Leif Nilsson

Plasticity of contractile endothelin‐B receptors in human arteries after organ culture

1 The pharmacology and mRNA expression of endothelin (ET) receptors in human omental arteries were characterized by use of functional contractile assays and the reverse transcriptase‐polymerase chain reaction (RT‐PCR). 2 In freshly obtained segments of human omental arteries, ET‐1 and ET‐3 induced concentration‐dependent contractions which were normalized to the response produced by 60 mM K+. ET‐1 produced a maximum contraction (Emax) amounting to 151 ± 17% of the K+ response. The pEC50 for this agonist was 8.64 ± 0.17. The effect of ET‐3 was less pronounced (Emax: 71 ± 22% and pEC50: 6.69 ± 0.17) than that of ET‐1. The ET receptors involved were characterized with FR139317 (a selective ETA receptor antagonist), PD 145065 (a mixed ETA and ETB receptor antagonist) and BQ 788 (an ETB receptor antagonist). A high concentration of these antagonists (10 μm) abolished the contractile responses to ET‐3, and produced a parallel rightward shift of the ET‐1 concentration‐response curve without changing the maximal effect. FR 139317 and PD 145065 were equally effective while BQ 788 was much less effective. This is consistent with ETA receptors mediating contraction in human omental arteries. 3 Arterial segments cultured for 5 days in serum‐free Dulbeccos medium at 37°C under sterile and humidified conditions retained contractility although responses to 60 mM K+ were somewhat reduced. ET‐3 was significantly more potent in the cultured arteries (pEC50: 8.56 ± 0.15) and achieved a greater maximum effect (Emax: 116 ± 19%). Responses were not antagonised by FR 139317 but were competitively blocked by PD 145065 and BQ 788 with the latter antagonist being the more potent. In contrast Emax (179 ± 17%) and pEC50 (8.66 ± 0.23) values for ET‐1 were not significantly different from those obtained with fresh arteries. PD 145065 still demonstrated a rightward shift of the ET‐1‐induced concentration‐response curve, whereas FR 139317 and BQ 788 caused non‐significant shifts. These findings suggest that functional ETB receptors contribute significantly to the endothelin contractile response in cultured arteries. 4 Two‐site analysis of the ET‐1 induced concentration‐response curve from cultured arteries suggests that ETB receptors, at the high potency component, and ETA receptors, at the low potency component, contribute both to the contractile response in relative proportion of 70% and 30%, respectively. Further analysis suggested that the ETA receptor would be capable of evoking at least 75% of the ET‐1 contraction in the absence of ETB receptors, although with a lower potency as compared to fresh arteries. 5 Electrophoresis of RT‐PCR products from the smooth muscle layer of freshly obtained human arteries indicated the presence of mRNA for both ETA and ETB receptors. Arteries cultured for 1 and 5 days demonstrated an increase of mRNA for the ETB receptor as compared to the ETA receptor. The identities of the PCR products were verified by restriction enzyme digestion. 6 In freshly obtained human omental arteries, the contractile effects of endothelins appear to be mediated predominantly by the ETA receptor subtype, with a negligible contribution by ETB receptors. Cultured arterial segments, however, exhibited a substantial ETB receptor mediated contractile response and an increase in ETB receptor mRNA content, consistent with an upregulation of functional ETBreceptors. These in vitro data suggest plasticity in the smooth muscle cell expression of contractile ETBreceptors.

