin-6 localized in tight junctions of rat podocytes
Authors: Zhao Linning , Yaoita Eishin , Nameta Masaaki , Zhang Ying , Cuellar Lino Munoz , Fujinaka Hidehiko , Xu Bo , Yoshida Yutaka , Hatakeyama Katsuyoshi , Yamamoto Tadashi
Published: March 2008

Tight junctions rarely exist in podocytes of the normal renal glomerulus, whereas they are the main intercellular junctions of podocytes in nephrosis and in the early stage of development. Claudins have been identified as tight junction-specific integral membrane proteins. Those of podocytes, however, remain to be elucidated. In the present study, we investigated the expression and localization of claudin-6 in the rat kidney, especially in podocytes. Western blot analysis and RT-PCR revealed that the neonatal kidney expressed much higher levels of claudin-6 than the adult kidney. Immunofluorescence microscopy showed intense claudin-6 staining in most of the tubules and glomeruli in neonates. The staining in tubules declined distinctly in adults, whereas staining in glomeruli was well preserved during development. Claudin-6 in glomeruli was distributed along the glomerular capillary wall and colocalized with zonula occludens-1. The staining became conspicuous after kidney perfusion with protamine sulfate (PS) to increase tight junctions in podocytes. Immunoelectron microscopy showed that immunogold particles for claudin-6 were accumulated at close cell-cell contact sites of podocytes in PS-perfused kidneys, whereas a very limited number of immunogold particles were detected, mainly on the basal cell membrane and occasionally at the slit diaphragm and close cell-cell contact sites in normal control kidneys. In puromycin aminonucleoside nephrosis, immunogold particles were also found mainly at cell-contact sites of podocytes. These findings indicate that claudin-6 is a transmembrane protein of tight junctions in podocytes during development and under pathological conditions.
Kir4.1/Kir5.1 channel forms the major K+channel in the basolateral membrane of mouse renal collecting duct principal cells
Authors: Lachheb Sahran , Cluzeaud Françoise , Bens Marcelle , Genete Mathieu , Hibino Hiroshi , Lourdel Stéphane , Kurachi Yoshihisa , Vandewalle Alain , Teulon Jacques , Paulais Marc
Published: March 2008

K+channels in the basolateral membrane of mouse cortical collecting duct (CCD) principal cells were identified with patch-clamp technique, real-time PCR, and immunohistochemistry. In cell-attached membrane patches, three K+channels with conductances of ∼75, 40, and 20 pS were observed, but the K+channel with the intermediate conductance (40 pS) predominated. In inside-out membrane patches exposed to an Mg2+-free medium, the current-voltage relationship of the intermediate-conductance channel was linear with a conductance of 38 pS. Addition of 1.3 mM internal Mg2+had no influence on the inward conductance ( Gin= 35 pS) but reduced outward conductance ( Gout) to 13 pS, yielding a Gin/ Goutof 3.2. The polycation spermine (6 × 10−7M) reduced its activity on inside-out membrane patches by 50% at a clamp potential of 60 mV. Channel activity was also dependent on intracellular pH (pHi): a sigmoid relationship between pHiand channel normalized current ( NPo) was observed with a p K of 7.24 and a Hill coefficient of 1.7. By real-time PCR on CCD extracts, inwardly rectifying K+(Kir)4.1 and Kir5.1, but not Kir4.2, mRNAs were detected. Kir4.1 and Kir5.1 proteins cellularly colocalized with aquaporin 2 (AQP2), a specific marker of CCD principal cells, while AQP2-negative cells (i.e., intercalated cells) showed no staining. Dietary K+had no influence on the properties of the intermediate-conductance channel, but a Na+-depleted diet increased its open probability by ∼25%. We conclude that the Kir4.1/Kir5.1 channel is a major component of the K+conductance in the basolateral membrane of mouse CCD principal cells.
Aquaporin-2 downregulation in kidney medulla of aging rats is posttranscriptional and is abolished by water deprivation
Authors: Combet S. , Gouraud S. , Gobin R. , Berthonaud V. , Geelen G. , Corman B. , Verbavatz J.-M.
Published: March 2008

