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1.
Proc Biol Sci ; 281(1786)2014 Jul 07.
Article in English | MEDLINE | ID: mdl-24827436

ABSTRACT

The notion of a critical community size (CCS), or population size that is likely to result in long-term persistence of a communicable disease, has been developed based on the empirical observations of acute immunizing infections in human populations, and extended for use in wildlife populations. Seasonal birth pulses are frequently observed in wildlife and are expected to impact infection dynamics, yet their effect on pathogen persistence and CCS have not been considered. To investigate this issue theoretically, we use stochastic epidemiological models to ask how host life-history traits and infection parameters interact to determine pathogen persistence within a closed population. We fit seasonal birth pulse models to data from diverse mammalian species in order to identify realistic parameter ranges. When varying the synchrony of the birth pulse with all other parameters being constant, our model predicted that the CCS can vary by more than two orders of magnitude. Tighter birth pulses tended to drive pathogen extinction by creating large amplitude oscillations in prevalence, especially with high demographic turnover and short infectious periods. Parameters affecting the relative timing of the epidemic and birth pulse peaks determined the intensity and direction of the effect of pre-existing immunity in the population on the pathogen's ability to persist beyond the initial epidemic following its introduction.


Subject(s)
Animals, Wild , Communicable Diseases/veterinary , Mammals , Seasons , Animals , Communicable Diseases/epidemiology , Communicable Diseases/microbiology , Models, Theoretical , Parturition , Population Density , Reproduction , Stochastic Processes
2.
Zoonoses Public Health ; 60(1): 2-21, 2013 Feb.
Article in English | MEDLINE | ID: mdl-22958281

ABSTRACT

Bats are hosts to a range of zoonotic and potentially zoonotic pathogens. Human activities that increase exposure to bats will likely increase the opportunity for infections to spill over in the future. Ecological drivers of pathogen spillover and emergence in novel hosts, including humans, involve a complex mixture of processes, and understanding these complexities may aid in predicting spillover. In particular, only once the pathogen and host ecologies are known can the impacts of anthropogenic changes be fully appreciated. Cross-disciplinary approaches are required to understand how host and pathogen ecology interact. Bats differ from other sylvatic disease reservoirs because of their unique and diverse lifestyles, including their ability to fly, often highly gregarious social structures, long lifespans and low fecundity rates. We highlight how these traits may affect infection dynamics and how both host and pathogen traits may interact to affect infection dynamics. We identify key questions relating to the ecology of infectious diseases in bats and propose that a combination of field and laboratory studies are needed to create data-driven mechanistic models to elucidate those aspects of bat ecology that are most critical to the dynamics of emerging bat viruses. If commonalities can be found, then predicting the dynamics of newly emerging diseases may be possible. This modelling approach will be particularly important in scenarios when population surveillance data are unavailable and when it is unclear which aspects of host ecology are driving infection dynamics.


Subject(s)
Chiroptera/virology , Communicable Diseases, Emerging/veterinary , Ecology/trends , Animals , Chiroptera/physiology , Communicable Diseases, Emerging/epidemiology , Communicable Diseases, Emerging/transmission , Disease Reservoirs , Humans , Models, Biological , Public Health , Zoonoses
3.
Arch Virol ; 153(6): 1139-42, 2008.
Article in English | MEDLINE | ID: mdl-18398562

ABSTRACT

The literature supports that unique rabies virus (RABV) variants are often compartmentalized in different species of bats. In Colorado, two divergent mtDNA lineages of big brown bats (Eptesicus fuscus) co-occur. RABV associated with this species also segregates into two clades. We hypothesized that unique RABV variants might be associated with mtDNA lineages of Colorado big brown bats. DNA was extracted from brain tissue of rabid big brown bats, the ND2 gene was amplified to determine mtDNA lineage, and the lineage was compared to a previously derived phylogenetic analysis of the RABV N gene. No correspondence was found between host bat lineage and RABV variant.


