bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental removal of introduced hedgehogs improves wader nest success in the Western Isles, Scotland
Authors: Jackson Digger B. 
Published: March 2003

Summary

Introduced predators are a major threat to island avifaunas world‐wide. In the Western Isles of Scotland, recently introduced hedgehogs Erinaceus europaeus have become a serious predator of bird eggs and are an important cause of declines of some waders (Charadrii).
Experiments at two sites in 1998 measured the effect on wader nest success resulting from hedgehog removal from fenced exclosures. The nest success of waders inside the plots (where hedgehog densities were zero or low) was approximately 2·4 times that of birds nesting in the adjacent control areas (where hedgehog densities were high). There was no evidence of a compensatory increase in egg loss to native avian predators.
The experiment was an integral part of a research programme to support wader conservation efforts. On the basis of the experiment it can be predicted that the removal of hedgehogs on a larger scale would result in a large increase in nest success.
The study also tested the practicalities of using relatively cheap fences against hedgehogs. Fences were generally effective, but on dry sandy ground rabbits Oryctolagus cuniculus burrowed under fences, enabling some hedgehogs to re‐enter plots. Well‐designed fences could be used as a conservation tool, both as a barrier to protect key sites, and to aid the trapping and removal of hedgehogs. However, fences cannot be seen as a long‐term solution to the problem.
Radio‐tagged hedgehogs removed from the plots and released nearby all attempted to re‐enter the plots. Two tracking methods revealed that displaced hedgehogs followed fences for distances up to 500 m looking for an entry point. There was no evidence that hedgehogs were able, or even attempted, to climb over or dig under fences.
The establishment of hedgehogs in the Western Isles provides an example of a threat to biodiversity following human‐mediated redistribution of a species native to the UK to parts of the UK (Scottish islands) outside the species’ natural range, an activity not currently prohibited by law. Policy action to deter or control species introduction should consider ecological range even within national boundaries.
Evidence for the presence of muscarinic M2 and M4 receptors in guinea‐pig gallbladder smooth muscle
Authors: Oktay Ş. , Cabadak H. , İskender E. , Gören Z. , Çallşkan E. , Orun O. , Aslan N. , Karaalp A. , Tolun A. , Ulusoy N. B. , Levey A. I. , El‐Fakahany E. E. , Kan B. 
Published: March 2003

1 The affinities of 10 selective muscarinic receptor antagonists against [3H]‐quinuclidinyl benzilate (QNB) binding were determined to characterize the muscarinic receptors present in guinea‐pig gallbladder smooth muscle. The highest correlation was obtained for the comparison between the pKi values for the gallbladder smooth muscle and M2 sites. Pirenzepine revealed two binding sites with affinities indicating the presence of muscarinic M2 receptors in abundance and a minor population of an additional site(s). 2 Carbachol produced gallbladder contractions, stimulated phosphoinositide (PI) hydrolysis and inhibited cAMP formation concentration‐dependently with pD2 values of 6.12 ± 0.11, 5.18 ± 0.33 and 7.19 ± 0.15, respectively. 3 Pirenzepine, 4‐DAMP, HHSiD, pF‐HHSiD, AF‐DX 116, methoctramine, AQ‐RA 741, guanylpirenzepine and AF‐DX 384 showed competitive antagonism against carbachol‐induced gallbladder contractions. There was no correlation between the pA2 values for the gallbladder and pKi values for the M2 sites, whereas significant correlations were found for the M1, M3 and M4 sites, the best correlation being between the pA2 values for the gallbladder and M4 subtypes. 4 Finally, the presence of both m2 and m4 receptor proteins were demonstrated by Western blot analysis. It is concluded that guinea‐pig gallbladder smooth muscle has both muscarinic M2 and M4 receptors, which are coupled to adenylate cyclase inhibition and PI hydrolysis. 5 Although it seems likely that M2 receptors do not play a primary role in carbachol‐induced guinea‐pig gallbladder contraction, the characterization of the muscarinic subtypes which mediate these contractile responses needs further evidence.
Peripheral blood lymphocyte muscarinic cholinergic receptors in airway hyperresponsiveness: a marker of cholinergic dysfunction?
Authors: Ricci A. , Mannino F. , Bronzetti E. , Felici L. , Adani O. , Gemma D. , Amenta F. 
Published: March 2003

