bluuebunny/crossref_metadata_2025 huggingface dataset:
Glutamate‐induced declustering of post‐synaptic adaptor protein Cupidin (Homer 2/vesl‐2) in cultured cerebellar granule cells
Authors: Shiraishi Yoko , Mizutani Akihiro , Yuasa Shigeki , Mikoshiba Katsuhiko , Furuichi Teiichi
Published: September 2003

Cupidin (Homer 2/vesl‐2) is a post‐synaptic adaptor protein that associates with glutamate receptor complexes and the actin cytoskeleton. We analyzed the developmental and activity‐dependent localization of Cupidin in mouse cerebellar granule cells. Cupidin is predominantly localized to granule cell post‐synapses connecting with mossy fiber terminals in developing post‐natal cerebellum, but is diminished in adult cerebellum. In cultured granule cells 7 days in vitro, Cupidin was present as synaptic and extra‐synaptic punctate clusters that largely co‐localized with the actin‐cytoskeletal binding partners F‐actin and drebrin, as well as a post‐synaptic scaffold protein PSD‐95. Upon stimulation with glutamate, Cupidin clusters were rapidly dissociated without protein degradation, and by short‐term but not sustained stimulation they were recovered after post‐incubation without glutamate. The glutamate‐induced declustering of Cupidin preceded that of F‐actin and drebrin, was elicited by NMDA receptor‐mediated Ca2+ influx, and was followed by a downstream pathway including MAPK/ERK and protein tyrosine kinase. Specific isoforms with post‐translational modification were reduced depending on Ca2+‐dependent protein phosphatase activity. In cultured hippocampal neurons, Homer family members Homer 1, Cupidin/Homer 2 and Homer 3 showed similar glutamate‐induced declustering. We suggest that Cupidin acts as a mobile adaptor protein that changes the distribution states, clustered versus declustered, in response to synaptic activity.
Regulation of microglial inflammatory response by histone deacetylase inhibitors
Authors: Suuronen Tiina , Huuskonen Jari , Pihlaja Rea , Kyrylenko Sergiy , Salminen Antero
Published: September 2003

The activation of microglial cells is involved in the pathogenesis of a variety of neurodegenerative diseases, stroke and traumatic brain injuries. Recent studies suggest that protein acetylation can affect the extent of inflammatory responses. Our aim was to elucidate whether histone deacetylase inhibitors, inducers of protein hyperacetylation, regulate the inflammatory response in neural models of inflammation in vitro and whether neurone–glia interactions affect this regulation. Interestingly, we observed that histone deacetylase inhibitors, such as trichostatin A (TSA) and suberoylanilide hydroxamic acid, strongly potentiated the lipopolysaccharide (LPS)‐induced inflammatory response in murine N9 and rat primary microglial cells as well in neural co‐cultures and hippocampal slice cultures. TSA clearly potentiated the LPS‐induced expression of interleukin (IL)‐6 and inducible nitric oxide synthase mRNAs, as well as the secretion of cytokines IL‐6, tumour necrosis factor‐α and macrophage inflammatory protein (MIP)‐2, and nitric oxide (NO). Co‐culture and slice culture experiments showed that the presence of astrocytes and neurones did not stimulate or prevent the pro‐inflammatory potentiation induced by histone deacetylase inhibitor in microglial cells. The potentiation of cytokine and NO responses was blocked by the nuclear factor kappa B (NF‐κB) inhibitors caffeic acid phenethyl ester and helenalin, demonstrating that the NF‐κB signalling pathway is involved. The DNA‐binding activity of the NF‐κB complex was strongly increased by LPS treatment but not enhanced by TSA. This suggests that potentiation of the inflammatory response is not dependent on the level of cytoplasmic NF‐κB activation or DNA‐binding activity but that site of action may be at the level of transcriptional regulation. Our results suggest that environmental stresses, ageing, diet and diseases that regulate protein acetylation status may also affect the inflammatory response.
Regulatory roles of presenilin‐1 and nicastrin in neuronal differentiation during in vitro neurogenesis
Authors: Sarkar Saumyendra N. , Das Hriday K.
Published: September 2003

Presenilin (PS) in association with nicastrin (NICA) forms a γ‐secretase complex that plays a crucial role in facilitating intramembranous processing of Notch, a signaling receptor that is essential for neuronal fate specification and differentiation. Loss of function studies have implicated a role for PS1 in regulating neuronal differentiation in association with the down‐regulation of Notch signaling during neurogenesis. By using a system for stable, as well as tetracycline‐inducible expression of interfering RNAs (RNAi), we studied the functions of PS1 during neuronal differentiation in the murine pluripotent p19 embryonic carcinoma cell line. After retinoic acid (RA) treatment and in the absence of doxycycline, neuronal progenitor cells in the p19 clone were found to extend their processes towards the neighboring colony to form network‐like connections, as revealed by neuron‐specific microtubule‐associated protein 2 staining and laser scanning confocal microscopy. However, doxycycline‐induced expression of PS1 small interfering RNA (siRNA) in the p19 clone resulted in a severe defect in the formation of network‐like connections. Expression of the NICA and Notch down‐stream effector genes Hes1 and Hes5 was unaffected in p19 cells expressing doxycycline‐induced PS1 siRNA. In contrast to PS1, constitutive inactivation of NICA by siRNA in p19 cells resulted in premature and partial differentiation without RA treatment. In these NICA siRNA‐expressing p19 cells the expression of the Notch1 down‐stream effector Hes1 gene was substantially reduced. After RA treatment the NICA siRNA clone failed to differentiate completely into networks of neurons. These results taken together provide direct evidence that PS1 and NICA may participate in neuronal differentiation during neurogenesis in vitro.
Pharmacokinetics of systemically administered tyrosine: a comparison of serum, brain tissue and in vivo microdialysate levels in the rat
Authors: Bongiovanni Rodolfo , Yamamoto Bryan K. , Simpson Catherine , Jaskiw George E.
Published: September 2003

