bluuebunny/crossref_metadata_2025_split huggingface dataset:
CCR5, CXCR4, and CD4 Are Clustered and Closely Apposed on Microvilli of Human Macrophages and T Cells
Authors: Singer Irwin I. , Scott Solomon , Kawka Douglas W. , Chin Jayne , Daugherty Bruce L. , DeMartino Julie A. , DiSalvo Jerry , Gould Sandra L. , Lineberger Janet E. , Malkowitz Lorraine , Miller Michael D. , Mitnaul Lyndon , Siciliano Salvatore J. , Staruch Mary Jo , Williams Hollis R. , Zweerink Hans J. , Springer Martin S. 
Published: July 2002

ABSTRACTThe chemokine receptors CCR5 and CXCR4 act synergistically with CD4 in an ordered multistep mechanism to allow the binding and entry of human immunodeficiency virus type 1 (HIV-1). The efficiency of such a coordinated mechanism depends on the spatial distribution of the participating molecules on the cell surface. Immunoelectron microscopy was performed to address the subcellular localization of the chemokine receptors and CD4 at high resolution. Cells were fixed, cryoprocessed, and frozen; 80-nm cryosections were double labeled with combinations of CCR5, CXCR4, and CD4 antibodies and then stained with immunogold. Surprisingly, CCR5, CXCR4, and CD4 were found predominantly on microvilli and appeared to form homogeneous microclusters in all cell types examined, including macrophages and T cells. Further, while mixed microclusters were not observed, homogeneous microclusters of CD4 and the chemokine receptors were frequently separated by distances less than the diameter of an HIV-1 virion. Such distributions are likely to facilitate cooperative interactions with HIV-1 during virus adsorption to and penetration of human leukocytes and have significant implications for development of therapeutically useful inhibitors of the entry process. Although the mechanism underlying clustering is not understood, clusters were observed in smalltrans-Golgi vesicles, implying that they were organized shortly after synthesis and well before insertion into the cellular membrane. Chemokine receptors normally act as sensors, detecting concentration gradients of their ligands and thus providing directional information for cellular migration during both normal homeostasis and inflammatory responses. Localization of these sensors on the microvilli should enable more precise monitoring of their environment, improving efficiency of the chemotactic process. Moreover, since selectins, some integrins, and actin are also located on or in the microvillus, this organelle has many of the major elements required for chemotaxis.
Nef-Induced CD4 Downregulation: a Diacidic Sequence in Human Immunodeficiency Virus Type 1 Nef Does Not Function as a Protein Sorting Motif through Direct Binding to β-COP
Authors: Janvier K. , Craig H. , Le Gall S. , Benarous R. , Guatelli J. , Schwartz O. , Benichou S. 
Published: July 2002

ABSTRACT
The Nef protein from the human immunodeficiency virus (HIV) induces CD4 cell surface downregulation by interfering with the endocytic machinery. It has been recently proposed that binding of HIV type 1 Nef to the β subunit of COPI coatomers participated in the Nef-induced CD4 downregulation through recognition of a novel diacidic motif found in the C-terminal disordered loop of Nef (V. Piguet, F. Gu, M. Foti, N. Demaurex, J. Gruenberg, J. L. Carpentier, and D. Trono, Cell 97:63–73, 1999). We have mutated the glutamate residues which formed this motif in order to document this observation. Surprisingly, mutation of the diacidic sequence of Nef did not significantly affect its ability (i) to interact with β-COP, (ii) to downregulate CD4 cell surface expression, and (iii) to address an integral resident membrane protein containing Nef as the cytoplasmic domain to the endocytic pathway. Our results indicate that these acidic residues are not involved in the connection of Nef with the endocytic machinery through binding to β-COP. Additional studies are thus required to characterize the residues of Nef involved in the binding to β-COP and to evaluate the contribution of this interaction to the Nef-induced perturbations of membrane trafficking.
Protective Cross-Reactive Cellular Immunity to Lethal A/Goose/Guangdong/1/96-Like H5N1 Influenza Virus Is Correlated with the Proportion of Pulmonary CD8+T Cells Expressing Gamma Interferon
Authors: Seo Sang Heui , Peiris Malik , Webster Robert G. 
Published: July 2002

