Strong magnetization and anisotropy of Mn5Ge3thin films on Ge(001).

We report on the growth of Mn5Ge3thin films on Ge(001) substrates following two methods: solid phase epitaxy (SPE) and reactive deposition epitaxy (RDE). We have varied the thickness of the films, in order to study the magnetization and anisotropy evolution. A strongly enhanced magnetization of 1580 kA m-1, compared to 1200 ± 150 kA m-1for films grown on Ge(111), has been measured on ultrathin films of 5 nm grown by RDE. Thicker films exhibited magnetizations <750 kA m-1. The films grown by SPE also exhibit strong magnetization of 1490 kA m-1and a drop of magnetization by increasing the film thickness. The effective magnetic anisotropy exhibits a more complex behavior: increases on the SPE films and decreases on the RDE films while increasing the thickness of the films. Magnetostatic and interfacial anisotropies were considered and calculated. The results are discussed in terms of the growth methods and microstructure of the films.

Detection and quantification of hepatitis E virus in the absence of IgG and IgM anti-HEV in HIV-positive patients.

AIMS: To improve RT-qPCR with an internal control and a synthetic standard curve to detect HEV in HIV co-infected patients. METHODS AND RESULTS: A single-stranded RNA (ssRNA) and a double-stranded DNA (dsDNA) synthetic curve were designed, compared to the international reference panel for HEV genotypes, and tested to quantify and detect a reference panel for HEV genotypes. The detection limit of the RNA synthetic curve (50 copies per ml) was better than the DNA synthetic curve (100 copies per ml) and the WHO standard curve (250 copies per ml). Then, 280 serum samples from HIV-positive patients were tested for HEV RNA, which was detected in 3·6% of serum samples. The viral load ranged from 2 × 102 copies per ml to 4·78 × 108 copies per ml. HEV IgM/IgG antibodies were not detected in the RNA-positive patients. Sequencing analysis of HEV showed that the virus belongs to genotype 3 (HEV GT3). CONCLUSIONS: Real-time PCR was a useful tool to estimate co-infection with HEV/HIV, even in patients with low viral loads and undetectable anti-HEV IgG and IgM antibodies. SIGNIFICANCE AND IMPACT OF THE STUDY: Hepatitis E virus genotype 3 (HEV GT3) has been associated with silent chronic hepatitis and cirrhosis in HIV-positive subjects worldwide, but there is a lack of data on this co-infection in Brazil.

Modification of crystal anisotropy and enhancement of magnetic moment of Co-doped SnO2 thin films annealed under magnetic field.

Co-doped SnO2 thin films were grown by sputtering technique on SiO2/Si(001) substrates at room temperature, and then, thermal treatments with and without an applied magnetic field (HTT) were performed in vacuum at 600°C for 20 min. HTT was applied parallel and perpendicular to the substrate surface. Magnetic M(H) measurements reveal the coexistence of a strong antiferromagnetic (AFM) signal and a ferromagnetic (FM) component. The AFM component has a Néel temperature higher than room temperature, the spin axis lies parallel to the substrate surface, and the highest magnetic moment m =7 µB/Co at. is obtained when HTT is applied parallel to the substrate surface. Our results show an enhancement of FM moment per Co(+2) from 0.06 to 0.42 µB/Co at. for the sample on which HTT was applied perpendicular to the surface. The FM order is attributed to the coupling of Co(+2) ions through electrons trapped at the site of oxygen vacancies, as described by the bound magnetic polaron model. Our results suggest that FM order is aligned along [101] direction of Co-doped SnO2 nanocrystals, which is proposed to be the easy magnetization axis.

Role of vanadium ions, oxygen vacancies, and interstitial zinc in room temperature ferromagnetism on ZnO-V2O5 nanoparticles.

In this work, we present the role of vanadium ions (V+5 and V+3), oxygen vacancies (VO), and interstitial zinc (Zni) to the contribution of specific magnetization for a mixture of ZnO-V2O5 nanoparticles (NPs). Samples were obtained by mechanical milling of dry powders and ethanol-assisted milling for 1 h with a fixed atomic ratio V/Zn?=?5% at. For comparison, pure ZnO samples were also prepared. All samples exhibit a room temperature magnetization ranging from 1.18?×?10-3 to 3.5?×?10-3 emu/gr. Pure ZnO powders (1.34?×?10-3 emu/gr) milled with ethanol exhibit slight increase in magnetization attributed to formation of Zni, while dry milled ZnO powders exhibit a decrease of magnetization due to a reduction of VO concentration. For the ZnO-V2O5 system, dry milled and thermally treated samples under reducing atmosphere exhibit a large paramagnetic component associated to the formation of V2O3 and secondary phases containing V+3 ions; at the same time, an increase of VO is observed with an abrupt fall of magnetization to σ?~?0.7?×?10-3 emu/gr due to segregation of V oxides and formation of secondary phases. As mechanical milling is an aggressive synthesis method, high disorder is induced at the surface of the ZnO NPs, including VO and Zni depending on the chemical environment. Thermal treatment restores partially structural order at the surface of the NPs, thus reducing the amount of Zni at the same time that V2O5 NPs segregate reducing the direct contact with the surface of ZnO NPs. Additional samples were milled for longer time up to 24 h to study the effect of milling on the magnetization; 1-h milled samples have the highest magnetizations. Structural characterization was carried out using X-ray diffraction and transmission electron microscopy. Identification of VO and Zni was carried out with Raman spectra, and energy-dispersive X-ray spectroscopy was used to verify that V did not diffuse into ZnO NPs as well to quantify O/Zn ratios.

