Qualitative and quantitative aspects of recent research on helminth parasites

Relationships between the species diversity of different taxa, the mean number of articles published per year on each taxon, and the mean impact factor of the journals in which they appear, were examined across six taxa of helminths: Nematomorpha, Acanthocephala, Monogenea, Trematoda, Cestoda and Nematoda, the latter including only animal parasitic nematodes. The mean annual output of scientific articles per taxon was not related to the species diversity of these taxa or, at least, not significantly. Thus, the large volume of publications on nematodes is not merely a reflection of their estimated diversity. There were significant differences among taxa in the mean impact factor of the journals in which papers on each taxon appeared, with nematodes having the highest mean score, followed by trematodes and cestodes. In addition, across the six taxa, the mean journal impact factor correlated positively and significantly with the mean annual number of papers published: not only are there more papers published on nematodes and trematodes than on nematomorphs or acanthocephalans, but they are also generally published in higher-ranking journals. These results suggest that there is an increasing gap in the quantity and general importance of the research carried out on different helminth taxa.     

Qualitative and quantitative aspects of intercalator-induced DNA strand breaks.

The intercalating agents, adriamycin and ellipticine, were previously found to produce DNA strand breaks associated with DNA-protein crosslinks in mouse leukemia L1210 cells. The current work explores the nature of the agents that produce this effect and the quantitative relationship between the breaks and crosslinks. The protein-associated DNA breaks were produced by a wide variety of intercalators in addition to the above-mentioned compounds: actinomycin D, daunoycin, ethidium and lucanthone (miracil D). Treatment with several drugs that bind to DNA without intercalation, or that inhibit DNA synthesis without binding to DNA, did not cause DNA breaks. The strand break and crosslink frequencies were quantitated by means of alkaline elution methods. The strand break and crosslink frequencies were found to be within a factor of 2 of each other over a range of concentrations of adriamycin and ellipticine. It is proposed that intercalation-induced distortion of the DNA helix leads to strand scission by a nuclease which becomes bound to one terminus of the break so as to form a DNA-protein crosslink.     

Reproduction of the anaphylactic reaction of isolated human smooth muscle organs and the effect of several adrenotropic substances]

A comparative study was carried out of passive sensitization of the lungs, bronchi, small and large intestine by the blood sera of patients sensitive to ambrosia pollen. Passive sensitization and subsequent anaphylactic contraction were reproduced on the isolated bronchi, lungs and the ileum. Development of this reaction was less constant in the large intestine, jejunum and the appendix. The value of anaphylactic reaction of human smooth muscle displayed significant changes with the treatment of the muscles by agents selectively acting on the beta-adrenergic receptors of these organs.     

Qualitative and quantitative aspects of 2-5A synthesizing capacity of different marine sponges

2-5A synthetase is an important component of the mammalian antiviral 2-5A system. At present, the existence of 2-5A synthetase in the lowest animals, the marine sponges, has been demonstrated, although this enzyme has not been found in bacteria, yeast or plants. Here, we studied the 2-5A synthesizing capacity and the product profile of a variety of marine sponges belonging to Demospongia subclasses Tetractinomorpha and Ceractinomorpha. The 2-5A synthetase activity varied largely, in the range of four orders of magnitude, depending on the sponge species. Compared with the enzymes of the mammalian 2-5A synthetase family, the most active sponge species exhibited a surprisingly high 2-5A synthetase specific activity. Unlike the mammalian 2-5A synthetases that produce 2-5A oligomers in the presence of a double-stranded RNA activator, the 2-5A synthetase(s) from sponges were active without the addition of dsRNA. The sponge species differed in their product profiles. A novel product pool formed by Chondrosia reniformis was identified as a series of long 2-5A oligomers (up to 17-mers) with the prevalence of heptamers and octamers. The large variability of qualitative and quantitative characteristics of sponge 2-5A synthetases may refer to the occurrence of a variety of 2-5A synthetase isozymes in sponges.