bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of the antiretroviral drug tenofovir in plasma from HIV‐infected adults by ultrafast isotope dilution MALDI‐triple quadrupole tandem mass spectrometry
Authors: Meesters Roland J. W. , van Kampen Jeroen J. A. , Scheuer Rachel D. , van der Ende Marchina E. , Gruters Rob A. , Luider Theo M. 
Published: March 2011

AbstractA new and reliable mass spectrometric method using an isotope dilution method in combination with matrix‐assisted laser desorption/ionization‐triple quadrupole tandem mass spectrometry (ID‐MALDI‐QqQ‐MS/MS) has been developed and validated for the determination of concentrations of the antiretroviral drug tenofovir (TNV) in plasma from HIV‐infected adults. The advantage of this new method is that (1) the method is ultrafast and (2) can be applied for high‐throughput measurement of TNV in plasma. The method is based on a simple plasma deproteinization step in combination with the use of [adenine‐13C5]‐TNV as the internal standard. TNV and [adenine‐13C5]‐TNV were monitored by multiple reaction monitoring using the transition m/z 288.0 → 176.2 and m/z 293.2 → 181.2 for TNV and [adenine‐13C5]‐TNV, respectively. The method was validated according to the most recent FDA guidelines for the development and validation of (new) bio‐analytical assays. Validated method parameters were: linearity, accuracy, precision and stability of the method. The lowest limit of quantification was 0.10 µmol/l, whereas the limit of detection determined at a signal‐to‐noise ratio (S/N = 3:1) in pooled drug free human control plasma was 0.04 µmol/l. The validated method was successfully applied and tested for its clinical feasibility by the analysis of plasma samples from selected HIV‐infected adults receiving the prodrug tenofovir disoproxil fumarate. Observed plasma TNV concentrations ranged between 0.11 and 0.76 µmol/l and measured plasma TNV concentrations were within the therapeutically relevant concentration range. Copyright © 2011 John Wiley & Sons, Ltd.
An LC–MS screening method with library identification for the detection of steroidsin dietary supplements
Authors: Becue Ilse , Poucke Christof Van , Peteghem Carlos Van 
Published: March 2011

AbstractFor many years anabolic‐androgenic steroids (AAS) are by far the most frequently detected pharmacological substances in doping control. In order to improve their performances, professional sportsmen are often tempted to take dietary supplements. However, due to the frequent and widespread occurrence of contaminated supplements, the use of such products is not without risk for the athletes involved. In order to minimize the chances of an unattended positive doping test or serious health problems, fast and reliable screening methods for the detection of anabolic steroids in dietary supplements are needed. A general screening procedure requires the fast and unambiguous detection of a large range of steroids. Gas chromatography–mass spectrometry (GC–MS) has been used intensively in the detection of doping substances for the past 40 years. Over time, many laboratories have delivered spectra to be included in standard reference databases, one of which is maintained by the National Institute of Standards and Technology (NIST) (Gaithersburg, MD, USA). In recent years, however, liquid chromatography coupled to mass spectrometry (LC–MS) has gained popularity. Unfortunately, existing GC–MS libraries are not applicable to LC–MS analysis. In the present study, a new mass spectral library of 88 steroids was developed, along with a fast UPLC–MS method. For the construction of this mass spectral library, three different mass spectra were measured for each steroid, with a sample cone voltage of 30, 60 and 100 V, respectively. This method was then successfully tested on contaminated dietary supplements which had previously been tested by means of a targeted LC–MS/MS method. Overall, the library search was shown to identify the same compounds as the MRM method. Copyright © 2011 John Wiley & Sons, Ltd.
Simple and sensitive determination of nitroimidazole residues in honey using stir bar sorptive extraction with mixed mode monolith followed by liquid chromatography
Authors: Huang Xiaojia , Lin Jianbin , Yuan Dongxing 
Published: March 2011

