bluuebunny/crossref_metadata_2025_split huggingface dataset:
Long‐term vegetation recovery on reclaimed coal surface mines in the eastern USA
Authors: Holl Karen D. 
Published: March 2003

Summary

While reclamation of degraded landscapes is becoming increasingly common, few studies have investigated the long‐term effects of reclamation efforts on plant conservation. The goals of this study were to determine whether vegetation communities on reclaimed mines approximate those of the surrounding forest, and to evaluate how intensive reclamation practices used to address short‐term erosion and water quality concerns affect long‐term recovery.
In 1992–93 and 1999 the vegetation on 15 coal surface mines reclaimed between the years 1967–87, and five periodically logged hardwood forest reference sites in south‐western Virginia, were surveyed.
Herbaceous species richness was similar on all sites, whereas woody species richness was higher in reference sites than in reclaimed sites.
Vegetation community composition on reclaimed sites continued to progress towards reference forest sites between the two sampling periods, but vegetation community composition even on the oldest sites (reclaimed > 35 years prior) still differed substantially from reference sites.
Herbaceous cover was higher and tree basal area was lower in reclaimed sites compared with reference sites at the first sampling period, but these differences were much less pronounced by the second sampling period.
The overall composition of the older reclaimed sites was similar to the reference forest sites, suggesting a high level of resilience in the forests studied. But, as with a number of previous studies of long‐term recovery on highly disturbed sites, a number of less common forest species still had not colonized reclaimed sites, raising the question of their value for conservation.
These results concur with a common theme that goals for short‐term and long‐term recovery of highly disturbed sites may conflict. Planting with aggressive non‐native ground cover species to minimize short‐term erosion may have slowed long‐term recovery on the sites studied. Widespread planting of Pinus strobus has not reduced species richness thus far, but may as the canopy closes. More emphasis should be given to long‐term recovery potential in developing mine reclamation plans, and strategies to further this goal should be tested.
Acute and persistant effects of smoking on the baroreceptor function
Authors: Gerhardt U. , Vorneweg P. , Riedasch M. , Hohage H. 
Published: March 2003

1. Recent studies showed that to smoke four cigarettes within one hour impairs baroreflex sensitivity in humans. In the present study, these effects were qualified more precisely from blood pressure and heart rate records by a sequence analysis and by Fourier analysis of Finapres‐registrations. 2. The Mayer waves of the heart rate PDS (power density spectrum), partially representing sympathetic activity, increased during smoking (83.7 ± 1.0 AU to 89.5 ± 1.1 AU, P≤ 0.05) and decreased after smoking (86 ± 1.0 AU, P≤ 0.05). They did, however, not reach baseline levels again within 30 min. Probably due to this, mean arterial blood pressure (64.3 ± 1.3 mmHg vs. 76.9 ± 1.3 mmHg, P < 0.05) and heart rate (71.8 ± 1.4 min–1 vs. 82.9 ± 1.4 min–1, P < 0.05) increased unequivocally after smoking. On the other hand, baroreflex sensitivity decreased dramatically from 15.4 ± 1 to 11.2 ± 0.6 ms mmHg–l (P < 0.05). This finding was associated with an increased heart rate variability after smoking (6 ± 0.5 min–1 vs. 9.2 ± 1 min–1) 3. Thus, the present study provides evidence that chronic tobacco (nicotine)‐abuse causes pathologic alterations of the baroreflex control. In synergism with other processes like elevated catecholamine blood levels, these alterations may contribute to the higher risk of cardiovascular diseases.
Changes of cardiac calcium homeostasis in spontaneously hypertensive rats
Authors: Manso A. M. , Encabo A. , Ferrer M. , Balfagón G. , Salaices M. , Marín J. 
Published: March 2003