Tyrosine uptake has been reported to differ across brain regions. However, such studies have typically been conducted over brief intervals and in anesthetized rats; anesthesia itself affects amino acid transport across the blood–brain barrier. To address these concerns, serum, brain tissue and in vivo microdialysate tyrosine levels were compared for 0–3 h after administration of tyrosine [0.138–1.10 mmol/kg intraperitoneally (i.p.)] to groups of awake rats. Serum and brain tissue tyrosine levels increased linearly with respect to dose. Basal tissue tyrosine levels varied significantly across brain regions [medial prefrontal cortex (MPFC), striatum, hypothalamus, and cerebellum], but the rate of tyrosine uptake was similar for hypothalamus, striatum and MPFC. For brain regions in which tyrosine levels in both microdialysate and tissue were assayed, namely MPFC and striatum, there was a high degree of correlation between tyrosine levels in tissue and in microdialysate. Increasing brain tyrosine levels had no effect on DA levels in MPFC microdialysate. We conclude that (i) regional differences in the response of dopamine neurons to systemic tyrosine administration cannot be attributed to pharmacokinetic factors; (ii) in vivo microdialysate provides an excellent index over time and across a wide range of tyrosine doses, of brain tissue tyrosine levels; and (iii) increases in brain tyrosine levels do not affect basal DA release in the MPFC.
Differential influence of increased polyol pathway on protein kinase C expressions between endoneurial and epineurial tissues in diabetic mice
Authors: Yamagishi Shin‐Ichiro , Uehara Kenji , Otsuki Saori , Yagihashi Soroku
Published: September 2003

To explore the relationship between polyol pathway and protein kinase C (PKC), we examined PKC activities and expressions of PKC isoforms separately in endoneurial and vessel‐rich epineurial tissues in diabetic mice transgenic for human aldose reductase (Tg). Tg and littermate control mice (Lm) were made diabetic by streptozotocin at 8 weeks of age and treated orally with aldose reductase inhibitor (ARI) (fidarestat 3–5 mg/kg/day) or placebo for 12 weeks. At the end, compared with non‐diabetic state, sorbitol contents were increased 6.4‐fold in endoneurium and 5.1‐fold in epineurium in diabetic Tg, whereas the increase was detected only in endoneurium in diabetic Lm. Endoneurial PKC activity was significantly reduced in diabetic Tg. By contrast, epineurial PKC activity was increased in both diabetic Lm and diabetic Tg and there was no significant difference between the two groups. These changes were all corrected by ARI treatment. Consistent with the changes of PKC activities, diabetic Tg showed decreased expression of PKCα in endoneurium, whereas there was an increased expression of PKCβII in epineurium in both diabetic Tg and diabetic Lm. These findings suggest the presence of dichotomous metabolic pathway between neural and vascular tissues in the polyol‐PKC‐related pathogenesis of diabetic neuropathy.
Substance P protects spiral ganglion neurons from apoptosis via PKC‐Ca2+‐MAPK/ERK pathways
Authors: Lallemend F. , Lefebvre P. P. , Hans G. , Rigo J. M. , Van De Water T. R. , Moonen G. , Malgrange B.
Published: September 2003

In the current study, we have investigated the ability of substance P (SP) to protect 3‐day‐old (P3) rat spiral ganglion neurons (SGNs) from trophic factor deprivation (TFD)‐induced cell death. The presence of SP high affinity neurokinin‐1 receptor (NK1) transcripts was detected in the spiral ganglion and the NK1 protein localized to SGNs both ex vivo and in vitro. Treatment with SP increased cytoplasmic Ca2+ in SGNs, further arguing for the presence of functional NK1 on these neurons. Both SP and the agonist [Sar9,Met(O2)11]‐SP significantly decreased SGN cell death induced by TFD, with no effect on neurite outgrowth. The survival promoting effect of SP was blocked by the NK1 antagonist, WIN51708. Both pan‐caspase inhibitor BOC‐D‐FMK and SP treatments markedly reduced activation of caspases and DNA fragmentation in trophic factor deprived‐neurons. The neuroprotective action of SP was antagonised by specific inhibitors of second messengers, including 1.2‐bis‐(O‐aminophenoxy)‐ethane‐N,N,N′,N′‐tetraacetic acid (BAPTA‐AM) to chelate cytosolic Ca2+, the protein kinase C (PKC) inhibitors bisindolylmaleimide I, Gö6976 and LY333531 and the MAPK/ERK inhibitor U0126. In contrast, nifedipine, a specific inhibitor of l‐type Ca2+ channel, and LY294002, a phosphatidylinositol‐3‐OH kinase (PI3K) inhibitor, had no effect on SP trophic support of SGNs. Moreover, activation of endogenous PKC by 4β‐phorbol 12‐myristate 13‐acetate (PMA) also reduced the loss of trophic factor‐deprived SGNs. Thus, NK1 expressed by SGNs transmit a survival‐promoting regulatory signal during TFD‐induced SGN cell death via pathways involving PKC activation, Ca2+ signalling and MAPK/ERK activation, which can be accounted for by an inhibition of caspase activation.
Opposed effects of lithium on the MEK‐ERK pathway in neural cells: inhibition in astrocytes and stimulation in neurons by GSK3 independent mechanisms
Authors: Pardo Raúl , Andreolotti Alberto G. , Ramos Belén , Picatoste Fernando , Claro Enrique
Published: September 2003