AbstractIn the present study, we developed a simple and sensitive method for the simultaneous determination of metronidazole (MTZ), ronidazole (RNZ), dimetridazole (DMZ), and tinidazole (TNZ) in honey. Honey samples were diluted with water, then directly treated by stir bar sorptive extraction (SBSE) based on poly(methacrylic acid‐3‐sulfopropyl ester potassium salt‐co‐divinylbenzene) monolithic material. The analytes were analyzed by HPLC equipped with diode array detector. In the optimized process, several parameters, including the composition of desorption solvent, pH value and ionic strength in sample matrix, extraction, and desorption time, were investigated in detail. Under the optimized conditions, the detection limits (S/N=3) and quantification limits (S/N=10) of the proposed method for the target compounds were achieved within the range of 0.47–1.52 and 1.54–5.0 μg/kg from spiked honey sample, respectively. The calibration curves showed the linearity ranging from 2 to 200 μg/kg for dimetridazole and tinidazole, 5–200 μg/kg for metronidazole and ronidazole. Method repeatability presented as intra‐ and interday precisions were found with the RSDs <4.43 and 4.41%, respectively. Finally, the developed method was successfully applied to the determination of nitroimidazoles in different honey samples and satisfactory recoveries of spiked target compounds were in the range of 71.1–114%.
Validation of elk resource selection models with spatially independent data
Authors: Coe Priscilla K. , Johnson Bruce K. , Wisdom Michael J. , Cook John G. , Vavra Martin , Nielson Ryan M. 
Published: March 2011

AbstractKnowledge of how landscape features affect wildlife resource use is essential for informed management. Resource selection functions often are used to make and validate predictions about landscape use; however, resource selection functions are rarely validated with data from landscapes independent of those from which the models were built. This problem has severely limited the application of resource selection functions over larger geographic areas for widely distributed species. North American elk (Cervus elaphus) is an example of a widely‐distributed species of keen interest to managers and for which validation of resource selection functions over large geographic areas is important. We evaluated the performance of resource selection functions developed for elk on one landscape in northeast Oregon with independent data from a different landscape in the same region. We compared predicted versus observed elk resource use for 9 monthly or seasonal periods across 3 yr. Results showed strong, positive agreement between predicted and observed use for 2 spring and 3 late summer‐early fall models (3‐yr r = 0.81–0.95). Predicted versus observed use was negatively or weakly positively correlated for 3 summer models and 1 mid‐fall model (3‐yr r = −0.57–0.14). Predicted and observed use correlated well when forage was limited (spring and late summer or early fall), corresponding to important biological stages for elk (parturition and breeding seasons). For these seasonal periods, model covariates such as rate of motorized traffic and canopy closure often were effective predictors of elk resource selection. The models we validated for spring and late summer‐early fall may be used to evaluate management activities in areas with similar landscape characteristics. © 2010 The Wildlife Society.
Ecological and methodological factors affecting detectability and population estimation in elusive species
Authors: Willson John D. , Winne Christopher T. , Todd Brian D. 
Published: March 2011

AbstractAlthough mark‐recapture methods are among the most powerful tools for monitoring wildlife populations, the secretive nature of some species requires a comprehensive understanding of the factors that affect capture probability to maximize accuracy and precision of population parameter estimates (e.g., population size and survivorship). Here, we used aquatic snakes as a case study in applying rigorous mark‐recapture methods to estimate population parameters for secretive species. Specifically, we used intensive field sampling and robust design mark‐recapture analyses in Program MARK to test specific hypotheses about ecological and methodological factors influencing detectability of two species of secretive aquatic snakes, the banded watersnake (Nerodia fasciata), and the black swamp snake (Seminatrix pygaea). We constructed a candidate set of a priori mark‐recapture models incorporating various combinations of time‐ and sex‐varying capture and recapture probabilities, behavioral responses to traps (i.e., trap‐happiness or trap‐shyness), and temporary emigration, and we ranked models for each species using Akaike's Information Criterion. For both banded watersnakes and black swamp snakes we found strong support for time‐varying capture and recapture probabilities and strong trap‐happy responses, factors that can bias population estimation if not accommodated in the models. We also found evidence of sex‐dependent temporary emigration in black swamp snakes. Our study is among the first comprehensive assessments of factors affecting detectability in snakes and provides a framework for studies aimed at monitoring populations of other secretive species. © 2010 The Wildlife Society.
Population estimation and monitoring of an endangered lagomorph
Authors: Schmidt Jason A. , Mccleery Robert A. , Schmidt Paige M. , Silvy Nova J. , Lopez Roel R. 
Published: March 2011

