Lamivudine is an oral nucleoside analogue widely used for the treatment of chronic hepatitis B. The main limitation of lamivudine use is the selection of resistant mutations that increases with time ...of utilization. Hepatitis B virus (HBV) isolates have been classified into eight genotypes (A to H) with distinct geographical distributions. HBV genotypes may also influence pathogenic properties and therapeutic features. Here, we analyzed the HBV genotype distribution and the nature and frequency of lamivudine resistant mutations among 36 patients submitted to lamivudine treatment for 12 to 84 months.
Half of the patients were homosexual men. Only 4/36 (11%) patients were HBV DNA negative. As expected for a Brazilian group, genotypes A (24/32 positive individuals, 75%), D (3/32, 9.3%) and F (1/32, 3%) were present. One sample was from genotype C, which is a genotype rarely found in Brazil. Three samples were from genotype G, which had not been previously detected in Brazil. Lamivudine resistance mutations were identified in 20/32 (62%) HBV DNA positive samples. Mean HBV loads of patients with and without lamivudine resistance mutations were not very different (2.7 x 107 and 6.9 x 107 copies/mL, respectively). Fifteen patients showed the L180M/M204V lamivudine resistant double mutation. The triple mutant rt173V/180M/204V, which acts as a vaccine escape mutant, was found in two individuals. The three isolates of genotype G were entirely sequenced. All three showed the double mutation L180M/M204V and displayed a large genetic divergence when compared with other full-length genotype G isolates.
A high (55%) proportion of patients submitted to long term lamivudine therapy displayed resistant mutations, with elevated viral load. The potential of transmission of such HBV mutants should be monitored. The identification of genotypes C and G, rarely detected in South America, seems to indicate a genotype distribution different to that observed in non treated patients. Disparities in routes of transmission (genotype G seems to be linked to homosexual behavior) and in pathogenic properties (genotype C is very aggressive) among HBV genotypes may explain the presence of rare genotypes in the present work.
Model for pp → 4π via 2ρ was outlined. The prediction for the cross section for this process was given for ATLAS and ALICE experimental cuts. This process has suffcient cross section to be observed ...in these experiments.
Data regarding Hepatitis B and C viruses (HBV and HCV) prevalence among military personnel in Brazil are lacking, but the work-related risk of exposure can be high. The objective of this study was to ...estimate the seroprevalence of HBV and HCV and the risk factors associated to HBV exposure among Brazilian military personnel.
A cross-sectional study was conducted and included 433 male military adults aged 18–25 years old working in Rio de Janeiro during October 2013. All individuals completed a questionnaire to assess their risk of exposure and provided a blood sample to HBV and HCV testing.
None of the participants presented HBsAg or anti-HBc IgM, 18 (4.1%) were positive for total anti-HBc, 247 (57.0%) were positive for anti-HBs, and 3 (0.7%) were anti-HCV reactive. The majority of military personnel with past HBV infection (anti-HBc reactive) and HBV immunity (anti-HBs reactive) had a history of prior dental procedures (88.9% and 77.3%), consumption of alcohol at least once a week (50% and 55.9%), and practiced oral sex (61.1% and 58.3%, respectively). In addition, anti-HBc positivity was common among individuals with a history of surgery (44.4%) and practice of anal sex (50%). At univariate analysis, age group was associated to anti-HBc and anti-HBs positivity.
Low rates of HBV and HCV infection were observed among Brazilian military personnel in comparison to the general Brazilian population. HBV immunity rates were relatively low indicating the need for vaccination campaigns in this group.
•A concept of calibration of on-board imaging systems is presented.•The calibration with the respect to linac is based on the concept of a multimodular phantom.•Phantom has been described by authors ...in Tabor Z et al., Medical Physics 2017.•Determination of two isocenters and three frames of reference is formulated as an optimization problem and solved.
To develop an assumption-free methodology for aligning the geometry of on-board imagers with the geometry of medical linear accelerators applied in image-guided radiotherapy (IGRT).
