bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of pentoxifylline on intestinal ischemia/reperfusion injury
Authors: Şener  , Akgün  , Şatıroğlu  , Topaloğlu  , Keyer‐Uysal
Published: March 2003

The small intestine is highly sensitive to oxygen free radical‐induced injury. Post‐ischemic intestinal tissue damage appears to be due to the formation of oxygen radicals. Free radical initiated lipid peroxidation (LP) following intestinal ischemia/reperfusion (I/R) may disrupt mucosal integrity. Indirectly, the radicals trigger the accumulation of neutrophils within the affected tissue, initiating inflammatory processes that lead to severe mucosal lesions.

In the present study we investigated the effect of pentoxifylline (PTX), a potent inhibitor of tumour necrosis factor production, on I/R induced intestinal injury. Wistar albino rats were divided into four groups: (1) Sham operation (S); (2) Sham operation + PTX (50 mg/kg i.v.) (S + PTX); (3) 1 h ischemia + 2 h reperfusion (I/R); and (4) I/R + PTX. Animals were sacrificed at the end of the reperfusion period and ileum samples were obtained. Malondialdehyde (MDA) levels, an end product of LP, glutathione (GSH) levels, a key antioxidant, and myeloperoxidase (MPO) activity (an index of polymorphonuclear neutrophils) stimulation, were determined in ileum homogenates.

The results of the present study indicate that ischemia/reperfusion results in a significant increase in MDA content and MPO activity with a significant decrease in GSH content. Treatment with PTX returns these biomarkers to control values. A mechanism of this protective effect may involve inhibition of neutrophil oxidative burst.
Role of bradykinin and tachykinins in the potentiation by enalapril of coughing induced by citric acid in pigs
Authors: Moreaux Benoit , Advenier Charles , Gustin Pascal
Published: March 2003

Angiotensin‐converting enzyme (ACE) inhibitors are among the first‐choice drugs for treating hypertension and congestive heart disease. It has been reported, however, that these drugs could induce chronic cough and airway hyperresponsiveness. The aim of this work was to assess in pigs the effects of bradykinin and tachykinins on citric‐acid‐induced coughing after ACE inhibitor pretreatment. Coughing was induced by challenging pigs with an aerosol of 0.8 M citric acid over 15 min. Coughs were counted by a trained observer for 30 min. The animals underwent two cough induction tests two days apart (days 1 and 3), the first being taken as a control. All drugs were injected intravenously 30 min before the second challenge. In the control group, no difference was observed between days 1 and 3. The ACE inhibitor enalapril (7.5 and 15 μg/kg) caused the cough frequency to increase significantly. In contrast, a dose‐related decrease was observed with Hoe140 (icatibant), a bradykinin B2 receptor antagonist (0.5 and 1 mg/kg). When both drugs were administered simultaneously (15 μg/kg for enalapril and 1 mg/kg for Hoe140), a significant increase was observed as compared with the control value obtained on day 1. When enalapril was combined with the three tachykinin receptor antagonists SR 140333 (NK1 receptor antagonist), SR 48968 (NK2 receptor antagonist) and SR 142801 (NK3 receptor antagonist), a significant decrease was observed as compared with control value obtained on day 1; the percentage of variation was also significantly different as compared with those observed in enalapril groups at both doses. These data suggest that ACE‐inhibitor‐induced enhancement of the cough reflex is mainly due to tachykinins and not to bradykinin in our pig model. Bradykinin, however, plays a major role in coughing induced by citric acid alone.
A nonpeptide vasopressin V1a receptor antagonist, SR 49059, does not prevent cisplatin‐induced emesis in piglets
Authors: Grélot Laurent , Girod Vincent , Dapzol Julien , Maffrand Jean Pierre , Serradeil‐Le Gal Claudine
Published: March 2003

We determined the pharmacological and the antiemetic properties of SR 49059, a selective nonpeptide V1a receptor antagonist, on cisplatin‐induced emesis in the piglet. Firstly, we clearly demonstrate that SR 49059 is a potent V1a receptor antagonist in vitro and in vivo in the piglet. In binding studies, [3H]‐SR 49059 exhibited high affinity for V1a receptors in piglet liver membranes (Kd of 0.76 ± 0.12 nM and Bmax of 138 ± 22 fmol/mg prot.). In vivo, in decerebrate piglets, SR 49059 (1 mg/kg iv) antagonized AVP (500 ng/kg iv)‐induced hypertension for at least 150 min and also blocked, for at least 270 min at 3 mg/kg iv, the pressor responses to exogenous LVP. After single and repeated iv or icv administration, we studied the antiemetic properties of SR 49059 on cisplatin‐induced emesis in piglets. Animals receiving an emetic dose of cisplatin (5.5 mg/kg, iv) were observed continuously for 60 h. Piglets acting as controls were iv administered with vehicle 15 min prior to cisplatin infusion (T0–15min), while experimental animals received a single iv administration of SR 49059 at the dose of 1 or 3 mg/kg. In additional piglets, we administered SR 49059 (3 mg/kg) every 12 h from T0–15min to T48–15min (cumulative dose, 15 mg/kg). Another set of animals – observed only during the acute phase – was administered with SR 49059 (10 mg/kg) every 3 h from T0–15min to T15–15min (cumulative dose, 60 mg/kg). Lastly, 10 piglets were given a bilateral icv injection of SR 49059 (500 μg and 1500 μg/side) 1 h prior to cisplatin infusion. In all groups treated with SR 49059, the latency of the first emetic episode and the incidence of vomiting during the acute, the delayed and the cumulative phases remained statistically similar to that observed in controls, suggesting that V1a receptors are not involved in the onset and completion of nausea and vomiting.
Melatonin increases pial artery tone and decreases the lower limit of cerebral blood flow autoregulation
Authors: Régrigny Olivier , Delagrange Philippe , Scalbert Elizabeth , Atkinson Jeffrey , Chillon Jean‐Marc
Published: March 2003