AbstractWe conducted the most intensive estimate of the endangered Lower Keys marsh rabbit (Sylvilagus palustris hefneri) metapopulation to date using pellet surveys and capture–recapture methodology. We livetrapped 83 rabbits, evaluated 5 closed population models, and selected the model that best represented the data. We considered the variation in behavioral response model the best model and correlated (r2 = 0.913) its patch population estimates to patch pellet densities. From the prediction equation, we generated a range‐wide metapopulation estimate of 317 rabbits, a western clade population of 257 rabbits, an eastern clade population of 25 rabbits, and translocated marsh rabbit populations of 35 and zero on Little Pine and Water keys, respectively. A subset of patches whose marsh rabbit subpopulations were last estimated in 1993 exhibited a 46% decline in abundance over 15 yr. Due to the low estimate of the eastern clade population, special effort should be initiated to avoid loss of genetic diversity. The prediction equation suffers from limited data at high pellet densities, patches with ≥5 pellets/m2. Future studies should investigate if the slope of the regression is indeed near 1 by sampling patches across the range of pellet densities, especially those with ≥5 pellets/m2. The equation provides managers a quick, efficient, and noninvasive method to estimate marsh rabbit abundance from pellet counts but the confidence of predicted rabbit densities from high pellet density patches is low. © 2011 The Wildlife Society
Comparing a bioenergetics model with feeding rates of caged European starlings
Authors: Jeffrey Homan H. , Stahl Randal S. , Linz George M. 
Published: March 2011

AbstractWe tested a bioenergetics model integrated within a mortality model that estimates numbers of European starlings (Sturnus vulgaris) poisoned with the avicide, Compound DRC‐1339 Concentrate. The bioenergetics model predicted daily metabolic rate. Accuracy and reliability of this variable is critical because other algorithms (e.g., toxicity regressions, feeding behavior) in the mortality model depend on metabolic rate to calculate the amount of DRC‐1339 ingested per bird. We tested the bioenergetics model by comparing its estimates of metabolic rate with those generated from measuring feeding rates of caged starlings during a feeding trial conducted outdoors during January 2008. Over the 12‐day feeding trial, daily feeding rates of caged starlings indicated that metabolic rates ranged from 157 kJ/bird per day to 305 kJ/bird per day. The bioenergetics model predicted metabolic rates ranging from 208 kJ/bird per day to 274 kJ/bird per day. There was no difference between these 2 independently derived estimates of daily metabolic rate (paired t‐test: t(11) = 1.4, P = 0.18). Using 95% confidence intervals calculated from variation of feeding rates among cages (n = 4, 6 birds/cage), the bioenergetics model's estimates were within 95% confidence intervals on 9 of 12 days and greater than the upper 95% confidence interval on 3 days. Daily estimates of metabolic rate were directly correlated between the bioenergetics model and the feeding‐rate model (r12 = 0.57, P = 0.05). A broad range of temperatures (−17°C to 14°C), wind speeds (0–40 km/hr), and percent cloud cover (0–100%) were encountered during the feeding trial. The bioenergetics model's predictions appeared robust to varying meteorological conditions typical of winters in middle latitudes of the interior United States. Compound DRC‐1339 Concentrate is used by USDA Wildlife Services to manage chronic infestations of starlings at livestock facilities, which occur mainly during fall and winter. Compared to other methods used for estimating DRC‐1339 mortality (e.g., counting birds pre‐ and posttreatment), bioenergetics modeling should improve the mortality model's overall accuracy and precision. © The Wildlife Society, 2011
Survival of white‐tailed deer neonates in Minnesota and South Dakota
Authors: Grovenburg Troy W. , Swanson Christopher C. , Jacques Christopher N. , Klaver Robert W. , Brinkman Todd J. , Burris Benjamin M. , Deperno Christopher S. , Jenks Jonathan A. 
Published: March 2011

