bluuebunny/crossref_metadata_2025 huggingface dataset:
Low-Level Expression and Reversion both Contribute to Reactivation of Herpes Simplex Virus Drug-Resistant Mutants with Mutations on Homopolymeric Sequences in Thymidine Kinase
Authors: Griffiths Anthony , Link Malen A. , Furness Caroline L. , Coen Donald M.
Published: June 2006

Many acyclovir-resistant herpes simplex virus isolates from patients contain insertions or deletions in homopolymeric sequences in the thymidine kinase (TK) gene (
tk
). Viruses that have one (G8) or two (G9) base insertions in a run of seven G's (G string) synthesize low levels of active TK (TK-low phenotype), evidently via ribosomal frameshifting. These levels of TK can suffice to permit reactivation from latently infected mouse ganglia, but in a majority of ganglia, especially with the G9 virus, reactivation of virus that has reverted to the TK-positive phenotype predominates. To help address the relative contributions of translational mechanisms and reversion in reactivation, we generated viruses with a base either inserted or deleted just downstream of the G string. Both of these viruses had a TK-low phenotype similar to that of the G8 and G9 viruses but with less reversion. Both of these viruses reactivated from latently infected trigeminal ganglia, albeit inefficiently, and most viruses that reactivated had a uniformly TK-low phenotype. We also generated viruses that have one insertion in a run of six C's or one deletion in a run of five C's. These viruses lack measurable TK activity. However, they reactivated from latently infected ganglia, albeit inefficiently, with the reactivating viruses having reverted to the wild-type TK phenotype. Therefore, for G-string mutants, levels of active TK as low as 0.25% generated by translational mechanisms can suffice for reactivation, but reversion can also contribute. For viruses that lack TK activity due to mutations on other homopolymeric sequences, reactivation can occur via reversion.
X-Ray Structures of the N- and C-Terminal Domains of a Coronavirus Nucleocapsid Protein: Implications for Nucleocapsid Formation
Authors: Jayaram Hariharan , Fan Hui , Bowman Brian R. , Ooi Amy , Jayaram Jyothi , Collisson Ellen W. , Lescar Julien , Prasad B. V. Venkataram
Published: June 2006

Coronaviruses cause a variety of respiratory and enteric diseases in animals and humans including severe acute respiratory syndrome. In these enveloped viruses, the filamentous nucleocapsid is formed by the association of nucleocapsid (N) protein with single-stranded viral RNA. The N protein is a highly immunogenic phosphoprotein also implicated in viral genome replication and in modulating cell signaling pathways. We describe the structure of the two proteolytically resistant domains of the N protein from infectious bronchitis virus (IBV), a prototype coronavirus. These domains are located at its N- and C-terminal ends (NTD and CTD, respectively). The NTD of the IBV Gray strain at 1.3-Å resolution exhibits a U-shaped structure, with two arms rich in basic residues, providing a module for specific interaction with RNA. The CTD forms a tightly intertwined dimer with an intermolecular four-stranded central β-sheet platform flanked by α helices, indicating that the basic building block for coronavirus nucleocapsid formation is a dimeric assembly of N protein. The variety of quaternary arrangements of the NTD and CTD revealed by the analysis of the different crystal forms delineates possible interfaces that could be used for the formation of a flexible filamentous ribonucleocapsid. The striking similarity between the dimeric structure of CTD and the nucleocapsid-forming domain of a distantly related arterivirus indicates a conserved mechanism of nucleocapsid formation for these two viral families.
Visualization of Intracellular Transport of Vesicular Stomatitis Virus Nucleocapsids in Living Cells
Authors: Das Subash C. , Nayak Debasis , Zhou You , Pattnaik Asit K.
Published: June 2006

The phosphoprotein (P) of vesicular stomatitis virus (VSV) is a subunit of the viral RNA polymerase. In previous studies, we demonstrated that insertion of 19 amino acids in the hinge region of the protein had no significant effect on P protein function. In the present study, we inserted full-length enhanced green fluorescent protein (eGFP) in frame into the hinge region of P and show that the fusion protein (PeGFP) is functional in viral genome transcription and replication, albeit with reduced activity. A recombinant vesicular stomatitis virus encoding PeGFP in place of the P protein (VSV-PeGFP), which possessed reduced growth kinetics compared to the wild-type VSV, was recovered. Using the recombinant VSV-PeGFP, we show that the viral replication proteins and the de novo-synthesized RNA colocalize to sites throughout the cytoplasm, indicating that replication and transcription are not confined to any particular region of the cytoplasm. Real-time imaging of the cells infected with the eGFP-tagged virus revealed that, following synthesis, the nucleocapsids are transported toward the cell periphery via a microtubule (MT)-mediated process, and the nucleocapsids were seen to be closely associated with mitochondria. Treatment of cells with nocodazole or Colcemid, drugs known to inhibit MT polymerization, resulted in accumulation of the nucleocapsids around the nucleus and also led to inhibition of infectious-virus production. These findings are compatible with a model in which the progeny viral nucleocapsids are transported toward the cell periphery by MT and the transport may be facilitated by mitochondria.
Genetic Changes in Hepatitis Delta Virus from Acutely and Chronically Infected Woodchucks
Authors: Casey John L. , Tennant Bud C. , Gerin John L.
Published: June 2006

