Magnetoelectric effects in the spiral magnets CuCl2 and CuBr2.

The nature and symmetry of transition mechanisms in the spin-spiral copper halides CuCl2 and CuBr2 are analyzed theoretically. The magnetoelectric effects observed in the two multiferroic compounds are described and their phase diagram at zero and applied magnetic fields are worked out. The emergence of the electric polarization at zero field below the paramagnetic phase is shown to result from the coupling of two distinct spin-density waves and to be only partly related to the Dzialoshinskii-Moriya interactions. Applying a magnetic field along the two-fold monoclinic axis of CuCl2 yields a decoupling of the spin-density waves modifying the symmetry of the phase and the spin-spiral orientation. The remarkable periodic dependences of the magnetic susceptibility and polarization, on rotating the field in the monoclinic plane, are described theoretically.

Genetic control of leaf curl in maize.

Among the many implications of climatic change on agriculture, drought is expected to continue to have a major impact on agribusinesses. Leaf curling is an anatomical characteristic that might be potentially used to enhance plant tolerance to water deficit. Hence, we aimed to study the genetic control of leaf curl in maize. From 2 contrasting inbred lines for the trait, generations F1, F2, and the backcrosses were obtained. All of these generations were evaluated in a randomized block design with 2 replicates. Leaf curl samples were collected from 3 leaves above the first ear at the tasseling stage, and quantified by dividing the width of the leaf blade with natural curling against its extended width. The mean and variance components were estimated by the weighted least square method. It was found that the trait studied has predominance of the additive effects, with genetic control being attributed to few genes that favor selection and exhibit minimal influence from the environment.

Noroviruses associated with acute gastroenteritis in a children's day care facility in Rio de Janeiro, Brazil.

Noroviruses (Norwalk-like viruses) are an important cause of gastroenteritis worldwide. They are the most common cause of outbreaks of gastroenteritis in the adult population and occur in nursing homes for the elderly, geriatric wards, medical wards, and in hotel and restaurant settings. Food-borne outbreaks have also occurred following consumption of contaminated oysters. This study describes the application of a reverse transcription-polymerase chain reaction (RT-PCR) assay using random primers (PdN6) and specific Ni and E3 primers, directed at a small region of the RNA-dependent RNA polymerase-coding region of the norovirus genome, and DNA sequencing for the detection and preliminary characterisation of noroviruses in outbreaks of gastroenteritis in children in Brazil. The outbreak samples were collected from children <5 years of age at the Bertha Lutz children's day care facility at Oswaldo Cruz Foundation (Fiocruz), Rio de Janeiro, that occurred between 1996 and 1998, where no pathogen had been identified. At the Bertha Lutz day care center facility, only Fiocruz's employee children are provided for, and they come from different social, economic and cultural backgrounds. Three distinct genogroup II strains were detected in three outbreaks in 1997/98 and were most closely related to genotypes GII-3 (Mexico virus) and GII-4 (Grimsby virus), both of which have been detected in paediatric and adult outbreaks of gastroenteritis worldwide.

Prevalence of human cytomegalovirus infection in pregnant and non-pregnant women.

OBJECTIVES: To determine human cytomegalovirus (HCMV) cervical reactivation in both pregnant and non-pregnant women and to ascertain whether or not it occurs in conjunction with hematogenic dissemination. METHODS: Clinical specimens were obtained from 40 pregnant and 62 non-pregnant women attended at the Ambulatory of the Gynecology-Obstetrics Unit of the Federal University of Espírito Santo (UFES) in Southeastern Brazil. Specimens under investigation were blood samples submitted to seroprevalence determination, antigenemia assay, HCMV-DNA detection, and vaginal secretion, submitted to HCMV-DNA detection. RESULTS: Viral seroprevalence was found in 98% of the women investigated, two of whom were found to be IgM positive, while no difference could be determined between pregnant and non-pregnant women. Antigenemia assay was negative in all cases. HCMV gB gene amplification was found in 5.1 and 8.5% of WBCs and in 10 and 14.5% of vaginal secretion from pregnant and non-pregnant women, respectively. CONCLUSION: The high seroprevalence observed is in accordance with previous Brazilian surveys. Antigenemia assay was unable to detect the occurrence of active infection in the immunocompetent women studied, most likely because it either occurred in a viral load undetectable by this assay or did not occur at all. Although the highest incidence of positivity was observed by gene amplification both in WBCs and secretion from non-pregnant than in pregnant women, the rate of viral detection was statistically similar for both groups.