ABSTRACTA/Goose/Guangdong/1/96-like H5N1 influenza viruses now circulating in southeastern China differ genetically from the H5N1 viruses transmitted to humans in 1997 but were their precursors. Here we show that the currently circulating H9N2 influenza viruses provide chickens with cross-reactive protective immunity against the currently circulating H5N1 influenza viruses and that this protective immunity is closely related to the percentage of pulmonary CD8+T cells expressing gamma interferon (IFN-γ). In vivo depletion of T-cell subsets showed that the cross-reactive immunity was mediated by T cells bearing CD8+and T-cell receptor (TCR) α/β and that the Vβ1 subset of TCR α/β T cells had a dominant role in protective immunity. The protective immunity induced by infection with H9N2 virus declined with time, lasting as long as 100 days after immunization. Shedding of A/Goose/Guangdong/1/96-like H5N1 virus by immunized chickens also increased with the passage of time and thus may play a role in the perpetuation and spread of these highly pathogenic H5N1 influenza viruses. Our findings indicate that pulmonary cellular immunity may be very important in protecting naïve natural hosts against lethal influenza viruses.
The Genomes of Sheeppox and Goatpox Viruses
Authors: Tulman E. R. , Afonso C. L. , Lu Z. , Zsak L. , Sur J.-H. , Sandybaev N. T. , Kerembekova U. Z. , Zaitsev V. L. , Kutish G. F. , Rock D. L. 
Published: July 2002

ABSTRACT

Sheeppox virus (SPPV) and goatpox virus (GTPV), members of the
Capripoxvirus
genus of the
Poxviridae
, are etiologic agents of important diseases of sheep and goats in northern and central Africa, southwest and central Asia, and the Indian subcontinent. Here we report the genomic sequence and comparative analysis of five SPPV and GTPV isolates, including three pathogenic field isolates and two attenuated vaccine viruses. SPPV and GTPV genomes are approximately 150 kbp and are strikingly similar to each other, exhibiting 96% nucleotide identity over their entire length. Wild-type genomes share at least 147 putative genes, including conserved poxvirus replicative and structural genes and genes likely involved in virulence and host range. SPPV and GTPV genomes are very similar to that of lumpy skin disease virus (LSDV), sharing 97% nucleotide identity. All SPPV and GTPV genes are present in LSDV. Notably in both SPPV and GTPV genomes, nine LSDV genes with likely virulence and host range functions are disrupted, including a gene unique to LSDV (LSDV132) and genes similar to those coding for interleukin-1 receptor, myxoma virus M003.2 and M004.1 genes (two copies each), and vaccinia virus F11L, N2L, and K7L genes. The absence of these genes in SPPV and GTPV suggests a significant role for them in the bovine host range. SPPV and GTPV genomes contain specific nucleotide differences, suggesting they are phylogenetically distinct. Relatively few genomic changes in SPPV and GTPV vaccine viruses account for viral attenuation, because they contain 71 and 7 genomic changes compared to their respective field strains. Notable genetic changes include mutation or disruption of genes with predicted functions involving virulence and host range, including two ankyrin repeat proteins in SPPV and three kelch-like proteins in GTPV. These comparative genomic data indicate the close genetic relationship among capripoxviruses, and they suggest that SPPV and GTPV are distinct and likely derived from an LSDV-like ancestor.
Minute Virus of Mice Small Nonstructural Protein NS2 Interacts and Colocalizes with the Smn Protein
Authors: Young Philip J. , Jensen Klaus T. , Burger Lisa R. , Pintel David J. , Lorson Christian L. 
Published: July 2002

ABSTRACT
The small nonstructural protein NS2 of the minute virus of mice (MVM) is required for efficient viral replication, although its mode of action is unclear. Here we demonstrate that NS2 and survival motor neuron protein (Smn) interact in vitro and in vivo. NS2 and Smn also colocalize in infected nuclei at late times following MVM infection.
Enhancing the Proteolytic Maturation of Human Immunodeficiency Virus Type 1 Envelope Glycoproteins
Authors: Binley James M. , Sanders Rogier W. , Master Aditi , Cayanan Charmagne S. , Wiley Cheryl L. , Schiffner Linnea , Travis Bruce , Kuhmann Shawn , Burton Dennis R. , Hu Shiu-Lok , Olson William C. , Moore John P. 
Published: July 2002