A woodchuck-derived hepatitis delta virus (HDV) inoculum was created by transfection of a genotype I HDV cDNA clone directly into the liver of a woodchuck that was chronically infected with woodchuck hepatitis virus. All woodchucks receiving this inoculum became positive for HDV RNA in serum, and 67% became chronically infected, similar to the rate of chronic HDV infection in humans. Analysis of HDV sequences obtained at 73 weeks postinfection indicated that changes had occurred at a rate of 0.5% per year; many of these modifications were consistent with editing by host RNA adenosine deaminase. The appearance of sequence changes, which were not evenly distributed on the genome, was correlated with the course of HDV infection. A limited number of modifications occurred in the consensus sequence of the viral genome that altered the sequence of the hepatitis delta antigen (HDAg). All chronically infected animals examined exhibited these changes 73 weeks following infection, but at earlier times, only one of the HDV carriers exhibited consensus sequence substitutions. On the other hand, sequence modifications in animals that eventually recovered from HDV infection were apparent after 27 weeks. The data are consistent with a model in which HDV sequence changes are selected by host immune responses. Chronic HDV infection in woodchucks may result from a delayed and weak immune response that is limited to a small number of epitopes on HDAg.
Simian Virus 40 Late Proteins Possess Lytic Properties That Render Them Capable of Permeabilizing Cellular Membranes
Authors: Daniels Robert , Rusan Nasser M. , Wilbuer Anne-Kathrin , Norkin Leonard C. , Wadsworth Patricia , Hebert Daniel N.
Published: June 2006

Many nonenveloped viruses have evolved an infectious cycle that culminates in the lysis or permeabilization of the host to enable viral release. How these viruses initiate the lytic event is largely unknown. Here, we demonstrated that the simian virus 40 progeny accumulated at the nuclear envelope prior to the permeabilization of the nuclear, endoplasmic reticulum, and plasma membranes at a time which corresponded with the release of the progeny. The permeabilization of these cellular membranes temporally correlated with late protein expression and was not observed upon the inhibition of their synthesis. To address whether one or more of the late proteins possessed an inherent capacity to induce membrane permeabilization, we examined the permeability of
Escherichia coli
that separately expressed the late proteins. VP2 and VP3, but not VP1, caused the permeabilization of bacterial membranes. Additionally, VP3 expression resulted in bacterial cell lysis. These findings demonstrate that VP3 possesses an inherent lytic property that is independent of eukaryotic signaling or cell death pathways.
Challenging the Role of Microtubules in
Tobacco Mosaic Virus
Movement by Drug Treatments Is Disputable
Authors: Seemanpillai Mark , Elamawi Rabab , Ritzenthaler Christophe , Heinlein Manfred
Published: June 2006

The movement protein (MP) of
Tobacco mosaic virus
interacts with microtubules during infection. Although this interaction is correlated with the function of MP in the cell-to-cell transport of viral RNA, a direct role of microtubules in the movement process was recently challenged by studies involving the treatment of plants with inhibitors of microtubule polymerization. Here, we report evidence suggesting that such treatments may not efficiently disrupt all microtubules. Thus, results obtained from studies using microtubule inhibitors may have to remain open to interpretation with regard to the involvement of microtubules in viral RNA trafficking.
Enhanced Baculovirus-Mediated Transduction of Human Cancer Cells by Tumor-Homing Peptides
Authors: Mäkelä Anna R. , Matilainen Heli , White Daniel J. , Ruoslahti Erkki , Oker-Blom Christian
Published: June 2006

Tumor cells and vasculature offer specific targets for the selective delivery of therapeutic genes. To achieve tumor-specific gene transfer, baculovirus tropism was manipulated by viral envelope modification using baculovirus display technology. LyP-1, F3, and CGKRK tumor-homing peptides, originally identified by in vivo screening of phage display libraries, were fused to the transmembrane anchor of vesicular stomatitis virus G protein and displayed on the baculoviral surface. The fusion proteins were successfully incorporated into budded virions, which showed two- to fivefold-improved binding to human breast carcinoma (MDA-MB-435) and hepatocarcinoma (HepG2) cells. The LyP-1 peptide inhibited viral binding to MDA-MB-435 cells with a greater magnitude and specificity than the CGKRK and F3 peptides. Maximal 7- and 24-fold increases in transduction, determined by transgene expression level, were achieved for the MDA-MB-435 and HepG2 cells, respectively. The internalization of each virus was inhibited by ammonium chloride treatment, suggesting the use of a similar endocytic entry route. The LyP-1 and F3 peptides showed an apparent inhibitory effect in transduction of HepG2 cells with the corresponding display viruses. Together, these results imply that the efficiency of baculovirus-mediated gene delivery can be significantly enhanced in vitro when tumor-targeting ligands are used and therefore highlight the potential of baculovirus vectors in cancer gene therapy.
Non-Macrophage-Tropic Human Immunodeficiency Virus Type 1 R5 Envelopes Predominate in Blood, Lymph Nodes, and Semen: Implications for Transmission and Pathogenesis
Authors: Peters Paul J. , Sullivan W. Matthew , Duenas-Decamp Maria J. , Bhattacharya Jayanta , Ankghuambom Chiambah , Brown Richard , Luzuriaga Katherine , Bell Jeanne , Simmonds Peter , Ball Jonathan , Clapham Paul R.
Published: June 2006