Changes in hepatitis A virus seroepidemiology in HIV-infected Brazilian patients.

Shifting of hepatitis A virus (HAV) epidemiology from a high towards an intermediate endemicity pattern and use of antiretroviral therapy increased the risk of HIV/HAV coinfection in developing countries. The aim of this study was to investigate the presence of HAV markers in a cohort of HIV-infected patients from 1988 to 2004. The presence of serum anti-HAV antibodies and HAV-RNA by real-time polymerase chain reaction was investigated in 581 patients. Total anti-HAV antibodies was found in 464/581 (79.8%) patients, however, a changing epidemiologic pattern of hepatitis A among HIV-infected patients from 1988 to 2004 was observed. Among patients susceptible to HAV (n = 117), 5 (4.2%) were coinfected with HAV, all of them had IgM anti-HAV antibodies and were serum HAV-RNA-positive. The high prevalence of anti-HAV antibodies in HIV-infected patients suggests that screening tests for anti-HAV antibodies should be performed before implementation of hepatitis A vaccination, especially in those patients from endemic countries.

Soroprevalência da sífilis em gestantes HIV-negativas, obtida de três testes diagnósticos: VDRL, ELISA, TPHA / Syphilis seroprevalwence in HIV-negative pregnant women, using tree diagnostic tests: VDRL, ELISA M and TPHA

A sífilis é uma infecçäo crônica com diversas manifestaçöes clínicas que ocorrem ao longo de estágios variados. Apesar do seu declínio última década, tem sido, novamente, um importante problema de saúde pública. No Brasil, a média de prevalência é de 4 por cento pelo VDRL, em gestantes atendidas em serviços públicos. Na gestaçäo constitui problema importante, pela gravidade das lesöes e pela possiblidade real da profilaxia medicamentosa. É grande a dificuldade de se proceder ao diagóstico nesta fase, e ainda sim, mesmo com tratamento apropriado, durante a gestaçäo a infecçäo fetal poderá ocorrer em mais de 14,0 por cento dos casos. O presente trabalho objetiva determinar a soroprevalência da sífilis por meio da realizaçäo de prova de VDRL confirmada por teste específico

Genotypic and phenotypic evidence of different drug-resistance mutation patterns between B and non-B subtype isolates of human immunodeficiency virus type 1 found in Brazilian patients failing HAART.

We have investigated the phenotypic and genotypic susceptibility of 14 HIV-1 strains isolated from individuals failing HAART therapy to protease inhibitors (PI). Proviral and plasma viral pol gene fragment were amplified, sequenced and subtyped. Nine samples clustered with protease subtype B reference strains and the remaining samples were classified as non-B subtype corresponding to subtype F (n = 4) and subtype A (n = 1). Although all patients were treated with similar P1 drug regimen, the non-B subtype isolates did not present the L90M and 184V mutations and used mainly G48V and V82A/F to achieve drug resistance. A strong cross-resistance phenotype among all four PI was associated with the mutation L90M in the subtype-B isolates, and with G48V and V82A/F in the non-B counterparts. This observation revealed that the non-B viruses tested had specific genotypic characteristics contrasting with the subtype-B isolates.

Drug-resistant reverse transcriptase genotyping and phenotyping of B and non-B subtypes (F and A) of human immunodeficiency virus type I found in Brazilian patients failing HAART.