Noroviruses associated with acute gastroenteritis in a children's day care facility in Rio de Janeiro, Brazil

Noroviruses (Norwalk-like viruses) are an important cause of gastroenteritis worldwide. They are the most common cause of outbreaks of gastroenteritis in the adult population and occur in nursing homes for the elderly, geriatric wards, medical wards, and in hotel and restaurant settings. Food-borne outbreaks have also occurred following consumption of contaminated oysters. This study describes the application of a reverse transcription-polymerase chain reaction (RT-PCR) assay using random primers (PdN6) and specific Ni and E3 primers, directed at a small region of the RNA-dependent RNA polymerase-coding region of the norovirus genome, and DNA sequencing for the detection and preliminary characterisation of noroviruses in outbreaks of gastroenteritis in children in Brazil. The outbreak samples were collected from children <5 years of age at the Bertha Lutz children's day care facility at Oswaldo Cruz Foundation (Fiocruz), Rio de Janeiro, that occurred between 1996 and 1998, where no pathogen had been identified. At the Bertha Lutz day care center facility, only Fiocruz's employee children are provided for, and they come from different social, economic and cultural backgrounds. Three distinct genogroup II strains were detected in three outbreaks in 1997/98 and were most closely related to genotypes GII-3 (Mexico virus) and GII-4 (Grimsby virus), both of which have been detected in paediatric and adult outbreaks of gastroenteritis worldwide.

Primary human herpesvirus-6 and -7 infections, often coinciding, misdiagnosed as measles in children from a tropical region of Brazil.

We investigated primary human herpesvirus-6 and -7 (HHV-6, HHV-7) infections as a cause of rashes incorrectly diagnosed as measles in Brazilian children. Sera from 124 patients, aged 4 months to 17 years, from the states of Rio de Janeiro and Espirito Santo, in whom measles, rubella and parvovirus B19 infections had been excluded, were studied using indirect immunofluorescence antibody avidity tests; 38 (31%) had evidence of primary HHV-6 and/or HHV-7 infections. Twenty four children had primary HHV-6 infection, either recent or coincident with the rash, and similarly 31 had primary HHV-7 infection. Remarkably, almost half (17) of primary infections were dual HHV-6 and HHV-7 infections with the majority, 12 (71%), in children less than 1 year old. HHV-7 infection occurred earlier than previously reported, perhaps due to socioeconomic and tropical conditions in this region of Brazil, and thus coincided with the HHV-6 infections. This study also highlights the difficulties of diagnosing a rash illness on clinical grounds alone.

Comparative sequence analysis of the P-, M- and L-coding region of the measles virus CAM-70 live attenuated vaccine strain

Measles virus is a highly contagious agent which causes a major health problem in developing countries. The viral genomic RNA is single-stranded, nonsegmented and of negative polarity. Many live attenuated vaccines for measles virus have been developed using either the prototype Edmonston strain or other locally isolated measles strains. Despite the diverse geographic origins of the vaccine viruses and the different attenuation methods used, there was remarkable sequence similarity of H, F and N genes among all vaccine strains. CAM-70 is a Japanese measles attenuated vaccine strain widely used in Brazilian children and produced by Bio-Manguinhos since 1982. Previous studies have characterized this vaccine biologically and genomically. Nevertheless, only the F, H and N genes have been sequenced. In the present study we have sequenced the remaining P, M and L genes (approximately 1.6, 1.4 and 6.5 kb, respectively) to complete the genomic characterization of CAM-70 and to assess the extent of genetic relationship between CAM-70 and other current vaccines. These genes were amplified using long-range or standard RT-PCR techniques, and the cDNA was cloned and automatically sequenced using the dideoxy chain-termination method. The sequence analysis comparing previously sequenced genotype A strains with the CAM-70 Bio-Manguinhos strain showed a low divergence among them. However, the CAM-70 strains (CAM-70 Bio-Manguinhos and a recently sequenced CAM-70 submaster seed strain) were assigned to a specific group by phylogenetic analysis using the neighbor-joining method. Information about our product at the genomic level is important for monitoring vaccination campaigns and for future studies of measles virus attenuation.

Comparative sequence analysis of the P-, M- and L-coding region of the measles virus CAM-70 live attenuated vaccine strain.