Human immunodeficiency virus type 1 (HIV-1) R5 isolates that predominantly use CCR5 as a coreceptor are frequently described as macrophage tropic. Here, we compare macrophage tropism conferred by HIV-1 R5 envelopes that were derived directly by PCR from patient tissue. This approach avoids potentially selective culture protocols used in virus isolation. Envelopes were amplified (i) from blood and semen of adult patients and (ii) from plasma of pediatric patients. The phenotypes of these envelopes were compared to those conferred by an extended panel of envelopes derived from brain and lymph node that we reported previously. Our results show that R5 envelopes vary by up to 1,000-fold in their capacity to confer infection of primary macrophages. Highly macrophage-tropic envelopes were predominate in brain but were infrequent in semen, blood, and lymph node samples. We also confirmed that the presence of N283 in the C2 CD4 binding site of gp120 is associated with HIV-1 envelopes from the brain but absent from macrophage-tropic envelopes amplified from blood and semen. Finally, we compared infection of macrophages, CD4+T cells, and peripheral blood mononuclear cells (PBMCs) conferred by macrophage-tropic and non-macrophage-tropic envelopes in the context of full-length replication competent viral clones. Non-macrophage-tropic envelopes conferred low-level infection of macrophages yet infected CD4+T cells and PBMCs as efficiently as highly macrophage-tropic brain envelopes. The lack of macrophage tropism for the majority of the envelopes amplified from lymph node, blood, and semen is striking and contrasts with the current consensus that R5 primary isolates are generally macrophage tropic. The extensive variation in R5 tropism reported here is likely to have an important impact on pathogenesis and on the capacity of HIV-1 to transmit.
Adenovirus RIDαβ Complex Inhibits Lipopolysaccharide Signaling without Altering TLR4 Cell Surface Expression
Authors: Delgado-Lopez Fernando , Horwitz Marshall S.
Published: June 2006

The transmembrane heterotrimer complex 10.4K/14.5K, also known as RID (for “receptor internalization and degradation”), is encoded by the adenovirus E3 region, and it down-regulates the cell surface expression of several unrelated receptors. We recently showed that RID expression correlates with down-regulation of the cell surface expression of the tumor necrosis factor (TNF) receptor 1 in several human cells. This observation provided the first mechanistic explanation for the inhibition of TNF alpha-induced chemokines by RID. Here we analyze the immunoregulatory activities of RID on lipopolysaccharide (LPS) and interleukin-1 beta (IL-1β)-mediated responses. Although both signaling pathways are strongly inhibited by RID, the chemokines up-regulated by IL-1β stimulation are only marginally inhibited. In addition, RID inhibits signaling induced by LPS without affecting the expression of the LPS receptor Toll-like receptor 4, demonstrating that RID need not target degradation of the receptor to alter signal transduction. Taken together, our data demonstrate the inhibitory effect of RID on two additional cell surface receptor-mediated signaling pathways involved in inflammatory processes. The data suggest that RID has intracellular targets that impair signal transduction and chemokine expression without evidence of receptor down-regulation.
Human Papillomavirus E7 Oncoprotein Dysregulates Steroid Receptor Coactivator 1 Localization and Function
Authors: Baldwin Amy , Huh Kyung-Won , Münger Karl
Published: June 2006

High-risk human papillomaviruses (HPVs) are present in virtually all cervical carcinomas. However, the majority of women infected with high-risk HPVs do not develop cervical cancer. Therefore, cofactors must contribute to the development and progression of cervical cancer. Although numerous studies have implicated steroid hormones as cofactors in the initiation and progression of cervical neoplasia, the molecular mechanisms by which they contribute to cervical carcinogenesis are currently unknown. These observations led us to investigate a newly discovered association of the high-risk HPV type 16 (HPV16) E7 oncoprotein with steroid receptor coactivator 1 (SRC-1), an essential component of steroid hormone signaling. HPV16 E7 has been previously reported to interact with p300 and p300/CBP-associated factor (PCAF), members of some SRC-1 transcriptional complexes. We demonstrate here that HPV16 E7 associates in vivo and in vitro with SRC-1 independently of p300 and PCAF. Luciferase reporter constructs under the control of either the interleukin-8 promoter or a promoter containing multimerized synthetic estrogen response elements were used to determine the effect of high- and low-risk HPV E7 expression on SRC-1-mediated transcription. In addition, histone acetyltransferase (HAT) assays were performed to determine the effect of HPV E7 on SRC-1-associated HAT activity. These experiments reveal that HPV16 E7 expression down-regulates SRC-1-mediated transcription and SRC-1-associated HAT activity. SRC-1 localization experiments show that SRC-1 is relocalized to the cytoplasm in the presence of high- and low-risk HPV E7 proteins. Our data suggest that HPV E7 proteins dysregulate hormone-dependent gene expression by association with and relocalization of SRC-1. Dysregulation of SRC-1 localization and function by HPV E7 may provide insight into the molecular mechanisms by which steroid hormones act as cofactors in the induction and progression of cervical neoplasia.
Severe Papillomavirus Infection Progressing to Metastatic Squamous Cell Carcinoma in Bone Marrow-Transplanted X-Linked SCID Dogs
Authors: Goldschmidt Michael H. , Kennedy Jeffrey S. , Kennedy Douglas R. , Yuan Hang , Holt David E. , Casal Margret L. , Traas Anne M. , Mauldin Elizabeth A. , Moore Peter F. , Henthorn Paula S. , Hartnett Brian J. , Weinberg Kenneth I. , Schlegel Richard , Felsburg Peter J.
Published: June 2006

