No abstract

We report the entire sequence (2864 nts) and secondary structure of the nuclear small subunit ribosomal RNA (SSU rRNA) gene (18S) from the twisted-wing parasite Caenocholax fenyesi texensis Kathirithamby & Johnston (Strepsiptera: Myrmecolacidae). The majority of the base pairings in this structural model map on to the SSU rRNA secondary and tertiary helices that were previously predicted with comparative analysis. These regions of the core rRNA were unambiguously aligned across all Arthropoda. In contrast, many of the variable regions, as previously characterized in other insect taxa, had very large insertions in C. f. texensis. The helical base pairs in these regions were predicted with a comparative analysis of a multiple sequence alignment (that contains C. f. texensis and 174 published arthropod 18S rRNA sequences, including eleven strepsipterans) and thermodynamic-based algorithms. Analysis of our structural alignment revealed four unusual insertions in the core rRNA structure that are unique to animal 18S rRNA and in general agreement with previously proposed insertion sites for strepsipterans. One curious result is the presence of a large insertion within a hairpin loop of a highly conserved pseudoknot helix in variable region 4. Despite the extraordinary variability in sequence length and composition, this insertion contains the conserved sequences 5'-AUUGGCUUAAA-3' and 5'-GAC-3' that immediately flank a putative helix at the 5'- and 3'-ends, respectively. The longer sequence has the potential to form a nine base pair helix with a sequence in the variable region 2, consistent with a recent study proposing this tertiary interaction. Our analysis of a larger set of arthropod 18S rRNA sequences has revealed possible errors in some of the previously published strepsipteran 18S rRNA sequences. Thus we find no support for the previously recovered heterogeneity in the 18S molecules of strepsipterans. Our findings lend insight to the evolution of RNA structure and function and the impact large insertions pose on genome size. We also provide a novel alignment template that will improve the phylogenetic placement of the Strepsiptera among other insect taxa.

The Mayo Clinic records linkage facility for residents of Rochester, Minnesota, Yielded 102 cases of ankylosing spondylitis (AS) diagnosed from 1935 through 1973. The incidence did not change significantly over the 39 years. Three times as many males as females were affected. In contrast to another recent report, survivorship of males with AS was not different from that of the general population, whereas survivorship of females with AS was reduced. The overall prevalence was 129/100,000.

Fourteen patients with systemic lupus erythematosus had splenectomies done between 1960 and 1982 for treatment of severe thrombocytopenia. Thrombocytopenia persisted or recurred within 1 month postoperatively in five patients and within 6 months in three others. Three patients had late recurrence (18, 30, and 54 months after splenectomy); in two it was probably related to withdrawal of immunosuppressive agents or corticosteroids. Median lowest platelet count before splenectomy and median platelet count at relapse or failure of splenectomy were both 8000/microL. Only two patients maintained normal platelet counts without need for corticosteroids or other treatment. These results differ from those in patients with idiopathic thrombocytopenic purpura. Other treatments should be tried before splenectomy is done for thrombocytopenia in patients with systemic lupus erythematosus.