Tomographic techniques for the study of exceptionally preserved fossils

Three-dimensional fossils, especially those preserving soft-part anatomy, are a rich source of palaeontological information; they can, however, be difficult to work with. Imaging of serial planes through an object (tomography) allows study of both the inside and outside of three-dimensional fossils. Tomography may be performed using physical grinding or sawing coupled with photography, through optical techniques of serial focusing, or using a variety of scanning technologies such as neutron tomography, magnetic resonance imaging and most usefully X-ray computed tomography. This latter technique is applicable at a variety of scales, and when combined with a synchrotron X-ray source can produce very high-quality data that may be augmented by phase-contrast information to enhance contrast. Tomographic data can be visualized in several ways, the most effective of which is the production of isosurface-based ‘virtual fossils’ that can be manipulated and dissected interactively

Association between human parvovirus B19 and arthropathy in Belém, Pará, north Brazil Associação entre parvovírus B19 e artropatias em Belém, Pará, norte do Brasil

A total of 220 patients with arthropathy were selected in Belém, Pará between January 1994 and December 2000, and screened for the presence of human parvovirus B19 IgM and IgG antibodies by enzyme-linked immunosorbent assay (ELISA). A subgroup (n = 132) of patients with high levels of antibodies (either IgM+/IgG+ or IgM-/IgG+) were examined for the presence of DNA by polymerase chain reaction/nested PCR. Recent/active infection (detection of IgM and/or IgG-specific antibodies and presence of viral DNA) was identified in 47.7% of the 132 individuals with arthropathy. In our study, women were significantly more affected (59.7%) than men (35.4%) (P = 0.0006). The age group of 11-20 years (84.6%), among female patients, and 21-30 years (42.1%), among male, were those with the highest incidence rates. The analysis of the temporal distribution of B19-associated arthropaties showed a cyclic pattern, with peak incidence rates occuring at 3-5 year intervals. Significant diference (P = 0.01) was observed when comparing both the highest (39.0%) and the lowest (11.0%) seropositivity rates for the years of 1995 and 2000, respectively. The interfalangial joints of hands and feet were mostly affected, with 50.0% and 48.0% of cases among both women and men, respectively. In a smaller proportion, other joints such as those of knee, ankle, pulse and shoulder were affected. As for the duration, symptoms lasted 1 to 5 days in 54.0% of the individuals, whereas in 46.0% of them the disease lasted 6-10 days, if considered the subgroup (n = 63) of patients with recent/active infection by parvovirus B19. In our study, joint clinical manifestations occurred symmetrically. Our results indicate that B19 may be an important agent of arthropathies in our region, and this underscores the need for specific laboratory diagnosis when treating patients suffering from acute arthropathy, mainly pregnant women.<br>Um total de 220 indivíduos portadores de artropatias foi selecionado em Belém, Pará, entre janeiro de 1994 e dezembro de 2000 e, posteriormente, examinado com o propósito de se detectarem anticorpos IgM e IgG para o parvovírus B19, utilizando-se a técnica imunoenzimática (ELISA). Um subgrupo (n = 132) de indivíduos com amostras de soro apresentando altos níveis de anticorpos (IgM+/IgG+ e IgM-/IgG+) foi usado para detecção de DNA do B19 através da reação em cadeia da polimerase (PCR) e do "nested" PCR. Infecção recente/ativa (detecção de IgM e/ou IgG mais a presença de DNA viral) foi diagnosticada em 47,7% dos 132 indivíduos apresentando comprometimento das articulações. O sexo feminino foi mais afetado (59,7%) que o masculino (35,4%), com diferença estatisticamente significativa (P = 0,0006). Os grupos etários mais atingidos foram os de 11-20 anos (84,6%), no sexo feminino, e 21-30 anos (42,1%), no masculino. A análise da distribuição temporal mostrou um padrão cíclico, com períodos de maior e menor atividade viral que variam de 3 a 5 anos. Diferença estatisticamente significativa (P = 0,01) foi observada quando comparadas as freqüências de positividade mais alta (39,0%) e mais baixa (11,0%) para os anos de 1995 e 2000, respectivamente. As articulações mais atingidas foram, em ordem de freqüência, as interfalangianas de mãos e pés, com 50,0% e 48,0% para o sexo feminino e masculino, respectivamente. Em menor proporção outras articulações tais como as do joelho, tornozelo, pulso e ombro foram afetadas. Quanto à duração das manifestações articulares, 54,0% evoluíram por 1-5 dias, e 46,0% ao longo de 6-10 dias, considerando o subgrupo (n = 63) de indivíduos com infecção recente/ativa para o B19 em ambos os sexos. Em nosso estudo, o comprometimento das articulações apresentou caráter simétrico. Os resultados encontrados demonstraram o freqüente acometimento articular associado às infecções recentes/ativas por parvovírus B19, ressaltando a necessidade do diagnóstico laboratorial dessa virose, principalmente entre gestantes