Canine X-linked severe combined immunodeficiency (XSCID) is due to mutations in the common gamma chain (γc) gene and is identical clinically and immunologically to human XSCID, making it a true homologue of the human disease. Bone marrow-transplanted (BMT) XSCID dogs not only engraft donor T cells and reconstitute normal T-cell function but, in contrast to the majority of transplanted human XSCID patients, also engraft donor B cells and reconstitute normal humoral immune function. Shortly after our initial report of successful BMT of XSCID dogs, it soon became evident that transplanted XSCID dogs developed late-onset severe chronic cutaneous infections containing a newly described canine papillomavirus. This is analogous to the late-onset cutaneous papillomavirus infection recently described for human XSCID patients following BMT. Of 24 transplanted XSCID dogs followed for at least 1 year post-BMT, 71% developed chronic canine papillomavirus infection. Six of the transplanted dogs that developed cutaneous papillomas were maintained for >3 1/2 years post-BMT for use as breeders. Four of these six dogs (67%) developed invasive squamous cell carcinoma (SCC), with three of the dogs (75%) eventually developing metastatic SCC, an extremely rare consequence of SCC in the dog. This finding raises the question of whether SCC will develop in transplanted human XSCID patients later in life. Canine XSCID therefore provides an ideal animal model with which to study the role of the γc-dependent signaling pathway in the response to papillomavirus infections and the progression of these viral infections to metastatic SCC.
Role of Maternal Autologous Neutralizing Antibody in Selective Perinatal Transmission of Human Immunodeficiency Virus Type 1 Escape Variants
Authors: Dickover Ruth , Garratty Eileen , Yusim Karina , Miller Catherine , Korber Bette , Bryson Yvonne
Published: June 2006

Perinatal human immunodeficiency virus type 1 (HIV-1) transmission is characterized by acquisition of a homogeneous viral quasispecies, yet the selective factors responsible for this genetic bottleneck are unclear. We examined the role of maternal autologous neutralizing antibody (aNAB) in selective transmission of HIV-1 escape variants to infants. Maternal sera from 38 infected mothers at the time of delivery were assayed for autologous neutralizing antibody activity against maternal time-of-delivery HIV-1 isolates in vitro. Maternal sera were also tested for cross-neutralization of infected-infant-first-positive-time-point viral isolates. Heteroduplex and DNA sequence analyses were then performed to identify the initial infecting virus as a neutralization-sensitive or escape HIV-1 variant. In utero transmitters (
n
= 14) were significantly less likely to have aNAB to their own HIV-1 strains at delivery than nontransmitting mothers (
n
= 17, 14.3% versus 76.5%,
P
= 0.003). Cross-neutralization assays of infected-infant-first-positive-time-point HIV-1 isolates indicated that while 14/21 HIV-1-infected infant first positive time point isolates were resistant to their own mother's aNAB, no infant isolate was inherently resistant to antibody neutralization by all sera tested. Furthermore, both heteroduplex (
n
= 21) and phylogenetic (
n
= 9) analyses showed that selective perinatal transmission and/or outgrowth of maternal autologous neutralization escape HIV-1 variants occurs in utero and intrapartum. These data indicate that maternal autologous neutralizing antibody can exert powerful protective and selective effects in perinatal HIV-1 transmission and therefore has important implications for vaccine development.
Implementation of the 2005 Coroners Rules Amendments: a survey of practice in England and Wales: Table 1
Authors: Delaney Russell J , Roberts Ian S D
Published: June 2006

Background:On 1 June 2005, amendments to the Coroners Rules 1984 were introduced in England and Wales. These principally cover the retention of tissues from autopsies and their subsequent disposal. This study assesses regional variations in the interpretations of the amendments, and their impact on local autopsy practice in Oxford.

Methods:A questionnaire was circulated to pathologists in 120 coronial jurisdictions, addressing conditions under which histological material could be retained. A local review of autopsy practice was conducted before and after the introduction of the amendments.

Results:Questionnaires were returned from 71 coronial jurisdictions. 35 (49%) coroners provided written guidelines on their interpretation of the amendments. In 52 (73%) jurisdictions, pathologists are authorised to retain material to confirm/refine causes of death from natural causes. In 77% of jurisdictions, coroner’s officers are responsible for obtaining instructions from the next of kin on subsequent retention, use or disposal of retained tissues. In Oxford, there has been a reduction in the proportion of cases in which histology is taken, but an increase in the proportion of cases in which a histology report is issued.

Conclusions:There is considerable regional variation in the interpretation of the 2005 Coroners Rules Amendments. These variations have potentially important implications for clinical practice.
Nasal polyposis in Peutz–Jeghers syndrome: a distinct histopathological and molecular genetic entity
Authors: de Leng Wendy W J , Westerman Anne Marie , Weterman Marian A J , Jansen Marnix , van Dekken Herman , Giardiello Francis M , de Rooij Felix W M , Paul Wilson J H , Offerhaus G Johan A , Keller Josbert J
Published: June 2006

Background:Peutz–Jeghers syndrome (PJS) is an autosomal dominant hamartomatous polyposis syndrome of the gastrointestinal tract, caused by a germlineSTK11/LKB1mutation. Nasal polyposis was described in the original report by Peutz. Recently, a molecular–genetic association between nasal polyposis and PJS has been reported.

Objective:To further explore the occurrence and pathogenesis of PJS-related nasal polyposis.

Methods:51 patients with PJS, 84 unaffected family members and 36 spouses from 18 families with PJS were questioned for the presence of nasal polyposis. 12 PJS-related nasal polyps, 1 carcinoma of the nasal cavity and 28 sporadic nasal polyps were analysed for loss of (wild type)STK11/LKB1, eosinophilia, squamous metaplasia, dysplasia and expression of cyclo-oxygenase 2 and p53.