Measles virus is a highly contagious agent which causes a major health problem in developing countries. The viral genomic RNA is single-stranded, nonsegmented and of negative polarity. Many live attenuated vaccines for measles virus have been developed using either the prototype Edmonston strain or other locally isolated measles strains. Despite the diverse geographic origins of the vaccine viruses and the different attenuation methods used, there was remarkable sequence similarity of H, F and N genes among all vaccine strains. CAM-70 is a Japanese measles attenuated vaccine strain widely used in Brazilian children and produced by Bio-Manguinhos since 1982. Previous studies have characterized this vaccine biologically and genomically. Nevertheless, only the F, H and N genes have been sequenced. In the present study we have sequenced the remaining P, M and L genes (approximately 1.6, 1.4 and 6.5 kb, respectively) to complete the genomic characterization of CAM-70 and to assess the extent of genetic relationship between CAM-70 and other current vaccines. These genes were amplified using long-range or standard RT-PCR techniques, and the cDNA was cloned and automatically sequenced using the dideoxy chain-termination method. The sequence analysis comparing previously sequenced genotype A strains with the CAM-70 Bio-Manguinhos strain showed a low divergence among them. However, the CAM-70 strains (CAM-70 Bio-Manguinhos and a recently sequenced CAM-70 submaster seed strain) were assigned to a specific group by phylogenetic analysis using the neighbor-joining method. Information about our product at the genomic level is important for monitoring vaccination campaigns and for future studies of measles virus attenuation.

Cytomegalovirus in human abortion in Espírito Santo, Brazil.

BACKGROUND: Despite the established implication of human cytomegalovirus (HCMV) in congenital infection, there are still conflicting reports regarding the association of HCMV with spontaneous abortion. Viral antigens and nucleic acid were already described in tissues from abortions cases, but did not indicate HCMV pathogenical role. OBJECTIVES: (1) To access viral seroprevalence (total and IgM antibodies) in pregnant, non-pregnant and in women in abortion process, (2) to evaluate if antigenemia assay can detect active infection in these populations, (3) to detect viral DNA in peripheral leukocytes, and (4) in abortion tissues. STUDY DESIGN: Blood samples from 95 patients in abortion process and from two control groups (40 pregnant and 60 non-pregnant women) were obtained for determination of viral seroprevalence, for detection of antigen and viral DNA by PCR from peripheral leukocytes. Specimens obtained from 88 patients in abortion process, spontaneous or induced, were submitted to gB gene amplification (PCR and nested-PCR). RESULTS: Viral seroprevalence were found in 97.3 with 2.5% of IgM positive cases. Antigenemia assay were negative in all cases, however, viral nucleic acid were found in 6.3 and in 6.0% of the patients in abortion and in control groups, respectively. Nucleic acid in conception tissue was present in 6.6%. CONCLUSION: This high seroprevalence observed is according to previous surveys in Brazil. If active infection due to viral reactivation occurred during the abortion process, it cannot be accessed by antigenemia or anti-IgM assays. Nucleic acid found by PCR in peripheral blood cells enriched with polymorphonuclear cells (PMN) corresponds to viral circulation in immunocompetent person, as similar results were found for the three groups. Although viral DNA had been found in 6.6% from abortion tissues, this result does not support HCMV as a major abortion-related factor as we could not found any correlation between abortion and active HCMV infection.

Human parvovirus B19 infection in HIV-positive patients.

Parvovirus B19 infects predominantly erythroid cells, leading to transient inhibition of erythropoiesis. Immunocompromised patients may be unable to produce neutralizing antibodies and may develop severe chronic anemia. Epidemiological studies done on Niterói population showed that B19 infection occurs periodically in late spring and summer. We report a study from 55 HIV infected patients attending an infectious diseases outpatient clinic in this city during a 5-month period in which B19 circulation was well documented. All patients were under anti-retroviral therapy. No anti-B19 IgM was found, but a high prevalence of IgG anti-B19 (91%) was observed. In six patients, B19 DNA was found by dot-blot hybridization techniques, but this was not confirmed by PCR. None of these 6 patients manifested anemia and only one had CD4 cell count below 200 x 10(7)/L. We conclude that persistent infection causing anemia is an infrequent finding in our HIV positive patients under drug therapy.

Papular-purpuric "gloves and socks" syndrome due to parvovirus B19: report of a case with unusual features.

We present a case of papular-purpuric "gloves and socks" syndrome (PPGSS) in an adult male with acute parvovirus B19 infection. The patient displayed the classical features of fever, oral lesions, and purpura on hands and feet, but the purpuric lesions on the feet evolved to superficial skin necrosis, a feature not previously described in this syndrome. We believe this is the first reported case of PPGSS occurring in Brazil.

Anti-VP1 and anti-VP2 antibodies detected by immunofluorescence assays in patients with acute human parvovirus B19 infection.