ABSTRACT
In virus-infected cells, the envelope glycoprotein (Env) precursor, gp160, of human immunodeficiency virus type 1 is cleaved by cellular proteases into a fusion-competent gp120-gp41 heterodimer in which the two subunits are noncovalently associated. However, cleavage can be inefficient when recombinant Env is expressed at high levels, either as a full-length gp160 or as a soluble gp140 truncated immediately N-terminal to the transmembrane domain. We have explored several methods for obtaining fully cleaved Env for use as a vaccine antigen. We tested whether purified Env could be enzymatically digested with purified protease in vitro. Plasmin efficiently cleaved the Env precursor but also cut at a second site in gp120, most probably the V3 loop. In contrast, a soluble form of furin was specific for the gp120-gp41 cleavage site but cleaved inefficiently. Coexpression of Env with the full-length or soluble form of furin enhanced Env cleavage but also reduced Env expression. When the Env cleavage site (REKR) was mutated in order to see if its use by cellular proteases could be enhanced, several mutants were found to be processed more efficiently than the wild-type protein. The optimal cleavage site sequences were RRRRRR, RRRRKR, and RRRKKR. These mutations did not significantly alter the capacity of the Env protein to mediate fusion, so they have not radically perturbed Env structure. Furthermore, unlike that of wild-type Env, expression of the cleavage site mutants was not significantly reduced by furin coexpression. Coexpression of Env cleavage site mutants and furin is therefore a useful method for obtaining high-level expression of processed Env.
The RNA Binding Domain of the Hantaan Virus N Protein Maps to a Central, Conserved Region
Authors: Xu Xiaolin , Severson William , Villegas Noah , Schmaljohn Connie S. , Jonsson Colleen B. 
Published: July 2002

ABSTRACT
The nucleocapsid (N) protein of hantaviruses encapsidates both viral genomic and antigenomic RNAs, although only the genomic viral RNA (vRNA) is packaged into virions. To define the domain within the Hantaan virus (HTNV) N protein that mediates these interactions, 14 N- and C-terminal deletion constructs were cloned into a bacterial expression vector, expressed, and purified to homogeneity. Each protein was examined for its ability to bind the HTNV S segment vRNA with filter binding and gel electrophoretic mobility shift assays. These studies mapped a minimal region within the HTNV N protein (amino acids 175 to 217) that bound vRNA. Sequence alignments made from several hantavirus N protein sequences showed that the region identified has a 58% identity and an 86% similarity among these amino acid sequences. Two peptides corresponding to amino acids 175 to 196 (N1) and 197 to 218 (N2) were synthesized. The RNA binding of each peptide was measured by filter binding and competition analysis. Three oligoribonucleotides were used to measure binding affinity and assess specificity. The N2 peptide contained the major RNA binding determinants, while the N1 peptide, when mixed with N2, contributed to the specificity of vRNA recognition.
Membrane Interactions of the Tick-Borne Encephalitis Virus Fusion Protein E at Low pH
Authors: Stiasny Karin , Allison Steven L. , Schalich Juliane , Heinz Franz X. 
Published: July 2002