Alignment of the on-board imaging (OBI) system with respect to the accelerator system is achieved using a multi-modular phantom described elsewhere (Tabor et al., 2017), enabling the geometry of the linear accelerator to be specified without any pre-assumptions.
The placement of two isocentres (of the on-board imager and of the therapeutic system) and of three frames of reference (those of the on-board imager, of the therapeutic system, and of the treatment table) is formulated as an optimization problem. It is solved by analysing the images of fiducial points positioned in 3D space in phantom modules attached to the treatment table and to the collimator of the accelerator. Fiducials are projected onto an imaging plane of unknown characteristics from a virtual source of unknown coordinates.
An analytical framework exploiting projection images of the proposed multi-modular phantom has been developed, enabling precise alignment of the reference frame related to the on-board imager with the reference frame related to the therapeutic system. Within the proposed framework, the necessary corrections of treatment table positioning prior to patient irradiation, are delivered in the treatment table coordinates.
In the present paper a general setup for the determination of imperfect geometry of radiotherapeutic devices has been proposed that is based on a geometric algebra framework. To account for this ...imperfect geometry, two methods of a calibration were presented, consisting of determining for each angular position of a gantry a correction shift which must be applied to the origin of a laboratory frame of reference to place it along a radiation axis for this angular position. Closed form solutions for these corrections are provided.
General description of an on-line procedure of calibration for IGRT (image guided radiotherapy) is given. The algorithm allows to improve targeting cancer by estimating its position in space and ...suggesting appropriate correction of the position of the patient. The description is given in the Geometric Algebra language which significantly simplifies calculations and clarifies presentation.
The effect of the photon emission (initial-state radiation) in the cross section of the process of direct production of the Higgs boson in future high luminosity electron and muon colliders is ...calculated. It was found that the cross section at the top of the Higgs boson resonance peak is reduced by a factor 0.348 for the electron collider and 0.548 for the muon collider. A centre-of-mass energy spread of the centre-of-mass energy of 4.2 MeV (equal to the Higgs width) would reduce peak cross section further, by a factor 0.170 and 0.256 (QED and energy spread) for electron and muon beams respectively. Possible uncertainties in the resummed QED calculations are discussed. Numerical results for the lineshape cross section including QED and many values of the centre-of-mass energy spread are provided.
Background and Aim: Resistance to lamivudine therapy of chronic hepatitis B virus (HBV) infection occurs by mutation in the YMDD motif of the reverse transcriptase (rt) domain (rtM204V/I) of the ...virus polymerase, and is usually accompanied by rtL180M mutation. Here we investigated virological factors associated with hepatic failure in a 58‐year‐old male, chronically HBV‐infected patient who died after 33 months of lamivudine therapy.
Methods: Nucleotide sequencing was performed from one sample collected before and two samples collected during lamivudine therapy.
Results: A peak of alanine aminotransferase and aspartate aminotransferase levels occurred after 19 months of lamivudine treatment, associated with the rtM204I mutation. After 32 months, the rtM204V mutation was predominant, accompanied by the lamivudine‐resistant rtL180M mutation. Furthermore, two rare polymerase (rtS117Y and rtV142A) and three HBsAg (L109I, F134L, and I208T) substitutions were observed. At that time, the patient was hospitalized with hepatic decompensation, followed by hepatic failure, and died one month later. HBV‐DNA was detected at moderate levels (8.3 × 104−2.6 × 106 copies/mL) throughout.
Conclusion: The results suggest that substitutions in polymerase (rtS117Y, rtV142A) and surface antigens (L109I, F134L, and I208T), associated with lamivudine‐resistant mutations at positions 180 and 204, were involved in this case of fatal hepatitis B.
Recently, there is a need for a general-purpose event generator of decays of an elementary particle or a hadron to a state of higher multiplicity (\(N > 2\)) that is simple to use and universal. We ...present the structure of such a library to produce generators that generate kinematics of decay processes and can be used to integrate any matrix element squared over phase space of this decay. Some test examples are presented, and results are compared with results known from the literature. As one of examples we consider the Standard Model Higgs boson decay into four leptons. The generators discussed here are compatible with the ROOT interface.
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