bluuebunny/crossref_metadata_2025_split huggingface dataset:
Accuracy of rapid radiographic film calibration for intensity‐modulated radiation therapy verification
Authors: Kulasekere Ravi , Moran Jean M. , Fraass Benedick A. , Roberson Peter L. 
Published: February 2007

A single calibration film method was evaluated for use with intensity‐modulated radiation therapy film quality assurance measurements. The single‐film method has the potential advantages of exposure simplicity, less media consumption, and improved processor quality control. Potential disadvantages include cross contamination of film exposure, implementation effort to document delivered dose, and added complication of film response analysis. Film response differences were measured between standard and single‐film calibration methods. Additional measurements were performed to help trace causes for the observed discrepancies. Kodak X‐OmatV (XV) film was found to have greater response variability than extended dose range (EDR) film. We found it advisable for XV film to relate the film response calibration for the single‐film method to a user‐defined optimal calibration geometry. Using a single calibration film exposed at the time of experiment, the total uncertainty of film response was estimated to be (1%) for XV (EDR) film at 50 (100) cGy and higher, respectively.PACS numbers: 87.53.‐j, 87.53.Dq
The dosimetric effect of inhomogeneity correction in dynamic conformal arc stereotactic body radiation therapy for lung tumors
Authors: Kavanagh Brian , Ding Meisong , Schefter Tracey , Stuhr Kelly , Newman Francis 
Published: February 2007

For patients treated with lung stereotactic body radiation therapy (SBRT) using dynamic conformal arcs, the influence of inhomogeneity correction (IC) on normal tissue and tumor dosimetry was studied. For the same numbers of monitor units, the planning target volume equivalent uniform doses calculated without path‐length IC were lower than those calculated with IC (mean difference 18%, range 1% to 34%; ). Normal lung dose differences were of the same magnitude in the opposite direction. In reports of SBRT, it will be helpful to maintain clear communication about the type of IC used to avoid future uncertainties about true normal tissue tolerance and tumor dose‐response relationships.PACS numbers: 87.50.Gi, 87.53.Bn, 87.53.Kn
Estimation of patient organ doses from CT examinations in Tanzania
Authors: Ngaile Justin E. , Msaki Peter K. 
Published: February 2007

Although the use of CT in medical diagnosis delivers radiation doses to patients that are higher than those from other radiological procedures, lack of optimized protocols could be an additional source of increased dose in developing countries. The aims of this study are, first, to determine the magnitude of radiation doses received by selected radiosensitive organs of patients undergoing CT examinations and compare them with other studies, and second, to assess how CT scanning protocols in practice affect patient organ doses. In order to achieve these objectives, patient organ doses from five common CT examinations were obtained from eight hospitals in Tanzania. The patient organ doses were estimated using measurements of CT dose indexes (CTDI), exposure‐related parameters, and the ImPACT spreadsheet based on NRPB conversion factors. A large variation of mean organ doses among hospitals was observed for similar CT examinations. These variations largely originated from different CT scanning protocols used in different hospitals and scanner type. The mean organ doses in this study for the eye lens (for head), thyroid (for chest), breast (for chest), stomach (for abdomen), and ovary (for pelvis) were 63.9 mGy, 12.3 mGy, 26.1 mGy, 35.6 mGy, and 24.0 mGy, respectively. These values were mostly comparable to and slightly higher than the values of organ doses reported from the literature for the United Kingdom, Japan, Germany, Norway, and the Netherlands. It was concluded that patient organ doses could be substantially minimized through careful selection of scanning parameters based on clinical indications of study, patient size, and body region being examined. Additional dose reduction to superficial organs would require the use of shielding materials.PACS numbers: 87.59 Fm; 87.66Jj; 87.52‐g
Evaluation of dosimetric effect of leaf position in a radiation field of an 80‐leaf multileaf collimator fitted to the LINAC head as a tertiary collimator
Authors: Kehwar Than S. , Bhardwaj Anup K. , Chakarvarti Shiv K. 
Published: February 2007