AbstractUnderstanding the influence of intrinsic (e.g., age, birth mass, and sex) and habitat factors on survival of neonate white‐tailed deer improves understanding of population ecology. During 2002–2004, we captured and radiocollared 78 neonates in eastern South Dakota and southwestern Minnesota, of which 16 died before 1 September. Predation accounted for 80% of mortality; the remaining 20% was attributed to starvation. Canids (coyotes [Canis latrans], domestic dogs) accounted for 100% of predation on neonates. We used known fate analysis in Program MARK to estimate survival rates and investigate the influence of intrinsic and habitat variables on survival. We developed 2 a priori model sets, including intrinsic variables (model set 1) and habitat variables (model set 2; forested cover, wetlands, grasslands, and croplands). For model set 1, model {Sage‐interval} had the lowest AICc (Akaike's information criterion for small sample size) value, indicating that age at mortality (3‐stage age‐interval: 0–2 weeks, 2–8 weeks, and >8 weeks) best explained survival. Model set 2 indicated that habitat variables did not further influence survival in the study area; β‐estimates and 95% confidence intervals for habitat variables in competing models encompassed zero; thus, we excluded these models from consideration. Overall survival rate using model {Sage‐interval} was 0.87 (95% CI = 0.83–0.91); 61% of mortalities occurred at 0–2 weeks of age, 26% at 2–8 weeks of age, and 13% at >8 weeks of age. Our results indicate that variables influencing survival may be area specific. Region‐specific data are needed to determine influences of intrinsic and habitat variables on neonate survival before wildlife managers can determine which habitat management activities influence neonate populations. © 2011 The Wildlife Society
Occupancy modeling of ruffed grouse in the Black Hills National Forest
Authors: Hansen Christopher P. , Millspaugh Joshua J. , Rumble Mark A. 
Published: March 2011

AbstractRuffed grouse (Bonasa umbellus) are a popular game bird and the management indicator species for quaking aspen (Populus tremuloides) in the Black Hills National Forest (BHNF), which requires development of a robust monitoring protocol to evaluate trends in ruffed grouse populations. We used roadside drumming surveys in spring 2007 and 2008 to estimate ruffed grouse occupancy and detection probabilities in the BHNF while simultaneously assessing the influence of sampling and site covariates on these processes. Ruffed grouse occupancy estimates were constant between spring 2007 and 2008 (Ψ = 0.12, SE = 0.03) and were positively influenced by the amount of aspen surrounding the site. Detection probability estimates were constant between spring 2007 and 2008 (p = 0.27, SE = 0.06) and were influenced by survey date in a quadratic form and negatively influenced by wind speed and time of the survey. Collectively, our results demonstrated that ruffed grouse occupancy and detection probabilities in the BHNF were low. Occupancy could be increased by increasing the extent of aspen. To improve monitoring efficiency and maximize probability of detecting ruffed grouse, ruffed grouse monitoring should be conducted during the peak of drumming (mid‐May), during favorable weather conditions such as low wind speeds and little precipitation, and during early morning, near sunrise. © 2010 The Wildlife Society.
Evaluating how hunters see and react to telemetry collars on white‐tailed deer
Authors: Jacques Christopher N. , van Deelen Timothy R. , Hall Wayne H. , Martin Karl J. , Vercauteren Kurt C. 
Published: March 2011

AbstractFates of individuals outfitted with radiotransmitters commonly are used for estimating survival rates in populations of large animals that are hunted. Despite precautions, this practice may be subject to complex biases associated with hunter reaction to presence of radiotransmitters. To assess this potential bias we conducted an experiment using artificial deer (i.e., decoys) to measure hunters' abilities to see deer and determine if deer seen were wearing radiocollars. We used logistic regression to quantify probabilities that seeing deer and subsequently seeing radiocollars might be influenced by distance, percent visual obstruction, body orientation, hunter experience, and antler characteristics of deer. Additionally, we evaluated how experience and antler characteristics of deer might influence a hunter's decision to harvest a radiocollared deer. We found that 25.8% of the potentially observable collared deer (n = 663) were subsequently observed by hunters. Odds of observing deer and radiocollars increased 95% and 230%, respectively, for each additional log(yr) of hunting experience. Willingness to harvest radiocollared deer increased 89% for each additional log(yr) of hunting experience and 144% for large‐antlered deer relative to antlerless deer. When hunting is an important source of mortality, analysts need to understand how potential biases associated with observing deer are associated with hunters' reactions to and subsequent decisions to harvest radiocollared animals. Our study suggested that presence of radiocollars may influence a deer's potential risk of being harvested and in turn bias telemetry‐based estimates of survival, given that hunting mortality is the largest component of total mortality in hunted deer populations. Collar‐based telemetry is used nearly universally by wildlife managers and researchers throughout North America and elsewhere to estimate and monitor the survival of big game populations that are managed through hunting. Our findings demonstrate that these estimates are likely subject to complex and systematic biases that managers should consider when evaluating future population‐level effects of managed hunting. © 2011 The Wildlife Society
Intercolony variation in growth of black brant goslings on the Yukon‐Kuskokwim Delta, Alaska
Authors: Fondell Thomas F. , Flint Paul L. , Sedinger James S. , Nicolai Christopher A. , Schamber Jason L. 
Published: March 2011