We studied a possible link between the melatonin‐induced increase in cerebral arteriolar tone and the melatonin‐induced shift in cerebral blood flow (CBF) autoregulation to a lower pressure level. Using the cranial window technique, we showed that intravenous infusion of melatonin constricted pial arterioles (–5.1 ± 1.3 and –5.4 ± 0.7 μm at 60 and 600 ng/kg/h, respectively). Perivascular application of luzindole alone had no significant effect but abolished vasoconstriction induced by melatonin (–0.5 ± 0.7 and + 3.0 ± 1.2 μm at 60 and 600 ng/kg/h respectively). Using a combination of the hydrogen clearance and cranial window techniques, we showed that intravenous infusion of melatonin had no effect on baseline CBF but shifted the lower limit (LL) of CBF autoregulation (stepwise hypotension) to a lower pressure (90 ± 2 mmHg in vehicle vs. 71 ± 3 and 51 ± 5 mmHg, both P < 0.05, after melatonin at 60 and 600 ng/kg/h, respectively). As melatonin had no effect on systemic blood pressure yet shifted the LL of CBF autoregulation, the security margin increased (28 ± 5 in controls vs. 38 ± 3 and 55 ± 5% after melatonin at 60 and 600 ng/kg/h, respectively, both P < 0.05). The higher i.v. infusion rate of melatonin increased the relative arteriolar dilatory response to hypotension but did not increase absolute diameter at any given pressure level. Our results show that melatonin shifts the LL of CBF autoregulation to a lower systemic pressure level. This effect does not appear to be explained by the effect of melatonin on cerebral arteriolar diameter.
Effects of some divalent cations on nitrergic relaxations in the mouse corpus cavernosum
Authors: Ertu Peyman Uçar , Büyükafsar Kansu , Kumcu Eda Karabal , Göçmen Cemil , Seçilmis Ata , Singirik Ergin , Dikmen Atilla , Baysal Firuz
Published: March 2003

Acute effects of some divalent cations (Cd2+, Ni2+, Co2+, Zn2+, Mn2+ and Sn2+) were investigated on neurogenic and endothelium‐dependent relaxations in the isolated mouse corpus cavernosum. Neither neurogenic nor endothelium‐dependent relaxation was affected by cations at the concentrations used (up to 100 μM), except Cd2+. Although Cd2+ (20 and 40 μM) did not cause any significant alteration in the acetylcholine‐ (ACh) or sodium nitroprusside‐ (SNP) induced relaxation, it inhibited electrical field stimulation‐ (EFS) produced relaxation significantly. Zn2+ and selenium could not reverse this inhibitory action. Cd2+ did block the EFS‐evoked guanethidine‐sensitive contraction in the presence of NG‐nitro‐L‐arginine. Elevation of external Ca2+ content significantly reduced the inhibitions due to Cd2+ on the EFS‐induced relaxation and on the EFS‐evoked guanethidine‐sensitive contraction. In the Ca2+‐omitted medium, EFS‐induced relaxation disappeared, while acetylcholine‐elicited relaxation resisted. Verapamil was ineffective on the relaxation produced by EFS or acetylcholine. However, it significantly diminished phenylephrine‐induced contractions. These findings suggest that unlike other cations at the concentrations used in the present study, Cd2+ may have an effect on an external Ca2+‐dependent mechanism at the neuronal level, and this effect may be responsible for its acute inhibitory action on the neurogenic relaxation in the mouse corpus cavernosum.
Vascular reactivity to angiotensin II alone or combined with a thromboxane A2 mimetic in the isolated perfused kidney of Lyon hypertensive rats
Authors: Oréa Valérie , Liu Kiao Ling , Benzoni Daniel
Published: March 2003

The aim of this study was to evaluate whether thromboxane A2‐prostaglandin H2 (TP) receptor activation potentiates the renal vasoconstrictor effect of Angiotensin II (Ang II) in genetically hypertensive rats of the Lyon strain (LH). Concentration‐response curves (CRCs) to Ang II (5 pM to 10 nM), to the specific TP receptor agonist U46619 (7.5–960 nM) and to a mixture of Ang II + U46619 (fixed molar ratio of 1 : 9) were obtained in single‐pass perfused kidneys isolated from 8 week‐old LH and low blood pressure (LL) control rats. Baseline vascular resistance was significantly increased in LH compared to LL kidneys. Comparison of the CRCs obtained for Ang II and U46619 showed that, in both strains, Ang II was about 100 times more potent than U46619. For both drugs, the pD2 or slope values did not differ among the two strains. Co‐activation of TP receptors, analyzed with the method of Pöch and Holzmann, tended to potentiate the effects of Ang II in LH but not in LL kidneys.