1 The aim of the present study was to assess the alterations in cardiac Ca2+ homeostasis induced by hypertension using electrically paced right ventricular strips from Wistar‐Kyoto (WKY) and spontaneously hypertensive rats (SHR). 2 Basal contractile force was higher in SHR than in WKY. Similarly, the β‐adrenoceptor agonist isoprenaline (10 n
m–10 μm) induced a concentration‐dependent positive inotropic effect that was higher in SHR than in WKY, which was in turn inhibited by the β‐adrenoceptor antagonist propranolol (1 μm) in both strains. 3 Preincubation of strips with the L‐type Ca2+ channel blockers, nifedipine (1 μm) or verapamil (10 μm), markedly inhibited the isoprenaline response, the inhibition being higher in SHR than in WKY. However, this inhibition was minor by the T‐type Ca2+ channel blocker mibefradil (10 μm). 4 Bay K 8644 (10 n
m–10 μm), a L‐type Ca2+ channel activator induced a concentration‐dependent positive inotropic effect, that was greater in SHR than WKY. 5 Nifedipine and verapamil (both 0.1 n
m–10 μm) inhibited in a concentration‐dependent way the inotropic effect induced by 0.3 μm isoprenaline or 1 μm Bay K 8644. The inhibition was higher in SHR than in WKY. Mibefradil (0.1 n
m–10 μm) only clearly inhibited the isoprenaline and Bay K 8644 inotropic effects at 10 μm in both strains. 6 The inhibitor of the sarcoplasmic reticulum Ca2+ release, ryanodine (10 n
m–10 μm), was a more effective depressor of isoprenaline‐induced response in SHR than in WKY. 7 These results suggest that cardiac Ca2+ homeostasis in SHR ventricular strips is altered compared with those of WKY, showing an increased Ca2+ entry through L‐type Ca2+ channels and release from sarcoplasmic reticulum; the participation of T‐type Ca2+ channels are irrelevant in this tissue.
Effects of noradrenaline, the calcium ionophore A23187, forskolin, sodium nitroprusside and glibenclamide on the degradation of extracellular adenosine 5′‐triphosphate by the rat isolated vas deferens
Authors: Tennant J. P. , Pearson A. , Hourani S. M. O. 
Published: March 2003

1 The effects of noradrenaline (NA), the calcium ionophore A23187, forskolin, sodium nitroprusside (SNP) and the K+‐channel blocker glibenclamide on the degradation by ectonucleotidases of extracellular adenosine 5′‐triphosphate (ATP) were studied in the rat vas deferens. 2 ATP (100 μm) was rapidly broken down by the rat vas deferens with a half‐life of 5.83 ± 0.40 min via adenosine 5′‐diphosphate (ADP) and adenosine 5′‐monophosphate (AMP), with the final degradation product being inosine and with little adenosine being detected in the samples. 3 Preincubation for 1 h with NA (10 μm), A23187 (10 μm), or glibenclamide (100 μm) had no significant effect on the breakdown of ATP or the production of metabolites. However, both forskolin (10 μm) and SNP (1 μm) significantly increased the concentrations of AMP detected with time. In the case of SNP (1 μm) there was also a significant reduction in the rate of production of inosine, while in the case of forskolin (10 μm) there was a significant increase in the rate of removal of ATP. 4 These results suggest that preincubation with SNP may inhibit 5′‐nucleotidase and so reduce the metabolism of AMP, while preincubation with forskolin may increase the activity of the ectonucleotidases responsible for production of AMP from ATP.
Effects of allopurinol, erythro‐9‐(2‐hydroxy‐3‐nonyl)adenine and S‐(4‐nitrobenzyl)‐6‐thioinosine on the degradation of adenosine 5′‐triphosphate in the rat colon muscularis mucosae
Authors: Tennant J. P. , Callaghan F. , Turner C. , Hourani S. M. O. 
Published: March 2003