Acute human parvovirus B19 infection is followed by an antibody response to the structural proteins of the viral capsid (VP1 and VP2). We used 80 sera collected from 58 erythema infectiosum and 6 transient aplastic crisis patients to test IgM and IgG antibodies against these two proteins in an immunofluorescence assay (IFA) using Sf9 cells infected with recombinant baculovirus expressing either VP1 or VP2 antigen. Although less sensitive than IgM capture enzyme immunoassay using native antigen (MACEIA), we could detect anti-VP1 or anti-VP2 IgM antibodies by IFA in 49 patients with acute infection (76.6%). Detection of IgG anti-VP1 and anti-VP2 by IFA, however, was as sensitive as IgG detection by indirect enzyme immunoassay. By applying IgG avidity IFA to sera of the 15 IgM IFA negative patients we were able to confirm acute infection in further 12 cases by IFA. Overall, acute infection was confirmed by IFA in 61 (95.3%) of the 64 patients.

Human parvovirus B19 infection in HIV-positive patients

Parvovirus B19 infects predominantly erythroid cells, leading to transient inhibition of erythropoiesis. Immunocompromised patients may be unable to produce neutralizing antibodies and may develop severe chronic anemia. Epidemiological studies done on Niterói population showed that B19 infection occurs periodically in late spring and summer. We report a study from 55 HIV infected patients attending an infectious diseases outpatient clinic in this city during a 5-month period in which B19 circulation was well documented. All patients were under anti-retroviral therapy. No anti-B19 IgM was found, but a high prevalence of IgG anti-B19 (91%) was observed. In six patients, B19 DNA was found by dot-blot hybridization techniques, but this was not confirmed by PCR. None of these 6 patients manifested anemia and only one had CD4 cell count below 200 x 10(7)/L. We conclude that persistent infection causing anemia is an infrequent finding in our HIV positive patients under drug therapy.

O parvovírus B19 infecta predominantemente células eritróides, causando inibição transitória da eritropoiese. Pacientes imunocomprometidos podem ser incapazes de produzir anticorpos neutralizantes, evoluindo com grave anemia crônica. Estudos epidemiológicos da população de Niterói mostraram que a infecção ocorre periodicamente no final da primavera e no verão. Descrevem-se 55 pacientes infectados pelo HIV atendidos num ambulatório de doenças infecciosas nesta cidade num período de cinco meses, no qual a circulação do parvovírus B19 foi documentada. Todos os pacientes estavam sob terapia anti-retroviral. Não se encontrou IgM anti-B19, mas notou-se uma prevalência alta de IgG anti-B19 (91%). Em seis pacientes verificou-se a presença de DNA do B19 por hibridização em dot-blot, o que não se confirmou por PCR. Nenhum destes seis pacientes tinha anemia, e apenas um tinha células CD4 abaixo de 200 x 107/L. Conclui-se que infecção persistente causando anemia é um achado infreqüente em nossos pacientes HIV positivos sob terapia medicamentosa.

Two family members with a syndrome of headache and rash caused by human parvovirus B19.

Human parvovirus B19 infection can cause erythema infectiosum (EI) and several other clinical presentations. Central nervous system (CNS) involvement is rare, and only a few reports of encephalitis and aseptic meningitis have been published. Here, we describe 2 cases of B19 infection in a family presenting different clinical features. A 30 year old female with a 7-day history of headache, malaise, myalgias, joint pains, and rash was seen. Physical examination revealed a maculopapular rash on the patient's body, and arthritis of the hands. She completely recovered in 1 week. Two days before, her 6 year old son had been admitted to a clinic with a 1-day history of fever, headache, abdominal pain and vomiting. On admission, he was alert, and physical examination revealed neck stiffness, Kerning and Brudzinski signs, and a petechial rash on his trunk and extremities. Cerebrospinal fluid analysis was normal. He completely recovered in 5 days. Acute and convalescent sera of both patients were positive for specific IgM antibody to B19. Human parvovirus B19 should be considered in the differential diagnosis of aseptic meningitis, particularly during outbreaks of erythema infectiosum. The disease may mimic meningococcemia and bacterial meningitis.

Aplastic crisis caused by parvovirus B19 in an adult patient with sickle-cell disease.

We describe a case of aplastic crisis caused by parvovirus B19 in an adult sickle-cell patient presenting with paleness, tiredness, fainting and dyspnea. The absence of reticulocytes lead to the diagnosis. Anti-B19 IgM and IgG were detected. Reticulocytopenia in patients with hereditary hemolytic anemia suggests B19 infection.