In conclusion, isolated perfused kidneys of LH rat did not exhibit an increased vascular sensitivity to acute infusion of Ang II or U46619 compared to control LL ones. In addition, the results suggest that the interactions between Ang II and TP receptor agonist may differ among the two strains.
Study of in vitro glucuronidation of hydroxyquinolines with bovine liver microsomes
Authors: Kanou Masanobu , Saeki Ken‐ichi , Kato Taka‐aki , Takahashi Kazuhiko , Mizutani Takaharu
Published: March 2003

Glucuronidation of drugs by UDP‐glucuronosyltransferase (UGT) is a major phase II conjugation reaction. Defects in UGT are associated with Crigler–Najjar syndrome and Gilbert's syndrome with severe hyperbilirubinaemias and jaundice. We analysed the reactivities of some hydroxyquinoline derivatives, which are naturally produced from quinoline by cytochrome P450. The analyses were carried out using a microassay system for UGT activity in bovine liver microsomes in the range 0.5–100 pmol/assay with the highly sensitive radio‐image analyser Fuji BAS2500 (Fujifilm, Tokyo, Japan). 3‐Hydroxylquinoline is a good substrate for glucuronidation, and the relative Kcat values were 3.1‐fold higher than the values for p‐nitrophenol. 5,6‐Dihydroquinoline‐5,6‐trans‐diol gave a similar Km value to that of 3‐hydroxyquinoline, but the Vmax value was approximately 1/15 of that of p‐nitrophenol and showed weak reactivity. Quinoline N‐oxide gave a low Vmax value and showed marginal activity. The Kcat values of 6‐hydroxyquinoline and 5‐hydroxyquinoline were 2.1‐ and 1.2‐fold higher than that of p‐nitrophenol, respectively. Fluoroquinoline (FQ) derivatives, such as 3FQ, 7,8diFQ and 6,7,8triFQ, did not show any substrate activities. These results suggest that there are therapeutic problems in administration of some quinoline drugs to patients with jaundice.
Influence of the nature of pre‐contraction on the responses to commonly employed vasodilator agents in rat‐isolated aortic rings
Authors: Streefkerk Jörn O. , de Groot Annemieke A. , Pfaffendorf Martin , van Zwieten Pieter A.
Published: March 2003

The relaxing properties of vasodilator drugs in vitro may depend on the characteristics of the contractile state of the vessel investigated.

Rat‐isolated thoracic aortas were exposed to different types of pre‐contraction. The following vasoconstrictor agents were used: phenylephrine (PhE), a selective α1‐adrenoceptor agonist; St 587, a partial α1‐adrenoceptor stimulant; U46619 (U‐46), a thromboxane A2 agonist; and potassium ions causing receptor‐independent depolarization of the membrane. After pre‐contraction, various differential vasodilator drugs were investigated: methacholine (MCh, endothelium dependent), sodium nitroprusside (SNP, NO donor), forskolin (FSK, adenylyl cyclase stimulant) and nifedipine, a Ca2+‐antagonist (selective l‐type calcium antagonist). The vasodilator activity of these compounds was quantified by their vasodilator potency value (pD2) and efficacy (Emax) obtained from their concentration–response curves.

PhE (0.1, 0.3, 3 μm) caused isometric responses of 4.8 ± 0.3, 6.5 ± 0.3 and 7.8 ± 0.5 mN, respectively. An increase of the PhE concentration from 0.1 to 3 μm did not influence the response to FSK while it reduced the pD2 of SNP (8.6 ± 0.1 to 7.35 ± 0.1). Under these conditions, only the Emax of MCh was reduced (96.3 ± 4.3% to 43.3 ± 6.9%). U46 (0.18, 0.3, 1 μm) increased the contractile force by 7.4 ± 0.4, 8.8 ± 0.3 and 10.4 ± 0.3 mN, respectively. Increasing the concentration of U‐46 from 0.18 to 1 μm affected only the efficacy of SNP (84 ± 4.4% to 17 ± 8.8%) and MCh (64.5 ± 12.3% to 0.0 ± 9.2%) and reduced the potency of FSK (7.91 ± 0.26 to 7.15 ± 0.10). The concentration of K+‐ions from 25 to 30 and 40 mm increased the contractile force by 4.0 ± 0.4, 7.0 ± 0.5 and 10.8 ± 0.4 mN, respectively. The increase in [K+ ] caused a potency decrease of FSK (7.1 ± 0.0 to 5.8 ± 0.0) whereas both efficacy and potency were reduced for SNP (95.6 ± 1.8% to 65.8 ± 1.9% and 8.7 ± 0.1 to 7.2 ± 0.1) and MCh (55.4 ± 3.5% to 24.5 ± 0.8% and 7.4 ± 0.3 to 6.1 ± 0.4). Inhibiting of the endothelial NO production by l‐NAME 100 μm resulted after pre‐contraction with PhE and potassium in comparable differences in properties for SNP. Pre‐contraction with St 587 1, 3, 10 and 30 μm shows comparable results after nifedepine relaxation.