Subject(s)
Animal Population Groups/genetics , Animal Population Groups/virology , Chiroptera/genetics , Chiroptera/virology , DNA, Mitochondrial/genetics , Rabies virus/genetics , Rabies/veterinary , Animals , Colorado/epidemiology , Genetic Variation , Molecular Sequence Data , NADH Dehydrogenase/genetics , Nucleocapsid Proteins/genetics , Rabies/epidemiology , Rabies/virology
4.
J Parasitol ; 93(3): 518-30, 2007 Jun.
Article in English | MEDLINE | ID: mdl-17626343

ABSTRACT

Ectoparasites of an urban population of big brown bats (Eptesicus fuscus) in Fort Collins, Colorado, were investigated during summers 2002, 2003, and 2004. Eleven species of ectoparasites were found (the macronyssid mite Steatonyssus occidentalis, the wing mite Spinturnix bakeri, the myobiid mites Acanthophthirius caudata and Pteracarus aculeus, the chirodiscid mite Alabidocarpus eptesicus, the demodicid mite Demodex sp., the chigger Leptotrombidium myotis, the soft tick Carios kelleyi, the batfly Basilia forcipata, the batbug Cimex pilosellus, and the flea Myodopsylla borealis). Five species were analyzed by prevalence and intensity (C. pilosellus, M. borealis, L. myotis, S. bakeri, and S. occidentalis) based on 2161 counts of 1702 marked individual bats over the 3 summer study periods. We investigated 4 factors potentially influencing prevalence and intensity: age class of the host, reproductive status of adult female hosts, roosts in which the hosts were found, and abiotic conditions during the year sampled. The macronyssid mite, S. occidentalis, was the most prevalent and abundant ectoparasite. Adult big brown bats had more ectoparasites than volant juveniles for most of the species analyzed. In a sample of known age bats at 1 large colony, bats of 4 yr of age or greater had higher ectoparasite loads of S. occidentalis and S. bakeri when compared with younger bats. Lactating female bats had the highest prevalence and intensities of most ectoparasites. Annual differences in ectoparasite prevalence and intensity were related to temperature and humidity, which can affect the nidicolous species of ectoparasites. Residents of 2 buildings sprayed insecticides in response to Cimex sp., and this appeared to reduce ectoparasitism of S. occidentalis and C. pilosellus present at these buildings. Intensity of S. occidentalis had no influence on annual survival of big brown bats.


Subject(s)
Arthropods/classification , Chiroptera/parasitology , Ectoparasitic Infestations/veterinary , Age Factors , Analysis of Variance , Animals , Argasidae/classification , Argasidae/growth & development , Arthropods/growth & development , Cimicidae/classification , Cimicidae/growth & development , Colorado/epidemiology , Diptera/classification , Diptera/growth & development , Ectoparasitic Infestations/epidemiology , Ectoparasitic Infestations/parasitology , Environment , Female , Host-Parasite Interactions , Humidity , Male , Mites/classification , Mites/growth & development , Prevalence , Siphonaptera/classification , Siphonaptera/growth & development , Temperature , Trombiculidae/classification , Trombiculidae/growth & development , Urban Population
5.
Arch Environ Contam Toxicol ; 40(1): 112-20, 2001 Jan.
Article in English | MEDLINE | ID: mdl-11116346