Lithium is widely used in the treatment of bipolar disorder, but despite its proven therapeutic efficacy, the molecular mechanisms of action are not fully understood. The present study was undertaken to explore lithium effects of the MEK/ERK cascade of protein kinases in astrocytes and neurons. In asynchronously proliferating rat cortical astrocytes, lithium decreased time‐ and dose‐dependently the phosphorylation of MEK and ERK, with 1 mm concentrations achieving 60 and 50% inhibition of ERK and MEK, respectively, after a 7‐day exposure. Lithium also inhibited [3H]thymidine incorporation into DNA and induced a G2/M cell cycle arrest. In serum‐deprived, quiescent astrocytes, pre‐exposure to lithium resulted in the inhibition of cell cycle re‐entry as stimulated by the mitogen endothelin‐1: under this experimental setting, lithium did not affect the rapid, peak phosphorylation of MEK taking place after 3–5 min, but was effective in inhibiting the long‐term, sustained phosphorylation of MEK. Lithium inhibition of the astrocyte MEK/ERK pathway was independent of inositol depletion. Further, compound SB216763 inhibited Tau phosphorylation at Ser396 and stabilized cytosolic β‐catenin, consistent with the inhibition of glycogen synthase kinase‐3β (GSK‐3β), but failed to reproduce lithium effects on MEK and ERK phosphorylation and cell cycle arrest. In cerebellar granule neurons, millimolar concentrations of lithium enhanced MEK and ERK phosphorylation in a concentration‐dependent manner, again through an inositol and GSK‐3β independent mechanism. These opposing effects in astrocytes and neurons make lithium treatment a promising strategy to favour neural repair and reduce reactive gliosis after traumatic injury.
Activation of stimulatory heterotrimeric G proteins increases glutathione and protects neuronal cells against oxidative stress
Authors: Lewerenz Jan , Letz Julia , Methner Axel
Published: September 2003

Oxidative glutamate toxicity in the neuronal cell line HT22 is a model for cell death by oxidative stress, where an excess of extracellular glutamate inhibits import of cystine, a building block of the antioxidant glutathione. The subsequent decrease in glutathione then leads to the accumulation of reactive oxygen species (ROS) and programmed cell death. We used pharmacological compounds known to interact with heterotrimeric G‐protein signalling and studied their effects on cell survival, morphology, and intracellular events that ultimately lead to cell death. Cholera toxin and phorbol esters were most effective and prevented cell death through independent pathways. Treating HT22 cells with cholera toxin attenuated the glutamate‐induced accumulation of ROS and calcium influx. This was, at least in part, caused by an increase in glutathione due to improved uptake of cystine mediated by the induction of the glutamate/cystine‐antiporter subunit xCT or, additionally, by the up‐regulation of the antiapoptotic protein Bcl‐2. Gs activation also protected HT22 cells from hydrogen peroxide or inhibition of glutathione synthesis by buthionine sulfoximine, and immature cortical neurones from oxidative glutamate toxicity. Thus, this pathway might be more generally implicated in protection from neuronal death by oxidative stress.
Alteration in calcium channel properties is responsible for the neurotoxic action of a familial frontotemporal dementia tau mutation
Authors: Furukawa Katsutoshi , Wang Yue , Yao Pamela J. , Fu Weiming , Mattson Mark P. , Itoyama Yasuto , Onodera Hiroshi , D'Souza Ian , Poorkaj Parvone H. , Bird Thomas D. , Schellenberg Gerard D.
Published: September 2003

Tau, a microtubule binding protein, is not only a major component of neurofibrillary tangles in Alzheimer's disease, but also a causative gene for hereditary frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP‐17). We show here that an FTDP‐17 tau mutation (V337M) in SH‐SY5Y cells reduces microtubule polymerization, increases voltage‐dependent calcium current (ICa) density, and decreases ICa rundown. The reduced rundown of ICa by V337M was significantly inhibited by nifedipine (L‐type Ca channel blocker), whereas ω‐conotoxin GVIA (N‐type Ca channel blocker) showed smaller effects, indicating that tau mutations affect L‐type calcium channel activity. The depolarization‐induced increase in intracellular calcium was also significantly augmented by the V337M tau mutation. Treatment with a microtubule polymerizing agent (taxol), an adenylyl cyclase inhibitor, or a protein kinase A (PKA) inhibitor, counteracted the effects of mutant tau on ICa. Taxol also attenuated the Ca2+ response to depolarization in cells expressing mutant tau. Apoptosis in SH‐SY5Y cells induced by serum deprivation was exacerbated by the V337M mutation, and nifedipine, taxol, and a PKA inhibitor significantly protected cells against apoptosis. Our results indicate that a tau mutation which decreases its microtubule‐binding ability augments calcium influx by depolymerizing microtubules and activating adenylyl cyclase and PKA.
Flow cytometric analysis of mitochondria from CA1 and CA3 regions of rat hippocampus reveals differences in permeability transition pore activation
Authors: Mattiasson Gustav , Friberg Hans , Hansson Magnus , Elmér Eskil , Wieloch Tadeusz
Published: September 2003