ABSTRACT
Membrane fusion of the flavivirus tick-borne encephalitis virus is triggered by the mildly acidic pH of the endosome and is mediated by envelope protein E, a class II viral fusion protein. The low-pH trigger induces an oligomeric rearrangement in which the subunits of the native E homodimers dissociate and the monomeric subunits then reassociate into homotrimers. Here we provide evidence that membrane binding is mediated by the intermediate monomeric form of E, generated by low-pH-induced dissociation of the dimer. Liposome coflotation experiments revealed that association with target membranes occurred only when liposomes were present at the time of acidification, whereas pretreating virions at low pH in the absence of membranes resulted in the loss of their ability to stably attach to liposomes. With the cleavable cross-linker ethylene glycolbis(succinimidylsuccinate), it was shown that a truncated soluble form of the E protein (sE) could bind to membranes only when the dimers were free to dissociate at low pH, and binding could be blocked by a monoclonal antibody that recognizes the fusion peptide, which is at the distal tip of the E monomer but is buried in the native dimer. Surprisingly, analysis of the membrane-associated sE proteins revealed that they had formed trimers. This was unexpected because this protein lacks a sequence element in the C-terminal stem-anchor region, which was shown to be essential for trimerization in the absence of a target membrane. It can therefore be concluded that the formation of a trimeric form of sE is facilitated by membrane binding. Its stability is apparently maintained by contacts between the ectodomains only and is not dependent on sequence elements in the stem-anchor region as previously assumed.
Molecular Organization of Mason-Pfizer Monkey Virus Capsids Assembled from Gag Polyprotein in
Escherichia coli
Authors: Nermut Milan V. , Bron Patrick , Thomas Daniel , Rumlova Michaela , Ruml Tomas , Hunter Eric 
Published: July 2002

ABSTRACT

We describe the results of a study by electron microscopy and image processing of Gag protein shells—immature capsids—of Mason-Pfizer monkey virus assembled in
Escherichia coli
from two truncated forms of the Gag precursor: Δp4Gag, in which the C-terminal p4Gag was deleted, and Pro(−)CA.NC, in which the N-terminal peptides and proline 1 of the CA domain were deleted. Negative staining of capsids revealed small patches of holes forming a trigonal or hexagonal pattern most clearly visible on occasional tubular forms. The center-to-center spacing of holes in the network was 7.1 nm in Δp4Gag capsids and 7.4 nm in Pro(−)CA.NC capsids. Image processing of Δp4Gag tubes revealed a hexagonal network of holes formed by six subunits with a single subunit shared between rings. This organization suggests that the six subunits are contributed by three trimers of the truncated Gag precursor. Similar molecular organization was observed in negatively stained Pro(−)CA.NC capsids. Shadowed replicas of freeze-etched capsids produced by either construct confirmed the presence of a hexagonal network of holes with a similar center-to-center spacing. We conclude that the basic building block of the cage-like network is a trimer of the Δp4Gag or Pro(−)CA.NC domains. In addition, our results point to a key role of structurally constrained CA domain in the trimeric interaction of the Gag polyprotein.
Physiological and anthropometric determinants of sport climbing performance
Authors: Mermier Christine M , Janot Jeffrey M , Parker Daryl L , Swan Jacob G 
Published: July 2002

Objective—To identify the physiological and anthropometric determinants of sport climbing performance.Methods—Forty four climbers (24 men, 20 women) of various skill levels (self reported rating 5.6–5.13c on the Yosemite decimal scale) and years of experience (0.10–44 years) served as subjects. They climbed two routes on separate days to assess climbing performance. The routes (11 and 30 m in distance) were set on two artificial climbing walls and were designed to become progressively more difficult from start to finish. Performance was scored according to the system used in sport climbing competitions where each successive handhold increases by one in point value. Results from each route were combined for a total climbing performance score. Measured variables for each subject included anthropometric (height, weight, leg length, arm span, % body fat), demographic (self reported climbing rating, years of climbing experience, weekly hours of training), and physiological (knee and shoulder extension, knee flexion, grip, and finger pincer strength, bent arm hang, grip endurance, hip and shoulder flexibility, and upper and lower body anaerobic power). These variables were combined into components using a principal components analysis procedure. These components were then used in a simultaneous multiple regression procedure to determine which components best explain the variance in sport rock climbing performance.Results—The principal components analysis procedure extracted three components. These were labelled training, anthropometric, and flexibility on the basis of the measured variables that were the most influential in forming each component. The results of the multiple regression procedure indicated that the training component uniquely explained 58.9% of the total variance in climbing performance. The anthropometric and flexibility components explained 0.3% and 1.8% of the total variance in climbing performance respectively.Conclusions—The variance in climbing performance can be explained by a component consisting of trainable variables. More importantly, the findings do not support the belief that a climber must necessarily possess specific anthropometric characteristics to excel in sport rock climbing.
Circumferential resection margin involvement: an independent predictor of survival following surgery for oesophageal cancer
Authors: Dexter S P L , Sue-Ling H , McMahon M J , Quirke P , Mapstone N , Martin I G 
Published: July 2002