This study evaluates changes in the dosimetric characteristics of a Varian Millennium 80‐leaf multileaf collimator (MLC) in a radiation field. In this study, dose rate, scatter factor, percentage depth dose, surface dose and dose in the buildup region, beam profile, flatness and symmetry, and penumbra width measurements were made for 6‐MV and 15‐MV photon beams. Analysis of widths between 50% dose levels of the beam profiles to reflect the field size at the level of profile measurement shows a significant difference between the fields defined by MLC and/or jaws and MLC (zero gap) and the fields defined by jaws only. The position of the MLC leaves in the radiation field also significantly affects scatter factors. A new relationship has, therefore, been established between the scatter factors and the position of the MLC, which will indeed be useful in the dose calculation for irregular fields. Penumbra widths increase with field size and were higher for fields defined by jaws and/or MLC than jaws and MLC (zero gap) by 1.5 mm to 4.2 mm and 3.8 mm to 5.0 mm, for 6‐MV, and 1.5 mm to 2.4 mm and 3.0 mm to 5.6 mm, for 15‐MV, at 20% to 80% and 10% to 90% levels, respectively. The surface dose and the dose in the buildup region were smaller for fields defined by jaws and MLC (zero gap) than the fields defined by jaws and/or MLC for both photon energies. No significant differences were found in percentage depth dose beyond , beam profiles above 80% dose level, and flatness and symmetry for both energies. The results of this study suggest that while one collects linear accelerator beam data with a MLC, the effects of the positions of the MLC leaves play an important role in dosimetric characteristics of 3D conformal radiation therapy as well as intensity‐modulated radiotherapy.PACS number: 87.53.Dq
The Differential Agglutination Test as a Diagnostic Aid in Cases of Toxoplasmic Lymphadenitis
Authors: Montoya Jose G. , Berry Andrew , Rosso Fernando , Remington Jack S. 
Published: February 2007

ABSTRACT
Lymphadenopathy (LN) is the most common clinical manifestation of acute acquired toxoplasma infection in humans. The diagnosis of toxoplasmic lymphadenitis (TL) is established by serological methods and/or lymph node biopsy. In the United States, the differential agglutination (of acetone [AC]-fixed versus that of formalin [HS]-fixed tachyzoites) test (AC/HS test) has primarily been used in assessments of pregnant women as a component of the toxoplasma serological profile to distinguish between recently acquired infections and infections acquired in the distant past. We studied the AC/HS test in patients with TL to define its usefulness in diagnosing individuals presenting with LN and to determine its kinetics after the onset of LN. One hundred nine consecutive patients (158 serum samples) diagnosed serologically and by lymph node biopsy as having TL were studied. Specific patterns in the AC/HS test were noted to be dependent on the time from the clinical onset of LN (COLN). Acute AC/HS patterns were observed for more than 75% of patients who according to their histories had developed their TL within 6 months after COLN. Acute patterns were not observed beyond the 12th month except for a single patient for whom an acute pattern (400/800) persisted to the 13th month after COLN. Equivocal patterns were observed up to 36 months after COLN. Nonacute patterns were observed only for serum samples drawn at least 13 months after COLN. A nonacute pattern in an individual at less than 12 months after COLN should suggest an etiology other than TL. In such cases, investigation for alternative causes, including malignancy, should be instigated.
Natural Mutations in the Receptor Binding Domain of Spike Glycoprotein Determine the Reactivity of Cross-Neutralization between Palm Civet Coronavirus and Severe Acute Respiratory Syndrome Coronavirus
Authors: Liu Li , Fang Qing , Deng Fei , Wang Hanzhong , Yi Christopher E. , Ba Lei , Yu Wenjie , Lin Richard D. , Li Taisheng , Hu Zhihong , Ho David D. , Zhang Linqi , Chen Zhiwei 
Published: February 2007

