bluuebunny/crossref_metadata_2025 huggingface dataset:
Andes Virus Recognition of Human and Syrian Hamster β
3
Integrins Is Determined by an L33P Substitution in the PSI Domain
Authors: Matthys Valery S. , Gorbunova Elena E. , Gavrilovskaya Irina N. , Mackow Erich R.
Published: October 2009

Andes virus (ANDV) causes a fatal hantavirus pulmonary syndrome (HPS) in humans and Syrian hamsters. Human α
v
β
3
integrins are receptors for several pathogenic hantaviruses, and the function of α
v
β
3
integrins on endothelial cells suggests a role for α
v
β
3
in hantavirus directed vascular permeability. We determined here that ANDV infection of human endothelial cells or Syrian hamster-derived BHK-21 cells was selectively inhibited by the high-affinity α
v
β
3
integrin ligand vitronectin and by antibodies to α
v
β
3
integrins. Further, antibodies to the β
3
integrin PSI domain, as well as PSI domain polypeptides derived from human and Syrian hamster β
3
subunits, but not murine or bovine β
3
, inhibited ANDV infection of both BHK-21 and human endothelial cells. These findings suggest that ANDV interacts with β
3
subunits through PSI domain residues conserved in both Syrian hamster and human β
3
integrins. Sequencing the Syrian hamster β
3
integrin PSI domain revealed eight differences between Syrian hamster and human β
3
integrins. Analysis of residues within the PSI domains of human, Syrian hamster, murine, and bovine β
3
integrins identified unique proline substitutions at residues 32 and 33 of murine and bovine PSI domains that could determine ANDV recognition. Mutagenizing the human β
3
PSI domain to contain the L33P substitution present in bovine β
3
integrin abolished the ability of the PSI domain to inhibit ANDV infectivity. Conversely, mutagenizing either the bovine PSI domain, P33L, or the murine PSI domain, S32P, to the residue present human β
3
permitted PSI mutants to inhibit ANDV infection. Similarly, CHO cells transfected with the full-length bovine β
3
integrin containing the P33L mutation permitted infection by ANDV. These findings indicate that human and Syrian hamster α
v
β
3
integrins are key receptors for ANDV and that specific residues within the β
3
integrin PSI domain are required for ANDV infection. Since L33P is a naturally occurring human β
3
polymorphism, these findings further suggest the importance of specific β
3
integrin residues in hantavirus infection. These findings rationalize determining the role of β
3
integrins in hantavirus pathogenesis in the Syrian hamster model.
Modulation of Hepatitis C Virus RNA Abundance and the Isoprenoid Biosynthesis Pathway by MicroRNA miR-122 Involves Distinct Mechanisms
Authors: Norman Kara L. , Sarnow Peter
Published: October 2009

MicroRNA 122 (miR-122) promotes hepatitis C virus (HCV) RNA abundance through a direct interaction with the viral RNA and stimulates the mevalonate pathway in the animal liver. We found that overexpression of miR-122 enhanced viral RNA accumulation without affecting genes in the mevalonate pathway, such as the 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) gene. However, inhibition of miR-122 decreased both HCV RNA and HMGCR RNA with little effects on the rates of HCV and HMGCR RNA synthesis. Loss of HCV RNA could not be restored by isoprenoid intermediate metabolites. Overall, these findings suggest that miR-122 modulates viral RNA abundance independently of its effect on isoprenoid metabolism.
Hepatitis B Virus Requires Intact Caveolin-1 Function for Productive Infection in HepaRG Cells
Authors: Macovei Alina , Radulescu Cristina , Lazar Catalin , Petrescu Stefana , Durantel David , Dwek Raymond A. , Zitzmann Nicole , Nichita Norica Branza
Published: October 2009

Investigation of the entry pathways of hepatitis B virus (HBV), a member of the familyHepadnaviridae, has been hampered by the lack of versatile in vitro infectivity models. Most concepts of hepadnaviral infection come from the more robust duck HBV system; however, whether the two viruses use the same mechanisms to invade target cells is still a matter of controversy. In this study, we investigate the role of an important plasma membrane component, caveolin-1 (Cav-1), in HBV infection. Caveolins are the main structural components of caveolae, plasma membrane microdomains enriched in cholesterol and sphingolipids, which are involved in the endocytosis of numerous ligands and complex signaling pathways within the cell. We used the HepaRG cell line permissive for HBV infection to stably express dominant-negative Cav-1 and dynamin-2, a GTPase involved in vesicle formation at the plasma membrane and other organelles. The endocytic properties of the newly established cell lines, designated HepaRGCav-1, HepaRGCav-1Δ1-81, HepaRGDyn-2, and HepaRGDyn-2K44A, were validated using specific markers for different entry routes. The cells maintained their properties during cell culture, supported differentiation, and were permissive for HBV infection. The levels of both HBV transcripts and antigens were significantly decreased in cells expressing the mutant proteins, while viral replication was not directly affected. Chemical inhibitors that specifically inhibit clathrin-mediated endocytosis had no effect on HBV infection. We concluded that HBV requires a Cav-1-mediated entry pathway to initiate productive infection in HepaRG cells.
Effect of Killer Immunoglobulin-Like Receptors in the Response to Combined Treatment in Patients with Chronic Hepatitis C Virus Infection
Authors: Vidal-Castiñeira J. R. , López-Vázquez A. , Díaz-Peña R. , Alonso-Arias R. , Martínez-Borra J. , Pérez R. , Fernández-Suárez J. , Melón S. , Prieto J. , Rodrigo L. , López-Larrea C.
Published: October 2009