BACKGROUNDFor rectal carcinoma, the presence of tumour within 1 mm of the circumferential margin is an important independent prognostic factor for both local recurrence and survival. Similar prospective data have not been reported for oesophageal carcinoma and we wished to ascertain the prognostic importance of this variable following potentially curative resection for oesophageal carcinoma.AIMTo prospectively assess the impact of circumferential margin involvement (tumour within 1 mm) following potentially curative resection for oesophageal carcinoma.PATIENTS AND METHODSIn a prospective study, resection specimens of 135 patients treated with potentially curative oesophageal resection alone were studied for the presence of tumour within 1 mm of the circumferential margin (margin positive), using inked margins and cross sectional slicing of the specimen. All tumours were also staged using the 1987 UICC TNM classification. Patients were followed for a mean of 19 months, and overall and cancer specific survival analysed.RESULTSThe finding of tumour cells within 1 mm of the circumferential margin (CRM+) was a significant and independent predictor of survival following potentially curative oesophageal resection. Overall, 64 (47%) patients were CRM+. Median survival in this group was 21 months compared with 39 months in the CRM− group (p=0.015). The impact of CRM status on survival was only seen in patients with a low nodal metastatic burden (<25% nodes positive). The odds ratio for the risk of dying from oesophageal cancer was 2.08 when the CRM was involved (p=0.013).CONCLUSIONSThe presence of tumour within 1 mm of the circumferential margin following potentially curative resection for oesophageal carcinoma is an important independent prognostic variable and should be reported routinely.
What price dissection? Dissection literally dissected
Authors: Francis Nathan R , Lewis Wayne 
Published: July 2002

Hamlet: Has this fellow no feelings of his business, that he sings at grave-making?Horatio: Custom hath made it in him a property of easiness.(Hamlet Act V, scene i)1Hamlet is appalled by the gravedigger's insensitivity towards death and corpses. Horatio explains that the gravedigger is so accustomed to such things that he no longer shares Hamlet's seriousness. We contend that human dissection may make in medical students and doctors the “property of easiness” in dealing with death and the human body, and that this may have negative consequences for medics and patients. It is perhaps worth emphasising at the outset what this essay is NOT about. We do not wish to call into question the value of dissection in medical education; to charge dissection with being an inefficient or ineffective means of teaching and learning human anatomy is not our intent. Instead, we explore, through the medium of literature, experiences of dissection, and what kind of student and doctor may be encouraged or produced by the dissection room; what price might be paid for a practical, first-hand experience of human anatomy.
Two patients with occupational asthma who returned to work with dust respirators: Table 1
Authors: Obase Yasushi , Shimoda Terufumi , Mitsuta Kazuko , Matsuse Hiroto , Kohno Shigeru 
Published: July 2002

OBJECTIVESTo assess the efficacy of dust respirators in preventing asthma attacks in patients with occupational asthma (asthma induced by buckwheat flour or wheat flour).METHODSThe effect of the work environment was examined in two patients with occupational asthma with and without the use of a commercially available mask or a dust respirator. Pulmonary function tests were performed immediately before and after work and at 1 hourly intervals for 14 hours after returning to the hospital.RESULTSIn patient 1, environmental exposure resulted in no symptoms during and immediately after work, but coughing, wheezing, and dyspnoea developed after 6 hours. Peak expiratory flow rate (PEFR) decreased by 44% 7 hours after leaving the work environment, showing only a positive late asthmatic reaction (LAR). In patient 2, environmental exposure resulted in coughing and wheezing 10 minutes after initiation during bread making, and PEFR decreased by 39%. After 7 hours, PEFR decreased by 34%. The environmental provocation tests in both patients were repeated after wearing a commercial respirator. This resulted in a complete suppression of LAR in patient 1 and of immediate asthmatic reaction (IAR) and LAR in patient 2.CONCLUSIONSTwo patients with asthma induced by buckwheat flour or wheat flour in whom asthmatic attacks could be prevented with a dust respirator are reported. Dust respirators are effective in preventing asthma attacks induced by buckwheat flour and wheat flour.