ABSTRACT
The severe acute respiratory syndrome (SARS) outbreak of 2002 and 2003 occurred as a result of zoonotic transmission. Coronavirus (CoV) found in naturally infected palm civet (civet-CoV) represents the closest genetic relative to SARS-CoV, but the degree and the determinants of cross-neutralization among these viruses remain to be investigated. Studies indicate that the receptor binding domain (RBD) of the SARS-CoV spike (S) glycoprotein contains major determinants for viral entry and neutralization. We aim to characterize the impact of natural mutations within the RBDs of civet-CoVs on viral entry and cross-neutralization. In this study, the S glycoprotein genes were recovered from naturally infected civets in central China (Hubei province), extending the geographic distribution of civet-CoV beyond the southeastern province of Guangdong. Moreover, pseudoviruses generated in our laboratory with four civet S genes, each with a distinct RBD, infected cells expressing human receptor angiotensin-converting enzyme 2, but with 90 to 95% less efficiency compared to that of SARS-CoV. These four civet S genes were also constructed as DNA vaccines to immunize mice. Immunized sera elicited against most civet S glycoproteins displayed potent neutralizing activities against autologous viruses but were much less efficient (50% inhibitory concentration, 20- to 40-fold) at neutralizing SARS-CoV and vice versa. Convalescence-phase sera from humans were similarly ineffective against the dominant civet pseudovirus. Our findings suggest that the design of SARS vaccine should consider not only preventing the reemergence of SARS-CoV but also providing cross-protection, thus interrupting zoonotic transmission of a group of genetically divergent civet CoVs of broad geographic origin.
Live Covisualization of Competing Adeno-Associated Virus and Herpes Simplex Virus Type 1 DNA Replication: Molecular Mechanisms of Interaction
Authors: Glauser Daniel L. , Strasser Regina , Laimbacher Andrea S. , Saydam Okay , Clément Nathalie , Linden R. Michael , Ackermann Mathias , Fraefel Cornel 
Published: February 2007

ABSTRACT

We performed live cell visualization assays to directly assess the interaction between competing adeno-associated virus (AAV) and herpes simplex virus type 1 (HSV-1) DNA replication. Our studies reveal the formation of separate AAV and HSV-1 replication compartments and the inhibition of HSV-1 replication compartment formation in the presence of AAV. AAV Rep is recruited into AAV replication compartments but not into those of HSV-1, while the single-stranded DNA-binding protein HSV-1 ICP8 is recruited into both AAV and HSV-1 replication compartments, although with differential staining patterns. Slot blot analysis of coinfected cells revealed a dose-dependent inhibition of HSV-1 DNA replication by wild-type AAV but not by
rep
-negative recombinant AAV. Consistent with this, Western blot analysis indicated that wild-type AAV affects the levels of the HSV-1 immediate-early protein ICP4 and the early protein ICP8 only modestly but strongly inhibits the accumulation of the late proteins VP16 and gC. Furthermore, we demonstrate that the presence of Rep in the absence of AAV DNA replication is sufficient for the inhibition of HSV-1. In particular, Rep68/78 proteins severely inhibit the formation of mature HSV-1 replication compartments and lead to the accumulation of ICP8 at sites of cellular DNA synthesis, a phenomenon previously observed in the presence of viral polymerase inhibitors. Taken together, our results suggest that AAV and HSV-1 replicate in separate compartments and that AAV Rep inhibits HSV-1 at the level of DNA replication.
Deamination-Independent Inhibition of Hepatitis B Virus Reverse Transcription by APOBEC3G
Authors: Nguyen David H. , Gummuluru Suryaram , Hu Jianming 
Published: February 2007

ABSTRACT
The APOBEC3 family of mammalian cytidine deaminases, including APOBEC3G (A3G), has been shown to function as innate antiviral factors against retroviruses and can also suppress the replication of the hepatitis B virus (HBV). The mechanism by which A3G inhibits HBV replication remains to be elucidated. In this study, we show that the inhibitory effect of APOBEC3 proteins on HBV replication was mainly at the DNA level, with only a minor effect on viral RNA packaging. The anti-HBV effect of A3G was independent of the DNA-editing function, and the mode of inhibition was not due to HBV DNA degradation. The editing-independent antiviral activity of A3G could target DNA-RNA hybrids as well as single-stranded DNA. Finally, we show that there was a preferential decrease in the accumulation of longer minus-strand DNA by A3G, compared to the shorter minus-strand DNA, and suggest that A3G exerts its inhibitory effect at very early stages during viral reverse transcription.
Major Subsets of Human Dendritic Cells Are Efficiently Transduced by Self-Complementary Adeno-Associated Virus Vectors 1 and 2
Authors: Veron Philippe , Allo Valérie , Rivière Christel , Bernard Jacky , Douar Anne-Marie , Masurier Carole 
Published: February 2007