ABSTRACT

Rocky Mountain Arsenal (RMA) National Wildlife Area, near Denver, Colorado, is a Superfund site contaminated by past military and industrial uses, including pesticide manufacturing. From an ecosystem standpoint, the most critical contaminants at RMA are certain cyclodiene insecticides and metabolites, p,p'-DDE, p,p'-DDT, arsenic, and mercury. Bats are important ecosystem components that can be impacted by persistent contaminants because of their position in the food chain and their potential longevity and thus duration of exposure. Big brown bats (Eptesicus fuscus) were captured (n = 51) while foraging at RMA in the summers of 1997 and 1998 for determination of concentrations of contaminants of concern in carcasses, brains, and stomach contents. Adult females (n = 15) were also tracked by radiotelemetry to determine locations of nearest maternity roosts for sampling of guano for contaminant analysis and inspection for potential contaminant-induced mortality. Bats captured while foraging at RMA had measurable quantities of dieldrin and DDE in masticated insect samples from stomach contents and significantly higher concentrations of dieldrin, DDE, DDT, and mercury (juveniles) in carcasses than big brown bats (n = 26) sampled at a reference area 80 km to the north. Concentrations of dieldrin and DDE in brains of bats captured while foraging at RMA were also greater than in bats from the reference area, but not high enough to suggest mortality. Maximum concentrations of DDE, DDT, and cyclodienes in brains of big brown bats were found in adult males from RMA. Guano from the two closest known roosts had significantly higher concentrations of dieldrin, DDE, and mercury than guano from two roosts at the reference area. Dieldrin concentrations in carcasses of bats from RMA were highest in juveniles, followed by adult males and adult females. DDE concentrations in carcasses were lowest in adult females at both sites and highest in adult males at RMA. No contaminant-related mortality was obvious at the small maternity colonies near RMA. Big brown bats show higher contamination than most other mammals previously sampled at this site. Concentrations and proportions of samples with detectable residues of dieldrin in carcasses of big brown bats from RMA were similar to or exceeded reports for this species from elsewhere in the United States some 25 years ago, prior to or just following restrictions on use of this compound.


Subject(s)
Arsenic/analysis , Chiroptera/metabolism , DDT/analysis , Dichlorodiphenyl Dichloroethylene/analysis , Hazardous Waste/analysis , Insecticides/analysis , Mercury/analysis , Animals , Brain/metabolism , Colorado , Environmental Monitoring , Female , Gastrointestinal Contents/chemistry , Male , Telemetry
6.
J Pharm Biomed Anal ; 23(2-3): 573-9, 2000 Aug 15.
Article in English | MEDLINE | ID: mdl-10933551

ABSTRACT

A liquid chromatography combined with tandem mass spectrometry assay for the determination of free levels of the highly protein bound drug phenytoin (5,5-diphenylhydantoin) in human plasma is described. The assay was demonstrated to be reliable, accurate and precise, and specific for phenytoin. The procedure involves isolation of the unbound drug from the drug/protein complex by ultrafiltration. Liquid-liquid extraction was employed to extract the resultant ultrafiltrate. PHT was separated on a 50 x 3 mm reversed-phase column using isocratic mobile phase conditions that yielded a run time of 1.5 min, enabling high throughput sample analysis. Linearity was obtained over the range 5.00 to 500 ng/ml. Both between-run and within-run coefficients of variation were less than 15% and accuracy's across the assay range were all within 100 +/- 10%. The assay was successfully implemented to support a clinical interaction study with phenytoin.


Subject(s)
Anticonvulsants/blood , Chromatography, Liquid/methods , Mass Spectrometry/methods , Phenytoin/blood , Hemolysis , Humans , Reproducibility of Results , Sensitivity and Specificity
9.
Science ; 288(5473): 1965d-6d, 2000 Jun 16.
Article in English | MEDLINE | ID: mdl-17835107
10.
Sci Total Environ ; 154(2-3): 179-200, 1994 Sep 16.
Article in English | MEDLINE | ID: mdl-7973606

ABSTRACT

The literature on organochlorine and metal contaminants in tissues of baleen whales includes data for approximately 1000 individuals in 10 species from various oceans of the world. Concentrations of these contaminants in tissues of baleen whales are low. Sources of variation in organochlorine concentrations in whales include age, sex, region of exposure, and feeding habits. Concentrations of sigma DDT and PCBs in baleen whales appear higher in the northern hemisphere than in the southern oceans, perhaps due to greater contamination of northern ecosystems and a higher incidence of fish in the diet. However, maximum concentrations are generally lower in tissues of baleen whales than in other marine mammal species, both on global and local scales. This is predictable based on the general distribution, habitats and trophic levels of baleen whales. We reviewed laboratory studies on the effects of selected organochlorine contaminants on direct mortality and impaired reproduction in other mammals, and critically examined observations attempting to link organochlorines to reproductive and population effects in marine mammals. There is no firm basis to conclude that the contaminants reviewed herein have affected baleen whale populations. Although more information on contaminants in baleen whales would be of value, as a matter of priority, research and management actions should focus on reducing human-caused mortality and increasing habitat carrying capacity for these species.