Killer immunoglobulin-like receptors (KIRs) are related to the activation and inhibition of NK cells and may play an important role in the innate response against infection with viruses such as hepatitis C virus (HCV). We examined whether the different combinations of KIRs with their HLA class I ligands influenced the response to combined treatment (pegylated alpha interferon and ribavirin) of patients infected by HCV. A total of 186 consecutive patients diagnosed with chronic HCV infection were analyzed. Seventy-seven patients exhibited HCV RNA levels at 6 months posttreatment and were called nonresponders (NR), while 109 cleared viral RNA and were named sustained viral responders (SVR). Patients were typed for HLA-B, HLA-Cw, KIR genes, and HCV genotype. In our study, the frequency of the KIR2DL2 allele was significantly increased in NR (P< 0.001; odds ratio [OR] = 1.95), as was the frequency of the KIR2DL2/KIR2DL2 genotype (P< 0.005; OR = 2.52). In contrast, the frequencies of the KIR2DL3 genotype (P< 0.001) and KIR2DL3/KIR2DL3 genotype (P< 0.05; OR = 0.54) were significantly increased in the SVR. Different combinations of KIR2DL2 and KIR2DL3 alleles with their ligands were analyzed. The frequency of the KIR2DL2/KIR2DL2-HLA-C1C2 genotype was significantly increased in the NR (P< 0.01; OR = 3.15). Additionally, we found a higher frequency of the KIR2DL3/KIR2DL3-HLA-C1C1 genotype in the SVR group (P< 0.05; OR = 0.33). These results were not affected by the HCV genotype. In conclusion, patients who carried the KIR2DL2/KIR2DL2-HLA-C1C2 genotype were less prone to respond to treatment. However, the KIR2DL3/KIR2DL3-HLA-C1C1 genotype clearly correlated with a satisfactory response to treatment, defined by the clearance of HCV RNA.
Novel Approach to the Formulation of an Epstein-Barr Virus Antigen-Based Nasopharyngeal Carcinoma Vaccine
Authors: Lutzky Viviana P. , Corban Monika , Heslop Lea , Morrison Leanne E. , Crooks Pauline , Hall David F. , Coman William B. , Thomson Scott A. , Moss Denis J.
Published: October 2009

Epstein-Barr virus (EBV) is associated with several malignant diseases including nasopharyngeal carcinoma (NPC), a common neoplasm throughout southeast Asia. Radiotherapy and chemotherapy can achieve remission, but a reemergence of disease is not uncommon. Therefore, there is a need for specific therapies that target the tumor through the recognition of EBV antigens. In NPC, latent membrane protein 1 (LMP1) and LMP2 offer the best opportunity for specific targeting since they are typically expressed and T-cell determinants in each of these proteins have been defined. We have attempted to maximize the opportunity of incorporating every possible CD4 and CD8 determinant in a single formulation. We have achieved this by generating a scrambled protein incorporating random overlapping peptide sets from EBNA1, LMP1, and LMP2, which was then inserted into a replication-deficient strain of adenovirus (adenovirus scrambled antigen vaccine [Ad-SAVINE]). This report describes the construction of this Ad-SAVINE construct, its utility in generating LMP1 and LMP2 responses in healthy individuals as well as NPC patients, and its capacity to define new epitopes. This formulation could have a role in NPC immunotherapy for all ethnic groups since it has the potential to activate all possible CD4 and CD8 responses within EBNA1 and LMPs.
Effects of Phosphorylation of Herpes Simplex Virus 1 Envelope Glycoprotein B by Us3 Kinase In Vivo and In Vitro
Authors: Imai Takahiko , Sagou Ken , Arii Jun , Kawaguchi Yasushi
Published: October 2009

We recently reported that the herpes simplex virus 1 (HSV-1) Us3 protein kinase phosphorylates threonine at position 887 (Thr-887) in the cytoplasmic tail of envelope glycoprotein B (gB) (A. Kato, J. Arii, I. Shiratori, H. Akashi, H. Arase, and Y. Kawaguchi, J. Virol. 83:250-261, 2009; T. Wisner, C. C. Wright, A. Kato, Y. Kawaguchi, F. Mou, J. D. Baines, R. J. Roller and D. C. Johnson, J. Virol. 83:3115-3126, 2009). In the studies reported here, we examined the effect(s) of this phosphorylation on viral replication and pathogenesis in vivo and present data showing that replacement of gB Thr-887 by alanine significantly reduced viral replication in the mouse cornea and development of herpes stroma keratitis and periocular skin disease in mice. The same effects have been reported for mice infected with a recombinant HSV-1 carrying a kinase-inactive mutant of Us3. These observations suggested that Us3 phosphorylation of gB Thr-887 played a critical role in viral replication in vivo and in HSV-1 pathogenesis. In addition, we generated a monoclonal antibody that specifically reacted with phosphorylated gB Thr-887 and used this antibody to show that Us3 phosphorylation of gB Thr-887 regulated subcellular localization of gB, particularly on the cell surface of infected cells.
Pathogenesis of Hepatitis C Virus Infection inTupaia belangeri
Authors: Amako Yutaka , Tsukiyama-Kohara Kyoko , Katsume Asao , Hirata Yuichi , Sekiguchi Satoshi , Tobita Yoshimi , Hayashi Yukiko , Hishima Tsunekazu , Funata Nobuaki , Yonekawa Hiromichi , Kohara Michinori
Published: October 2009