Aging kidney is associated in humans and rodents with polyuria and reduced urine concentrating ability. In senescent female WAG/Rij rats, this defect is independent of arginine-vasopressin (AVP)/V2receptor/cAMP pathway. It has been attributed to underexpression and mistargeting of aquaporin-2 (AQP2) water channel in the inner medullary collecting duct (IMCD). We showed previously that dDAVP administration could partially correct this defect. Since AQP2 can also be regulated by AVP-independent pathways in water deprivation (WD), we investigated AQP2 and phosphorylated AQP2 (p-AQP2) regulation in thirsted adult (10 mo old) and senescent (30 mo old) female WAG/Rij rats. Following 2-day WD, urine flow rate decreased and urine osmolality increased in both groups. However, in agreement with significantly lower cortico-papillary osmotic gradient with aging, urine osmolality remained lower in senescent animals. WD induced sixfold increase of plasma AVP in all animals which, interestingly, did not result in higher papillary cAMP level. Following WD, AQP2 and p-AQP2 expression increased hugely in 10- and 30-mo-old rats and their mistargeting in old animals was corrected. Moreover, the age-related difference in AQP2 regulation was abolished after WD. To further investigate the mechanism of AQP2 underexpression with aging, AQP2 mRNA was quantified by real-time RT-PCR. In the outer medulla, preservation of AQP2 protein expression was achieved through increased AQP2 mRNA level in senescent rats. In the IMCD, no change in AQP2 mRNA was detected with aging but AQP2 protein expression was markedly lower in 30-mo-old animals. In conclusion, there is a posttranscriptional downregulation of AQP2 with aging, which is abolished by WD.
Intrinsic Frequency Tuning in ELL Pyramidal Cells Varies Across Electrosensory Maps
Authors: Mehaffey W. Hamish , Maler Leonard , Turner Ray W.
Published: March 2008

The tuning of neuronal responsiveness to specific stimulus frequencies is an important computation across many sensory modalities. The weakly electric fish Apteronotus leptorhynchus detects amplitude modulations of a self-generated quasi-sinusoidal electric organ discharge to sense its environment. These fish have to parse a complicated electrosensory environment with a wide range of possible frequency content. One solution has been to create multiple representations of the sensory input across distinct maps in the electrosensory lateral line lobe (ELL) that participate in distinct behavioral functions. E- and I-type pyramidal cells in the ELL that process sensory input further exhibit a preferred range of stimulus frequencies in relation to the different behaviors and sensory maps. We tested the hypothesis that variations in the intrinsic spiking mechanism of E- and I-type pyramidal cells contribute to map-specific frequency tuning. We find that E-cells exhibit a systematic change in their intrinsic spike characteristics and frequency tuning across sensory maps, whereas I-cells are constant in both spike characteristics and frequency tuning. As frequency tuning becomes more high-pass in E-cells, the refractory variables of spike half-width and afterhyperpolarization magnitude increase, spike threshold increases, adaptation becomes faster, and the gain of the spiking response decreases. These findings indicate that frequency tuning across sensory maps in the ELL is supported by differences in the intrinsic spike characteristics of pyramidal cells, revealing a link between cellular biophysical properties and signal processing in sensory maps with defined behavioral roles.
The Human Thalamus is Crucially Involved in Executive Control Operations
Authors: Marzinzik Frank , Wahl Michael , Schneider Gerd-Helge , Kupsch Andreas , Curio Gabriel , Klostermann Fabian
Published: March 2008

The processing of executive control is thought to involve cortical as well as thalamic brain areas. However, the questions of how thalamic structures contribute to the control of behavior and how cortical versus thalamic processing is coordinated remain to be settled. We therefore aimed at specifying respective activations during the performance of a go/no-go task. To this end, an electroencephalogram was recorded simultaneously from scalp and thalamic electrodes in seven patients undergoing deep brain stimulation. Meanwhile, left- or right-directed precues were presented indicating with which index finger a button press should be putatively executed. Thereafter, 2 sec elapsed until a go or no-go stimulus determined if the prepared movement had to be performed or withheld. In fronto-central scalp as well as in thalamic recordings, event-related potentials upon go versus no-go instructions were expressed differentially. This task effect was unrelated to motor processes and emerged significantly prior at thalamic than at scalp level. Amplitude fluctuations of depth and scalp responses showed site- and task-dependent correlations, particularly between thalamic and no-go-related activities at frontal recording sites. We conclude that an early classification of go and no-go instructions is performed already thalamically. It further appears that this information is subsequently utilized by cortical areas engaged in the definite inhibition of the prepared action.
Left-lateralized N170 Effects of Visual Expertise in Reading: Evidence from Japanese Syllabic and Logographic Scripts
Authors: Maurer Urs , Zevin Jason D. , McCandliss Bruce D.
Published: March 2008

