Maximum-likelihood divergence date estimates based on rRNA gene sequences suggest two scenarios of Trypanosoma cruzi intraspecific evolution.

The phylogenetic relationships of Trypanosoma cruzi strains were inferred using maximum-likelihood from complete 18S rDNA sequences and D7-24Salpha rDNA regions from 20 representative strains of T. cruzi. For this we sequenced the 18S rDNA of 14 strains and the D7-24Salpha rDNA of four strains and aligned them to previously published sequences. Phylogenies inferred from these data sets identified four groups, named Riboclades 1, 2, 3, and 4, and a basal dichotomy that separated Riboclade 1 from Riboclades 2, 3, and 4. Substitution models and other parameters were optimized by hierarchical likelihood tests, and our analysis of the 18S rDNA molecular clock by the likelihood ratio test suggests that a taxa subset encompassing all 2,150 positions in the alignment supports rate constancy among lineages. The present analysis supports the notion that divergence dates of T. cruzi Riboclades can be estimated from 18S rDNA sequences and therefore, we present alternative evolutionary scenarios based on two different views of T. cruzi intraspecific divergence. The first assumes a faster evolutionary rate, which suggests that the divergence between T. cruzi I and II and the extant strains occurred in the Tertiary period (37-18 MYA). The other, which supports the hypothesis that the divergence between T. cruzi I and II occurred in the Cretaceous period (144-65 MYA) and the divergence of the extant strains occurred in the Tertiary period of the Cenozoic era (65-1.8 MYA), is consistent with our previously proposed hypothesis of divergence by geographical isolation and mammalian host coevolution.

Typing of Candida glabrata in clinical isolates by comparative sequence analysis of the cytochrome c oxidase subunit 2 gene distinguishes two clusters of strains associated with geographical sequence polymorphisms.

We tested whether comparative sequence analysis of the mitochondrion-encoded cytochrome c oxidase subunit 2 gene (COX2) could be used to distinguish intraspecific variants of Candida glabrata. Mitochondrial genes are suitable for investigation of close phylogenetic relationships because they evolve much faster than nuclear genes, which in general exhibit very limited intraspecific variation. For this survey we used 11 clinical isolates of C. glabrata from three different geographical locations in Brazil, 10 isolates from one location in the United States, 1 American Type Culture Collection strain as an internal control, and the published sequence of strain CBS 138. The complete coding region of COX2 was amplified from total cellular DNA, and both strands were sequenced twice for each strain. These sequences were aligned with published sequences from other fungi, and the numbers of substitutions and phylogenetic relationships were determined. Typing of these strains was done by using 17 substitutions, with 8 being nonsynonymous and 9 being synonymous. Also, cDNAs made from purified mitochondrial polyadenylated RNA were sequenced to confirm that our sequences correspond to the expressed copies and not nuclear pseudogenes and that a frameshift mutation exists in the 3' end of the coding region (position 673) relative to the Saccharomyces cerevisiae sequence and the previously published C. glabrata sequence. We estimated the average evolutionary rate of COX2 to be 11.4% sequence divergence/10(8) years and that phylogenetic relationships of yeasts based on these sequences are consistent with rRNA sequence data. Our analysis of COX2 sequences enables typing of C. glabrata strains based on 13 haplotypes and suggests that positions 51 and 519 indicate a geographical polymorphism that discriminates strains isolated in the United States and strains isolated in Brazil. This provides for the first time a means of typing of Candida strains that cause infections by use of direct sequence comparisons and the associated divergence estimates.

Epidemiological study on high grade trauma. Friuli VG Major Trauma Study Group.

A better understanding of trauma epidemiology may allow to enhance the organisation of trauma systems with a potentially relevant impact on the level of trauma care. A one year epidemiology study (1st March 1998-28th February 1999) was planned in Friuli Venezia Giulia with the aim to collect all prehospital, hospital and outcome data of patients who sustained a major trauma (ISS > 15) within the regional border. In 12 months 15,429 traumatized patients (14,108 residents) were admitted to any one of the Regional hospitals. Over 1% of the whole population sustained injuries severe enough to cause hospital admission. 630 people (77.3% male, 27.7% female average age 42 ys) had a major trauma. The incidence of major trauma is 525 per million people per year. RTA was by far the most important cause of major injuries (78.6%) followed by work accidents (6.8%), domestic (5.9%) and sport accidents (1.9%). Only 1.2% of all the major injuries was the consequence of interpersonal violence. One hundred-sixty-six trauma victims died on the spot (149) or before hospital arrival (17). 464 patients with major injuries reached the hospital alive. More than two third of the patients with ISS > 15, suffered from a multiple trauma. 70% had a severe injury to the head (AIS > or = 3). Head trauma occurred as an isolated injury in only 35.3%. Hospital mortality within 30 days from admission (trauma death) was 25.1%. The results of the follow-up at 6 months are still incomplete. However the preliminary data clearly show that a high percentage of the patients who were discharged alive from the ICU had a good neurologic recovery.