Rheumatoid Diseases Involving the Cervical Spine I. History, Definition, and Diagnosis: New Trends and Technologies.

The cervical spine might be involved in several conditions: congenital, traumatic, and chronic inflammatory and or degenerative rheumatic disorders. Among the inflammatory rheumatic conditions that can affect the cervical spine, rheumatoid arthritis (RA) is the most common, affecting up to 86% of patients and leading to cervical spine instability and subsequent myelopathy. Other inflammatory diseases include juvenile idiopathic arthritis (JIA) and the spondyloarthritis group (SpA), including psoriatic arthritis. Since many patients do not show symptoms of cervical involvement, diagnosis is often delayed. Radiographs are the first line imaging modality used to detect such involvement, but MRI and CT are superior in terms of early diagnosis and surgical planning.In this review, we provide an overview of cervical involvement in RA, JIA, and SpA.

New perspectives on the evolutionary history of hepatitis B virus genotype F.

Hepatitis B virus (HBV) is a globally distributed human pathogen. The aim of this work was to analyze the evolutionary history of HBV genotype F, emphasizing on the study of subgenotypes prevalent in the Southern area of South America. Complete genomes of HBV genotype F from 36 samples from Argentina and Chile were sequenced and analyzed by phylogenetic and Bayesian coalescent methods along with sequences obtained from GenBank database. The phylogeography separated not only Central American from South American isolates but also revealed that different subgenotypes are distributed in constrained although not exclusive areas of the continent. The result obtained with time-stamped complete genomes failed to explain the wide geographical distribution and the clustering observed in this genotype. Conversely, the use of Bayesian coalescent analyses with substitution rates as priors, instead of the co-estimation of tMRCA and substitution rate, allowed us to propose a far origin for the HBV genotype F based on the phylogeographical and epidemiological data.

Diversity of hepatitis B and C viruses in Chile.

Although there is a low prevalence rate (around 1% of the population) of infection with hepatitis B virus (HBV) and hepatitis C virus (HCV) in Chile, little is known about the diversity and molecular characteristics of the circulating viruses. In the present study, 40 HBV and 57 HCV samples from Santiago City, Chile, were examined. The phylogenetic analysis of HBV samples showed the autochthonous genotype F as the most represented genotype in the study (67.5%), while genotypes A, B, C, and D were less frequent (7.5%, 5%, 7.5%, and 12.5%, respectively). The frequency of circulation of HBV genotypes observed is in accordance with the genetic background of the Chilean population. Most of the HCV samples tested belonged to subtype 1b (82%). The coalescent analysis conducted for both the NS5A and NS5B regions of the HCV strains showed similar population growth rates, with a most recent common ancestor estimated to date between 1893 and 1901. This result may indicate that genotype 1b strains circulating in Chile have epidemiological features similar to those described for HCV genotype 1b in Brazil and the United States. However, the most recent common ancestor for Chile is older than that reported recently for genotype 1b in Argentina.

Molecular characterization of hepatitis B virus genotype A from Argentina and Brazil.

To study the diversification of hepatitis B virus genotype A in Latin America, we analyzed seven new Argentinian isolates and published sequences from Argentina and Brazil and other countries from the region. We found that the European subgenotype A2 prevailed in most of the countries except for Brazil, where the African subgenotype A1 predominated. A2 isolates did not differ significantly from the GenBank sequences, whereas some A1 isolates carried, concomitantly, amino acids characteristic of the subgenotypes A3 (R(501) in P protein) and A2 (D(355) in P/T(54) in preS2). This combination is absent in the A1 subgenotype around the world. We discuss the origin, distribution and introduction of those subgenotypes in the Americas.

Hepatitis B virus genetic diversity in Argentina: dissimilar genotype distribution in two different geographical regions; description of hepatitis B surface antigen variants.

BACKGROUND: The hepatitis B virus (HBV) molecular epidemiological data of Argentina are still scarce, since most of the previous analyses have been performed in the Metropolitan Region. OBJECTIVES: To deepen the current molecular and epidemiological information about the geographical distribution of HBV genotypes and subgenotypes, and to describe the hepatitis B surface antigen (HBsAg) variants circulating in Argentina. STUDY DESIGN: Eighty-eight Argentine partial HBsAg sequences from both the Northern and the Metropolitan Regions of the country were analyzed along with 67 Argentine HBV sequences existing in GenBank. RESULTS: Phylogenetic and amino acid sequence analysis grouped the 88 samples as genotypes A (14.8%), D (21.6%) and F (63.6%). In the Northern Region, 44 out of the 48 sequences analyzed (91.7%) grouped as genotype F. Differently, in the Metropolitan Region, the 40 samples grouped as genotype F (30.0%), genotype D (42.5%), and genotype A (27.5%). An elevated proportion (14.8%) of the genomes presented mutations in the major hydrophilic region (MHR). CONCLUSIONS: The different genotype distribution in both Argentine regions indicates that the epidemiological landscape of HBV infection appears to be the result of the diverse human migratory movements that have given shape to the present population. Our findings show that the prevalence of HBsAg variants is quite significant among the Argentine population.

Molecular epidemiology of hepatitis B virus in Latin America.

Hepatitis B virus (HBV) is an etiological agent of acute and chronic liver disease existing throughout the world. The high genetic variability of HBV is reflected by eight genotypes (A to H), each one with a particular geographical prevalence. The global pattern of HBV genotypes is associated with the distribution of human populations among the different continents and may reflect the patterns of human migrations. Genotypes F and H are considered indigenous to Latin America. The most prevalent genetic group of Central and South America, genotype F, is subdivided into two subtypes and five clusters associated with defined geographic areas. Genotype H has been described in Mexico and Central America. This pattern provides a tool to reconstruct the initial immigration of ancestral Amerindians from Asia and their further spread through Central and South America. Other HBV genotypes found in different Latin American countries may reflect migration from other geographical areas into the region. Genotypes A and D are the signature of the European colonization that started in the sixteenth century, including slave trade from Africa. Genotypes B and C indicate the arrival of people from Southeast Asia. The impact of HBV genotypes on the natural course of HBV infection and response to treatment has been studied recently and controversial results have been obtained. The majority of the current information concerns with genotypes B and C. In contrast, very few data are available on the Latin American HBV genotypes F and H. It has been reported that liver failure and death may be more frequent in patients infected with genotype F. More studies are needed to assess the association between H13V genotypes and clinical course of infection, especially in Latin America.

Evolutionary history of Hepatitis B virus genotype F: an in-depth analysis of Argentine isolates.

A revised analysis on the evolutionary history of hepatitis B virus (HBV) genotype F is herein presented with the incorporation of two new complete genomes from Argentina. The study of the phylogenetic-tree topology, genetic distances, and amino acid mutations confirmed with high reliability the existence of four different genetic clusters of this genotype. Argentine isolates were located in two groups of viruses that showed a great inner homogeneity but, interestingly, divergence between them was in the order of that existing among groups from different locations. Although the origin of these two viral populations is not clear, they do not seem to derive from each other, therefore the existence of at least two founder viral populations in Argentina is a more acceptable explanation.