Mitochondria are important in the pathophysiology of several neurodegenerative diseases, and mitochondrial production of reactive oxygen species (ROS), membrane depolarization, permeability changes and release of apoptogenic proteins are involved in these processes. Following brain insults, cell death often occurs in discrete regions of the brain, such as the subregions of the hippocampus. To analyse mitochondrial structure and function in such subregions, only small amounts of mitochondria are available. We developed a protocol for flow cytometric analysis of very small samples of isolated brain mitochondria, and analysed mitochondrial swelling and formation of ROS in mitochondria from the CA1 and CA3 regions of the hippocampus. Calcium‐induced mitochondrial swelling was measured, and fluorescent probes were used to selectively stain mitochondria (nonyl acridine orange), to measure membrane potential (tetramethylrhodamine‐methyl‐ester, 1,1′,3,3,3′,3′‐hexamethylindodicarbocyanine‐iodide) and to measure production of ROS (2′,7′‐dichlorodihydrofluorescein‐diacetate). We found that formation of ROS and mitochondrial permeability transition pore activation were higher in mitochondria from the CA1 than from the CA3 region, and propose that differences in mitochondrial properties partly underlie the selective vulnerability of the CA1 region to brain insults. We also conclude that flow cytometry is a useful tool to analyse the role of mitochondria in cell death processes.
Modulation of mitochondrial membrane potential and reactive oxygen species production by copper in astrocytes
Authors: Gyulkhandanyan Armen V. , Feeney Chris J. , Pennefather Peter S.
Published: September 2003

In monolayers of cultured rat astrocytes a number of agents that induce oxidative stress act synergistically with exposure to copper leading to rapid depolarization of the mitochondrial membrane potential (Ψm) and increased reactive oxygen species (ROS) production. Copper sensitized astrocytes to the action of menadione, an intracellular generator of superoxide anion radical, exogenous hydrogen peroxide (H2O2) and rotenone, an inhibitor of mitochondrial electron transport chain complex I. However, significant differences were observed in the ability to modulate the copper‐enhanced oxidative stress depending on which stressor was used. The inhibitor of mitochondrial permeability transition cyclosporin A attenuated the effect of copper and rotenone, but had no protective action in the case of H2O2/copper and menadione/copper combinations. The H2O2 scavenger pyruvate was effective at protecting mitochondria against damage associated with the combined exposure to H2O2/copper and menadione/copper but not to the rotenone/copper combination. The antioxidant Trolox was ineffective at protecting against any of these actions and indeed had a damaging effect when combined with copper. The membrane‐permeable copper chelator neocuproine combined with sensitizing concentrations of menadione caused a decrease in Ψm, mimicking the action of copper. Penicillamine, a membrane‐impermeable copper chelator, was effective at reducing copper sensitization. Endogenous copper, mobilized during periods of oxidative stress, may play a role in the pathophysiology of brain injury. Our results suggest that this might be particularly dangerous in dysfunctional conditions in which the mitochondrial electron transport chain is compromised.
Prion protein expression modulates neuronal copper content
Authors: Brown David R.
Published: September 2003

The prion protein is a copper (Cu)‐binding protein. The abnormal isoform of this protein is associated with the transmissible spongiform encephalopathies or prion diseases. In prion diseases, the prion protein loses its Cu binding capacity. The effect of prion protein expression on the Cu content of the brain was investigated. Transgenic mice, either overexpressing the prion protein or expressing a mutant form lacking the Cu‐binding region of the protein, were compared with wild‐type mice and mice in which expression of the protein was knocked out. Age‐dependent differences in Cu content of the brain were detected. Also, synaptosomal fractions from the brains of the mice showed different Cu content depending on the expression of the prion protein. Mice expressing prion protein, but without the Cu‐binding domain showed reduced Cu content. Mice overexpressing the prion protein showed little difference in Cu in the brain compared with wild type but also the prion protein expressed by the mice showed a reduction in the level of Cu bound. These results confirm that prion protein expression modulates the Cu level found at the synapse and this effect is dependent on its Cu binding capacity. Loss of normal Cu binding by the prion protein altered age‐related increases in metals in the brain. This may explain why many forms of human prion disease do not develop until late in life.
Live Seafood Species as Recipes for Invasion
Authors: Chapman John W. , Miller Todd W. , Coan Eugene V.
Published: September 2003

Abstract: A global market in seafood disperses many live organisms to distant locations. These organisms can be released into environments of the new locations, where they can establish reproductive populations. The risks of such introductions remain poorly resolved. We therefore surveyed bivalves ( oysters, mussels, and clams ) that are commercially available as seafood in the western United States. Twenty‐four of the 37 available marine and estuarine bivalve species are nonindigenous. Eleven of these 24 nonindigenous species have established, self‐sustaining populations in northeast Pacific environments. Three of the remaining 13 nonindigenous species have been introduced outside their natural ranges elsewhere in the world. We estimated the risks of some of these species being introduced by performing binomial probability analyses on these data. Our results suggest that there is a significant risk of introducing live seafood species into northeast Pacific ecosystems. Efforts to warn distributors and consumers to screen imported seafood species for invasiveness, to monitor estuaries and coastal ecosystems for early detection, and to develop rapid‐response plans for containing new invaders are warranted.
Growth, Conservation, and the Necessity of New Alliances
Authors: Johns David M.
Published: September 2003

