Distribution of insertion element IS1 in natural isolates of Escherichia coli

Total DNAs from twelve natural isolates of Escherichia coli from animals and humans were examined by hybridization with a probe for IS1. Considerable variation in copy number was found. In the case of two strains isolated from the same individual, one strain contained no copies of IS1 and the other, much greater than 30. Evidence was also obtained for the existence of IS1-like elements (iso-IS1s) of greater than 15% sequence divergence relative to the IS1 from antibiotic resistance plasmid R100.

Distribution of the insertion sequence IS1 in gram-negative bacteria

Translocation of DNA segments is a recombinational event seen in both eukaryotic and prokaryotic chromosomes, and it is thought to be involved in controlling gene expression and in the evolution of chromosomes. In bacteria, insertion (IS) and transposable (Tn) elements not only translocate their own DNA, but also promote the rearrangement of both bacterial chromosomes and the plasmic genomes carrying them. The insertion element IS1 is one such element which is 768 base pairs long. IS1 is involved in the generation of deletion mutations and in the fusion of two different plasmid genomes. It can also promote the translocation of DNA segments flanked by two copies of IS1 to give rise to transposable elements responsible for antibiotic resistance and enterotoxin production. We report here the distribution of the IS1 sequence in various bacterial DNAs, particularly in the family Enterobacteriaceae. Comparison of the results with the phylogenetic relationship of these bacteria suggests that IS1 was transferred from one bacterium to another after their divergence and in some bacteria the copy number of IS1 increased by translocation. The increase in the number of copies of IS1 in bacteria may increase the probability of the genetic rearrangement responsible for the generation of resistance and enterotoxin plasmids, the existence of which is a serious problem in medical microbiology.

Pulse methylprednisolone in rheumatoid arthritis: a double-blind cross-over trial

Ten patients with rheumatoid arthritis unresponsive to conventional therapy participated in a double-blind cross-over trial in which they randomly received either a "pulse" or 1 g of methylprednisolone or placebo, intravenously, once a month for 6 months. Both the drug-first and placebo-first groups had the same mean American Rheumatism Association functional classification, 2.5. During the study patients on methylprednisolone "pulses," compared to placebo, showed significantly better mean tender-joint counts, walking times, and grip strength (p < 0.05). The drug-treated patients also had significantly lower levels of immune complexes (p < 0.01) and IgG (p < 0.01). Effects could still be measured an average of 2.9 +/- 0.4 months after the last dose of methylprednisolone. No significant side effects were noted during the therapy. Despite these findings, "pulse" methylprednisolone did not appear to significantly retard radiologic progression of the arthritis.

Prolonged thoracic-duct drainage in rheumatoid arthritis and systemic lupus erythematosus

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Genetic determination of lipopolysaccharide: locus of O-specific unit polymerase in group E of salmonella

By genetic analysis of a semirough mutant of Salmonella muenster we show that a gene determining the polymerization of the repeating units of the O-3, 10-type lipopolysaccharide side chain in Salmonella of group E resides in the his-linked rfb cluster.

Genetic mapping of the antigenic determinants of two polysaccharide K antigens, K10 and K54, in Escherichia coli

The genes controlling synthesis of the Escherichia coli acidic polysaccharide capsular antigens K10 and K54 were transferred by conjugation to E. coli strains of other serotypes. The genes concerned with these K antigen determinants showed genetic linkage with the serA locus. We propose to name the K antigen-controlling gene kpsA. The genetic determinants of the two K antigens could also be transferred to enteropathogenic serotypes, even though such strains have never been found in nature with special acidic polysaccharide K antigens. A noncapsulated derivative, K(-), of the K10 strain can transfer the genetic determinant of the K antigen, demonstrating the probable existence of another chromosomal locus involved in the production of such acidic polysaccharide K antigens.

National health insurance in Finland: its impact and evaluation

Relationships between medical services research and health policy are examined in the light of a study evaluating a major health policy measure in Finland, the national health insurance scheme introduced in 1964. A nationwide health interview survey was made immediately prior to introduction of the scheme and again four years later. The results show that the ratio between care obtained and care needed had become more uniform among various population groups after the inception of national health insurance than previously. Only a small increase was found in the overall utilization rates of most types of health services. Also, the number of restricted activity days did not increase with the introduction of daily sickness allowances. In spite of minor deficiencies, the changes caused by the implementation of the national health insurance seem to have been in accordance with its main objectives. However, the results suggest that financial arrangements, i.e., health insurance, must be accompanied by other measures (in Finland an increase in the supply of ambulatory health services) if the objectives of health policy are to be obtained on a more satisfactory scale. The applicability of this evaluation study to the planning of other health activities is also discussed.