Genome type analysis of Brazilian adenovirus strains of serotypes 1,2,3,5, and 7 collected between 1976 and 1995.

A collection of 92 epidemiologically unrelated isolates of Ad1 (n = 14), Ad2 (n = 29), Ad3 (n = 19), Ad5 (n = 16), and Ad7 (n = 14) collected in the cities of Belem do Pará (1 degree S 48 degrees W) and Rio de Janeiro (23 degrees S 43 degrees W) between 1976 and 1995 from patients with respiratory disease and conjunctivitis were characterized by restriction enzyme analysis of genomic DNA. Among the strains of subgenus B, two different genome types of serotype 7, 7b and 7e, were identified. The analysis of their temporal distribution throughout the study period suggested an alternating appearance of these two DNA variants. Only one genome type of Ad3, 3p, was detected during the sampling period. Further analysis with Xba I, Bcl I, and Hpa I indicated that it is a p1-like genome type. Both previously described and new genomic variants were identified among subgenus C strains. Genome types D1, D7, D10, and one not previously described were identified among the 14 Ad1 strains analyzed. Genome types D2, D5, D25, and 13 new DNA variants were identified among the 29 Ad2 isolates. Genome type D38 and 5 new variants were found among the 16 strains of Ad5. In spite of the relatively small size of the sample analyzed, the results of this study confirm the important genetic variability previously observed for members of subgenus C by other authors.

Feto-placentary pathology in human parvovirus B19 infection.

In view of the scarce references concerning the histological data in congenital parvovirus human B19 infection, we intend to provide a description of the pathological features observed in six autopsies. The virus was detected by DNA hybridization (ISH-DBH), PCR and electronmicroscopy (EM) in paraffin-embedded feto-placentary tissues. These cases constitute a subset from 86 Non Immunologic Hydrops Fetalis (NIHF) cases, in which a systemic complex of inflammatory/degenerative lesions of unknown etiology was visualized by optical microscopy. In one case a syphilitic process was detected, typefying a double infection. All fetuses showed a similar pathology--hydrops, hepato-splenomegaly, lung hypoplasia and erythroblastemia, the specific histological feature being the presence of intranuclear inclusions in the erythroid progenitors, in the erythropoietic visceral tissue and in blood marrow. Complex cardiopathy allied to abnormal lung lobulation and polisplenia were observed once; in 2 cases endocardial fibroelastosis was diagnosed. The pulmonary lesions were represented by dysmaturity allied to interstitial mononuclear infiltration. The hepatic consisted of cholestasis, portal fibrosis, canalicular proliferation, hemossiderosis, focal necroses and giant cell transformation. The central nervous system lesions were predominantly anoxic although the autolysis impaired a correct diagnosis.

Genetic an antigenic analysis of adenovirus type 3 strains showing intermediate behavior in standard seroneutralization test.

During an epidemiological survey of acute respiratory infection in Rio de Janeiro, among 208 adenovirus isolates, we found two strains that we were not able, by a standard neutralization procedure, to distinguish between type 3 or 7. However, DNA restriction pattern for the two strains with different enzymes were analyzed and showed a typical Ad3h profile. Using a cross-neutralization test in which both Ad3p and Ad7p antisera were used in different concentration against 100 TCID50 of each adenovirus standard and both isolates, we were able to confirm that the two isolates belong to serotype 3. An hemagglutination inhibition test also corroborated the identification of both strains as adenovirus type 3. Comparing Ad3h and Ad3p genome, we observed 16 different restriction enzyme sites, three of which were located in genomic regions encoding polypeptides involved in neutralization sites.

Enteroviruses isolated from patients with acute respiratory infections during seven years in Rio de Janeiro (1985-1991).

Enteroviruses were investigated in respiratory secretions collected from patients with acute respiratory infections (ARI) over a seven year period (1985-1991), as part of a longitudinal study of ARI aetiology. All the viruses that are most commonly associated with ARI were found in this study. Among the virus isolates, enteroviruses were only less frequent than respiratory syncytial viruses, adenoviruses and influenzaviruses. Forty five enterovirus samples were isolated from patients with either upper respiratory tract infections (URTI) or lower respiratory tract infections (LRTI). From these enterovirus isolates, thirty one samples were identified as poliovirus (n = 18) and non polio enterovirus (n = 13) by serum neutralization. Poliovirus were identified as type 1 and 2 and all of them were vaccinal strains. From thirteen non polio enterovirus, twelve were identified as echovirus serotypes 1, 2, 7, 11, 19 and 31. The remainder was identified as coxsackievirus B4.