The present experiments clearly demonstrate that the characteristics of the applied pre‐contraction strongly, but differentially influence both the potency and efficacy of various vasodilator drugs in vitro. Accordingly, in vitro characterization of vasodilator drugs should be performed under a carefully standardized protocol of pre‐contraction.
Blood distribution of levocetirizine, a new non‐sedating histamine H1‐receptor antagonist, in humans
Authors: Bree Françoise , Thiault Laetitia , Gautiers Gwenaelle , Benedetti Margherita Strolin , Baltes Eugène , Rihoux Jean‐Pierre , Tillement Jean‐Paul
Published: March 2003

The aim of the present study was to determine (1) the extent of levocetirizine binding to human blood cells, plasma and individual plasma proteins; (2) the parameters for levocetirizine binding to individual plasma proteins both at their physiological concentrations and, for human serum albumin (HSA), at a lower saturating concentration; and (3) to simulate levocetirizine distribution in human blood using the information obtained at physiological haematocrit (H) for blood cells and at physiological concentrations for individual plasma proteins. The nature of the main binding sites of HSA, i.e. site I (warfarin) and site II (diazepam), preferentially involved in levocetirizine binding was also investigated.

Over the range of therapeutic concentrations and multiples thereof, levocetirizine is extensively bound to blood components, the free fraction remaining constant (6.45%) and the fraction bound to blood cells and to plasma proteins accounting for 27.43 and 66.11%, respectively. The binding of levocetirizine to HSA in the presence of physiological concentrations of non‐esterified fatty acids (NEFAs) is the main interaction of levocetirizine in blood (50.68% of overall blood binding). This interaction is fatty acid sensitive, with decreasing concentrations of NEFA increasing the amount of bound drug and vice versa. Levocetirizine is also bound to α1‐acid‐glycoprotein and high‐density lipoproteins (5.17 and 6.89% of overall blood binding, respectively). The displacement of levocetirizine by diazepam is consistent with the binding of this drug to HSA at site II, as diazepam is a specific marker for this site. The binding of levocetirizine to HSA at site II being characterized by a low association constant, other drugs sharing the same site with high association constants cannot displace levocetirizine except at very high plasma concentrations. In any case, at therapeutic concentrations of levocetirizine and at physiological protein concentrations, the observation that none of the levocetirizine binding proteins is saturated suggests that very little or no variation of the free fraction will occur although a different distribution of its bound forms is possible.
Metabolism of tresperimus by rat aorta semicarbazide‐sensitive amine oxidase (SSAO)
Authors: Claud P. , Artur Y. , Guichard J.‐P. , Laine R.
Published: March 2003

Tresperimus (Cellimis®), a new immunosuppressive agent, is mainly eliminated in the rat through metabolism, in which the oxidative deamination of the primary amine of the drug plays a major role. We have previously demonstrated in vivo the significant involvement of semicarbazide‐sensitive amine oxidase (SSAO) in this reaction. Rat aorta, a tissue with one of the highest specific SSAO activities, was tested as a new in vitro model to elucidate tresperimus metabolism, using a combination of liquid chromatography/mass spectrometry (LC/MS) and high‐performance liquid chromatography (HPLC) analyses. The metabolites resulting from the main metabolic pathway of the drug were formed in rat aorta homogenates. The use of various SSAO, lysyl oxidase and monoamine oxidase inhibitors confirmed that SSAO is predominantly involved in the main site of tresperimus metabolism but also in every metabolic pathway of the drug, including deamination of tresperimus metabolites M3 (desaminopropyl derivative of tresperimus) and M6 (guanidinohexylamine). A microsomal fraction of the rat aorta was used to characterize tresperimus deamination. The moderate affinity of membrane‐bound SSAO for tresperimus, with a Km value of 66 µm, was counterbalanced by a catalytic efficiency superior to that of certain physiological substrates of SSAO, such as methylamine. The rat aorta provided an interesting model with which to study tresperimus metabolism, highlighting the important role that SSAO could play as a phase I oxidative enzyme in the metabolism of certain exogenous amines at the vascular level.
Cardiovascular autonomic nervous system tests: reference values in young people (15–19 years) and influence of age and gender
Authors: Tonhajzerová Ingrid , Javorka Kamil , Javorka Michal , Petrášková Mária
Published: March 2003

Objective:  The aim of this study was to determine values of the deep breathing test (DB), orthostatic test (OT) and Valsalva manoeuvre (VM) parameters in young people and influence of age and gender.

Methods:  A total of 206 healthy subjects (100 girls, 106 boys) at the age of 15–19 years, BMI 21·3±2·3 (mean ± SD) were examined by system Varia Pulse TF3.

Results:  Reference values of DB, OT, VM parameters are presented as arithmetic mean ± SD and percentiles (P90, P75, P50, P25, P10). In the whole group HRrest was lower in 19‐year‐old group, in OT this difference was significant already in 18‐year‐old group compared with 15‐year‐old group. DB: I/E was significantly increased in 19‐year‐old group compared with 15‐year‐old group. HRrest was higher in girls compared with boys in the whole group. DB: I/E was significantly lower in girls compared with boys. OT: 30:15 and HRmax/HRrest were significantly decreased in girls compared with boys.

