Complete mitochondrial genomes confirm the distinctiveness of the horse-dog and sheep-dog strains of Echinococcus granulosus

Unlike other members of the genus, Echinococcus granulosus is known to exhibit considerable levels of variation in biology, physiology and molecular genetics. Indeed, some of the taxa regarded as 'genotypes' within E. granulosus might be sufficiently distinct as to merit specific status. Here, complete mitochondrial genomes are presented of 2 genotypes of E. granulosus (G1-sheep-dog strain: G4-horse-dog strain) and of another taeniid cestode, Taenia crassiceps. These genomes are characterized and compared with those of Echinococcus multilocularis and Hymenolepis diminuta. Genomes of all the species are very similar in structure, length and base-composition. Pairwise comparisons of concatenated protein-coding genes indicate that the G1 and G4 genotypes of E. granulosus are almost as distant from each other as each is from a distinct species, E. multilocularis. Sequences for the variable genes atp6 and nad3 were obtained from additional genotypes of E. granulosus, from E. vogeli and E. oligarthrus. Again, pairwise comparisons showed the distinctiveness of the G1 and G4 genotypes. Phylogenetic analyses of concatenated atp6, nad1 (partial) and cox1 (partial) genes from E. multilocularis, E. vogeli, E. oligarthrus, 5 genotypes of E. granulosus, and using T. crassiceps as an outgroup, yielded the same results. We conclude that the sheep-dog and horse-dog strains of E. granulosus should be regarded as distinct at the specific level.

Responsiveness, affinity constants and beta-adrenoceptor reserves for isoprenaline on aortae from normo-, pre and hypertensive rats

The objective of this study was to determine the responsiveness, affinity constants and beta-adrenoceptor reserves for isoprenaline on the isolated aorta in the maturation of normotensive and hypertensive rats. The effects of a very slowly reversible antagonist, bromoacetylalprenololmenthane (BAAM), on the relaxant responses of the aortae of 5- and 14-week-old Wistar Kyoto normotensive rats (WKY) and spontaneously hypertensive rats (SHRs) to isoprenaline were determined. Five-week-old SHRs are pre-hypertensive and the aortic rings are less responsive to isoprenaline than age-matched WKY (pD(2) values: WKY, 8.40; SHRs, 8.03). Similar relaxant responses to forskolin were obtained on the aortae of 5- and 14-week-old WKY and SHRs. The K-A value for isoprenaline at the aortic beta(2)-adrenoceptors of the 5-week-old WKY was 2.1 x 10(-7) M, and similar values were obtained on the aortae of 5-week-old SHR and 14-week-old WKY and SHRs. In the maturation of the WKY aortae from 5 to 14 weeks, there was a reduction in the maximum response, a major loss of sensitivity and a loss of 2-adrenoceptor reserve for isoprenaline. On 5-week-old SHR aorta, the sensitivity to isoprenaline was 2.5-fold lower, and the beta(2)-adrenoceptor reserve was less than on age-matched WKY. In the development of hypertension on the SHR aorta from 5 to 14 weeks, there was a reduction in the maximum response to isoprenaline. At 14 weeks, the sensitivity and the 2-adrenoceptor reserve to isoprenaline were similar, but the maximum responses were lower on the SHR than WKY. As there are differences in pre-hypertensive SHR and age-matched WKY aortic responses to isoprenaline, it is no longer valid to consider that the loss of responsiveness to isoprenaline in hypertension is solely owing to the hypertension. There are no changes in affinity, but major changes in the sensitivity, maximum responses and aortic beta(2)-adrenoceptor reserves to isoprenaline in the maturation of normotensive and pre-hypertensive aortae.

Functional beta(1)- and beta(2)-adrenoceptors in the left and right atrium of pre-hypertensive rats

There is a small increase in the functional beta(2)-adrenoceptor response on the spontaneously hypertensive rat (SHR) left atrium in the early stages of hypertension. In the present study, the functional beta(1)- and beta(2)-adrenoceptors of the left and right atrium in SHR pre-hypertension and age-matched (5-week-old) Wistar Kyoto (WKY) rats were characterized. Contractility methods with isoprenaline, T-0509 (a selective beta(1)-adrenoceptor agonist) and procaterol (a selective beta(2)-adrenoceptor agonist) were used. At 5 weeks, the SHRs were pre-hypertensive. Isoprenaline was more potent on the left atrium of 5-week-old SHRs than WKY rats. Bisoprolol, a selective beta(1)-adrenoceptor antagonist, was more potent against isoprenaline and T-0509 on the SHR than WKY rat left atrium. ICI 118,551, a selective beta(2)-adrenoceptor antagonist, was more potent against procaterol and T-0509 on the SHR than WKY rat left atrium. The results with bisoprolol and ICI 118,551 suggest that there are more functional beta(1)- and beta(2)-adrenoceptors on the left atrium of 5-week-old SHRs than WKY rats. Isoprenaline, T-0509 and procaterol were equipotent on the right atrium of 5-week-old WKY rats and SHRs. Bisoprolol was more potent against isoprenaline, T-0509 and procaterol on the SHR than WKY rat right atrium. ICI 118,551 was more potent against T-0509, but not isoprenaline and procaterol, on the SHR than WKY rat left atrium. This suggests there are more functional beta(1)-adrenoceptors, and probably more functional beta(2)-adrenoceptors, on the right atrium of 5-week-old SHRs than WKY rats. These functional differences in beta(1)-and beta(2)-adrenoceptor-mediated responses of the left and right atria of pre-hypertensive SHRs cannot be caused by hypertension, and may be associated with the onset of hypertension.

Immunogenicity of recombinant HBsAg/HCV particles in mice pre-immunised with hepatitis B virus-specific vaccine

Due to their spatial structure virus-like particles (VLPs) generally induce effective immune responses. VLPs derived from the small envelope protein (HBsAg-S) of hepatitis B virus (HBV) comprise the HBV vaccine. Modified HBsAs-S VLPs, carrying the immunodominant hypervariable region (HVR1) of the hepatitis C virus (HCV) envelope protein E2 within the exposed 'a'-determinant region (HBsAg/HVR1-VLPs), elicited HVR1-specific antibodies in mice. A high percentage of the human population is positive for anti-HBsAg antibodies (anti-HBs), either through vaccination or natural infection. We, therefore, determined if pre-existing anti-HBs could influence immunisation with modified VLPs. Mice were immunised with a commercial HBV vaccine, monitored to ensure an anti-HBs response, then immunised with HBsAg/HVR1-VLPs. The resulting anti-HVR1 antibody titre was similar in mice with or without pre-existing anti-HBs. This suggests that HBsAg/HVR1-VLPs induce a primary immune response to HVR1 in anti-HBs positive mice and, hence, they may be used successfully in individuals already immunised with the HBV vaccine. (C) 2003 Elsevier Science Ltd. All rights reserved.

Systematic review of the role of pre-oxygenation for tracheal suctioning in ventilated newborn infants

Pre-oxygenation for endotracheal suctioning for mechanically ventilated infants is routine practice in many neonatal intensive care units. In the present systematic review the evidence to support its use is discussed and the authors conclude that no confident recommendations can be made from the results of this review.