The lack of a small-animal model has hampered the analysis of hepatitis C virus (HCV) pathogenesis. The tupaia (Tupaia belangeri), a tree shrew, has shown susceptibility to HCV infection and has been considered a possible candidate for a small experimental model of HCV infection. However, a longitudinal analysis of HCV-infected tupaias has yet to be described. Here, we provide an analysis of HCV pathogenesis during the course of infection in tupaias over a 3-year period. The animals were inoculated with hepatitis C patient serum HCR6 or viral particles reconstituted from full-length cDNA. In either case, inoculation caused mild hepatitis and intermittent viremia during the acute phase of infection. Histological analysis of infected livers revealed that HCV caused chronic hepatitis that worsened in a time-dependent manner. Liver steatosis, cirrhotic nodules, and accompanying tumorigenesis were also detected. To examine whether infectious virus particles were produced in tupaia livers, naive animals were inoculated with sera from HCV-infected tupaias, which had been confirmed positive for HCV RNA. As a result, the recipient animals also displayed mild hepatitis and intermittent viremia. Quasispecies were also observed in the NS5A region, signaling phylogenic lineage from the original inoculating sequence. Taken together, these data suggest that the tupaia is a practical animal model for experimental studies of HCV infection.
Role of a Putative gp41 Dimerization Domain in Human Immunodeficiency Virus Type 1 Membrane Fusion
Authors: Liu Jie , Deng Yiqun , Li Qunnu , Dey Antu K. , Moore John P. , Lu Min
Published: October 2009

The entry of human immunodeficiency virus type 1 (HIV-1) into a target cell entails a series of conformational changes in the gp41 transmembrane glycoprotein that mediates the fusion of the viral and target cell membranes. A trimer-of-hairpins structure formed by the association of two heptad repeat (HR) regions of the gp41 ectodomain has been implicated in a late step of the fusion pathway. Earlier native and intermediate states of the protein are postulated to mediate the antiviral activity of the fusion inhibitor enfuvirtide and of broadly neutralizing monoclonal antibodies (NAbs), but the details of these structures remain unknown. Here, we report the identification and crystal structure of a dimerization domain in the C-terminal ectodomain of gp41 (residues 630 to 683, or C54). Two C54 monomers associate to form an asymmetric, antiparallel coiled coil with two distinct C-terminal α-helical overhangs. This dimer structure is conferred largely by interactions within a central core that corresponds to the sequence of enfuvirtide. The mutagenic alteration of the dimer interface severely impairs the infectivity of Env-pseudotyped viruses. Moreover, the C54 structure binds tightly to both the 2F5 and 4E10 NAbs and likely represents a potential intermediate conformation of gp41. These results should enhance our understanding of the molecular basis of the gp41 fusogenic structural transitions and thereby guide rational, structure-based efforts to design new fusion inhibitors and vaccine candidates intended to induce broadly neutralizing antibodies.
The Requirement for Cellular Transportin 3 (TNPO3 or TRN-SR2) during Infection Maps to Human Immunodeficiency Virus Type 1 Capsid and Not Integrase
Authors: Krishnan Lavanya , Matreyek Kenneth A. , Oztop Ilker , Lee Kyeongeun , Tipper Christopher H. , Li Xiang , Dar Mohd J. , KewalRamani Vineet N. , Engelman Alan
Published: October 2009

Recent genome-wide screens have highlighted an important role for transportin 3 in human immunodeficiency virus type 1 (HIV-1) infection and preintegration complex (PIC) nuclear import. Moreover, HIV-1 integrase interacted with recombinant transportin 3 protein under conditions whereby Moloney murine leukemia virus (MLV) integrase failed to do so, suggesting that integrase-transportin 3 interactions might underscore active retroviral PIC nuclear import. Here we correlate infectivity defects in transportin 3 knockdown cells with in vitro protein binding affinities for an expanded set of retroviruses that include simian immunodeficiency virus (SIV), bovine immunodeficiency virus (BIV), equine infectious anemia virus (EIAV), feline immunodeficiency virus (FIV), and Rous sarcoma virus (RSV) to critically address the role of integrase-transportin 3 interactions in viral infection. Lentiviruses, with the exception of FIV, display a requirement for transportin 3 in comparison to MLV and RSV, yielding an infection-based dependency ranking of SIV > HIV-1 > BIV and EIAV > MLV, RSV, and FIV. In vitro pulldown and surface plasmon resonance assays, in contrast, define a notably different integrase-transportin 3 binding hierarchy: FIV, HIV-1, and BIV > SIV and MLV > EIAV. Our results therefore fail to support a critical role for integrase binding in dictating transportin 3 dependency during retrovirus infection. In addition to integrase, capsid has been highlighted as a retroviral nuclear import determinant. Accordingly, MLV/HIV-1 chimera viruses pinpoint the genetic determinant of sensitization to transportin 3 knockdown to the HIV-1 capsid protein. We therefore conclude that capsid, not integrase, is the dominant viral factor that dictates transportin 3 dependency during HIV-1 infection.
Interaction of the Betapapillomavirus E2 Tethering Protein with Mitotic Chromosomes
Authors: Sekhar Vandana , Reed Shawna C. , McBride Alison A.
Published: October 2009

During persistent papillomavirus infection, the viral E2 protein tethers the viral genome to the host cell chromosomes, ensuring maintenance and segregation of the viral genome during cell division. However, E2 proteins from different papillomaviruses interact with distinct chromosomal regions and targets. The tethering mechanism has been best characterized for bovine papillomavirus type 1 (BPV1), where the E2 protein tethers the viral genome to mitotic chromosomes in complex with the cellular bromodomain protein, Brd4. In contrast, the betapapillomavirus human papillomavirus type 8 (HPV8) E2 protein binds to the repeated ribosomal DNA genes that are found on the short arm of human acrocentric chromosomes. In this study, we show that a short 16-amino-acid peptide from the hinge region and the C-terminal DNA binding domain of HPV8 E2 are necessary and sufficient for interaction with mitotic chromosomes. This 16-amino-acid region contains an RXXS motif that is highly conserved among betapapillomaviruses, and both arginine 250 and serine 253 residues within this motif are required for mitotic chromosome binding. The HPV8 E2 proteins are highly phosphorylated, and serine 253 is a site of phosphorylation. The HPV8 E2 chromosome binding sequence also has sequence similarity with chromosome binding regions in the gammaherpesvirus EBNA and LANA tethering proteins.
Changes of mucosal immunity and antioxidation activity in elite male Taiwanese taekwondo athletes associated with intensive training and rapid weight loss
Authors: Tsai M-L , Chou K-M , Chang C-K , Fang S-H
Published: October 2009

Objective

The aim of this study was to investigate the cumulative effects of prolonged, intensive training and rapid weight loss on immunological parameters and antioxidation activity of elite male Taiwanese taekwondo athletes.