1 The effects on ATP breakdown of some modulators of adenosine transport or metabolism were studied in the rat colon muscularis mucosae, a tissue which contracts to ATP and is thought to contain P2Y1 receptors. The compounds tested were the xanthine oxidase inhibitor allopurinol, the adenosine deaminase inhibitor erythro‐9‐(2‐hydroxy‐3‐nonyl)adenine (EHNA) and the adenosine uptake blocker S‐(4‐nitrobenzyl)‐6‐thioinosine (NBTI). 2 The degradation of adenosine 5′‐triphosphate (ATP) (100 μm) and the appearance of metabolites was followed by high pressure liquid chromatography during incubation of isolated tissue preparations alone or in the presence of the drugs, following preincubation with the drugs for 1 h. 3 In the absence of drugs ATP was rapidly degraded by the rat colon muscularis mucosae with a half‐life of 6.1 ± 0.7 min, the major breakdown product being inosine rather than adenosine. Allopurinol (1 μm) and NBTI (10 μm) had no effect on the rate of breakdown of ATP or on the pattern of metabolites produced. EHNA (1 or 10 μm) also had no effect on the half‐life of ATP, but in the presence of EHNA (1 μm) the rate of production of inosine was significantly reduced and some adenosine was detected, while in the presence of 10 μm EHNA the production of inosine was abolished and adenosine became the final breakdown product. 4 These results indicate that allopurinol (1 μm) and NBTI (10 μm) have no detectable effect on extracellular purine metabolism in this tissue, and that the build‐up of adenosine produced by treatment with EHNA does not have a feedback effect on ATP breakdown.
The role of heart rate in the modulation of the decreased cardiac output induced by acute nitric oxide synthesis inhibition in anaesthetized dogs
Authors: Faro R. , Tanus‐Santos J. E. , Zappellini A. , Antunes E. , De Nucci G. 
Published: March 2003

1 The role of the heart rate modulating the decrease in cardiac output induced by the nitric oxide synthesis inhibitor Nω‐nitro‐L‐arginine methyl ester (L‐NAME) was investigated in anaesthetized dogs. This was achieved in dogs in which a positive pacemaker (PM) cable was located at the right ventricle. 2 The haemodynamic events were evaluated: mean arterial blood pressure (MABP), systemic vascular resistance index (SVRI), stroke volume index (SVI), heart rate (HR) and cardiac index (CI). 3 The infusion of L‐NAME (0.01–10 mg kg−−1) in the animals with the PM off caused a dose‐dependent rise in MABP and SVRI, accompanied by significant decreases of HR and SVI. A resulting decrease in CI was observed at all doses of L‐NAME used. 4 In the animals with the PM on, HR was maintained stable. Under this condition, the increase in MABP and SVRI as well as the decrease in SVI induced by the L‐NAME infusion did not significantly differ from the PM‐off animals. However, the resulting decreased CI was markedly attenuated compared to PM‐off animals but significant decreases in CI were still observed at higher doses of L‐NAME. 5 The results suggest that HR plays an important role in the L‐NAME‐mediated decreased cardiac output but other factors might also be involved.
Prostanoid release and constrictor responses to noradrenaline in the rat mesenteric vascular bed in non‐insulin‐dependent diabetes mellitus
Authors: Peredo H. A. 
Published: March 2003

1 The administration of streptozotocin (STZ) to 2‐day old rats induced a non‐insulin‐dependent diabetes mellitus (NIDDM)‐like state, with mild hyperglycaemia and no alterations in body weight at the adult age. 2 In the isolated and perfused mesenteric vascular bed of NIDDM animals, the constrictor responses to either noradrenaline (NA) or potassium chloride (KCl) were not modified as compared with age‐matched non‐diabetic controls. 3 The reduction in NA contractions induced by the cyclooxygenase inhibitor, 10 μM indomethacin in the control group was absent in the NIDDM rats. 4 The increase in the NA‐induced contractions caused by endothelium removal was suppressed by indomethacin in the controls but not in the NIDDM group. 5 The prostanoid release from the mesenteric vascular beds of NIDDM rats was markedly reduced as compared with non‐diabetic controls. Noradrenaline increased production of the constrictor prostaglandin (PG) F2α in control but not in NIDDM rats. 6 In summary, these results show that in STZ‐induced NIDDM rats, there is an impairment of the prostanoid production, as well as a suppression of the role of prostanoids in the contractile effects of NA in the mesenteric vascular bed. These alterations are more severe than those previously observed in a model of insulin‐dependent diabetes mellitus (IDDM), in which hyperglycaemia and reduction of body weight were more marked. The conclusion is that, in these models of diabetes and in the preparation studied, vascular alterations and modifications of glycaemia and body weight are not closely related.
Effect of in vivo and in vitro ethanol on adrenergic and purinergic responses of the bisected rat vas deferens to low and high frequency pulses
Authors: Boselli C. , Govoni S. 
Published: March 2003