Conclusion:  Reference values of DB, OT, VM parameters were determined in young people at the age of 15–19 years. The most sensitive test for ascertainment of developmental changes was test of deep breathing. I/E was increased in the 19‐year‐old group compared with 15‐year‐old group indicating an increase of vagal activity. Girls had decreased some parameters of deep breathing and orthostatic test compared with boys in the same group (15–19 years).
Impact of Hybridization on a Threatened Trout of the Southwestern United States
Authors: Dowling Thomas E. , Childs Michael R.
Published: March 2003

Trouts native to the American Southwest provide an excellent example of the plight of endangered fishes from this region. The native species, Apache trout and Gila trout (Oncorhynchus apache and O. gilae, respectively) have faced drastic reduction in habitat and detrimental interactions with introduced species, resulting in a dramatic decrease in numbers and sizes of populations. We used biochemical methods to identify diagnostic markers for the estimation of genetic relatedness and analysis of hybridization among native trouts and introduced cutthroat and rainbow trouts (O. clarki and O. mykiss, respectively). Restriction endonuclease analysis of mitochondrial DNA (mtDNA) indicated that Apache and Gila trout were very similar to each other, and more similar to rainbow trout than cutthroat. Diagnostic allozyme marker loci indicated that Apache trout hybridized extensively with rainbows in four populations and provided no evidence for reproductive isolation between the forms. Analysis of mtDNA, however, indicated that introduced haplotypes were rare in these same individuals, identifying a bias in the direction of gene exchange between species. The potential reproductive isolation and lack of information concerning population structure necessitate further study of Apache trout to determine the appropriate management strategy for this threatened species. This case demonstrates that extreme care must be exercised when considering elimination of any contaminated population lest the unique genetic identity of the native taxon be lost forever.
Rethinking the Stock Concept: A Phylogeographic Approach
Authors: DIZON ANDREW E. , LOCKYER CHRISTINA , PERRIN WILLIAM F. , DEMASTER DOUGLAS P. , SISSON JOYCE
Published: March 2003

Abstract: The “stock” is the fundamental population unit of legally mandated conservation efforts, yet its formal definition in the scientific literature and in two U.S. conservation acts is varied and so general that attempts to apply it in practice are arbitrary. Because choice of stocks deserving management protection is sometimes politically contentious, improvement of the working definition is important.

A key element should be the degree to which a population can be considered an evolutionarily significant unit. We propose that a hierarchial classification scheme be applied to stock designations. Category I populations, having the highest probability of being evolutionarily significant units, are characterized by a discontinuous genetic divergence pattern where locally adapted and closely related genome assemblages are separated from others geographically and by significant genetic distances. Category II populations are similarly characterized by significant genetic diversity, but with weak geographic partitioning. Category III populations are the converse of II, having little genetic differentiation between assemblages that are clearly separate and likely to be reproductively isolated. Category IV assemblages have the lowest probability of being evolutionarily significant units and are characterized by extensive gene flow and no subdivision by extrinsic barriers. In addition to phylogeographic designation, the following information is used in the classification, as indicated by single‐letter abbreviations: distribution (a), population response (b), phenotypic (c), and genotypic (d) information. Included are evidence both for and against designating population as a separate stock. In the designation “Type II a/bc,” for example, information to the right of the solidus would be evidence for “lumping,” to the left would be for “splitting.” Missing letter abbreviations would signify lack of reliable data. Note that phylogeographic designation depends on the results of selection operating to produce a locally adapted genome (indicated by differences in demographic, phenotypic, and genotypic measures) and on gene flow (indicated by differences in distribution or by movement data).

Hierarchial stock categorization allows resource managers to direct limited resources to the populations most deserving of protection, that is, the populations that are most likely to be evolutionarily significant units. Using this comprehensive classification of stock allows preliminary, conservative splitting of assemblages where data are lacking without the danger that these divisions will become entrenched as biological dogma.
Using Vegetation Analysis to Facilitate the Selection of Conservation Sites in Eastern Paraguay
Authors: Keel Shirley , Gentry Alwyn H. , Spinzi Lucio
Published: March 2003

This study demonstrates the use of vegetation analysis in the selection of priority areas for conservation. The analysis is based on field data derived from narrow rectangular sample plots and includes information from the database of Paraguay’s Conservation Data Center. Ten 100‐m2 sample plots were laid out for each survey site. We compared three sites, Mbaracayú, Tarumá, and Parabel, all forests located in the ecoregion of Selva Central in eastern Paraguay. Subtropical and physiognomically similar, the sites are dominated by a single species, either Sorocea bonplandii or Actinostemon concolor, but differ in species richness. Vegetation analysis permitted us to calculate the total number of species, including liana species, the number of economic plants, and the number of rare, uncommon, and vulnerable species, and thus to quantify the conservation worthiness of the candidate sites. Our study pinpoints Mbaracayú as a mature, resource‐rich forest with the highest habitat and plant species diversity and several local endemics. We maintain that it is the area of Paraguay’s Selva Central most important for conservation.
Primate Conservation along the Tana River, Kenya: An Examination of the Forest Habitat
Authors: Medley Kimberly E.
Published: March 2003