Design

16 Elite male taekwondo athletes (mean age, 21.6 (1.3) years; mean height, 173.7 (5.5) cm) volunteered to participate in this study. Beginning at 30 days before a national competition, saliva samples were obtained during a 7-week training, the competition and the postcompetition period. Levels of salivary IgA, cortisol, lactoferrin and free-radical scavenging activity were measured at 30-, 14-, 7- and 1-day precompetition and 1-, 7- and 19-day postcompetition. Body weight and body fat were also recorded.

Results

The mean body weight was notably decreased during the week immediately before the competition. Results reveal that the levels of salivary IgA were differentially regulated during the training, competition and recovery period, while the salivary cortisol and lactoferrin concentrations and free-radical scavenging activity were not appreciably affected during the training and the competition period. Furthermore, the results of an upper respiratory tract infection incidence indicate that following the decreases of mucosal immunity, the risk of acquiring infection was significantly increased.

Conclusions

Our results demonstrated that mucosal immunity in elite male taekwondo athletes is modulated by exercise and rapid weight reduction during the training, competition and recovery period. Cumulative effects of prolonged intensive training and rapid weight reduction suppressed mucosal immunity. Furthermore, because of the “open window” of impaired immunity during the precompetition period, the incidence of upper respiratory tract infection was significantly increased after the competition.
Are there risk factors in alpine skiing? A controlled multicentre survey of 1278 skiers
Authors: Hasler R M , Dubler S , Benneker L M , Berov S , Spycher J , Heim D , Zimmermann H , Exadaktylos A K
Published: October 2009

Objective:

To analyse risk factors in alpine skiing.

Design:

A controlled multicentre survey of injured and non-injured alpine skiers.

Setting:

One tertiary and two secondary trauma centres in Bern, Switzerland.

Patients and methods:

All injured skiers admitted from November 2007 to April 2008 were analysed using a completed questionnaire incorporating 15 parameters. The same questionnaire was distributed to non-injured controls. Multiple logistic regression was performed. Patterns of combined risk factors were calculated by inference trees. A total of 782 patients and 496 controls were interviewed.

Results:

Parameters that were significant for the patients were: high readiness for risk (p = 0.0365, OR 1.84, 95% CI 1.04 to 3.27); low readiness for speed (p = 0.0008, OR 0.29, 95% CI 0.14 to 0.60); no aggressive behaviour on slopes (p<0.0001, OR 0.19, 95% CI 0.09 to 0.37); new skiing equipment (p = 0.0228, OR 59, 95% CI 0.37 to 0.93); warm-up performed (p = 0.0015, OR 1.79, 95% CI 1.25 to 2.57); old snow compared with fresh snow (p = 0.0155, OR 0.31, 95% CI 0.12 to 0.80); old snow compared with artificial snow (p = 0.0037, OR 0.21, 95% CI 0.07 to 0.60); powder snow compared with slushy snow (p = 0.0035, OR 0.25, 95% CI 0.10 to 0.63); drug consumption (p = 0.0044, OR 5.92, 95% CI 1.74 to 20.11); and alcohol abstinence (p<0.0001, OR 0.14, 95% CI 0.05 to 0.34). Three groups at risk were detected: (1) warm-up 3–12 min, visual analogue scale (VAS)speed>4 and bad weather/visibility; (2) VASspeed4–7, icy slopes and not wearing a helmet; (3) warm-up >12 min and new skiing equipment.

Conclusions:

Low speed, high readiness for risk, new skiing equipment, old and powder snow, and drug consumption are significant risk factors when skiing. Future work should aim to identify more precisely specific groups at risk and develop recommendations—for example, a snow weather index at valley stations.
Exercise and diet in weight management: updating what works
Authors: Macfarlane D J , Thomas G N
Published: October 2009

The world is facing major problems associated with the rapid increase in levels of overweight and obesity. Solving this problem via appropriate modifications to exercise habits and/or diet appears easy, but in practice it is inordinately difficult and only a small percentage manage to maintain their weight loss over the long term. However, a number of strategies can be used to increase the chances of success. Medical doctors, dieticians and other allied health professionals are potentially well placed to provide guidance to those at risk of overweight/obesity. This review is aimed at supporting major initiatives targeting an increase in community physical activity to help reduce the prevalence of overweight/obesity, such as the “Change4Life” campaign in the UK (http://www.nhs.uk/change4life) and the “Exercise is Medicine” campaign in the USA (http://www.exerciseismedicine.org). By providing a concise summary of the evidence-based research that can be easily understood by a wide range of health professionals, this review hopes to provide a useful document that can be used to enhance preventive counselling by promoting appropriate changes in lifestyle that will ultimately increase levels of physical activity, as well as reduce levels of overweight/obesity and other associated chronic hypokinetic conditions.
The lymphatic system controls intestinal inflammation and inflammation-associated colon cancer through the chemokine decoy receptor D6
Authors: Vetrano Stefania , Borroni Elena M , Sarukhan Adelaida , Savino Benedetta , Bonecchi Raffaella , Correale Carmen , Arena Vincenzo , Fantini Massimo , Roncalli Massimo , Malesci Alberto , Mantovani Alberto , Locati Massimo , Danese Silvio
Published: October 2009

Background and aims

Inflammatory CC chemokines have long been associated with cancer, but unequivocal evidence of a role in clinically relevant models of carcinogenesis is lacking. D6, a promiscuous decoy receptor that scavenges inflammatory CC chemokines, plays a non-redundant role in reducing the inflammatory response in various organs. As inflammation is a key player in the development of inflammatory bowel disease (IBD) and IBD-associated colorectal cancer, we investigated D6 expression in human colitis and colon cancer, and its role in experimental colitis and inflammation-associated colon cancer.