1 This study investigates the effect of acute in vivo and in vitro ethanol administration on the contractions evoked electrically and by exogenous noradrenaline and α,β‐methylene‐ATP in the rat bisected vas deferens. 2 In vivo ethanol treatment (3 g kg–1, i.p.) significantly potentiated the early purinergic (phase I) and the delayed adrenergic (phase II) phases evoked by single‐pulse stimulation of the epididymal portion of the rat vas deferens, leaving unaffected both phases in the prostatic portion. In vitro 50 mM ethanol significantly depressed phase I leaving unaffected phase II in both portions from untreated rats. In vitro ethanol significantly depressed phase I in the epididymal portion from in vivo ethanol treated animals and potentiated phase II in both portions. 3 In vivo ethanol treatment (3.0 g kg–1, i.p.) selectively impaired the response to noradrenaline only in the prostatic portion of rat vas deferens while it was devoid of any action on α,β‐methylene‐ATP contractions. Ethanol 50 mMin vitro was devoid of any action on the response to exogenous noradrenaline and α,β‐methylene‐ATP in both tissues. 4 In vivo ethanol treatment slightly but significantly increased the phasic response in the epididymal portion to trains of stimuli (2–30 Hz). In vitro 50 mM ethanol was ineffective against the phasic and tonic contractions elicited by the tetanus in both portions. 5 It is concluded that ethanol treatment affects purinergic and adrenergic pathways of transmission possibly leading to a disruption of physiological contractions necessary to seminal emission.
A review of Bahamian ant (Hymenoptera: Formicidae) biogeography
Authors: Morrison Lloyd W. 
Published: March 2003

Abstract. The results of recent surveys for ants on Staniel Cay, Exumas (and surrounding small cays) and the northeastern region of Andros are presented. These records are compiled with all previously published collection records of ants from the Bahamas into a single database. A list of all known Bahamian species is presented, in accord with current taxonomy. Distributions within the Bahamas are given, along with the status of each species with reference to its origin (endemic, native, or exotic). At present seventy‐five named species of ants are known from the Bahamas, which shares 60% of its ant fauna with Florida and 71% with Cuba. More than one third of the species (37%) are exotics, which appear to exist primarily in areas characterized by human disturbance, and apparently have not invaded the native vegetation to a large degree.Both historical and ecological factors are likely to have played important roles in shaping present‐day Bahamian ant species diversity and distribution. The number of species on all major Bahamian islands from which ants have been collected is presented as a function of island area. Most islands have not been very thoroughly surveyed. The species‐area relationship for the more thoroughly surveyed islands is relatively flat (z= 0.06). Further collecting in this archipelago will probably lead to the discovery of additional species.
History, island area and habitat availability determine land snail species richness of Aegean islands
Authors: Welter‐Schultes F. W. , Williams M. R. 
Published: March 2003

Summary Aim We examined the species‐area relation of Aegean land snails, comparing different models to describe the relation. By examining those factors other than area that may also affect species richness, we tested whether the Aegean land snail fauna was more influenced by equilibrial migration and colonization processes, or rather is conservative and relictual. Location The Aegean archipelago (Greece). Methods Sixty‐five islands were examined. Data were taken from own collections and from literature sources. Multiple regression analysis was used to test the null hypothesis of no relationship between species richness and island area, elevation, distance to the next larger island, and the presence and extent of calcareous substrate. Results The single most important factor determining land snail species number was area. While colonization‐extinction dynamics have frequently been cited to explain this result, this conclusion was not tenable in this study as it was contradicted by species number not being related to the islands’ distances to neighbouring larger islands, after accounting for other factors affecting species number. We also found that habitat diversity affected species richness even after accounting for the effects of area: both increased elevation and greater extent of calcareous substrate on islands resulted in higher species number. This effect was most likely due to the fact that particular ecological conditions increased the probability that particular species could survive on an island.We compared the utility of the power and extreme‐value function models of the species‐area relation and found that both gave substantially the same results. However, fitting the power function model using nonlinear regression was of questionable utility. Main conclusions We conclude that the snail fauna of the Aegean is relictual, not equilibrial. The unusually high number of land snail species found on Crete is consistent with this conclusion. Crete is a currently united island which was separated into at least six smaller islands for 7–9 million years during the Neogene. Our results are consistent with the hypothesis that Crete still hosts a large number of endemic species of these paleoislands, resulting in a total number of species in excess of what would be expected based on area alone.
The worldwide transfer of ants: geographical distribution and ecological invasions
Authors: McGlynn Terrence P. 
Published: March 2003