ABSTRACTDendritic cells (DC) are antigen-presenting cells pivotal for inducing immunity or tolerance. Gene transfer into DC is an important strategy for developing immunotherapeutic approaches against infectious pathogens and cancers. One of the vectors previously described for the transduction of human monocytes or DC is the recombinant adeno-associated virus (rAAV), with a genome conventionally packaged as a single-stranded (ss) molecule. Nevertheless, its use is limited by the poor and variable transduction efficiency of DC. In this study, AAV type 1 (AAV1) and AAV2 vectors, which expressed the enhanced green fluorescent protein and were packaged as ss or self-complementary (sc) duplex strands, were used to transduce different DC subsets generated ex vivo and the immunophenotypes, states of differentiation, and functions of the subsets were carefully examined. We show here for the first time that a single exposure of monocytes (Mo) or CD34+progenitors (CD34) to sc rAAV1 or sc rAAV2 leads to high transduction levels (5 to 59%) of differentiated Mo-DC, Mo-Langerhans cells (LC), CD34-LC, or CD34-plasmacytoid DC (pDC), with no impact on their phenotypes and functional maturation of these cells, compared to those of exposure to ss rAAV. Moreover, we show that all these DC subpopulations can also be efficiently transduced after commitment to their differentiation pathways. Furthermore, these DC subsets transduced with sc rAAV1 expressing a tumor antigen were potent activators of a CD8+-T-cell clone. Altogether, these results show the high potential of sc AAV1 and sc AAV2 vectors to transduce ex vivo conventional DC, LC, or pDC or to directly target them in vivo for the design of new DC-based immunotherapies.
Developmental Regulation of Human Cytomegalovirus Receptors in Cytotrophoblasts Correlates with Distinct Replication Sites in the Placenta
Authors: Maidji Ekaterina , Genbacev Olga , Chang Hsin-Ti , Pereira Lenore 
Published: February 2007

ABSTRACTCytomegalovirus (CMV), the major viral cause of congenital disease, infects the uterus and developing placenta and spreads to the fetus throughout gestation. Virus replicates in invasive cytotrophoblasts in the decidua, and maternal immunoglobulin G (IgG)-CMV virion complexes, which are transcytosed by the neonatal Fc receptor across syncytiotrophoblasts, infect underlying cytotrophoblasts in chorionic villi. Immunity is central to protection of the placenta-fetal unit: infection can occur when IgG has a low neutralizing titer. Here we used immunohistochemical and function-blocking methods to correlate infection in the placenta with expression of potential CMV receptors in situ and in vitro. In placental villi, syncytiotrophoblasts express the virion receptor epidermal growth factor receptor (EGFR) but lack integrin coreceptors, and virion uptake occurs without replication. Focal infection can occur when transcytosed virions reach EGFR-expressing cytotrophoblasts that selectively initiate expression of αV integrin. In cell columns, proximal cytotrophoblasts lack receptors and distal cells express integrins α1β1 and αVβ3, enabling virion attachment. In the decidua, invasive cytotrophoblasts expressing coreceptors upregulate EGFR, thereby dramatically increasing susceptibility to infection. Our findings indicate that virion interactions with cytotrophoblasts expressing receptors in the placenta (i) change as the cells differentiate and (ii) correlate with spatially distinct sites of CMV replication in maternal and fetal compartments.
Mutational Evidence of Internal Fusion Loops in Herpes Simplex Virus Glycoprotein B
Authors: Hannah Brian P. , Heldwein Ekaterina E. , Bender Florent C. , Cohen Gary H. , Eisenberg Roselyn J. 
Published: February 2007