Results

In humans, D6 was mainly expressed by lymphatic vessels and leukocytes in the mucosa of individuals with IBD and colon cancer, as well as the mucosa of control individuals. Mice lacking expression of D6 were significantly more susceptible to experimental colitis than wild-type mice and failed to resolve colitis, with significantly higher levels of several pro-inflammatory chemokines. In bone marrow chimeric mice, the ability of D6 to regulate colitis was tracked to the stromal/lymphatic compartment, with no contribution of haemopoietic cells. Finally, after administration of the carcinogen azoxymethane, D6−/− mice showed increased susceptibility to colitis-associated cancer in the distal segment of the colon compared with wild-type mice.

Conclusions

D6 expressed on lymphatic vessels plays a key role in the control of intestinal inflammation and the development of inflammation-associated colon cancer. Our results reveal a new unexpected role for the lymphatic system in the pathogenesis of IBD and intestinal cancer, and candidate chemokines as novel players in tumour promotion and progression.
Isolation and genetic analysis of self-sterility and perithecial pigmentation mutants in a homothallic isolate of Nectria haematococca
Authors: Babai-Ahary A. , Daboussi-Bareyre M. J. , Parisot D.
Published: October 2009

Mutants with altered sexual reproduction were isolated from a homothallic wild-type strain of Nectria haematococca (Berk. & Br.) Wr. and genetically analysed. Most were self- and inter-sterile but some were interfertile and were used to improve genetic analysis by allowing an easy detection of hybrid perithecia. The study of these mutants also provides information about various aspects of the perithecial development in this organism.
Ultrastructure of cell division in the unicellular red alga Porphyridium purpureum
Authors: Schornstein Kathleen L. , Scott Joe
Published: October 2009

Mitosis in the unicellular red alga Porphyridium purpureum was studied with the electron microscope. During early prophase two bipartite nucleus associated organelles (NAOs) are seen in a region that will become one of the division poles. The division axis is established by the migration of one NAO. Microbodies are associated with the poles throughout the mitotic cycle. At prometaphase the nuclear envelope (NE) subjacent to each NAO forms a nuclear pocket which breaks down or opens to form a large gap. Concomitant with polar gap formation the large NAO portion proximal to the NE disperses whereas the smaller distal NAO portion remains throughout subsequent mitotic stages. At metaphase a plate arrangement of chromatin is seen and indistinct kinetochores are associated with a single microtubule. Chromatin moves to the poles followed by pronounced interzonal midpiece (IZM) elongation. After IZM abscission the nuclei migrate to opposite ends of the elongating cell. Cytokinesis occurs by means of an ingrowing cleavage furrow. A comparison of mitotic ultrastructural characteristics in Porphyridium with data available on mitosis in other red algae suggests that structural diversity may be of taxonomic significance; a comparison with other lower eukaryotes suggests that the overall features of mitosis in red algae do not support the general belief that this group is one of the most primitive of all eukaryotes.
EFFECTS OF ELECTROMAGNETIC FIELD ON GRAVITATIONAL COLLAPSE
Authors: SHARIF M. , ABBAS G.
Published: October 2009

In this paper, the effect of electromagnetic field has been investigated on the spherically symmetric gravitational collapse with the perfect fluid in the presence of positive cosmological constant. Junction conditions between the static exterior and non-static interior spherically symmetric spacetimes are discussed. We study the apparent horizons and their physical significance. It is found that electromagnetic field reduces the bound of cosmological constant by reducing the pressure and hence collapsing process is faster as compared to the perfect fluid case. This work gives the generalization of the perfect fluid case to the charged perfect fluid. Results for the perfect fluid case are recovered.
LARGE MIXING ANGLE STERILE NEUTRINOS AND PULSAR VELOCITIES
Authors: KISSLINGER LEONARD S. , HENLEY ERNEST M. , JOHNSON MIKKEL B.
Published: October 2009

We investigate the momentum given to a protoneutron star, the pulsar kick, during the first ten seconds after temperature equilibrium is reached. Using a model with two sterile neutrinos obtained by fits to the MiniBooNE and LSND experiments, which is consistent with a new global fit, there is a large mixing angle, and the effective volume for emission is calculated. Using formulations with neutrinos created by URCA processes in a strong magnetic field, so the lowest Landau level has a sizable probability, we find that with known parameters, the asymmetric sterile neutrino emissivity might account for large pulsar kicks.
AdS2×S2 GEOMETRIES AND THE EXTREME QUANTUM-CORRECTED BLACK HOLES
Authors: MATYJASEK JERZY , TRYNIECKI DARIUSZ
Published: October 2009