Subject(s)
Hydrocarbons, Chlorinated/analysis , Metals/analysis , Water Pollutants, Chemical/analysis , Whales/metabolism , Animals , Conservation of Natural Resources , Ecosystem , Environmental Exposure , Female , Male
11.
Sci Am ; 271(1): 66-72, 1994 Jul.
Article in English | MEDLINE | ID: mdl-8066426
12.
J Pharm Biomed Anal ; 12(3): 319-24, 1994 Mar.
Article in English | MEDLINE | ID: mdl-7913344

ABSTRACT

Capillary electrophoresis (CE) has been used to separate the CBI derivatives of the neurotransmitters gamma-aminobutyric acid, glycine, glutamate, aspartate, norepinephrine and dopamine from 18 other amino acids present in the rat brain. The procedure, which requires an injection volume of < 10 nl, gave detection limits of 24-40 fmol using UV detection at 420 nm. Efficiencies for the derivatized amino acids varied from 344,000 to 444,000 theoretical plates. The method was applied successfully to the quantitation of the amino acid neurotransmitters and several other amino acids in a rat brain homogenate.


Subject(s)
Brain Chemistry , Electrophoresis , Neurotransmitter Agents/isolation & purification , Animals , Aspartic Acid/isolation & purification , Dopamine/isolation & purification , Glutamates/isolation & purification , Glutamic Acid , Glycine/isolation & purification , Norepinephrine/isolation & purification , Rats , gamma-Aminobutyric Acid/isolation & purification
13.
Electrophoresis ; 15(1): 79-86, 1994 Jan.
Article in English | MEDLINE | ID: mdl-8143684

ABSTRACT

The use of capillary electrophoresis/electrochemistry (CEEC) for the analysis of microdialysis samples obtained for pharmacokinetic and neurochemical studies is described, as well as the development of new types of electrodes and waveforms which increase the selectivity of this technique for specific classes of analytes. CEEC with a carbon fiber electrode was employed for the analysis of microdialysis samples. Microdialysis is an in vivo sampling technique that yields very small samples for analysis (less than 1 microL). Therefore, capillary electrophoresis, with its small volume requirements, is an excellent choice for the analytical method. CEEC was used to study the pharmacokinetics of L-dopa and the release of aspartate and glutamate following a high K+ infusion in the brain. Several modified electrodes which increase the applicability of CEEC in pharmaceutical and biomedical analysis are described. One of these is a gold/mercury electrode which is highly selective for thiols and was used for the determination of glutathione in a rat brain. An alternative method for the detection of thiols employed a chemically modified electrode containing cobalt phthalocyanine. In this case, an electrocatalyst reduces the overpotential of thiols at the carbon electrode and makes it possible to detect them at a much lower and more selective oxidation potential. This electrode was used for the detection of cysteine in urine. The development of pulsed amperometric detection for capillary electrophoresis is also described and is demonstrated by the detection of glucose in blood. Lastly, a method for the detection of peptides based on the formation of a copper complex and detection at a carbon fiber electrode is discussed.