1 Muscarinic cholinergic receptors were assayed in human peripheral blood lymphocytes of healthy control and airway hyperresponsive subjects using a radioligand binding assay technique and the muscarinic cholinergic receptor antagonist [3H]‐quinuclidinyl benzilate (QNB) as a radioligand. Subjects investigated were divided in four different groups based on threshold responses to methacholine inhaled as challenge test. 2 [3H]‐QNB was bound to human peripheral blood lymphocytes in a manner consistent with the labelling of muscarinic cholinergic receptors. Dissociation constant (Kd) values of [3H]‐QNB binding were similar in the different groups examined, whereas maximum density of binding sites (Bmax) was increased in airway hyperresponsive subjects in comparison with healthy controls. 3 The above findings indicate that the density of muscarinic cholinergic receptors is increased in peripheral blood lymphocytes of airway hyperresponsive subjects. 4 This suggests that airway hyperresponsiveness is associated with cholinergic hyperreactivity and is probably a systemic cholinergic dysfunction since it is accompanied by changes in the density of muscarinic cholinergic receptors expressed by peripheral blood lymphocytes.
Involvement of nitric oxide in the mediation of NANC inhibitory neurotransmission of guinea‐ pig trachea
Authors: Venugopalan C. S. , Krautmann M. J. , Holmes E. P. , Maher T. J. 
Published: March 2003

1 The involvement of nitric oxide (NO) in the non‐adrenergic non‐cholinergic inhibitory (NANC‐i) neurotransmission was evaluated in guinea‐pigs anaesthetized with chloralose–urethane, using a tracheal pouch preparation. 2 The tracheal pouch, a surgically isolated segment of trachea with intact nerve and blood supply, is an in situ method to demonstrate NANC‐i response after complete cholinergic and adrenergic blockade using atropine (5 mg kg−−1) and propranolol (1 mg kg−−1), respectively. Cervical vagi and sympathetic trunks were isolated and cut cranially. The distal ends of the vagi were positioned on bipolar electrodes for subsequent stimulation with 5 V pulses for 2 ms duration at 15 Hz for a total of 90 s. The relaxation response was measured as a pressure drop (cm of H2O) in the pouch. Each experimental group was composed of six animals. 3 NANC‐i responses to two consecutive nerve stimulations at 25 min apart were reproducible. 4 Pouch relaxation responses to electrical nerve stimulations were determined before and after incubation of the pouch with Nω‐nitro‐l‐arginine methyl ester (l‐NAME; 10−−5 m), a NO synthase (NOS) inhibitor, for 30 min. l‐NAME significantly, but not completely, inhibited the NANC‐i response of the pouch, suggesting involvement of NO in the NANC‐i neurotransmission. 5 The pouch relaxations to vagal stimulations were inhibited significantly after incubation with oxyHb indicating that NO was released. 6 The amount of methaemoglobin (metHb) formed from oxyhaemoglobin (oxyHb) during vagal stimulation was measured by spectrophotometry. Comparison of the values between the control and after nerve stimulation indicated a trend (P = 0.07) toward greater metHb formation in the pouch perfusate after nerve stimulation. 7 NANC‐i responses were not significantly inhibited by incubation of the pouch with either of the guanylate cyclase inhibitors, methylene blue or 1H‐[1,2,4]oxadiazolo[4,3‐a]quinoxalin‐1‐one (ODQ). However, a trend toward significance (P ≤ 0.07) was observed. 8 This study demonstrated that NO is involved in NANC‐i neurotransmission. However, the findings did not conclusively support the contention that NO is the sole neurotransmitter of NANC inhibition. It is possible that NO produced relaxation of guinea‐pig trachea through a cGMP‐independent mechanism.
Species‐dependent effects of adenosine receptor agonists on contractile responses of vas deferens to ATP
Authors: Smith Andrew D. , Moloney Susan , Khoyi Mohammad A. , Westfall David P. 
Published: March 2003