Results:Nasal polyps occurred in 8 of 51 patients with PJS, and were not reported by non-affected family members (p<0.001). GermlineSTK11/LKB1mutations were identified in all patients with PJS and nasal polyposis. Loss of heterozygosity was found in four of eight PJS-related nasal polyps, but not in sporadic nasal polyps (p = 0.002). PJS-related nasal polyps showed less eosinophilia than sporadic nasal polyps (p<0.001). Expression of cyclo-oxygenase 2 was found in 11 of 12 PJS-related nasal polyps and 19 of 28 sporadic nasal polyps (p>0.05). Overexpression of p53 was not found.

Conclusions:Nasal polyposis occurs in a significant number of Dutch patients with PJS, one of whom developed a carcinoma in the nasal cavity. The loss of heterozygosity, and the absence of eosinophilia suggest a distinct pathogenesis compared with sporadic nasal polyposis.
Immunohistochemical analysis of low-grade and high-grade prostate carcinoma: relative changes of parathyroid hormone-related protein and its parathyroid hormone 1 receptor, osteoprotegerin and receptor activator of nuclear factor-kB ligand
Authors: Pérez-Martínez Francisco C , Alonso Verónica , Sarasa José L , Nam-Cha Syon-Ghyun , Vela-Navarrete Remigio , Manzarbeitia Félix , Calahorra Francisco J , Esbrit Pedro
Published: June 2006

Aim:To investigate multiple bone cytokines produced by prostate carcinoma (PCa) as a novel strategy to differentiate potential aggressiveness in localised PCa using immunohistochemical analysis.

Methods:A total of 47 cases of PCa undergoing radical prostatectomy or transurethral prostatic resection at our institution (Fundación Jiménez Díaz (Grupo Capio), Madrid, Spain) between January 1991 and June 1998 were identified as low-grade (⩽4; n = 22) or high-grade (⩾7, excluding 7 (3+4) cases; n = 25) PCa according to Gleason grade. PCa specimens were immunostained for: parathyroid hormone (PTH)-related protein (PTHrP), the PTH1 receptor, osteoprotegerin and receptor activator of nuclear factor-κ B ligand (RANKL), as well as Ki67 (a proliferation marker) and CD34 (an angiogenesis marker).

Results:PCa samples showed an increased immunostaining for both osteoprotegerin and RANKL, associated with tumour grade and PTHrP positivity, in the tumoral epithelium. Using a score value of 4—corresponding to moderate staining—as cut-off, the best sensitivity value was for PTHrP (with C-terminal antiserum C6; 100 %); wheras the best specificity value was for RANKL (95 %).

Conclusions:All the evaluated factors are overexpressed mainly in the high-grade tumours. Our findings indicate that, in most patients with PCa (with Ki67 values between 1% and 9%), sequential determination of C-terminal PTHrP and RANKL immunoreactivities is a useful approach to discriminate low-grade and high-grade tumours.
MEMORY BOOSTS COOPERATION
Authors: ALONSO-SANZ RAMÓN , MARTÍN MARGARITA
Published: June 2006

The standard spatial formulation of the iterated Prisoner's Dilemma is ahistoric (memoryless): i.e., only the results generated in the last round are taken into account in deciding the next choice. Historic memory can be implemented by featuring players by a summary of their previous winnigs and choices. Here we study the effect of limited trailing memory: only the last three iterations are recorded. The effects of full and discounted memory are assessed. It is concluded that this short-type memory stimulates cooperation.
LATTICE BOLTZMANN SIMULATION ON NATURAL CONVECTION HEAT TRANSFER IN A TWO-DIMENSIONAL CAVITY FILLED WITH HETEROGENEOUSLY POROUS MEDIUM
Authors: YAN WEI-WEI , LIU YANG , GUO ZHAO-LI , XU YOU-SHENG
Published: June 2006

The natural convection problem in a square cavity filled with heterogeneously porous medium is solved by lattice Boltzmann method. The temperature distribution is fully coupled with the fluid velocity through relaxation time. The present calculated results are in good agreement with available published data. It is found that the porosity of porous media near the walls has significant influence on the heat transfer, and the porosity of middle porous medium has little influence on the natural convection. It is of particular interest for thermal management in electronic packages, since it can reduce the space of air.
FLUCTUATIONS, ENVIRONMENT, MUTATIONS ACCUMULATION AND AGEING
Authors: BIECEK PRZEMYSŁAW , CEBRAT STANISŁAW
Published: June 2006

We present a model of evolution of the age structured population based on the Monte Carlo method. We have assumed that the health status of an individual is described by variance of its fluctuations. Each expressed deleterious mutation increases the fluctuations. Additionally, the fluctuations of the environment are superimposed on the fluctuations of individuals in the population. An individual dies if the combination of both stochastic processes trespass the limit (level of homeostasis) set as the model parameter.