Summary AimThis is the first comprehensive account of the biogeography of ants transferred and at least temporarily established outside their native habitat. LocationUsing museum and literature records, I established the distributions of transferred ant species. MethodsI used taxonomic and functional groups to assess how geographical spread as a transferred species is affected by taxonomy and life history. Results147 ant species in forty‐nine genera have been recorded outside of their native habitat. The proportion of transferred ants is similar to the number of genera and species in each subfamily. The species‐rich subfamily Myrmicinae contains nearly 50% of all transferred species, while many of the species‐poor subfamilies have absolutely no transferred species. A disproportionate high number of transferred ants originate from the Neotropical and Oriental biogeographic regions. The Pacific Islands are the recipients of the most transferred ant species. Most transferred ants belong to the CRYPTIC, OPPORTUNIST, and GENERALIZED MYRMICINE functional groups, while there are no recorded transfers of army ants or leaf‐cutting ants. Both invasive and human commensal ‘tramp’ ant species are nonrandom subsets of transferred ants. Main conclusions‘Tramp’ species and invasive species tend to have widespread geographical distributions, and share life history characteristics including queen number, nest structure, and foraging behaviour. Combining observations of functional groups and biogeography may lead to a better understanding of the factors contributing to the spread of transferred species.
Species turnover, community boundaries and biogeographical composition of dung beetle assemblages across an altitudinal gradient in South Africa
Authors: Davis Adrian L. V. , Scholtz Clarke H. , Chown Steven L. 
Published: March 2003

SummaryAimTo identify biogeographical boundaries which are obscured by faunal overlap and habitat modification.LocationKwaZulu‐Natal in south‐east, South Africa beyond the southern tip of the Moçambique Coastal Plain.MethodsSpecies abundance data for dung beetles (Scarabaeidae: Scarabaeinae) were collected at six levels from the coastal escarpment (30°16′S – 500 m) to the top of the nearby Drakensberg (29°35′S – 2850 m). Cross‐altitudinal boundaries were identified using clustering techniques, beta‐diversity indices, and range edge analysis. Biogeographical data for the species were drawn from an extensive reference collection and used to classify the biogeographical affinities of the assemblages.ResultsThree discrete communities are defined (<10% similarity) from species abundance distributions. These communities occur in coastal forest (500 m), coastal to highveld grassland (500–1500 m), and montane grassland (1900–2850 m). Two of these communities are biogeographically homogeneous comprising >89% east coast endemics (coastal forest) or >84% South African montane endemics (montane grassland) in terms of abundance. The third community in coastal to highveld grassland is biogeographically more heterogeneous. Predominant biota of this community comprise both South African highveld endemics and elements with distributions extending into the tropics. At highveld levels (1500 m), there are proportionately more highveld endemics whereas at lowland levels (500 m), there are proportionately more tropical elements. At 1000 m, there was a change in the balance between these two groups across an anthropogenic gradient due to a decline in the proportion of endemics in favour of temperate/tropical generalists. This gradient from a natural grassland fragment to improved pastures of Kikuyu grass also parallels a decline in species richness and abundance. Species turnover analyses showed three different cross‐altitudinal patterns. Range‐edge analysis showed a trimodal pattern of species turnover (peaks in forest and the Drakensberg foothills as in the community analysis but also at 1000 m). Five beta‐diversity indices showed either a bimodal pattern of turnover (forest/grassland and foothills/middle Drakensberg slopes) or a trimodal turnover pattern (forest/grassland, highveld/Drakensberg foothills, Drakensberg peaks).Main conclusionsClear altitudinal zonation is revealed by community and biogeographical analysis but one natural biogeographical boundary may be obscured by the process of habitat modification. This boundary at 1000 m is revealed by range‐edge analysis and is supported by findings for plant communities. Beta‐diversity, species turnover patterns diverged slightly from those suggested by the community and range‐edge analyses.