Abstract: There is no substitute for direct protection of species and ecosystems. But unless growth in human numbers and material consumption is checked, direct protection will become impossible. Conservation biologists and conservation advocates do not by themselves possess the political resources necessary to achieve adequate direct protection or to check growth. There are many other constituencies, however, whose interests are threatened by growth. Conservation biologists should develop alliances with these constituencies to create a social force that can bring to bear the necessary pressure to change government, corporate, and individual behavior. Building such alliances requires more than traditional forms of education and outreach. It requires reaching people at the deepest levels of culture and personality. Conservation biologists can and should play a role in mobilizing support for conservation through better informed and more carefully crafted outreach.
Site‐Selection Algorithms and Habitat Loss
Authors: Cabeza Mar , Moilanen Atte
Published: September 2003

Abstract:Site‐selection algorithms are used in reserve design to select networks of sites that maximize biodiversity, given some constraints. These algorithms are based on a snapshot of species occurrence, and they typically aim to minimize the area or cost needed to represent all the species once or a few times. Most of these algorithms ignore the question of how well species are likely to persist in the set of selected sites in the long term. Furthermore, the role of the unselected habitat in biodiversity persistence has received no attention in this context. We used a theoretical approach to evaluate the long‐term performance of reserve networks in preserving biodiversity by using a model of spatiotemporal population dynamics ( a metapopulation model ). We compared extinction rates of species in reserve networks in two situations: when all sites remain suitable habitat for the species and, conversely, when the habitat in the unselected sites is lost. We made this comparison to explore the significance of unselected sites for spatial population dynamics and for the continued presence of species in the reserve network. Basic site‐selection algorithms are liable to perform badly in terms of biodiversity maintenance because the persistence of species may be strongly dependent on sites not included in the reserve network. Our results support recent calls for the integration of spatial population modeling into reserve network design. Advances in metapopulation theory provide tools that can be used for this purpose.
Effects of Prescribed Burning on Amphibian Diversity in a Southeastern U.S. National Forest
Authors: Schurbon Jamie M. , Fauth John E.
Published: September 2003

Abstract: Fire alters the abundance and diversity of many species, but its effects on amphibians are poorly known. We tested whether prescribed burning affected amphibian abundance and diversity within the Francis Marion National Forest, South Carolina, by monitoring assemblages at 15 temporary ponds with five different burn histories: 0, 1, 3, 5, and 12 years after burns. We also monitored terrestrial and aquatic environmental variables likely to influence amphibian diversity, such as leaf‐litter depth, pond water chemistry, and distance to neighboring ponds. Fire had significant negative effects. Immediate effects ( burning during the study ) explained 12.8% and 10.8% of the variation in anuran and amphibian abundance, respectively, whereas short‐term effects explained 31.8% and 24.6% of variation in amphibian species richness and evenness, respectively. Species richness increased and evenness decreased with time since burn, primarily because salamanders were rarely encountered at sites burned within 2 years. These sites had the shallowest leaf litter and highest soil temperature variances. Environmental factors unrelated to burning also significantly influenced amphibian diversity. Water chemistry explained 31.1% of variation in species richness, 32.2% of evenness, and>25% of anuran, salamander, and total amphibian abundances. Salamanders were most sensitive to water chemistry factors, particularly pH. Our results suggest that decreasing the frequency of prescribed burns from the current 2–3 years to 3–7 years will better maintain diverse amphibian and plant assemblages. Substituting growing‐season burns for the current practice of winter and spring burns would avoid repeatedly interrupting amphibian breeding and would maintain the desired longleaf pine community.
Factors Influencing Perceptions of Conflict and Tolerance toward Cheetahs on Namibian Farmlands
Authors: Marker L. L. , Mills M. G. L. , Macdonald D. W.
Published: September 2003

Abstract: Namibia has the largest remaining population of free‐ranging cheetahs ( Acinonyx jubatus ) in the world, 90% of which are found outside protected areas on commercial farms. We conducted a baseline survey of Namibian farmers between 1991 and 1993, with a yearly follow‐up thereafter until 1999, to quantify the perceptions of farmers toward cheetahs. Specifically, we sought to identify factors that cause cheetahs to be perceived as pests and management practices that mitigate this perception. The baseline survey revealed that farmers who regarded cheetahs as problems removed an average of 29 cheetahs annually, whereas those who did not consider them problematic removed a mean of 14 annually. These figures dropped significantly to 3.5 and 2.0 cheetahs per year after the introduction of educational materials. The perception that cheetahs are pests was significantly associated with game farms, and the presence of “play trees” on farms emerged as a significant corollary of both negative perceptions and removals of cheetahs. Between 1991 and 1999, the mean annual number of cheetah removals significantly decreased from 19 to 2.1. Late in the study, cheetah killing was more closely correlated with perceived problems than in the early years of the study. These findings suggest that although cheetahs are still perceived as a problem, farmers' tolerance toward cheetahs has increased. Management strategies and economic incentives that promote cheetah conservation, such as the formation of conservancies, development of ecotourism, and marketing of “predator‐friendly” meat, are essential for conserving cheetahs outside protected areas.
Using Population Viability Analysis to Develop Recovery Criteria for Endangered Insects: Case Study of the Fender's Blue Butterfly
Authors: Schultz Cheryl B. , Hammond Paul C.
Published: September 2003