The genes are switched on chronologically, what leads to accumulating defective genes expressed during the late periods of life in the genetic pool of the population. That results in the specific age structured population, in accordance with the predictions of Medawar's hypothesis of ageing and the results of the Penna model simulations. A decrease of the variation of the environmental noise increases the average expected lifespan of individuals.
The Crime Drop and Beyond
Authors: Blumstein Alfred , Wallman Joel
Published: June 2006

▪ Abstract  Violent crime in the United States has traveled a striking path in the past 20 years, from a sharp spike in the late 1980s to a dramatic drop beginning around 1993 that lasted until a flattening occurred at the beginning of the new century. The upturn of the 1980s was driven almost exclusively by a sharp increase in gun violence among young people, whereas the downturn was a joint product of a turndown in youth violence and a steady drop in violence among adults over 30 that has been ongoing for at least 25 years. These trends have intrigued lay observers and students of crime alike, with advocates of various explanations of crime arguing that the key for the rise, fall, or both lies with one or another favored determinant: prisons, drugs, guns, policing, economics, or demography, including abortion. In this review, we discuss both the crime trends and their candidate explanations, concluding that the most reasonable accounts involve a complex interaction among several of these factors.
Measurement of mouse vascular smooth muscle and atheroma cell proliferation by 2H2O incorporation into DNA
Authors: Chu Alice , Ordonez Eric T. , Hellerstein Marc K.
Published: June 2006

Vascular smooth muscle cell (VSMC) and leukocyte proliferation are central features of atherosclerosis. Using 2H2O to label the deoxyribose moiety of newly synthesized DNA in VSMC and atheroma cells from mouse aorta, we developed a method to measure DNA replication and, hence, cell division. Cell turnover/proliferation in aortae from normal and apolipoprotein E (ApoE)-knockout ( ApoE−/−) mice was measured. Mice were injected with 2H2O to achieve 2% body water enrichments and then maintained on 4% 2H2O in drinking water for weeks to months. DNA from the intimal-medial layer of the aorta was extracted and hydrolyzed to deoxyribonucleosides. Purified deoxyadenosine was derivatized to pentane tetraacetate for analysis of 2H enrichment by gas chromatography-mass spectrometry. VSMC proliferation was measurable but slow in adult mice (0.12 ± 0.08%/day) and higher in young mice (0.25 ± 0.08%/day). VSMC delabeling revealed that 2H died away slowly in VSMC DNA, confirming the low turnover rate. Atheroma cell proliferation was elevated in ApoE−/− mice fed low- or high-fat diets for 15 wk, concurrent with histological appearance of atherosclerosis. Validation of the method for VSMC was confirmed by comparison of in vitro rat VSMC proliferation rates using 2H2O with cell counts and bromodeoxyuridine proliferative index. In summary, proliferation of VSMC and atheroma cells can be quantified reliably and sensitively without radioactivity and may be an informative biomarker in vascular hyperplastic diseases, including atherosclerosis.
Differential Controls Over Tactile Detection in Humans by Motor Commands and Peripheral Reafference
Authors: Chapman C. Elaine , Beauchamp Evelyne
Published: June 2006

The purpose of this study was to determine the extent to which motor commands and peripheral reafference differentially control the detection of near-threshold, tactile stimuli. Detection of weak electrical stimuli applied to the index finger (D2) was evaluated with two bias-free measures of sensory detection, the index of detectability ( d′) and the proportion of stimuli detected. Stimuli were presented at different delays prior to and during two motor tasks, D2 abduction, and elbow extension; both tasks were tested in two modes, active and passive. For both active tasks, the peak decrease in tactile suppression occurred at the onset of electromyographic activity. The time course for the suppression of detection during active and passive D2 abduction was identical, and preceded the onset of movement (respectively, −35 and −47 ms). These results suggest that movement reafference alone, acting through a mechanism of backward masking, could explain the modulation seen with D2 movement. In contrast, tactile suppression was significantly earlier for active elbow movements (−59 ms) as compared with passive (−21 ms), an observation consistent with both the motor command and peripheral reafference contributing to the suppression of detection of stimuli applied to D2 during movements about a proximal joint. A role for the motor command in tactile gating during distal movements cannot be discounted, however, because differences in the strength and distribution of the peripheral reafference may also have contributed to the proximo-distal differences in the timing of the suppression.
Functional Consequences of Presynaptic Inhibition During Behaviorally Relevant Activity
Authors: Frerking M. , Ohliger-Frerking P.
Published: June 2006

Presynaptic inhibition is a widespread mechanism for regulating transmitter release in the CNS. Presynaptic inhibitors act as a high-pass filter, but the functional consequence of this filtering during the synaptic processing of behaviorally relevant activity remains unknown. Here we use analytical approaches to examine the effects of presynaptic inhibition on synaptic output in response to activity patterns from CA3 pyramidal cells during the performance of a complex behavioral task. We calculate that presynaptic inhibition enhances the contrast between background activity and responses to environmental cues and that neuronal responses to location are subject to stronger contrast enhancement than neuronal responses to olfactory information. Our analysis suggests that presynaptic inhibition also enhances the importance of integrative inputs that respond to many behavioral cues during the task at the expense of specific inputs that respond to only a few of these cues.
Natural Neural Output That Produces Highly Variable Locomotory Movements
Authors: Hooper Scott L. , Guschlbauer Christoph , von Uckermann Géraldine , Büschges Ansgar
Published: June 2006