Development of drug resistance is the inevitable consequence of incomplete suppression of virus plasma levels in HIV-1-infected patients treated with highly active antiretroviral therapy. Resistance mutations previously characterized have been found in B subtype viruses of developed countries. Moreover, mutation profiles for non-B and more divergent B subtype viruses found in developing countries shall be analyzed together with their ex vivo phenotyping in order to establish an exact correlation between the genotyping data and the clinical management counseling for those uncommon virus subtypes. In the present study, we evaluated the mutation profile for individuals infected with B subtype and non-B subtype viruses. Viral DNA fragments corresponding to the RT gene were amplified, sequenced, and subtyped. Phenotyping analysis for reverse transcriptase nucleoside (NRTI) and nonnucleoside inhibitor susceptibility was performed using the recombinant virus assay technology. Brazilian non-B subtypes (subtype F, n = 4, and subtype A, n = 1) isolates showed essentially the same B subtype mutation profile, presenting an NRTI drug resistance with similar MIC50% and MIC90% values for all drugs analyzed regardless of their subtypes. A strong cross-resistance phenotype among AZT, 3TC, and abacavir could be seen in all isolates analyzed. A novel result was that some RT sequences not only revealed the presence of G333D/E mutations but also correlated to the presence of mutation T386I that could abrogate the M184V-surpassing effect of L210W or L210W plus G333D/E. These findings suggest that Brazilian non-B subtype HIV-1 strains use an identical RT drug resistance mutation pattern when compared to B isolates and will contribute to the validation of the genotypic and phenotypic tests in these predominant worldwide-spread viral variants.

Immune complex-dissociated p24 antigenemia in the diagnosis of human immunodeficiency virus infection in vertically infected Brazilian children.

PIP: A retrospective cohort study evaluated the presence of immune complex-dissociated (ICD) p24 antigen in frozen plasma samples of 40 children born to HIV-seropositive mothers and followed in the outpatient clinic of Gaffree-Guinle University Hospital. ICD has been helpful in the early diagnosis of infants born of HIV-seropositive mothers within the first 2 months of life. After testing all charts were reviewed for evidence of HIV-related clinical findings and determination of HIV serology until the child reached 24 months of age. The children were all born to HIV-infected Brazilian women between 1984 and 1992. 17 boys (mean age at first evaluation for HIV infection, 17.3 months) and 23 girls (mean age at first evaluation, 16.8 months) were included. Of the 17 boys, 9 were Caucasian and 8 were African-Brazilian; 11 girls were Caucasian and 12 were African-Brazilian. An immune complex disruption procedure was performed at the Universidade do Rio de Janeiro on 100-mcl aliquots of serial plasma samples from the 40 patients enrolled. 200 mcl of treated plasma were then assayed for the presence of p24 antigen through a quantitative enzyme immunoassay. 21 of 40 (52%) infants were identified as HIV-infected through persistent HIV seropositivity after 18 months of age. ICD p24 antigen was detected in at least 1 plasma specimen from 15 of 21 (71.4%) of HIV-infected children, whereas p24 antigen was present in 11 of 21 (52.4%) children infected with HIV. The sensitivity of ICD p24 antigen in diagnosing HIV infection in this cohort of children was 71.4%, whereas that of p24 antigen was 52.4%. The highest mean titers of HIV ICD p24 antigen were observed between 7 and 12 months of life. A history of breast-feeding was present in 18 of 21 (86%) of the HIV-infected infants and in only 5 of 19 (26%) of the uninfected children (p 0.001). In 21 HIV-infected children, 12 (57%) were asymptomatic and 9 (43%) were symptomatic at the time the first ICD p24 antigen test was obtained.^ieng

A simplified surveillance case definition of AIDS derived from empirical clinical data. The Clinical AIDS Study Group, and the Working Group on AIDS case definition.

A clinical AIDS case definition is needed for surveillance in countries where the CDC case definition is not practical. To derive such a definition, we compared 110 HIV-seropositive and 135 randomly selected HIV-seronegative adult medical-ward inpatients in Brazil. Multivariate analysis of clinical signs and symptoms and simple diagnoses resulted in a discriminant function with sensitivity of 89% and specificity of 96% in predicting for AIDS. These data were the empirical basis for a clinical definition of AIDS in adults drafted in a Caracas, Venezuela, workshop sponsored by the Pan American Health Organization. The revised "Caracas" definition presented here requires a positive HIV serology, the absence of cancer or other cause of immunosuppression, plus > or = 10 cumulative points, as follows: Kaposi's sarcoma (10 points); extrapulmonary/noncavitary pulmonary tuberculosis (10); oral candidiasis or hairy leukoplakia (5); cavitary pulmonary/unspecified tuberculosis (5); herpes zoster < 60 years of age (5); CNS dysfunction (5); diarrhea > or = 1 month (2); fever > or = 1 month (2); cachexia or > 10% weight loss (2); asthenia > or = 1 month (2); persistent dermatitis (2); anemia, lymphopenia, or thrombocytopenia (2); persistent cough or any pneumonia except TB (2); and lymphadenopathy > or = 1 cm at > or = 2 noninguinal sites for > or = 1 month (2). This definition has a sensitivity of 95% and a specificity of 100% (91% without HIV serology) when applied to the Brazilian patients in this study. The Caracas definition has been adopted by Brazil, Honduras, and Surinam, and is in validation elsewhere. The use of a reasonably sensitive and specific case definition commensurate with available diagnostic resources should facilitate AIDS surveillance in developing countries.