Abstract: The U. S. Endangered Species Act ( ESA ) requires that recovery plans establish “objective, measurable” criteria on which to base listing decisions. Recovery plans are more effective if these criteria are clearly linked to the biology of species of interest. We reviewed recovery plans for 27 listed insect species. Recovery criteria for threatened and endangered insects were poorly linked to species biology. We used population viability analysis to develop quantitative recovery criteria for insects whose population sizes can be estimated, and applied this framework in the context of a recently listed butterfly, the Fender's blue (  Icaricia icarioides fenderi ). We used a simple diffusion‐approximation approach developed to estimate extinction risk from count‐based census data. The method assumes that future trends can be predicted based on current conditions and that observer error is minimal. Of 12 sites we surveyed for at least 8 years, only one population had a high likelihood of persistence. Given observed variation in population growth rate ( σ 2 = 0.79 ) and an initial population size of 300 butterflies, a minimum average growth rate ( λ ) of 1.83 would be needed for there to be a 95% probability that a population would survive 100 years. As the number of independent sites increased, the minimum λ required to have a 95% probability that at least a population at one site would survive 100 years declined. For downlisting, we recommend that three independent sites be maintained or restored in each region of the Fender's blue, with minimum average growth rates of at least λ = 1.55 over 10 years. Given that 41 insect species are listed under the ESA, development of quantitative recovery criteria would be useful and feasible for at‐risk insect species whose population sizes can be estimated.
Endangered Species Constrained by Natural and Human Factors: the Case of Brown Bears in Northern Spain
Authors: Naves Javier , Wiegand Thorsten , Revilla Eloy , Delibes Miguel
Published: September 2003

Abstract: We developed a conceptual framework for classifying habitat quality that requires the construction of separate habitat models for each key demographic feature; the framework can be applied when the factors that determine different demographic processes differ substantially. For example, survival of large carnivores is mainly determined by human‐induced mortality, whereas nutritional condition determines reproductive rate. Hence, a two‐dimensional habitat model built for reproduction and survival yields five hypothetical habitat categories: matrix, with no reproduction and/or very high mortality; sink, with low reproduction and high mortality; refuge, with low reproduction and low mortality; attractive sink, with high reproduction and high mortality; and source, with high reproduction and low mortality. We applied this framework to two endangered brown bear (   Ursus arctos ) populations in the Cantabrian Mountains, Spain. Our aim was to generate working hypotheses about the quality and spatial arrangement of bear habitat to analyze the present conditions of the different population nuclei and to facilitate identification of core areas of high conservation value, conflictive areas, or areas with unoccupied potential habitat. We used a geographic information system and two spatial long‐term data sets on presence and reproduction and performed logistic regressions for building a two‐dimensional model. The analysis reveals that both populations exist under different suboptimal conditions: the eastern population mainly occupies areas of suboptimal natural habitat and relatively low human impact, whereas the western population is located mainly in areas with high human impact but otherwise good natural quality. To test hypotheses about demographic features of the obtained habitat categories, we classified data on historic extinction in northern Spain ( fourteenth to nineteenth centuries ) with the two‐dimensional model. Extinction probabilities within each habitat category confirmed the hypotheses: most extinctions occurred in matrix habitat, and the fewest occurred in source habitat.
Biological Criteria for Buffer Zones around Wetlands and Riparian Habitats for Amphibians and Reptiles
Authors: Semlitsch Raymond D. , Bodie J. Russell
Published: September 2003

Abstract: Terrestrial habitats surrounding wetlands are critical to the management of natural resources. Although the protection of water resources from human activities such as agriculture, silviculture, and urban development is obvious, it is also apparent that terrestrial areas surrounding wetlands are core habitats for many semiaquatic species that depend on mesic ecotones to complete their life cycle. For purposes of conservation and management, it is important to define core habitats used by local breeding populations surrounding wetlands. Our objective was to provide an estimate of the biologically relevant size of core habitats surrounding wetlands for amphibians and reptiles. We summarize data from the literature on the use of terrestrial habitats by amphibians and reptiles associated with wetlands ( 19 frog and 13 salamander species representing 1363 individuals; 5 snake and 28 turtle species representing more than 2245 individuals ). Core terrestrial habitat ranged from 159 to 290 m for amphibians and from 127 to 289 m for reptiles from the edge of the aquatic site. Data from these studies also indicated the importance of terrestrial habitats for feeding, overwintering, and nesting, and, thus, the biological interdependence between aquatic and terrestrial habitats that is essential for the persistence of populations. The minimum and maximum values for core habitats, depending on the level of protection needed, can be used to set biologically meaningful buffers for wetland and riparian habitats. These results indicate that large areas of terrestrial habitat surrounding wetlands are critical for maintaining biodiversity.
Conservation in Conflict: the Tale of Two Endangered Species
Authors: Roemer Gary W. , Wayne Robert K.
Published: September 2003