The Tana River National Primate Reserve, Kenya, was established in 1976 to preserve the endemic and endangered Tana River red colobus (Colobus badius rufomitratus) and crested mangabey (Cercocebus galeritus galeritus). Between 1975 and 1985 their populations declined by 80% and 45%, respectively. A study addressing primate‐to‐habitat relationships was conducted in 12 forest areas to determine what attributes appear most important to the in situ preservation of both endangered primates. Correlations among the abundances of primate groups, their group sizes, and the structural, resource, disturbance, and spatial attributes of the forest were used to distinguish the quality of forest patches. Intraforest habitat quality was examined, using canonical variate analysis to discriminate primate ranging patterns based on canopy and subcanopy tree composition. The colobus and mangabey show positive relationships to interior‐forest habitat and appear susceptible to forest disturbances that reduce forest area or that increase forest edge and intraforest disturbance. Forest loss, fragmentation, and consequent reduction in the area‐to‐perimeter ratio of the remaining forests measured from 1960 to 1975 provide a partial explanation for the decline in primate populations. The results suggest that a combination of primary food items and seasonal food resources in large, high‐stature, closed‐canopy forests is the best predictor of high‐quality habitat for these monkeys. Stewardship should be directed at the preservation of these areas or the restoration of forests toward this habitat model
Modeling Problems in Conservation Genetics Using Captive Drosophila Populations: Consequences of Equalization of Family Sizes
Authors: Borlase Suzanne C. , Loebel David A. , Frankham Richard , Nurthen Roderick K. , Briscoe David A. , Daggard Grant E.
Published: March 2003

Equalization of family sizes is recommended for use in captive breeding programs, as it is predicted to double effective population sizes, reduce inbreeding, and slow the loss of genetic variation. The effects of maintaining small captive populations with equalization of family sizes versus random choice of parents on levels of inbreeding genetic variation, reproductive fitness, and effective population sizes (Ne) were evaluated in 10 lines of each treatment maintained with four pairs of parents per generation. The mean inbreeding coefficient (F) increased at a significantly slower rate with equalization than with random choice (means of 0.35 and 0.44 at generation 10). Average heterozygosities at generation 10, based on six polymorphic enzyme loci, were significantly higher with equalization (0.149) than with random choice (0.085), compared to the generation 0 level of 0.188. The competitive index measure of reproductive fitness at generation 11 was more than twice as high with equalization as with random choice, both being much lower than in the outbred base population. There was considerable variation among replicate lines within treatments in all the above measures and considerable overlap between lines from the two treatments. Estimates of Ne for equalization were greater than those for random choice, whether estimated from changes in average heterozygosities or from changes in F. Equalization of family sizes can be unequivocally recommended for use in the genetic management of captive populations.
Conservation in Action: Past, Present, and Future of the National Park System of Costa Rica*
Authors: Boza Mario A.
Published: March 2003

Costa Rica’s national parks stand as a model for the preservation of biodiversity in the tropics, with 622,000 ha, or 12.2%, of the country set aside in preserves. In 1970, efforts to establish the parks were met with indifference but a practical strategy for nature conservation and favorable opportunities led to success, including establishment of Poas Volcano, Cahuita, Santa Rosa and Tortuguero National Parks in 1970–1971. Since then we have concentrated on four main activities. (1) procuring funds and personnel; (2) obtaining national and international support; (3) developing conservation education programs; and (4) getting environmental legislation passed Today we continue to build the national park system. We are creating a system of national forests, encouraging commercial reforestation and management of private land, consolidating the national parks system, and continuing to raise funds. Because most tourism is based on the national parks, we are asking the tourism industry to do its fair share to support the parks and to encourage wise use and conservation. Many organizations use funds to maintain an international bureaucracy rather than supporting direct conservation in the field. We do not need more planning studies and documents to tell us what to do, but instead we need funds to make environmental conservation a reality at the grass‐roots level. International environmental standards should be set by a United Nations environmental organization that is empowered to infringe on the sovereignty of individual states in environmental matters. Future concerns for the national parks of Costa Rica include the economic situation, conservation education, the need to demonstrate the monetary value of conservation, population growth, the need for citizen involvement and the need for effective environmental legislation.
Toward Conservation of Midcontinental Shorebird Migrations
Authors: Skagen Susan K. , Knopf Fritz L.
Published: March 2003

Shorebirds represent a highly diverse group of species, many of which experience tremendous energy demands associated with long‐distance migratory flights. Transcontinental migrants are dependent upon dynamic freshwater wetlands for stopover resources essential for replenishment of lipid reserves and completion of migration. Patterns of shorebird migration across midcontinental wetlands were detected from migration reports to American Birds and information provided by U.S. Fish and Wildlife Service national wildlife refuges. Patterns in species composition and abundance varied geographically, emphasizing the uniqueness of different regions to migrating shorebirds. Smaller species and neotropical migrants moved primarily across the Great Plains, whereas larger species and North American migrants predominated in assemblages in the intermountain west Shorebirds were broadly dispersed in wetland habitats with dynamic water regimes. Whereas populations of shorebirds in coastal systems appear to concentrate at sites of seasonally predictable and abundant food resources, we propose that transcontinental shorebirds disperse and use wetlands opportunistically. This migration system exemplifies the need for large‐scale, coordinated regional management efforts that recognize the dynamic nature of ecosystem processes.
Attitudes toward a Proposed Reintroduction of Black‐Footed Ferrets (Mustela nigripes)
Authors: Reading Richard P. , Kellert Stephen R.
Published: March 2003