Subject(s)
Electrophoresis/methods , Animals , Blood Glucose/analysis , Brain Chemistry , Capillary Action , Cysteine/urine , Dialysis , Electrochemistry , Glutathione/analysis , Levodopa/pharmacokinetics , Peptides/analysis , Rats
14.
J Chromatogr A ; 652(2): 377-83, 1993 Oct 22.
Article in English | MEDLINE | ID: mdl-8287132

ABSTRACT

A Cu(II)-coated capillary has been developed for the determination of peptides by capillary electrophoresis with electrochemical detection. Capillaries were prepared by forcing a solution 48 microM in CuSO4, 120 microM in tartaric acid, 2.4 mM in NaOH and 120 microM in KI through them for 25 min; the resulting capillaries are stable for at least 12 h. Under alkaline conditions, peptides complex with Cu(II) present on the walls of the capillary to form Cu(II)-peptide complexes which can be detected oxidatively at a carbon fiber electrode. Di-, tri-, tetra- and pentaglycine were determined with a detection limit of 7 x 10(-7) M for triglycine. N-Terminal-blocked peptides can also be determined via this method. This system is more sensitive than direct detection of peptides by UV at 210 nm and exhibits higher selectivity than commonly employed derivatization procedures based on reactions with a primary amine functionality.


Subject(s)
Copper/chemistry , Electrophoresis/methods , Peptides/analysis , Amino Acid Sequence , Electrochemistry , Molecular Sequence Data , Spectrophotometry, Ultraviolet
15.
J Chromatogr ; 608(1-2): 189-95, 1992 Sep 11.
Article in English | MEDLINE | ID: mdl-1430021

ABSTRACT

Capillary electrophoresis (CE) with electrochemical detection (ED) was used to determine extracellular levels of aspartate, glutamate and alanine in samples from the frontoparietal cortex of the rat which were obtained by microdialysis. The method was used to monitor the effect on the overflow of the excitatory amino acids aspartate and glutamate of an influx of high concentrations of potassium ion. Samples were derivatized with naphthalenedialdehyde-cyanide prior to analysis. Detection limits for aspartate and glutamate were 80 and 100 nM, respectively. CE-ED is extremely useful for the analysis of microdialysis samples because of the very small sample volumes required by this analytical technique. The use of ED provides the requisite sensitivity and allows verification of peak purity by voltammetry.


Subject(s)
Amino Acids/analysis , Animals , Brain Chemistry , Dialysis , Electrochemistry , Electrophoresis , Indicators and Reagents , Male , Potassium/pharmacology , Rats , Rats, Sprague-Dawley
16.
Talanta ; 39(4): 443-7, 1992 Apr.
Article in English | MEDLINE | ID: mdl-18965399

ABSTRACT

The use of carbon paste electrodes modified with [Ru(bpy)(2)(PVP)(10)Cl]Cl for the mediated detection of nitrite is described. This surface modifier substantially lowers the overpotential for nitrite oxidation, hence permitting its determination at a lower potential. Various electrode characteristics were optimized, including the modifier loading and the monitoring potential, using batch amperometry. Standard calibration curves yielded slopes of 0.30 microA/microM over the linear range 5 x 10(-8)-5 x 10(-4)M nitrite with a detection limit of 3 x 10(-8)M (1.38 ppb) nitrite. The modified electrode response was shown to be relatively stable over a period of 5 days with a signal diminution of 8%. Electrode-to-electrode precision was measured as 11.4%. Flow-injection studies indicated the suitability of this electrode as a detector in flowing streams.

17.
J Wildl Dis ; 27(4): 706-9, 1991 Oct.
Article in English | MEDLINE | ID: mdl-1758040

ABSTRACT

An immature female striped dolphin (Stenella coeruleoalba) found dead on a northwestern Florida beach in 1988 exhibited severe inflammation bilaterally in the dorsal and mid-thalamus in association with adult trematodes (Nasitrema sp.) and trematode eggs. Numerous specimens of Nasitrema sp. also were present in the pterygoid sinuses. Pneumonia in association with a heavy growth of Vibrio damsela was observed also. This report confirms the occurrence of Nasitrema sp.-associated encephalitis in striped dolphins and in small cetaceans from the Gulf of Mexico.


