Occult hepatitis B virus infection among blood donors from the Brazilian Amazon: implications for transfusion policy.

BACKGROUND: Brazil requires the performance of both a test for hepatitis B surface antigen (HBsAg) and a test for antibodies to the core of hepatitis B for blood donor screening. Blood centres in regions of high HBV endemicity struggle to maintain adequate stocks in face of the high discard rates due to anti-HBc reactivity. We evaluated the potential infectivity of donations positive for anti-HBc in search of a rational approach for the handling of these collections. STUDY DESIGN AND METHODS: We tested anti-HBc reactive blood donations from the state of Amazonas for the presence of HBV DNA and for titres of anti-HBs. The study population consists of village-based donors from the interior of Amazonas state. RESULTS: Among 3600 donations, 799 were anti-HBc reactive (22·2%). We were able to perform real-time PCR for the HBV S gene on specimens from 291 of these donors. Eight of these samples were negative for HBsAg and positive for HBV DNA and were defined as occult B virus infections (2·7%). Six of those eight specimens had anti-HBs titres above 100 mIU/ml, indicating the concomitant presence of the virus with high antibody titres. CONCLUSION: A small proportion of anti-HBc reactive donors carry HBV DNA and anti-HBs testing is not useful for predicting viremia on them. This finding indicates the possibility of HBV transmission from asymptomatic donors, especially in areas of high HBV prevalence. Sensitive HBV DNA nucleic acid testing may provide another level of safety, allowing eventual use of anti-HBc reactive units in critical situations.

Immunological/virological peripheral blood biomarkers and distinct patterns of sleeping quality in chronic hepatitis C patients.

The rational of this study we intended to investigate whether the peripheral blood immunological/virological biomarkers were associated with distinct patterns of sleeping quality in patients with chronic hepatitis C-(HCV). Distinct well-established indexes/scores were used to categorize the sleeping quality of HCV patients, including the Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale and Fatigue Severity Scores. Our findings demonstrated that HCV patients classified as 'good sleeper' displayed an enhanced frequency of circulating CD8(+) T cells, lower frequency of activated (CD69(+)) neutrophils and eosinophils but enhanced frequency of activated lymphocytes besides lower seric levels of IL-4/IL-8/IL-10 but higher levels of IL-12, besides lower HCV virus load and lower anti-HCV IgG levels. In contrast, HCV patients classified as 'poor sleeper' displayed enhanced levels of activated neutrophils and eosinophils but lower frequency of activated lymphocytes, higher seric levels of IL-6/TNF-α/IL-10 but lower levels of IL-12 besides higher HCV virus load and increased anti-HCV IgG levels. Positive correlation was further confirmed by the relationship between the leucocyte activation status, the cytokine levels, the HCV viral load and the anti-HCV IgG reactivity with the PSQI indexes. Analysis of cytokine signature curves demonstrated that lower frequency of IL-10 was observed in HCV patients classified as 'good sleepers', whereas enhanced frequency of IL-6 was found HCV patients classified as 'poor sleepers'. In conclusion, our data suggest that immunological biomarkers (leucocytes activation status and seric cytokines levels) are likely to be associated with sleeping quality patterns in HCV patients, suggesting their putative use for clinical monitoring purposes.

Grain boundary enrichment in the FePt polymorphic A1 to L1(0) phase transformation.

A series of Fe(54+/-1)Pt(46+/-1) thin films have been sputter-deposited and annealed at various times and temperatures to facilitate the A1 to L1(0) polymorphic phase transformation. The annealing times span one minute to tens of minutes over temperatures of 300-800 degrees C. The films were characterized by X-ray and electron diffraction and atom probe tomography. This time-temperature regime provides 'snap-shots' into the compositional segregation evolution at the grain boundaries during the polymorphic phase transformation. The as-deposited A1 phase showed a preferential segregation of Pt to the grain boundaries. The reduction of Pt enrichment at the boundaries was observed for all L1(0) ordered films.

The influence of voxel size on atom probe tomography data.

A methodology for determining the optimal voxel size for phase thresholding in nanostructured materials was developed using an atom simulator and a model system of a fixed two-phase composition and volume fraction. The voxel size range was banded by the atom count within each voxel. Some voxel edge lengths were found to be too large, resulting in an averaging of compositional fluctuations; others were too small with concomitant decreases in the signal-to-noise ratio for phase identification. The simulated methodology was then applied to the more complex experimentally determined data set collected from a (Co(0.95)Fe(0.05))(88)Zr(6)Hf(1)B(4)Cu(1) two-phase nanocomposite alloy to validate the approach. In this alloy, Zr and Hf segregated to an intergranular amorphous phase while Fe preferentially segregated to a crystalline phase during the isothermal annealing step that promoted primary crystallization. The atom probe data analysis of the volume fraction was compared to transmission electron microscopy (TEM) dark-field imaging analysis and a lever rule analysis of the volume fraction within the amorphous and crystalline phases of the ribbon.

Field evaporation behavior in [0 0 1] FePt thin films.

Though the atom probe has provided unprecedented atomic identification and spatial imaging capability, the basic reconstruction assumption of a smooth hemispherical tip shape creates significant challenges in yielding high fidelity chemical information for atomic species with extreme differences in fields required for field evaporation. In the present study, the evaporation behavior and accompanying artifacts are examined for the super-cell lattice structure of L1(0) FePt, where alternating Fe and Pt planes exist in the [0 0 1] orientation. Elemental Fe and Pt have significant differences in field strengths providing a candidate system to quantify these issues. Though alloys can result in changes in the elemental field strength, the intrinsic nature of elemental planes in [0 0 1] L1(0) provides a system to determine to what extent basic assumptions of elemental field strengths can break down in understanding reconstruction artifacts in this intermetallic alloy. The reconstruction of field evaporation experiments has shown depletion of Fe at the (0 0 2) pole and zone axes. Compositional profiles revealed an increase in Fe and atom count moving outward from the pole. The depletion at the low indexed pole and zone axes was determined to be the result of local magnification and electrostatic effects. The experimental results are compared to an electrostatic simulation model.