Sociological considerations are crucial to recovery efforts such as the proposed reintroduction of endangered black‐footed ferrets (Mustela nigripes) into Phillips County, Montana. Many past reintroduction attempts have failed or been less successful because they neglected these concerns. This study examined knowledge, attitudes, and opinions of ranchers toward black‐footed ferrets, prairie dogs (Cynomys spp.), and the proposed ferret reintroduction using informal, unstructured interviews and a mail sample survey. Ranchers within the proposed reintroduction site were antagonistic toward the program, the ferret, and especially the prairie dogs upon which black‐footed ferrets depend for survival. Of six sample groups, local ranchers scored highest on negativistic, libertarian/dominionistic, and utilitarian attitude scales and lowest on moralistic, humanistic, and naturalistic/ecologistic attitude scales. Their attitudes were most similar to those of ranchers statewide, followed by residents of Phillips County, Montana, Billings, Montana, residents, and members of the Montana Wildlife Federation; they were least similar to attitudes of members of conservation organizations other than the Montana Wildlife Federation. Local ranchers perceived themselves as having little knowledge of black‐footed ferrets, even though they received significantly higher scores on the black‐footed ferret knowledge scales than did most other groups, and they perceived themselves as having great knowledge of prairie dogs, even though their scores on the prairie dog knowledge scales were no better than any other group. These results are useful for ranking the suitability of reintroduction sites, for formulating policies, and for developing more effective public relations campaigns. The results highlight the need for education and public relations programs that do more than simply provide facts and information. Well‐conceived public relations programs should use pressure, purchase, and persuasion to try to change or neutralize opposition and to develop, conserve, and strengthen support. Endangered species reintroduction and recovery programs will rarely succeed if they do not actively consider and incorporate the values, attitudes, behaviors, and desires of the local public.
Ex Situ Conservation of Wild Plant Species: Time to Reassess the Genetic Assumptions and Implications of Seed Banks
Authors: Hamilton Matthew B.
Published: March 2003

Ex situ conservation of wild plant species through seed banking is currently being recommended as a conservation strategy to help preserve the biological and genetic diversity of wild plants. Here I argue that ex situ collections may be ineffective at preserving genetic diversity and the evolutionary potential of populations for adaptive or neutral evolution. Treating the collection of genetic variation for seed banks as simply a problem in efficient sampling of neutral, allelic genetic polymorphism is a limited view of the types and organization of genetic variation present in wild plant species. Perspectives on genetic variation from neutral alleles to quantitative variation are necessary when considering evolutionary change. Quantitative genetic variation and genetic correlations determine the degree and form of response to natural selection on polygenic traits. Population variation in the amount of quantitative genetic variation or structure of genetic correlations argues that different populations will respond differently to the action of natural selection and are therefore unique evolutionary entities. Unavoidable selection on single traits will cause indirect selection on genetically correlated traits, possibly resulting in phenotypic changes and a reduction of genetic variation. Genotype‐by‐environment interactions demonstrate that the success of releasing seed bank genotypes in natural populations is dependent on the likelihood that seed bank material contains genotypes of high relative fitness in introduction habitats. Such actions can cause introduction of nonadaptive genotypes that will depress population fitness. Because not all types of genetic variation are highly positively correlated, sampling methods based on the neutral theory of alleles or allelic data will not necessarily capture representative quantitative genetic variation. More research on the relationship and evolutionary significance of allelic and quantitative genetic variation in collections and wild populations is needed. Initial and ongoing data on the fate of different types of genetic variation are required to determine the relative success or failure of ex situ conservation methods and to test assumptions of current programs. In situ conservation of ecosystems may offer distinct advantages for many plant species by preserving both genetic and ecological information.
Amphibian Declines and Climate Disturbance: The Case of the Golden Toad and the Harlequin Frog
Authors: Pounds J. Alan , Crump Martha L.
Published: March 2003

The endemic golden toad (Bufo periglenes) was abundant in Costa Rica’s Monteverde Cloud Forest Preserve in April–May 1987 but afterwards disappeared, along with local populations of the harlequin frog (Atelopus varius). We examine the possible relationship between these sudden declines and unusually warm, dry conditions in 1987. For our analyses of local weather patterns, we define a 12‐month (July–June) amphibian moisture‐temperature cycle consisting of four periods: (1) late wet season; (2) transition into dry season; (3) dry season; and (4) post‐dry‐season (early‐wet‐season) recovery. The 1986–1987 cycle was the only one on record (of 20 analyzed) with abnormally low rainfall in all four periods, and temperature anomalies in 1987 reached record highs. Flow in local aquifer‐fed streams during the dry season and post‐dry‐season recovery period reached a record low. This climate disturbance, associated with the 1986–1987 El Niño/Southern Oscillation, was more severe than a similar event associated with the 1982–1983 El Niño, though this earlier oscillation was the strongest of the past century. Demographic data for one harlequin frog population, gathered during these two climatic events, support the hypothesis that in 1987, shortly before the population collapsed, the frogs underwent an unprecedented shift in distribution within the habitat in response to desiccating conditions. The juxtaposition of these rare demographic events suggests they were causally linked yet sheds little light on mechanisms underlying the sudden decline. While desiccation or direct temperature effects may have been factors leading to high adult mortality, moisture‐temperature conditions may have interacted with some other, unidentifted agent. We discuss two hypotheses concerning possible synergistic effects: In the climate‐linked epidemic hypothesis, microparasites are the additional agent. In the climate‐linked contaminant pulse hypothesis, atmospheric contaminants scavenged by mist and cloud water in montane areas reach critical concentrations when conditions are abnormally warm and dry.
Puerto Rican Parrots and Potential Limitations of the Metapopulation Approach to Species Conservation
Authors: Wilson Marcia H. , Kepler Cameron B. , Snyder Noel F.R. , Derrickson Scott R. , Dein F. Josh , Wiley James W. , Wunderle Joseph M. , Lugo Ariel E. , Graham David L. , Toone William D.
Published: March 2003