The second-order term of the approximate stress–energy tensor of the quantized massive scalar field in the Bertotti–Robinson and Reissner–Nordström spacetimes is constructed within the framework of the Schwinger–DeWitt method. It is shown that although the Bertotti–Robinson geometry is a self-consistent solution of the (Λ = 0) semiclassical Einstein field equations with the source term given by the leading term of the renormalized stress–energy tensor, it does not remain so when the next-to-leading term is taken into account and requires the introduction of a cosmological term. The addition of the electric charge to the system does not change this behavior. The near horizon geometry of the extreme quantum-corrected Reissner–Nordström black hole is analyzed. It has the AdS2 ×S2 topology and the sum of the curvature radii of the two-dimensional submanifolds is proportional to the trace of the second-order term. It suggests that the "minimal" approximation should be constructed from the first two terms of the Schwinger–DeWitt expansion
Role of TRPC1 channel in skeletal muscle function
Authors: Zanou Nadège , Shapovalov Georges , Louis Magali , Tajeddine Nicolas , Gallo Chiara , Van Schoor Monique , Anguish Isabelle , Cao My Linh , Schakman Olivier , Dietrich Alexander , Lebacq Jean , Ruegg Urs , Roulet Emmanuelle , Birnbaumer Lutz , Gailly Philippe
Published: October 2009

Skeletal muscle contraction is reputed not to depend on extracellular Ca2+. Indeed, stricto sensu , excitation-contraction coupling does not necessitate entry of Ca2+. However, we previously observed that, during sustained activity (repeated contractions), entry of Ca2+ is needed to maintain force production. In the present study, we evaluated the possible involvement of the canonical transient receptor potential (TRPC)1 ion channel in this entry of Ca2+ and investigated its possible role in muscle function. Patch-clamp experiments reveal the presence of a small-conductance channel (13 pS) that is completely lost in adult fibers from TRPC1−/− mice. The influx of Ca2+ through TRPC1 channels represents a minor part of the entry of Ca2+ into muscle fibers at rest, and the activity of the channel is not store dependent. The lack of TRPC1 does not affect intracellular Ca2+ concentration ([Ca2+]i) transients reached during a single isometric contraction. However, the involvement of TRPC1-related Ca2+ entry is clearly emphasized in muscle fatigue. Indeed, muscles from TRPC1−/− mice stimulated repeatedly progressively display lower [Ca2+]i transients than those observed in TRPC1+/+ fibers, and they also present an accentuated progressive loss of force. Interestingly, muscles from TRPC1−/− mice display a smaller fiber cross-sectional area, generate less force per cross-sectional area, and contain less myofibrillar proteins than their controls. They do not present other signs of myopathy. In agreement with in vitro experiments, TRPC1−/− mice present an important decrease of endurance of physical activity. We conclude that TRPC1 ion channels modulate the entry of Ca2+ during repeated contractions and help muscles to maintain their force during sustained repeated contractions.
Elevated Ca2+sparklet activity during acute hyperglycemia and diabetes in cerebral arterial smooth muscle cells
Authors: Navedo Manuel F. , Takeda Yukari , Nieves-Cintrón Madeline , Molkentin Jeffery D. , Santana Luis F.
Published: October 2009

Ca+sparklets are subcellular Ca2+signals produced by the opening of L-type Ca2+channels (LTCCs). In cerebral arterial myocytes, Ca2+sparklet activity varies regionally, resulting in low and high activity, “persistent” Ca2+sparklet sites. Although increased Ca2+influx via LTCCs in arterial myocytes has been implicated in the chain of events contributing to vascular dysfunction during acute hyperglycemia and diabetes, the mechanisms underlying these pathological changes remain unclear. Here, we tested the hypothesis that increased Ca2+sparklet activity contributes to higher Ca2+influx in cerebral artery smooth muscle during acute hyperglycemia and in an animal model of non-insulin-dependent, type 2 diabetes: the dB/dB mouse. Consistent with this hypothesis, acute elevation of extracellular glucose from 10 to 20 mM increased the density of low activity and persistent Ca2+sparklet sites as well as the amplitude of LTCC currents in wild-type cerebral arterial myocytes. Furthermore, Ca2+sparklet activity and LTCC currents were higher in dB/dB than in control myocytes. We found that activation of PKA contributed to higher Ca2+sparklet activity during hyperglycemia and diabetes. In addition, we found that the interaction between PKA and the scaffolding protein A-kinase anchoring protein was critical for the activation of persistent Ca2+sparklets by PKA in cerebral arterial myocytes after hyperglycemia. Accordingly, PKA inhibition equalized Ca2+sparklet activity between dB/dB and wild-type cells. These findings suggest that hyperglycemia increases Ca2+influx by increasing Ca2+sparklet activity via a PKA-dependent pathway in cerebral arterial myocytes and contributes to vascular dysfunction during diabetes.
Polyploidy impairs human aortic endothelial cell function and is prevented by nicotinamide phosphoribosyltransferase
Authors: Borradaile Nica M. , Pickering J. Geoffrey
Published: October 2009

Polyploid endothelial cells are found in aged and atherosclerotic arteries. However, whether increased chromosome content has an impact on endothelial cell function is unknown. We show here that human aortic endothelial cells become tetraploid as they approach replicative senescence. Furthermore, accumulation of tetraploid endothelial cells was accelerated during growth in high glucose. Interestingly, induction of polyploidy was completely prevented by modest overexpression of the NAD+ regenerating enzyme, nicotinamide phosphoribosyltransferase (Nampt). To determine the impact of polyploidy on endothelial cell function, independent of replicative senescence, we induced tetraploidy using the spindle poison, nocodazole. Global gene expression analyses of tetraploid endothelial cells revealed a dysfunctional phenotype characterized by a cell cycle arrest profile (decreased CCNE2/A2, RBL1, BUB1B; increased CDKN1A) and increased expression of genes involved in inflammation ( IL32, TNFRSF21/10C, PTGS1) and extracellular matrix remodeling ( COL5A1, FN1, MMP10/14). The protection from polyploidy conferred by Nampt was not associated with enhanced poly(ADP-ribose) polymerase-1 or sirtuin (SIRT) 2 activity, but with increased SIRT1 activity, which reduced cellular reactive oxygen species and the associated oxidative stress stimulus for the induction of polyploidy. We conclude that human aortic endothelial cells are prone to chromosome duplication that, in and of itself, can induce characteristics of endothelial dysfunction. Moreover, the emergence of polyploid endothelial cells during replicative aging and glucose overload can be prevented by optimizing the Nampt-SIRT1 axis.
TGF-β suppresses the upregulation of MMP-2 by vascular smooth muscle cells in response to PDGF-BB
Authors: Risinger George M. , Updike Dawn L. , Bullen Elizabeth C. , Tomasek James J. , Howard Eric W.
Published: October 2009