We recorded fast extensor tibiae motor neuron activity during single-legged treadmill walking in the stick insect, Carausius morosus. We used this activity to stimulate the extensor muscle motor nerve, observed the resulting extensor muscle contractions under isotonic conditions, and quantified these contractions with a variety of measures. Extensor contractions induced in this manner were highly variable, with contraction measures having SDs of 12 to 51%, and ranges of 82 to 275%, when expressed as percentages of the means, an unexpectedly wide range for a locomotory pattern. Searches for correlations among the contraction measures showed that, in general, this high variability is not reduced by contraction measure covariation. Comparing responses (to identical input) across animals showed that extensor muscles from different animals generally significantly differed from one another. However, correlation analyses on these data suggested that these differences do not indicate that multiple extensor muscle subtypes exist. Extensor muscles instead appear to belong to a single class, albeit one with high animal to animal variability. These data thus provide another well-quantified example (along with Aplysia feeding) of a repetitive but highly variable motor pattern (in contrast to the high rhythmicity and stereotypy present in most other well-quantified repetitive motor patterns). We suggest this high variability could be an adaptive combination of locomotion, active sensing, and crypsis arising from the relatively low demand for locomotion in Carausius behavior, the highly fragmented environment the animal inhabits, and its need to avoid predatory attention.
The ERBB4/HER4 Intracellular Domain 4ICD Is a BH3-Only Protein Promoting Apoptosis of Breast Cancer Cells
Authors: Naresh Anjali , Long Weiwen , Vidal Gregory A. , Wimley William C. , Marrero Luis , Sartor Carolyn I. , Tovey Sian , Cooke Timothy G. , Bartlett John M.S. , Jones Frank E.
Published: June 2006

ERBB4/HER4 (referred to here as ERBB4) is a unique member of the epidermal growth factor receptor (EGFR) family of receptor tyrosine kinases. In contrast to the other three members of the EGFR family (i.e., EGFR, ERBB2/HER2/NEU, and ERBB3), which are associated with aggressive forms of human cancers, ERBB4 expression seems to be selectively lost in tumors with aggressive phenotypes. Consistent with this observation, we show that ERBB4 induces apoptosis when reintroduced into breast cancer cell lines or when endogenous ERBB4 is activated by a ligand. We further show that ligand activation and subsequent proteolytic processing of endogenous ERBB4 results in mitochondrial accumulation of the ERBB4 intracellular domain (4ICD) and cytochrome c efflux, the essential and committed step of mitochondrial regulated apoptosis. Our results indicate that 4ICD is functionally similar to BH3-only proteins, proapoptotic members of the BCL-2 family required for initiation of mitochondrial dysfunction through activation of the proapoptotic multi-BH domain proteins BAX/BAK. Similar to other BH3-only proteins, 4ICD cell-killing activity requires an intact BH3 domain and 4ICD interaction with the antiapoptotic protein BCL-2, suppressed 4ICD-induced apoptosis. Unique among BH3-only proteins, however, is the essential requirement of BAK but not BAX to transmit the 4ICD apoptotic signal. Clinically, cytosolic but not membrane ERBB4/4ICD expression in primary human breast tumors was associated with tumor apoptosis, providing a mechanistic explanation for the loss of ERBB4 expression during tumor progression. Thus, we propose that ligand-induced mitochondrial accumulation of 4ICD represents a unique mechanism of action for transmembrane receptors, directly coupling a cell surface signal to the tumor cell mitochondrial apoptotic pathway. (Cancer Res 2006; 66(12): 6412-20)
Role of Hypoxia-Inducible Factor (HIF)-1α versus HIF-2α in the Regulation of HIF Target Genes in Response to Hypoxia, Insulin-Like Growth Factor-I, or Loss of von Hippel-Lindau Function: Implications for Targeting the HIF Pathway
Authors: Carroll Veronica A. , Ashcroft Margaret
Published: June 2006

Overexpression of hypoxia-inducible factors (HIF), HIF-1α and HIF-2α, leads to the up-regulation of genes involved in proliferation, angiogenesis, and glucose metabolism and is associated with tumor progression in several cancers. However, the contribution of HIF-1α versus HIF-2α to vascular endothelial growth factor (VEGF) expression and other HIF-regulated target genes under different conditions is unclear. To address this, we used small interfering RNA (siRNA) techniques to knockdown HIF-1α and/or HIF-2α expression in response to hypoxia, insulin-like growth factor (IGF)-I, or renal carcinoma cells expressing constitutively high basal levels of HIF-1α and/or HIF-2α due to loss of von Hippel-Lindau (VHL) function. We found that HIF-1α primarily regulates transcriptional activation of VEGF in response to hypoxia and IGF-I compared with HIF-2α in MCF-7 cells. We also observed a reciprocal relationship between HIF-1α and HIF-2α expression in hypoxia in these cells: HIF-2α siRNA enhanced HIF-1α–mediated VEGF expression in MCF-7 cells in response to hypoxia, which could be completely blocked by cotransfection with HIF-1α siRNA. In contrast, in renal carcinoma cells that constitutively express HIF-1α and HIF-2α due to loss of VHL function, we found that high basal VEGF, glucose transporter-1, urokinase-type plasminogen activator receptor, and plasminogen activator inhibitor-1 expression was predominantly dependent on HIF-2α. Finally, we showed that a newly identified small-molecule inhibitor of HIF-1, NSC-134754, is also able to significantly decrease HIF-2α protein expression and HIF-2α–regulated VEGF levels in renal carcinoma cells. Our data have important implications for how we target the HIF pathway therapeutically. (Cancer Res 2006; 66(12): 6264-70)
HSulf-1 Inhibits Angiogenesis and Tumorigenesis In vivo
Authors: Narita Keishi , Staub Julie , Chien Jeremy , Meyer Kristy , Bauer Maret , Friedl Andreas , Ramakrishnan Sundaram , Shridhar Viji
Published: June 2006