Population viability analyses for a number of endangered species have incorporated a metapopulation approach. The risk assessments of these viability analyses have indicated that some extant populations should be subdivided into numerous subgroups with exchange of individuals among them in order to reduce the chance of catastrophic loss of the species. However, routine application of a policy of extensive subdivision may have detrimental consequences for certain endangered species. We examine the Puerto Rican Parrot as a case history in which this policy is ill‐advised. In 1989, apopulation viability analysis was conducted for the parrot. The document recommended subdivision of the existing small captive flock into three groups. One of these captive flocks would consist of individuals transferred to a multi‐species facility in the continental United States. Subsequently, individuals from this facility would be exchanged with the insular captive population(s) and the relict wild flock. For two reasons, implementation of this recommendation might have led to serious repercussions. First, this parrot, like many endangered species, has gone through a genetic bottleneck and may have a heightened susceptibility to disease. Multi‐species facilities are a high‐risk environment favoring the transmission of pathogens, especially when the facilities are located outside the natural ranges of a particular species. Second, the parrot is a K‐selected species for which mate selection is idiosyncratic. This type of species often proves difficult to breed in captivity in small groups. Part of the problem in mate selection may be reduced by a policy allowing frequent transfers of individuals among facilities, but such movements increase the chances of spreading disease in the metapopulation. Thus, population viability analyses need to acknowledge that proliferation of captive subgroups accompanied by exchanges of individuals can in themselves carry substantial risks that must be weighed against the presumed benefits of subdivision.
Conservation Corridors and Contagious Disease: A Cautionary Note
Authors: Hess George R.
Published: March 2003

Recent conservation proposals frequently include the establishment of corridors to connect isolated patches of wildlife habitat. Much attention has been focused on the potential benefits of corridors with little note given to potentially adverse consequences. A simulation model is developed here to study the effect of corridors on the survival of a metapopulation in the presence of a fatal disease that is spread by direct contact between susceptible and infected individuals. For the disease modeled here, a landscape of patches connected by corridors generally suffers fewer metapopulation extinctions than a landscape of isolated patches. However, under a narrow range of conditions, results suggest that corridors may dramatically increase the probability of metapopulation extinction. This occurs when disease‐induced mortality is low enough to allow infected individuals to spread the disease, but high enough to reduce population levels to the point that random demographic and environmental events cause frequent metapopulation extinctions. This has important implications for the design and management of conservation reserve networks. Although discussion focuses primarily on conservation corridors, the model results apply to any management techniques that increase the movement of individuals among populations.
Ad Hoc Reservations: Forward or Backward Steps in Developing Representative Reserve Systems?
Authors: Pressey R.L.
Published: March 2003

A major reason for land reservation has been the relative lack of value of selected sites for major commercial land uses or for human habitation. Other important reasons include scenery, recreation, tourist potential, the influence of lobby groups, and historical protection for uses such as hunting or water supply. There are two main disadvantages of such ad hoc approaches to reserve planning. One is the bias in the content of regional reserve systems, leaving some species, communities, or ecosystems without protection, often the ones most in need of strict reservation. The second is that ad hoc reservations can make the goal of representing regional biodiversity more expensive, reducing the likelihood of protecting many elements of biodiversity. Ad hoc approaches to reservation persist despite clearly stated representation goals, improving data bases, and systematic techniques for reserve selection. The main causes need to be understood and addressed if the potential value of reservation for protecting biodiversity is to be realized.
Scale Perspectives on Avian Diversity in Western Riparian Ecosystems
Authors: Knopf Fritz L. , Samson Fred B.
Published: March 2003

Conservation of riparian vegetation in western North America has, in part, emphasized providing habitats for a locally diverse avifauna. Site diversity, especially relative to the number of species present, is generally high within riparian avifaunas. Between‐habitat diversity changes across a watershed, with riparian species assemblages differing most from upland assemblages at the highest and lowest elevations. This pattern can be attributed to enhanced avian movements within the riparian vegetation. The corridors for bird movements, in turn, facilitate faunal mixing on a broader scale, influencing regional diversity within landscapes. Riparian ecosystems are viewed as connectors of forests across fragmented landscapes. In western settings, however, they are highly linearized forests transecting watersheds between upland associations of high elevations and very different associations at lower elevations. Regionally, riparian vegetation represents linear islands that are internally both floristically and faunistically dynamic rather than mere bridges of homogeneous vegetation in landscape networks. The significance of riparian vegetation as habitat for western birds has been defined primarily at the local level. Conservation activities favoring site diversity are short‐sighted, however, and could have severe consequences for unique elements of riparian avifaunas. Conservation actions must evaluate how local activities alter potential dispersal opportunities for ecological‐generalist versus riparian‐obligate species. Maintaining the character and integrity of riparian avifaunas requires planning from regional and continental perspectives.