AbstractRecent declines in black brant (Branta bernicla nigricans) are likely the result of low recruitment. In geese, recruitment is strongly affected by habitat conditions experienced by broods because gosling growth rates are indicative of forage conditions during brood rearing and strongly influence future survival and productivity. In 2006–2008, we studied gosling growth at 3 of the 4 major colonies on the Yukon‐Kuskokwim Delta, Alaska. Estimates of age‐adjusted gosling mass at the 2 southern colonies (approx. 30% of the world population of breeding black brant) was low (gosling mass at 30.5 days ranged 346.7 ± 42.5 g to 627.1 ± 15.9 g) in comparison to a third colony (gosling mass at 30.5 days ranged 640.0 ± 8.3 g to 821.6 ± 13.6 g) and to most previous estimates of age‐adjusted mass of brant goslings. Thus, our results are consistent with the hypothesis that poor gosling growth is negatively influencing the brant population. There are 2 non‐mutually exclusive explanations for the apparent growth rates we observed. First, the population decline may have been caused by density‐independent factors and habitat capacity has declined along with the population as a consequence of the unique foraging feedback between brant and their grazing habitats. Alternatively, a reduction in habitat capacity, as a result of changes to the grazing system, may have negatively influenced gosling growth, which is contributing to the overall long‐term population decline. We found support for both explanations. For colonies over habitat capacity we recommend management to enhance foraging habitat, whereas for colonies below habitat capacity we recommend management to increase nesting productivity. © 2010 The Wildlife Society.
Implications of chronic wasting disease, cougar predation, and reduced recruitment for elk management
Authors: Sargeant Glen A. , Weber Duane C. , Roddy Daniel E. 
Published: March 2011

AbstractEmerging diseases and expanding carnivore populations may have profound implications for ungulate harvest management and population regulation. To better understand effects of chronic wasting disease (CWD) and cougar (Puma concolor) predation, we studied mortality and recruitment of elk (Cervus elaphus) at Wind Cave National Park (WICA) during 2005–2009. We marked 202 elk (83 subadult M and 119 subadult and ad F) with Global Positioning System (GPS) collars, observed 28 deaths during 74,220 days of monitoring, and investigated 42 additional deaths of unmarked elk found dead. Survival rates were similar for males and females and averaged 0.863 (SE = 0.025) annually. Leading causes of mortality included hunting (0.065, SE = 0.019), CWD (0.034, SE = 0.012), and cougar predation (0.029, SE = 0.012). Marked elk killed by hunters and cougars typically were in good physical condition and not infected with CWD. Effects of mortality on population growth were exacerbated by low rates of pregnancy (subadults = 9.5%, SE = 6.6%; ad = 76.9%, SE = 4.2%) and perinatal survival (0.49, SE = 0.085 from 1 Feb to 1 Sep). Chronic wasting disease, increased predation, and reduced recruitment reduced the rate of increase for elk at WICA to approximately λ = 1.00 (SE = 0.027) during the past decade. Lower rates of increase are mitigating effects of elk on park vegetation, other wildlife, and neighboring lands and will facilitate population control, but may reduce opportunities for elk hunting outside the park. © 2011 The Wildlife Society