1 Experiments were carried out to examine the postjunctional actions of adenosine receptor agonists on the smooth muscle of the vas deferens of the guinea‐pig and rabbit. 2 Although they produced neither contraction nor relaxation by themselves, adenosine analogues enhanced contractions of the guinea‐pig vas deferens induced by 10 μm ATP. The rank order of potency was N6‐cyclopentyladenosine (CPA) > 5′‐N‐ethylcarboxamidoadenosine (NECA) > adenosine > CGS 21680. Dose–response curves for NECA were shifted to the right by the nonselective adenosine receptor antagonist 8(p‐sulphophenyl)theophylline (8‐SPT; 100 μm) and by the selective A1‐receptor antagonist 1,3‐dipropyl‐8‐cyclopentylxanthine (DPCPX; 1 m
m). 3 In the rabbit vas deferens, contractions induced by ATP (1 m
m) were inhibited rather than facilitated by NECA. Neither CPA, R(–)‐N6‐(2‐phenyl isopropyl)‐adenosine (R‐PIA) nor CGS 21680 had any effect. 4 The results indicate that the smooth muscle of the guinea‐pig vas deferens expresses facilitatory adenosine A1 receptors but not adenosine A2 receptors. In contrast, in rabbit there are postjunctional inhibitory adenosine A2A receptors but not adenosine A1 receptors.
Effect of hydroquinone, hydroxocobalamin and carboxy‐PTIO on non‐adrenergic non‐cholinergic nerve mediated relaxations of the rat duodenum
Authors: Correia N. A. , Cavalcanti P. M. S. , Oliveira R. B. , Ballejo G. 
Published: March 2003

1 Relaxation induced by NANC‐nerve stimulation is reduced by nitric oxide synthase (NOS) inhibitors but not by superoxide generators or NO scavengers, casting doubts on the precise nature of the neurotransmitter being released by these nerves. The lack of effect of superoxide anion generators to inhibit nitrergic nerve‐mediated relaxations has been attributed to the protective action of high tissue levels of superoxide dismutase (SOD). 2 The effects of hydroquinone, hydroxocobalamin and carboxy‐PTIO, three NO inactivators which do not depend on superoxide anion generation, upon nitrergic nerve‐mediated relaxations of the rat proximal duodenum were determined in order to elucidate whether they are mediated by free NO. 3 GABA and nicotine caused relaxations of isolated segments of the rat proximal duodenum in a concentration‐dependent manner that were abolished by tetrodotoxin (TTX). Similarly, transmural electrical stimulation (TES) caused frequency‐dependent relaxations that were also abolished by TTX. 4 The NOS inhibitors L‐NAME and L‐NOARG reduced in a concentration‐dependent manner nerve‐mediated relaxations elicited by TES, nicotine and GABA. The effect of NOS inhibitors was prevented by
l‐arginine but not
d‐arginine. 5 NO caused concentration‐dependent relaxations that were not affected by TTX or L‐NOARG but were abolished by hydroquinone, hydroxocobalamin and carboxy‐PTIO. In contrast, these compounds failed to affect TES‐, nicotine‐ and GABA‐induced relaxations. The lack of effect of hydroquinone, hydroxocobalamin and carboxy‐PTIO upon nerve‐mediated relaxations was unaltered by pretreatment with the SOD irreversible inhibitor DETCA. 6 The present findings show that nitrergic nerve‐mediated relaxations of the rat duodenum are unaffected by NO inactivators that do not generate superoxide anion. It is suggested that either a NO‐containing molecule that is unreactive with the inactivators tested is the inhibitory neurotransmitter released by nitrergic nerves or that NOS activity fulfills another role in nitrergic nerves which could be related to the release of an still unidentified transmitter.
Effects of reduced sympathetic activity on myocardial metaiodobenzylguanidine (MIBG) washout
Authors: Gao D.‐W. , Talke P. O. , Dae M. W. 
Published: March 2003

1 Increase in myocardial sympathetic activity contributes markedly to the pathophysiology of conditions such as congestive heart failure and is also associated with myocardial infarction. However, measurement of myocardial sympathetic activity in vivo is difficult. 2 The present study assesses the effectiveness of metaiodobenzylguanidine (MIBG) imaging to characterize modulation of sympathetic activity, as induced by dexmedetomidine, a highly specific α‐2 adrenoceptor agonist. 3 We imaged washout of [125I]‐MIBG from rabbit heart before and during two consecutive 45‐min intravenous infusions of dexmedetomidine (10 μg kg–1 followed by 16 μg kg−1) (n=9) or of saline (n=9). 4 Heart rate (HR), and mean blood pressure (BP) were measured before and at the end of each study period. Plasma noradrenaline (NA) was measured before and after study drug infusion. The hearts were then excised and biopsied for MIBG tissue concentration [MIBG] (%kg‐dose g−1). 5 Relative to saline controls, dexmedetomidine significantly decreased HR, BP, plasma NA and MIBG washout. There was an inverse correlation between MIBG washout and residual [MIBG] in the myocardium (r=−0.75, P < 0.01). 6 These data suggest that a reduction of sympathetic nervous system activity causes a decrease in myocardial MIBG washout in vivo in rabbits, and confirms the usefulness of MIBG scintigraphy as a non‐invasive tool to measure changes in myocardial sympathetic activity.
Contractile effects of tacrolimus in human and rat isolated renal arteries
Authors: Schwertfeger E. , Wehrens J. , Oberhauser V. , Katzenwadel A. , Rump L. C. 
Published: March 2003