Surgical treatment versus thrombolysis in acute arterial occlusion: A randomised controlled study

Thrombolytic treatment has been tried in various forms for acute limb ischaemia with varying degrees of success but is also often accompanied by bleeding problems. The present investigation compares the effect of surgical thrombectomy (TE) and thrombolysis (TL) using recombinant tissue plasminogen activator (rt-PA). Twenty patients with a need for intervention owing to ischaemia lasting more than 24 h but less than 14 days were included. Patients randomised to TE were operated under epidural anaesthesia and patients in the TL group received 30 mg rt-PA during a 3 h period through a catheter placed into the thrombus and advanced as lysis was achieved. Thrombectomy resulted in an immediate restitution of blood flow in six out of nine cases, in three cases a bypass procedure was performed, and one of these failed with a resultant amputation. Thrombolysis gave a good primary result in six cases which lasted in four of them. Three had a subsequent percutaneous transluminal angioplasty. Partial lysis was seen in two cases and a further two failed. Five went to surgery with three bypass and two fogarty procedures being necessary. There was no hospital mortality and there were no bleeding complications due to the rt-PA treatment in this series. In 19 out of 20 patients the circulation was re-established. Appropriate handling of acute ischaemic conditions implies the use of both thrombolysis and appropriate surgical procedures, including distal bypass grafts.

Waterbird Populations and Pressures in the Baltic Sea

This report outlines the results of the internationally coordinated census of wintering waterbirds in the Baltic Sea 2007-2009 undertaken under the SOWBAS project (Status of wintering Waterbird pop ...

Neuropeptide Y potentiates noradrenaline-induced contraction through the neuropeptide Y Y1 receptor

To elucidate which neuropeptide Y receptor subtype is responsible for the neuropeptide Y-induced potentiation of the noradrenaline-evoked contraction in human omental arteries we used antisense oligodeoxynucleotide (Antisense), the new selective neuropeptide Y Y1 receptor antagonist, BIBP3226 {(R)-N2-(diphenylacetyl)-N-[(4-hydroxyphenyl) methyl]-D-arginine-amide} and the reverse transcriptase-polymerase chain reaction (RT-PCR). Neuropeptide Y significantly potentiated the noradrenaline-induced contraction in non-incubated vessels (pEC50 6.4 +/- 0.2 vs. 5.9 +/- 0.2) and in vessels incubated with 1 microM Sense oligodeoxynucleotide (Sense) (pEC50 6.0 +/- 0.1 vs. 5.6 +/- 0.2). In vessels incubated with 1 microM Antisense the potentiating effect of neuropeptide Y was completely abolished. BIBP3226 (1 microM) inhibited the neuropeptide Y-induced potentiation in human omental arteries (pEC50 5.8 +/- 0.3 vs. 6.4 +/- 0.2). Finally, messenger RNA for the neuropeptide Y Y1 receptor was detected using RT-PCR. On the basis of our results we conclude that the neuropeptide Y-induced potentiation of the noradrenaline-induced contraction is mediated by the neuropeptide Y Y1 receptor.

Moult and moult migration of Greylag Geese Anser anser from a population in Scania, south Sweden

The moult migration of Greylag Geese Anser anser from Scania, southernmost Sweden, was studied based on resightings of neck-banded individuals marked in the breeding areas. Most geese seen in moulting areas were recorded in the marking area both before and after moult. Up to 1992, 72% of all neck-banded Greylag Geese recorded from a moulting area were reported from Oostvaardersplassen in the Netherlands, 600 km from the marking area. After 1992, there was a change in the moult migration and the majority of the reports of moulting Greylag Geese from Scania were from the Danish island of Saltholm a distance of 50 km away. Owing to the increase in the Greylag Goose population, the moulting site at Oostvardersplassen probably reached its carrying capacity and the geese had to move their moult site. The moult migration of the study population is discussed in relation to the food availability of the two main moulting sites.

Latitudinal-related variation in wintering population trends of greylag geese (Anser Anser) along the Atlantic flyway: A response to Climate Change?