Abstract: With its umbrella of provisions, the U.S. Endangered Species Act (  ESA ) provides critical protection to threatened or endangered wildlife. It provides minimal guidance, however, on identifying taxa worthy of conservation, lacks guidelines for resolving endangered species conflicts, and subsequent recovery programs often focus on the species rather than the ecosystem. These deficiencies are exemplified by the recovery program for the San Clemente Loggerhead Shrike (   Lanius ludovicianus mearnsi ) and the recent proposed rule to grant federal protection to one of its predators, the island fox (   Urocyon littoralis ). Recovery actions that have included euthanasia of foxes have likely contributed to a 40–60% decline in the population size of the San Clemente Island fox (   U. l. clementae ), a subspecies listed by the state of California as threatened. The U.S. Fish and Wildlife Service proposes to list four other subspecies of the island fox as endangered but excludes the San Clemente Island fox and the sixth and last subspecies, the San Nicolas Island fox (   U. l. dickeyi ), ignoring their evolutionary distinctness and the recent decline in population size of U. l. clementae. Using published morphological and genetic information, we show that the shrike's current taxonomic and legal status should be reevaluated. We also reexamine the current recovery program for the shrike and conclude that the implementation of the ESA's provisions to protect the shrike was species‐centric. The shrike recovery program is primarily centered on two approaches: the release of captive‐bred shrikes and control of native and non‐native predators. The predator control program has contributed to the endangerment of the distinct San Clemente Island fox. Given that five of the six fox subspecies face extirpation, the proposed rule to list only four of the six as endangered is inadequate. This endangered‐species conflict might have been avoided through a more balanced ecosystem approach that considers the ecological role of all native taxa and strives to enhance habitats critical to both the shrike and the fox.
Prospects for Ecosystem Management in the Crown of the Continent Ecosystem, Canada–United States: Survey and Recommendations
Authors: Pedynowski Dena
Published: September 2003

Abstract: I examined prospects for international ecosystem management in the Crown of the Continent Ecosystem ( COCE ), a transboundary region of the Rocky Mountains that straddles the border between Canada and the United States. From the spring of 2000 to the fall of 2001, I conducted 33 semi‐structured interviews with middle‐ and upper‐level public land and resource managers, administered a brief attitude survey to the interviewees, and analytically reviewed the management policies of and historical cooperative ventures between public land and resource jurisdictions in the region. Through a qualitative analysis of the data collected, I identified 10 challenges to enhancing transboundary cooperation in the COCE that were consistently present throughout the region. I describe and analyze these issues in terms of ( 1 ) determining common policy goals and management priorities, (  2 ) developing information resources at the scale of the greater ecosystem, and ( 3 ) supporting a political and institutional atmosphere conducive to collaboration. Survey results suggest that international transboundary cooperation is less supported, in terms of higher management support, support from staff and colleagues, and access to sufficient information, than transboundary cooperation within a province or state. I conclude with recommendations for three concrete initiatives that public land management jurisdictions in the COCE can undertake to facilitate further ecosystem management opportunities: ( 1 ) formalizating transboundary cooperation, ( 2 ) developing a cumulative‐effects analysis of the COCE, and ( 3 ) thoughtfully presenting transboundary efforts within agencies and to the public.
Biodiversity across a Rural Land‐Use Gradient
Authors: Maestas Jeremy D. , Knight Richard L. , Gilgert Wendell C.
Published: September 2003

Abstract: Private lands in the American West are undergoing a land‐use conversion from agriculture to exurban development, although little is known about the ecological consequences of this change. Some nongovernmental organizations are working with ranchers to keep their lands out of development and in ranching, ostensibly because they believe biodiversity is better protected on ranches than on exurban developments. However, there are several assumptions underlying this approach that have not been tested. To better inform conservation efforts, we compared avian, mesopredator, and plant communities across the gradient of intensifying human uses from nature reserves to cattle ranches to exurban developments. We conducted surveys at randomly selected points on each type of land use in one Colorado watershed between May and August of 2000 and 2001. Seven bird species, characterized as human commensals or tree nesters, reached higher densities ( all p < 0.02 ) on exurban developments than on either ranches or reserves. Six bird species, characterized as ground and shrub nesters, reached greater densities ( all p < 0.015 ) on ranches, reserves, or both of these types of land use than on exurban developments. Domestic dogs ( Canis familiaris ) and house cats (  Felis catus ) were encountered almost exclusively on exurban developments, whereas coyotes ( Canis latrans ) were detected more frequently ( p = 0.047 ) on ranchlands than exurban developments. Ranches had plant communities with higher native species richness and lower non‐native species richness and cover than did the other types of land use ( all p < 0.10 ). Our results support the notion that ranches are important for protecting biodiversity and suggest that future conservation efforts may require less reliance on reserves and a greater focus on private lands.
HCV viral load in anti‐HCV‐reactive donors and infectivity for their recipients
Authors: Operskalski Eva A. , Mosley James W. , Tobler Leslie H. , Fiebig Eberhard W. , Nowicki Marek J. , Mimms Larry T. , Gallarda James , Phelps Bruce H. , Busch Michael P.
Published: September 2003

BACKGROUND:  An attempt has been made to determine the minimum level of HCV nucleic acid in donors associated with infection of recipients. This is important for considerations about assay sensitivity, use of minipool versus single‐donation testing, and continued use of serologic testing.