The N170 component of the event-related potential (ERP) reflects experience-dependent neural changes in several forms of visual expertise, including expertise for visual words. Readers skilled in writing systems that link characters to phonemes (i.e., alphabetic writing) typically produce a left-lateralized N170 to visual word forms. This study examined the N170 in three Japanese scripts that link characters to larger phonological units. Participants were monolingual English speakers (EL1) and native Japanese speakers (JL1) who were also proficient in English. ERPs were collected using a 129-channel array, as participants performed a series of experiments viewing words or novel control stimuli in a repetition detection task. The N170 was strongly left-lateralized for all three Japanese scripts (including logographic Kanji characters) in JL1 participants, but bilateral in EL1 participants viewing these same stimuli. This demonstrates that left-lateralization of the N170 is dependent on specific reading expertise and is not limited to alphabetic scripts. Additional contrasts within the moraic Katakana script revealed equivalent N170 responses in JL1 speakers for familiar Katakana words and for Kanji words transcribed into novel Katakana words, suggesting that the N170 expertise effect is driven by script familiarity rather than familiarity with particular visual word forms. Finally, for English words and novel symbol string stimuli, both EL1 and JL1 subjects produced equivalent responses for the novel symbols, and more left-lateralized N170 responses for the English words, indicating that such effects are not limited to the first language. Taken together, these cross-linguistic results suggest that similar neural processes underlie visual expertise for print in very different writing systems.
Autobiographical Memory and Patterns of Brain Atrophy in Fronto-temporal Lobar Degeneration
Authors: McKinnon Margaret C. , Nica Elena I. , Sengdy Pheth , Kovacevic Natasa , Moscovitch Morris , Freedman Morris , Miller Bruce L. , Black Sandra E. , Levine Brian
Published: March 2008

Autobiographical memory paradigms have been increasingly used to study the behavioral and neuroanatomical correlates of human remote memory. Although there are numerous functional neuroimaging studies on this topic, relatively few studies of patient samples exist, with heterogeneity of results owing to methodological variability. In this study, fronto-temporal lobar degeneration (FTLD), a form of dementia affecting regions crucial to autobiographical memory, was used as a model of autobiographical memory loss. We emphasized the separation of episodic (recollection of specific event, perceptual, and mental state information) from semantic (factual information unspecific in time and place) autobiographical memory, derived from a reliable method for scoring transcribed autobiographical protocols, the Autobiographical Interview [Levine, B., Svoboda, E., Hay, J., Winocur, G., & Moscovitch, M. Aging and autobiographical memory: Dissociating episodic from semantic retrieval. Psychology and Aging, 17, 677–689, 2002]. Patients with the fronto-temporal dementia (FTD) and mixed fronto-temporal and semantic dementia (FTD/SD) variants of FTLD were impaired at reconstructing episodically rich autobiographical memories across the lifespan, with FTD/SD patients generating an excess of generic semantic autobiographical information. Patients with progressive nonfluent aphasia were mildly impaired for episodic autobiographical memory, but this impairment was eliminated with the provision of structured cueing, likely reflecting relatively intact medial-temporal lobe function, whereas the same cueing failed to bolster the FTD and FTD/SD patients' performance relative to that of matched comparison subjects. The pattern of episodic, but not semantic, autobiographical impairment was enhanced with disease progression on 1- to 2-year follow-up testing in a subset of patients, supplementing the cross-sectional evidence for specificity of episodic autobiographical impairment with longitudinal data. This behavioral pattern covaried with volume loss in a distributed left-lateralized posterior network centered on the temporal lobe, consistent with evidence from other patient and functional neuroimaging studies of autobiographical memory. Frontal lobe volumes, however, did not significantly contribute to this network, suggesting that frontal contributions to autobiographical episodic memory may be more complex than previously appreciated.