Subject(s)
Brain/parasitology , Dolphins/parasitology , Encephalitis/veterinary , Trematode Infections/veterinary , Animals , Brain/pathology , Encephalitis/parasitology , Female , Florida , Lung/microbiology , Pneumonia/complications , Pneumonia/veterinary , Thalamus/parasitology , Thalamus/pathology , Trematode Infections/complications , Trematode Infections/parasitology , Trematode Infections/pathology , Vibrio Infections/complications , Vibrio Infections/veterinary
18.
Brain Behav Evol ; 35(4): 185-94, 1990.
Article in English | MEDLINE | ID: mdl-2379080

ABSTRACT

Neuroanatomical structure was examined in the brains of West Indian manatees (Trichechus manatus) using computer-based morphometric methods. Although manatees have a small relative brain size, volume estimates of the major brain regions indicate that the telencephalon comprises 71% of total brain volume and is 90% cerebral cortex. These values are comparable to those seen among a diversity of taxa having large relative brain size, including many primates. Manatee brains also exhibit well-defined cortical lamination. The measured gyration index (an index of cortical folding) was 1.06, representing a highly lissencephalic condition. These findings demonstrate that small relative brain size and lissencephaly do not constrain the elaboration of internal brain structures. The marked lissencephalic condition is unusual for brains of this absolute size range, and may be related to the thickness of the cortical gray matter and underlying white matter.


Subject(s)
Biological Evolution , Brain/anatomy & histology , Cerebral Cortex/anatomy & histology , Fishes/anatomy & histology , Species Specificity , Animals , Cerebellum/anatomy & histology , Diencephalon/anatomy & histology , Medulla Oblongata/anatomy & histology , Mesencephalon/anatomy & histology , Organ Size/physiology , Pons/anatomy & histology , Telencephalon/anatomy & histology
19.
J Am Vet Med Assoc ; 185(11): 1331-4, 1984 Dec 01.
Article in English | MEDLINE | ID: mdl-6511576

ABSTRACT

Necropsy and microscopic examinations of 16 West Indian manatees (Trichechus manatus) revealed that the mortality of many of the animals was associated with environmental factors such as human-inflicted trauma and cold winters. Natural disease processes accounted for the death of only 1 manatee. In 3 manatees, the cause of death could not be determined.


Subject(s)
Mammals , Animals , Animals, Wild , Bacterial Infections/veterinary , Cold Temperature/adverse effects , Female , Florida , Intussusception/veterinary , Jejunal Diseases/veterinary , Male , Meningoencephalitis/veterinary , Mortality , Parasitic Diseases, Animal , Wounds and Injuries/mortality , Wounds and Injuries/veterinary
20.
J Toxicol Environ Health ; 7(6): 883-92, 1981 Jun.
Article in English | MEDLINE | ID: mdl-7265315

ABSTRACT

Thirty breeding pairs of mallards (Anas platyrhynchos) were randomly assigned to one of five treatment groups and were fed breeder mash containing 0, 12.5, 50.0, 200.0, or 800.0 ppm Ni (as the sulfate) for 90 d. Ni ingestion had no effect on egg production, hatchability, or survival of ducklings. After 90 d birds were bled, sacrificed, and necropsied. There were no significant differences in hematocrit; concentrations of hemoglobin, plasma triglyceride, and cholesterol; of plasma activities of ornithine carbamoyltransferase and alanine aminotransferase. A black tarry feces was noted in the high Ni dose group at necropsy, but no gross or histopathologic lesions were observed. Although absolute concentrations of Ni in tissues were low, there were significant accumulations in kidneys of birds fed Ni at all dietary levels and in feathers, blood, and livers of birds fed high doses of Ni compared with controls.


Subject(s)
Ducks/physiology , Nickel/toxicity , Animals , Birth Weight/drug effects , Chemical and Drug Induced Liver Injury/pathology , Female , Kidney Diseases/chemically induced , Kidney Diseases/pathology , Liver Diseases/pathology , Male , Nickel/metabolism , Reproduction/drug effects , Tissue Distribution
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