The unusually high quality of census data for large waterbirds in Europe facilitates the study of how population change varies across a broad geographical range and relates to global change. The wintering population of the greylag goose Anser anser in the Atlantic flyway spanning between Sweden and Spain has increased from 120 000 to 610 000 individuals over the past three decades, and expanded its wintering range northwards. Although population sizes recorded in January have increased in all seven countries in the wintering range, we found a pronounced northwards latitudinal effect in which the rate of increase is higher at greater latitudes, causing a constant shift in the centre of gravity for the spatial distribution of wintering geese. Local winter temperatures have a strong influence on goose numbers but in a manner that is also dependent on latitude, with the partial effect of temperature (while controlling for the increasing population trend between years) being negative at the south end and positive at the north end of the flyway. Contrary to assumptions in the literature, the expansion of crops exploited by greylag geese has made little contribution to the increases in population size. Only in one case (expansion of winter cereals in Denmark) did we find evidence of an effect of changing land use. The expanding and shifting greylag population is likely to have increasing impacts on habitats in northern Europe during the course of this century.

Recent changes in the status of Steller's Eider Polysticta stelleri wintering in Europe: a decline or redistribution?

Stellers Eider Polysticta stelleri has a restricted arctic breeding range. The world population declined to c. 220,000 individuals in the late 1990s from an estimated 400,000-500,000 in the 1960s. The species has a limited global wintering distribution, occurring in marine habitats in north-east Europe, islands close to Kamchatka in Russia, and the eastern Aleutian Islands and south-west Alaska. European wintering numbers were estimated at 30,000-50,000 in the early 1990s, when the population was considered of favourable conservation status. Recent census data from the most important European wintering sites show annual declines of 8% in Norway since 1984, 9% in Estonia since 1994 and 22% in Lithuania since 1995, suggesting an overall 65% reduction in Europe. Counts in 1994 suggested that 30-50% of the European population wintered in Russia at that time. Current census data from Russia show similar declines along monitored sections of the Kola Peninsula wintering grounds since 1994. Accounting for trends in Russia, the current European wintering population could possibly stand at 10,000-15,000 individuals (a more than a 50% decline in 10 years), qualifying this population as Endangered under IUCN criteria. The changes in Baltic/Norwegian wintering numbers did not correlate with changes in the extent of ice-free marine waters in the Kola Peninsula/White Sea areas, but changes in annual numbers in Norway were correlated with winter North Atlantic Oscillation indices. Variation in annual numbers in the Baltic Sea correlated with projected number of juveniles among wintering birds. However, none of the possible causes discussed in this paper could fully explain the decline in Stellers Eider, confirming the need for comprehensive monitoring of the population throughout its winter range and for cohesive demographic monitoring to target effective conservation action. (Less)

Mechanisms of Action of the Dilatory Response to Calcitonin Gene—Related Peptide in Guinea Pig Basilary Artery

Calcitonin gene-related peptide (CGRP) is a 37-amino acid peptide and is one of the most potent vasodilators found in perivascular nerve fibers. There are several mechanisms by which vasodilators can exert their effects. Among these are the opening of potassium channels, blockade of calcium channels, and release of intracellular C a 2 + , release of an endothelium-derived relaxing factor (EDRF), and stimulation of adenylate cyclase. The aim of the present study was to examine the effects of CGRP on these different second messenger systems on isolated guinea pig basilar artery by using a sensitive i,i vitro system.

Long-term trends and changes in numbers and distribution of some wintering waterfowl species along the swedish baltic coast

Regular counts of wintering waterfowl have been undertaken as a part of the International Waterfowl Census (IWC) and the National Swedish Environmental Monitoring Program since 1964. After the first years, a network of annually surveyed sites was established for the calculation of annual indices. Country-wide surveys (also including aerial counts) were undertaken 1971–1974, 1987–1989, 1992–1993 (partial) and 2004. During the survey period, increasing trends were found in Mallard (Anas platyrhynchos), Tufted Duck (Aythya fuligula), Pochard (Aythya ferina), Goldeneye (Bucephala clangula), Red-breasted Merganser (Mergus serrator), Mute Swan (Cygnus olor) and Cormorant (Phalacrocorax carbo). Some of these trends reflect genuine population changes; others are related to changing winter conditions, e.g. the establishment of a new wintering tradition for Wigeon (Anas penelope). Tufted Duck and Goldeneye decreased in the south and increased in the northern part of the coast. Mallard, on the other hand, increased ...