We previously identified HSulf-1 as a down-regulated gene in several tumor types including ovarian, breast, and hepatocellular carcinomas. Loss of HSulf-1, which selectively removes 6-O-sulfate from heparan sulfate, up-regulates heparin-binding growth factor signaling and confers resistance to chemotherapy-induced apoptosis. Here we report that HSulf-1 expression in MDA-MB-468 breast carcinoma clonal lines leads to reduced proliferation in vitro and reduced tumor burden in athymic nude mice in vivo. Additionally, xenografts derived from HSulf-1–expressing stable clones of carcinoma cells showed reduced vessel density, marked necrosis, and apoptosis, indicative of inhibition of angiogenesis. Consistent with this observation, HSulf-1–expressing clonal lines showed reduced staining with the endothelial marker CD31 in Matrigel plug assay, indicating that HSulf-1 expression inhibits angiogenesis. More importantly, HSulf-1 expression in the xenografts was associated with a reduced ability of vascular endothelial cell heparan sulfate to participate in a complex with fibroblast growth factor 2 (FGF-2) and its receptor tyrosine kinase FGF receptor 1c. In vitro, short hairpin RNA–mediated down-regulation of HSulf-1 in human umbilical vein endothelial cells (HUVEC) resulted in an increased proliferation mediated by heparan sulfate–dependent FGF-2, hepatocyte growth factor, and vascular endothelial growth factor 165 (VEGF165) but not by heparan sulfate–independent VEGF121. HSulf-1 down-regulation also enhanced downstream signaling through the extracellular signal–regulated kinase pathway compared with untreated cells. Consistent with the role of heparan sulfate glycosaminoglycan sulfation in VEGF-mediated signaling, treatment of HUVEC cells with chlorate, which inhibits heparan sulfate glycosaminoglycan sulfation and therefore mimics HSulf-1 overexpression, led to an attenuated VEGF-mediated signaling. Collectively, these observations provide the first evidence of a novel mechanism by which HSulf-1 modulates the function of heparan sulfate binding VEGF165 in proliferation and angiogenesis. (Cancer Res 2006; 66(12): 6025-32)
Hydrogen Peroxide Produced by Angiopoietin-1 Mediates Angiogenesis
Authors: Kim Young Mee , Kim Kyung Eun , Koh Gou Young , Ho Ye-Shih , Lee Kong-Joo
Published: June 2006

Angiopoietin-1 (Ang1) mediates angiogenesis by enhancing endothelial cell survival and migration. It is also known that Ang1 activates Tie2, an endothelial-specific tyrosine kinase receptor, but the molecular mechanism of this process is not clear. In this study, we investigated whether reactive oxygen species (ROS) production plays a role in Ang1-mediated angiogenesis. We found that human umbilical vein endothelial cells treated with Ang1 produce ROS transiently, which was suppressed by NADPH oxidase inhibitor, diphenylene-iodonium chloride, and rotenone. The Ang1-induced ROS was identified as hydrogen peroxide (H2O2) using adenovirus-catalase infection. Removal of H2O2 by adenovirus-catalase significantly suppressed Ang1-induced in vitro endothelial cell migration, in vivo tubule formation and angiogenesis, and activation of p44/42 mitogen-activated protein kinase (MAPK), involved in cell migration, and delayed the deactivation of Akt phosphorylation involved in cell survival. Supporting to in vitro data, Ang1-induced vascular remodeling in catalase (−/−) mice was more prominent than in catalase (+/+) mice: Ang1-induced increases of the diameter of terminal arterioles and the postcapillary venules in catalase (−/−) mice were significant compared with catalase (+/+) mice. These results show that Ang1-induced H2O2 plays an important role in Ang1-mediated angiogenesis by modulating p44/42 MAPK activity. (Cancer Res 2006; 66(12): 6167-74)
Interleukin-23 and Interleukin-27 Exert Quite Different Antitumor and Vaccine Effects on Poorly Immunogenic Melanoma
Authors: Oniki Shuntaro , Nagai Hiroshi , Horikawa Tatsuya , Furukawa Junya , Belladonna Maria Laura , Yoshimoto Takayuki , Hara Isao , Nishigori Chikako
Published: June 2006

Recent studies revealed that two novel interleukin (IL)-12-related cytokines, IL-23 and IL-27, have potent antitumor activities. However, the antitumor effects were mainly evaluated in relatively highly immunogenic tumors and have not been fully evaluated against nonimmunogenic or poorly immunogenic tumors. In this study, we investigated the antitumor efficacies of IL-23 and IL-27 on poorly immunogenic B16F10 melanoma and found that the antitumor responses mediated by IL-23 and IL-27 were clearly different. In syngeneic mice, mouse single-chain (sc) IL-23-transfected B16F10 (B16/IL-23) tumors exhibited almost the same growth curve as B16F10 parental tumor about until day 20 after tumor injection and then showed growth inhibition or even regression. In contrast, scIL-27-transfected B16F10 (B16/IL-27) tumors exhibited significant retardation of tumor growth from the early stage. In vivo depletion assay revealed that the antitumor effect of B16/IL-23 was mainly mediated by CD8+ T cells and IFN-γ whereas that of B16/IL-27 mainly involved natural killer cells and was independent of IFN-γ. We also found that antitumor effects of B16/IL-23 and B16/IL-27 were synergistically enhanced by treatment with IL-18 and IL-12, respectively. Furthermore, B16/IL-23-vaccinated mice developed protective immunity against parental B16F10 tumors but B16/IL-27-vaccinated mice did not. When combined with prior in vivo depletion of CD25+ T cells, 80% of B16/IL-23-vaccinated mice completely rejected subsequent tumor challenge. Finally, we showed that the systemic administration of neither IL-23 nor IL-27 induced such intense toxicity as IL-12. Our data support that IL-23 and IL-27 might play a role in future cytokine-based immunotherapy against poorly immunogenic tumors. (Cancer Res 2006; 66(12): 6395-404)