During platelet-derived growth factor (PDGF)-BB-mediated recruitment to neovascular sprouts, vascular smooth muscle cells (VSMCs) dedifferentiate from a contractile to a migratory phenotype. This involves the downregulation of contractile markers such as smooth muscle (SM) α-actin and the upregulation of promigration genes such as matrix metalloproteinase (MMP)-2. The regulation of MMP-2 in response to PDGF-BB is complex and involves both stimulatory and inhibitory signaling pathways, resulting in a significant delay in upregulation. Here, we provide evidence that the delay in MMP-2 upregulation may be due to the autocrine expression and activation of transforming growth factor (TGF)-β, which is known to promote the contractile phenotype in VSMCs. Whereas PDGF-BB could induce the loss of stress fibers and focal adhesions, TGF-β was able to block or reverse this transition to a noncontractile state. TGF-β did not, however, suppress early signaling events stimulated by PDGF-BB. Over time, though PDGF-BB induced increased TGF-β1 levels, it suppressed TGF-β2 and TGF-β3 expression, leading to a net decrease in the total TGF-β pool, resulting in the upregulation of MMP-2. Together, these findings indicate that MMP-2 expression is suppressed by a threshold level of active TGF-β, which in turn promotes a contractile VSMC phenotype that prevents the upregulation of MMP-2.
Functional analysis and theoretical modeling of ferroportin reveals clustering of mutations according to phenotype
Authors: Wallace Daniel F. , Harris Jonathan M. , Subramaniam V. Nathan
Published: October 2009

Ferroportin disease is a heterogeneous iron release disorder resulting from mutations in the ferroportin gene. Ferroportin protein is a multitransmembrane domain iron transporter, responsible for iron export from cells, which, in turn, is regulated by the peptide hormone hepcidin. Mutations in the ferroportin gene may affect either regulation of the protein's transporter function or the ability of hepcidin to regulate iron efflux. We have used a combination of functional analysis of epitope-tagged ferroportin variants coupled with theoretical modeling to dissect the relationship between ferroportin mutations and their cognate phenotypes. Myc epitope-tagged human ferroportin expression constructs were transfected into Caco-2 intestinal cells and protein localization analyzed by immunofluorescence microscopy and colocalization with organelle markers. The effect of mutations on iron efflux was assessed by costaining with anti-ferritin antibodies and immunoblotting to quantitate cellular expression of ferritin and transferrin receptor 1. Wild-type ferroportin localized mainly to the cell surface and intracellular structures. All ferroportin disease-causing mutations studied had no effect on localization at the cell surface. N144H, N144T, and S338R mutant ferroportin retained the ability to transport iron. In contrast, A77D, V162Δ, and L170F mutants were iron transport defective. Surface staining experiments showed that both ends of the protein were located inside the cell. These data were used as the basis for theoretical modeling of the ferroportin molecule. The model predicted phenotypic clustering of mutations with gain-of-function variants associated with a hypothetical channel through the axis of ferroportin. Conversely, loss-of-function variants were located at the membrane/cytoplasm interface.
Blood pressure and renal blow flow responses in heme oxygenase-2 knockout mice
Authors: Stec David E. , Vera Trinity , Storm Megan V. , McLemore Gerald R. , Ryan Michael J.
Published: October 2009

Heme oxygenase (HO) is the enzyme responsible for the breakdown of heme-generating carbon monoxide (CO) and biliverdin in this process. HO-2 is the constitutively expressed isoform in most tissues, such as the kidney and vasculature. CO generated by HO is believed to be an important vasodilator in the renal circulation along with another gas, nitric oxide (NO). To determine the importance of HO-2 in the regulation of blood pressure and renal blood flow (RBF), we treated HO-2 knockout (KO) mice chronically with either ANG II or NG-nitroarginine methyl ester (l-NAME). Basal blood pressures were not different between wild-type (WT), heterozygous (HET), or KO mice and averaged 113 ± 3 vs. 115 ± 2 vs. 116 ± 2 mmHg. Similar increases in blood pressure to chronic ANG II as well as l-NAME treatment were observed in all groups with blood pressures increasing an average of 30 mmHg in response to ANG II and 15 mmHg in response to l-NAME. Basal RBFs were not different between the groups averaging 6.0 ± 0.5 ( n = 6) vs. 4.8 ± 0.6 ( n = 10) vs. 5.8 ± 0.7 ( n = 6) ml·min−1·g−1 kidney weight in WT, HET, and KO mice. HO-2 KO and HET mice exhibited an attenuated decrease in RBF in response to acute administration of ANG II, while no differences were observed with l-NAME. Our data indicate that blood pressure and RBF responses to increased ANG II or inhibition of nitric oxide are not significantly enhanced in HO-2 KO mice.
Size and conformation of Ficoll as determined by size-exclusion chromatography followed by multiangle light scattering
Authors: Fissell William H. , Hofmann Christina L. , Smith Ross , Chen Michelle H.
Published: October 2009