Identification of mixed HIV-1/HIV-2 infections in Brazil by polymerase chain reaction.

Analysis of sera from hospitalized Brazilian patients by whole-virus lysate-based enzyme immunoassay and Western blot indicated that 0.4% were reactive to HIV-2 alone while 4% were reactive to both HIV-1 and HIV-2. When these sera were tested for HIV antibody by type-specific peptide enzyme immunoassays, dual seropositivity was confirmed in only 0.4% of patients. To define genetically the HIV strains within the population, we analyzed peripheral blood mononuclear cells from selected seropositive patients for the presence of HIV-1 and HIV-2 proviral DNA using the polymerase chain reaction (PCR). Independent primers/probes sets were used for the amplification and detection of viral sequences from the long terminal repeat (LTR), gag, and protease (prt) gene regions. Our findings confirmed the serologic evidence of HIV-2 in Brazil and determined the extent of mixed HIV-1 and HIV-2 infections. Detailed evaluation of the amplified viral protease sequences by endonuclease restriction analysis and DNA sequencing independently confirmed mixed HIV-1 and HIV-2 infections in the two patients seropositive for HIV-1 and HIV-2. The data further indicated that these isolates are distinct from the HIV laboratory standards. We interpret the combination of culture and PCR findings to demonstrate the presence of both HIV-1 and HIV-2 in Brazil.

Immunological abnormalities of acquired immunodeficiency syndrome and related disorders in patients from Rio de Janeiro, Brazil

Alteraçöes imunológicas na Síndrome de Imunodeficiência Adquirida em pacientes do Rio de Janeiro, Brasil. O perfil imunológico de 15 pacientes com Síndrome de Imunodeficiência Adquirida (AIDS) e 11 com Síndrome de Linfadenipatia Crônica, foram estudados. Os pacientes com AIDS mostraram reduzida percentagem de linfócitos T (CD3) totais e T auxiliares (CD4), aumento relativo no número de linfócito T-supressores (CD8) e uma marcante inversäo na relaçäo T-auxiliares/supressores (CD4/CD8). A resposta linfoproliferativa para PHA, ConA, PPD e PWN, estava diminuída. Foi também observado hipergamaglobulinemia e níveis aumentados de complexos imunes circulantes. Os pacientes com Síndrome de Linfadenopatia Crônica também mostraram importantes alteraçöes imunológicas, mas näo täo intensas como nos de AIDS. Estes dados säo similares aos observados nos Estados Unidos e na Europa (U)

Immunological abnormalities of acquired immunodeficiency syndrome and related disorders in patients from Rio de Janeiro, Brazil.

The immunological profile of acquired immunodeficiency syndrome (AIDS) and chronic lymphadenopathy syndrome (CLAS) in 15 and 11 Brazilian patients, respectively, was studied. The AIDS patients showed reduced percentage of total T (CD3) and T-helper-inducer (CD4) lymphocytes, relative increase in numbers of T-suppressor-cytotoxic (CD8) cells and a marked inversion of T-helper-inducer/suppressor-cytotoxic (CD4/CD8) ratio. Lymphoproliferative responses to PHA, ConA, PPD and PWM were diminished. Hypergammaglobulinemia and high levels of circulating immune complexes were also found. The CLAS patients also showed important immunological alterations, but not so intense as those with AIDS. These data seems to be similar to those observed in other parts of the world.

Isolation and antigenic characterization of human immunodeficiency virus (HIV) in Brazil.

A retrovirus infecting a Brazilian AIDS patient was isolated and characterized in terms of its reactivity with sera from individuals infected with human immunodeficiency viruses 1 and 2 (HIV-1 and HIV-2). The Western blot analysis revealed that the Brazilian isolate is very similar to the well characterized HIV-1 strain. The serum of the patient from whom the virus was isolated did not react with the 140 kDa envelope glycoprotein specific for HIV-2.

Detection of IgG-bearing erythrocytes by a sensitive Staphylococcus aureus protein A-binding radioassay: possible usefulness for the differential diagnosis of connective tissue diseases.

We describe a sensitive radioassay for detecting erythrocyte-associated immunoglobulin employing the immunoglobulin-specific reagent Staphylococcus aureus protein A. The assay was used to determine the extent to which erythrocytes from patients with different connective tissue disease bind radiolabelled protein A. Increased amounts of protein A were bound by erythrocytes from patients with systemic lupus erythematosus or with progressive systemic sclerosis when compared to a control group, whereas there was no significant binding to erythrocytes from patients with rheumatoid arthritis or with polymyositis-dermatomyositis. The assay, because of its high sensitivity and of the availability of the reagent in pure form, should be useful for the investigation of cell-bound antibodies and for the differential diagnosis of connective tissue diseases.