ABSTRACT
Herpes simplex virus type 1 (HSV-1) glycoprotein B (gB) is one of four glycoproteins necessary and sufficient for HSV cellular entry. Recently, the crystal structures of HSV-1 gB and vesicular stomatitis virus glycoprotein G were determined. Surprisingly, the two proteins share remarkable structural homology. Both proteins are homotrimeric and center about a long alpha-helix, features reminiscent of class I fusion proteins, such as influenza virus hemagglutinin or paramyxovirus F. However, these structures revealed that G has internal fusion loops, similar to the fusion loops of the class II fusion proteins, and that these loops are structurally conserved in gB. To examine whether these putative fusion loops are important for gB function, we mutated potential membrane-interacting (hydrophobic) residues to charged amino acids. Of most interest were mutant gB proteins that were expressed on the cell surface and were recognized by monoclonal antibodies against conformational epitopes but lacked the ability to function in cell-cell fusion assays. We find that three of the five hydrophobic amino acids targeted in these loops, tryptophan 174, tyrosine 179, and alanine 261, are integral in the function of gB. Our data suggest that they are part of an important functional domain. We hypothesize that two loops in domain 1 of HSV gB function as fusion loops. Our data are further evidence that gB is a viral fusogen and suggest clues as to how gB may function.
Resistance to Chronic Wasting Disease in Transgenic Mice Expressing a Naturally Occurring Allelic Variant of Deer Prion Protein
Authors: Meade-White Kimberly , Race Brent , Trifilo Matthew , Bossers Alex , Favara Cynthia , Lacasse Rachel , Miller Michael , Williams Elizabeth , Oldstone Michael , Race Richard , Chesebro Bruce 
Published: February 2007

ABSTRACT
Prion protein (PrP) is a required factor for susceptibility to transmissible spongiform encephalopathy or prion diseases. In transgenic mice, expression of prion protein (PrP) from another species often confers susceptibility to prion disease from that donor species. For example, expression of deer or elk PrP in transgenic mice has induced susceptibility to chronic wasting disease (CWD), the prion disease of cervids. In the current experiments, transgenic mice expressing two naturally occurring allelic variants of deer PrP with either glycine (G) or serine (S) at residue 96 were found to differ in susceptibility to CWD infection. G96 mice were highly susceptible to infection, and disease appeared starting as early as 160 days postinfection. In contrast, S96 mice showed no evidence of disease or generation of disease-associated protease-resistant PrP (PrPres) over a 600-day period. At the time of clinical disease, G96 mice showed typical vacuolar pathology and deposition of PrPres in many brain regions, and in some individuals, extensive neuronal loss and apoptosis were noted in the hippocampus and cerebellum. Extraneural accumulation of PrPres was also noted in spleen and intestinal tissue of clinically ill G96 mice. These results demonstrate the importance of deer PrP polymorphisms in susceptibility to CWD infection. Furthermore, this deer PrP transgenic model is the first to demonstrate extraneural accumulation of PrPres in spleen and intestinal tissue and thus may prove useful in studies of CWD pathogenesis and transmission by oral or other natural routes of infection.
A New Crucial Protein Interaction Element That Targets the Adenovirus E4-ORF1 Oncoprotein to Membrane Vesicles
Authors: Chung Sang-Hyuk , Frese Kristopher K. , Weiss Robert S. , Prasad B. V. Venkataram , Javier Ronald T. 
Published: February 2007

ABSTRACT

Human adenovirus type 9 exclusively elicits mammary tumors in experimental animals, and the primary oncogenic determinant of this virus is the
E4-ORF1
oncogene, as opposed to the well-known
E1A
and
E1B
oncogenes. The tumorigenic potential of E4-ORF1, as well as its ability to oncogenically stimulate phosphatidylinositol 3-kinase (PI3K), depends on a carboxyl-terminal PDZ domain-binding motif (PBM) that mediates interactions with several different membrane-associated cellular PDZ proteins, including MUPP1, PATJ, MAGI-1, ZO-2, and Dlg1. Nevertheless, because certain E4-ORF1 mutations that alter neither the sequence nor the function of the PBM abolish E4-ORF1-induced PI3K activation and cellular transformation, we reasoned that E4-ORF1 must possess an additional crucial protein element. In the present study, we identified seven E4-ORF1 amino acid residues that define this new element, designated domain 2, and showed that it mediates binding to a 70-kDa cellular phosphoprotein. We also discovered that domain 2 or the PBM independently promotes E4-ORF1 localization to cytoplasmic membrane vesicles and that this activity of domain 2 depends on E4-ORF1 trimerization. Consistent with the latter observation, molecular-modeling analyses predicted that E4-ORF1 trimerization brings together six out of seven domain 2 residues at each of the three subunit interfaces. These findings importantly demonstrate that PI3K activation and cellular transformation induced by E4-ORF1 require two separate protein interaction elements, domain 2 and the PBM, each of which targets E4-ORF1 to vesicle membranes in cells.