The characteristics of the glomerular filtration barrier (GFB) are challenging to measure, as macromolecular solutes in blood may be metabolized or transported by various cells in the kidney. Urinary solute concentrations generally reflect the cumulative influence of multiple transport processes rather than the intrinsic behavior of the GFB alone. Synthetic tracer molecules which are not secreted, absorbed, or modified by the kidney are useful tools. Ficoll, a globular polymer of epichlorohydrin and sucrose, is round, physiologically inert, and easily labeled, making it a nearly ideal glomerular probe. Fissell et al. reported filtration data suggesting that Ficoll was not as spherical as had been previously suggested (Fissell WH, Manley S, Dubnisheva A, Glass J, Magistrelli J, Eldridge AN, Fleischman AJ, Zydney AL, Roy S. Am J Physiol Renal Physiol 293: F1209–F1213, 2007). More recently, two investigators published comparisons of neutral and anionic Ficoll clearance that suggest Ficoll may undergo conformational changes when chemically derivatized (Asgeirsson D, Venturoli D, Rippe B, Rippe C. Am J Physiol Renal Physiol 291: F1083–F1089, 2006; Guimaraes MAM, Nikolovski J, Pratt LM, Greive K, Comper WD. Am J Physiol Renal Physiol 285: F1118–F1124, 2003). To investigate Ficoll's characteristics further, we examined two commercial preparations, Ficoll 70 and Ficoll 400, by size-exclusion chromatography using a differential refractive index detector combined with light-scattering and viscosity detectors. A slope of 0.45 was obtained from the plot of the logarithm of molecular mass against the logarithm of root-mean square radius. The Mark-Houwink exponent values of 0.34 and 0.36 were calculated for Ficoll 70 and Ficoll 400, respectively. These results suggest Ficoll's conformation in physiological saline solution is likely intermediate between a solid sphere and a well-solvated linear random coil. The measurements help explain our previous observations and guide interpretation of in vivo experiments.
Intrarenal mouse renin-angiotensin system during ANG II-induced hypertension and ACE inhibition
Authors: Gonzalez-Villalobos Romer A. , Satou Ryousuke , Ohashi Naro , Semprun-Prieto Laura C. , Katsurada Akemi , Kim Catherine , Upchurch G. M. , Prieto Minolfa C. , Kobori Hiroyuki , Navar L. Gabriel
Published: October 2009

Angiotensin-converting enzyme (ACE) inhibition (ACEi) ameliorates the development of hypertension and the intrarenal ANG II augmentation in ANG II-infused mice. To determine if these effects are associated with changes in the mouse intrarenal renin-angiotensin system, the expression of angiotensinogen (AGT), renin, ACE, angiotensin type 1 receptor (AT1R) mRNA (by quanitative RT-PCR) and protein [by Western blot (WB) and/or immunohistochemistry (IHC)] were analyzed. C57BL/6J male mice (9–12 wk old) were distributed as controls ( n = 10), ANG II infused (ANG II = 8, 400 ng·kg−1·min−1for 12 days), ACEi only (ACEi = 10, lisinopril, 100 mg/l), and ANG II infused + ACEi (ANG II + ACEi = 11). When compared with controls (1.00), AGT protein (by WB) was increased by ANG II (1.29 ± 0.13, P < 0.05), and this was not prevented by ACEi (ACEi + ANG II, 1.31 ± 0.14, P < 0.05). ACE protein (by WB) was increased by ANG II (1.21 ± 0.08, P < 0.05), and it was reduced by ACEi alone (0.88 ± 0.07, P < 0.05) or in combination with ANG II (0.80 ± 0.07, P < 0.05). AT1R protein (by WB) was increased by ANG II (1.27 ± 0.06, P < 0.05) and ACEi (1.17 ± 0.06, P < 0.05) but not ANG II + ACEi [1.15 ± 0.06, not significant (NS)]. Tubular renin protein (semiquantified by IHC) was increased by ANG II (1.49 ± 0.23, P < 0.05) and ACEi (1.57 ± 0.15, P < 0.05), but not ANG II + ACEi (1.10 ± 0.15, NS). No significant changes were observed in AGT, ACE, or AT1R mRNA. In summary, reduced responses of intrarenal tubular renin, ACE, and the AT1R protein to the stimulatory effects of chronic ANG II infusions, in the presence of ACEi, are associated with the effects of this treatment to ameliorate augmentations in blood pressure and intrarenal ANG II content during ANG II-induced hypertension.
Rap1 mediates protective effects of iloprost against ventilator-induced lung injury
Authors: Birukova Anna A. , Fu Panfeng , Xing Junjie , Birukov Konstantin G.
Published: October 2009

Prostaglandin I2 (PGI2) has been shown to attenuate vascular constriction, hyperpermeability, inflammation, and acute lung injury. However, molecular mechanisms of PGI2 protective effects on pulmonary endothelial cells (EC) are not well understood. We tested a role of cAMP-activated Epac-Rap1 pathway in the barrier protective effects of PGI2 analog iloprost in the murine model of ventilator-induced lung injury. Mice were treated with iloprost (2 μg/kg) after onset of high tidal volume ventilation (30 ml/kg, 4 h). Bronchoalveolar lavage, histological analysis, and measurements of Evans blue accumulation were performed. In vitro, microvascular EC barrier function was assessed by morphological analysis of agonist-induced gap formation and monitoring of Rho pathway activation and EC permeability. Iloprost reduced bronchoalveolar lavage protein content, neutrophil accumulation, capillary filtration coefficient, and Evans blue albumin extravasation caused by high tidal volume ventilation. Small-interfering RNA-based Rap1 knockdown inhibited protective effects of iloprost. In vitro, iloprost increased barrier properties of lung microvascular endothelium and alleviated thrombin-induced EC barrier disruption. In line with in vivo results, Rap1 depletion attenuated protective effects of iloprost in the thrombin model of EC permeability. These data describe for the first time protective effects for Rap1-dependent signaling against ventilator-induced lung injury and pulmonary endothelial barrier dysfunction.