1 We tested the vasoactive properties of the immunosuppressive drug FK 506 (tacrolimus) in preconstricted rat and human isolated renal arteries in vitro. 2 In rat renal arteries, tacrolimus (3, 10 μM) showed a direct and dose‐dependent contractile effect by maximally 23 μm (10% of the noradrenaline effect), which was only observed in the presence of intact endothelium. Moreover, a lower concentration of tacrolimus (1 μM) potentiated pressor responses to the sympathetic neurotransmitter noradrenaline but not to ATP in this species. ATP‐ (0.01–10 μM) induced vasodilation was not affected by tacrolimus (1 μM). 3 In contrast, in human interlobar arteries, tacrolimus failed to induce direct vasoconstriction and did not significantly potentiate constrictor responses to noradrenaline. Acetylcholine‐(1 μM) induced vasodilation was much smaller in human than in rat renal arteries suggesting the lack of functional endothelium in the human preparation. 4 The findings suggest that tacrolimus releases an endothelium‐derived constricting factor in rat renal arteries to increase vascular tone and to potentiate pressor responses to noradrenaline. In human interlobar arteries, this effect of tacrolimus is not observed probably because of the absence of functional endothelium or the necessary mediator mechanism.
Continuity or discontinuity? Vegetation change in the Hadrianic–Antonine frontier zone of northern Britain at the end of the Roman occupation
Authors: Dumayne‐Peaty Lisa 
Published: March 2003

Summary Aim The aim of this paper is to determine the nature of vegetation change in the Hadrianic‐Antonine frontier zone of northern Britain at the end of the Roman occupation. The concepts of continuity and change are important issues in palynological and archaeological studies and it has been assumed traditionally that large‐scale woodland regeneration occurred in the area at the end of the Romano‐British period. Location Hadrianic–Antonine frontier zone of northern Britain. Methods Pollen analysis of peat profiles, radiocarbon dating Results and main conclusions The pollen diagrams suggest that woodland regeneration occurred around the time of the withdrawal of Roman troops at Fozy Moss, Northumbria; Glasson Moss, Cumbria; Bolton Fell Moss (marg), Cumbria; Letham Moss, Stirlingshire; Cranley Moss, Lanarkshire; Carsegowan Moss, Wigtonshire and Dogden Moss, Berwickshire. Regeneration started at Blairbech Bog, Dumbartonshire and Ellergower Moss, Dumfriesshire before the Roman occupation began. The landscape around Walton Moss, Cumbria remained open later and regeneration of woodland did not take place until the latter half of the sixth century AD. Woodland regeneration at each of the sites was also associated with a decline in agricultural production, and renewed clearance did not occur until Anglian, monastic or Scandinavian settlement took place.
The geographical relationships of the British and Irish flora: a comparison of pteridophytes, flowering plants, liverworts and mosses
Authors: Preston C. D. , Hill M. O. 
Published: March 2003