STUDY DESIGN AND METHODS:  A total of 5387 specimens from the Transfusion‐Transmitted Viruses Study in the 1970s were screened for antibody to HCV (anti‐HCV). The outcome in recipients of seroreactive donations was examined for viremia and seroconversion. Present techniques for both groups included third‐generation EIA, RIBA, quantitative RT‐PCR assay, and transcription‐mediated amplification (TMA) assay.

RESULTS:  A total of 156 recipients of components from 180 anti‐HCV‐reactive donors were identified. One‐hundred seven of these were HCV‐naïve before transfusion and received a single, confirmed seropositive unit; 94 (88%) became infected. Eighty‐five recipients had donors whose HCV RNA level was quantifiable by RT‐PCR (range, 182‐3,310,000 copies/mL). Eighty‐three (98%) seroconverted. Of the remaining 22, a total of 10 received units positive for HCV RNA detected only by TMA; all 10 recipients seroconverted. Of the remaining 12 recipients of anti‐HCV+, TMA‐negative units, 1 recipient seroconverted.

CONCLUSIONS:  High rates of transmission were seen at all levels of viremia, and one donor transmitted with undetectable levels in the TMA assay. Current HCV RNA testing will therefore not interdict all infectious units, even with single‐donation testing, and serologic screening must be continued.
Pathogen inactivation of RBCs: PEN110 reproductive toxicology studies
Authors: Chapman John R. , Moore Kristen , Butterworth Byron E.
Published: September 2003

BACKGROUND: The novel PEN110 chemistry (INACTINE, V.I. Technologies) process for the purification of blood for transfusions involves treating WBC‐reduced RBCs with PEN110 to inactivate a wide spectrum of pathogens. The washed RBC preparation has a residual PEN110 level of less than 0.00005 mg per mL. It is important to verify that the trace amounts of residual PEN110 in blood prepared for transfusions will not produce adverse effects on reproduction, fertility, or fetal development.

STUDY DESIGN AND METHODS: A fertility and early embryonic development study was conducted in male and female Sprague‐Dawley rats at IV doses of up to 0.5 mg PEN110 per kg of body weight following standard re‐gulatory protocols. A fetal developmental study was conducted in Hra:(NZW)SPF pregnant rabbits at IV doses of up to 1.0 mg per kg of body weight following standard regulatory protocols. In both cases the highest dose was shown to be a maximum tolerated dose in pregnant animals based on body weight gain during pregnancy.

RESULTS: In the fertility and early embryonic devel‐opment study, no treatment‐related effects were noted on estrous cycles, pregnancy rate, implantation sites, corpora lutea, number of resorptions, and live embryos in female rats or sperm motility, sperm morphology, and sperm counts in male rats. In the fetal developmental study, PEN110 had no effect on embryofetal viability and growth. This is consistent with other data indicating that PEN110 is rapidly cleared by urinary excretion. On a mg per kg of body weight dose basis, the no‐observed‐effect level doses for rats in the fertility study and rabbits in the developmental study were 2,000 and 4,000 (320 and 1,300 scaled to dose per unit body surface area [DBSA]) times that which a person would receive given 1 unit of treated blood. Considering the cumulative animal dosages, the safety factor values increase to 48,000‐ and 60,000‐fold (7,700 and 19,400 scaled to dose per unit body surface area).

CONCLUSION: These results indicate that the trace amount of residual PEN110 in the purified blood com‐ponent is well below the level that could present a risk of reproductive toxicity to the patient.
Randomized placebo‐controlled study of oral calcium carbonate supplementation in plateletpheresis: II. Metabolic effects
Authors: Bolan Charles D. , Cecco Stacey A. , Yau Yu Ying , Wesley Robert A. , Oblitas Jaime M. , Rehak Nadja N. , Leitman Susan F.
Published: September 2003

BACKGROUND:  The metabolic effects of oral calcium (Ca) supplementation during plateletpheresis were evaluated in a randomized, placebo‐controlled trial.

STUDY DESIGN AND METHODS:  Twenty‐three donors underwent four plateletpheresis procedures each, receiving in random order, elemental Ca (Ca) 1 or 2 g orally, or a corresponding placebo, 30 minutes before donation. Ten of these donors underwent a fifth procedure using a 4‐g Ca dose. All procedures were performed at a fixed citrate infusion rate of 1.5 mg per kg per minute.

RESULTS:  Oral Ca induced dose‐sensitive changes in parathyroid hormone (iPTH), total (tCa), and ionized (iCa) calcium levels. Compared to placebo, the greatest improvement in tCa and iCa levels occurred after the 2‐g Ca dose (tCa of 73, 89, and 25% above placebo levels at 60 min, using 1, 2, and 4 g of oral Ca, respectively). Twenty‐four hours after apheresis, serum tCa and iCa levels were higher, and iPTH levels lower, in donors who received oral Ca rather than placebo. Marked increases in urinary Ca and magnesium (Mg) excretion occurred at the completion of apheresis, were unaffected by Ca dose, and returned to baseline within 24 hours. Plateletpheresis also induced significant changes in serum alkaline phosphatase, 1,25‐dihydroxyvitamin D, and osteocalcin levels immediately and at 24 hours after apheresis.

CONCLUSION:  Plateletpheresis induces marked acute metabolic effects, with sustained changes evident up to 24 hours after the completion of apheresis. Oral Ca supplementation exerts a significant but clinically modest impact on selected laboratory variables associated with these effects. Further studies are indicated to examine the long‐term impact of plateletpheresis, with or without Ca supplementation, on donor Ca balance and bone density.