Characterization of a 54-nucleotide gap region in the 28S rRNA gene of Schistosoma mansoni

We have analyzed 572 bp in the 28S rDNA of the human blood fluke Schistosoma mansoni which correspond to expansion segment 5 of domain IV as defined by Clark et al. for the Xenopus laevis 28S rRNA. S1 nuclease mapping and primer extension analysis comparing this region with the mature 28S rRNA indicate that there are 54 nucleotides present in the 28S rDNA which are absent from the mature rRNA. This defines a gap that creates two 28S rRNA subunits (28S alpha and 28S beta). Comparison of the S. mansoni sequence with rDNAs of other organisms which contain gaps in their 28S rRNA shows that the overall features are conserved except that the S. mansoni gap is less A + T-rich. The conserved features include: (1) the location of the gap within the 28S rRNA; (2) the predicted secondary structure of the gap, containing a stem-loop with a UAAU sequence within the loop; and (3) a conserved CGAAAGGG on the 3' side of the gap.

[Anti-inflammatory effect of aconitines]

Aconitines are the total alkaloids isolated from the main root of Aconitum carmichaeli. They have marked suppressive effect on the swelling of rat's hind paw induced by injections of fresh egg protein, carrageenin, histamine and 5-HT, on the mouse's ear oedema induced by bimethylphenyl, on the exudate and proliferation of granulation tissue of granuloma pouch induced by croton oil, on the leukocyte migration and on the contents of PGE in the exudate of the swelling hind paw induced by injecting carrageenin. Aconitines have been found useful in inhibiting significantly such immune inflammations as reversible passive Arthus reaction, rat's delayed skin hypersensitivity and adjuvant arthritis. They have also a noticeable analgesic effect.

Effects of activating spinal alpha-adrenoreceptors on sympathetic nerve activity in the rat

The effects of several alpha-adrenoreceptor agonists and antagonists administered intrathecally at T10 level on renal sympathetic nerve activity (RSNA) were examined, in chloralose-urethane anaesthetised rats. Intrathecal noradrenaline (NA, 0.5-500 micrograms) produced one of 3 responses depending on dose, an inhibition of RSNA at low doses, an excitation of RSNA at high doses, or a biphasic effect. Intrathecal adrenaline (5-200 micrograms) was inhibitory in the main but some doses elicited poorly repeatable brief excitation followed by prolonged inhibition. Intrathecal methoxamine (ME; 2.5 ng-25 micrograms) caused a dose-dependent increase in RSNA (mean maximum response 27 +/- 0.5%). The excitatory effects of NA and ME were blocked (72% +/- 12%) by pretreatment with intrathecal prazosin (PRA, 20-200 ng) but not by yohimbine (YOH, 200 ng). Intrathecal guanabenz (GUA 3-15 micrograms) caused a dose-dependent inhibitory effect on RSNA (mean maximum 32% +/- 5%). The inhibitory effects of NA, adrenaline and GUA were blocked by pretreatment with intrathecal YOH (200 ng-2 micrograms). Intrathecal PRA (200 ng) had no effect on the inhibitory effects of NA and GUA. Intravenous administration of each of the adrenoreceptor agonists (apart from adrenaline), at similar doses to those given intrathecally, in most cases had no significant effect on RSNA; in a few cases the opposite effects to those produced by intrathecal administration were seen.