SummaryAimTo compare the wider distribution of the pteridophytes, flowering plants, liverworts and mosses recorded as natives of Britain and Ireland, and to assess the proportion and distribution of species in each group which belong to predominantly extra‐European genera.LocationThe species native to the British Isles are considered in relation to their distribution in the Northern Hemisphere, and predominantly extra‐European genera are identified by consideration of the distribution and centre of numerical diversity of the genera worldwide.MethodsA recent classification of the pteridophytes, flowering plants, liverworts and mosses into floristic elements is used in a quantitative study of the distribution of species in the four groups, the patterns of occurrence being compared by standardized residuals.ResultsMosses and liverworts have more northerly distributions than the flowering plants in the Northern Hemisphere; pteridophytes show an intermediate pattern. There are marked differences in the longitudinal ranges of the groups south of the Boreal biome, with vascular plants tending to be confined to Europe or western Eurasia whereas cryptogams are more likely to occur additionally in North America or have a circumpolar distribution. The proportion of predominantly extra‐European genera is particularly high in the pteridophytes and the liverworts and in these groups the rich hyperoceanic flora of the British Isles is almost entirely composed of species in genera that attain their centre of diversity in the tropics.Main conclusionsMajor taxonomic groups show different distribution patterns, reflecting their rates of evolution and powers of dispersal. The flowering plants, as the least mobile and most rapidly evolving group, have a greater proportion of their species in the European and Eurosiberian elements and a higher proportion of species from extra‐European genera in the more northerly elements.
Insular biogeography of mammals in Canadian parks: a re‐analysis
Authors: Gurd D. Brent , Nudds Thomas D. 
Published: March 2003

Summary Aim
Glenn & Nudds (1989) compared mammal species richness in Canadian parks to estimated species‐area relationships prior to European settlement to test if parks presently contain their historical compliment of species. However, the data they used to estimate the presettlement species‐area relationships were not commensurate with the scale of the parks and were not independent. This uncertainty reduces the utility of Glenn and Nudds analysis to detect which, if any, parks are experiencing mammal extirpations and ultimately to direct conservation efforts to enhance mammal conservation in Canada. We improved Glenn and Nudds methods and re‐assesed the conservation status of mammals in Canadian parks. Location Canada. Methods We constructed species‐area curves for disturbance tolerant and intolerant species in five mammal regions of Canada by sampling historical range maps using plots of 10– 10,000 km2. We compared these estimates of expected species richness to current species richness in thirty‐six parks and contrast our results with those of Glenn and Nudds. Results All ten re‐estimated species‐area regressions had higher intercepts than those reported by Glenn and Nudds; four had lower slopes. Of seventy‐two cases analysed, we found twenty in which parks had fewer species than expected and four in which parks had more species than expected, compared to fourteen and thirty‐three, respectively, reported by Glenn and Nudds. Changes in both the regression parameters and increases in the prediction intervals accounted for the disparity between these results. Park residuals were not significantly different from zero in eight of ten analyses. Residuals for parks in the Alleghenian‐Illinoian mammal province were negative and decreased with increasing park size. Main conclusions Improvement of Glenn and Nudds methods had an effect on both the parameter estimates and precison of the presettlement species‐area curves. As a result, mammal conservation in some Canadian parks is worse than Glenn and Nudds reported. Six additional parks contained fewer disturbance intolerant species than predicted. However, Glenn and Nudds finding of systematic differences between expected and observed species richness in parks in the densely populated region of southern Ontario, southern Quebec and the maritime provinces was not an artefact of their methods. In this region, seven of ten parks appear to have lost disturbance‐sensitive species of mammals. The pattern of species loss in this region was consistent with the idea that these parks have become isolated from mammal dispersal by surrounding habitat change and have experienced local species extirpations.
Changes in woody community structure and composition under constrasting landuse systems in a semi‐arid savanna, South Africa
Authors: Higgins Steven I. , Shackleton Charlie M. , Robinson E. Robbie 
Published: March 2003

SummaryWe aimed to explore the farm scale effects of three landuse types, communal grazing, wildlife management and commercial cattle farming, on the woody vegetation of a semiarid savanna. Location The study farms were located within a single bioclimatic zone in semiarid savanna, South Africa. Methods The species composition and structure of woody vegetation on three farms of each of three landuse types were sampled. Results We found that communal grazing land sites were classified outside the topland‐bottomland vegetation dichotomy characteristic of this region. Comparisons of size class distributions showed the communal grazing lands had fewer small and large individuals; suggesting both lower levels of regeneration and regenerative capacity in the communal grazing lands. The species richness and biomass of woody plants was lower on communal grazing lands than on private game reserves and commercial cattle farms. The longevity of tree species explains the observed lag between changes in abundance and species loss; we consequently predict that there will be future losses of species in the communal grazing lands. By classifying species into a range of use‐categories we showed that utilization and species loss was not limited to certain plant use categories. Higher levels of wood harvesting measured in the communal grazing lands are likely to be responsible for the observed differences. Main conclusions It is concluded that communal grazing management at this study site has substantially changed the composition and structure of woody plant communities, and that these changes have reduced the current availability of natural resources and will reduce resource production in the future.