Publications by authors named "Larry Hansen"

The common bottlenose dolphin () is a global marine mammal species for which some populations, due to their coastal accessibility, have been monitored diligently by scientists for decades. Health assessment examinations have developed a comprehensive knowledge base of dolphin biology, population structure, and environmental or anthropogenic stressors affecting their dynamics. Bottlenose dolphin health assessments initially started as stock assessments prior to acquisition.

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During 2013-2015, an outbreak of dolphin morbillivirus (DMV) occurred in the western North Atlantic, which resulted in the stranding of over 1,600 common bottlenose dolphins . There are currently five coastal and 10 bay, sound, and estuary dolphin stocks along the U.S.

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Electrocardiography (ECG) was performed on captured free-ranging bottlenose dolphins (Tursiops truncatus) during a health assessment exercise and compared with that of a Navy collection of dolphins habituated to handling out of water in order to assess possible cardiovascular impacts of capture and handling. Six-lead recordings (I, II, III, aVr, aVl, and aVf) in the frontal plane and direct thorax leads were collected from both groups, with a modified base-apex lead additionally employed with the Navy collection dolphins. Measured and calculated parameters included amplitudes of P, R, S, and T waves and total QRS complex; T:S and T:QRS ratios; heart rate; durations of P wave; QRS complex, PR, QT, and RR intervals; maximum minus minimum RR interval; ST segment elevation-depression; and mean electrical axis (MEA).

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Persistent organic pollutants (POPs) including legacy POPs (PCBs, chlordanes, mirex, DDTs, HCB, and dieldrin) and polybrominated diphenyl ether (PBDE) flame retardants were determined in 300 blubber biopsy samples from coastal and near shore/estuarine male bottlenose dolphins (Tursiops truncatus) sampled along the U.S. East and Gulf of Mexico coasts and Bermuda.

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Bottlenose dolphins (Tursiops truncatus) inhabiting coastal waters in the northern Gulf of Mexico have been impacted by recurrent unusual mortality events over the past few decades. Several of these mortality events along the Florida panhandle have been tentatively attributed to poisoning from brevetoxin produced by the dinoflagellate Karenia brevis. While dolphins in other regions of the Florida coast are often exposed to K.

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Objective: To develop robust reference intervals for hematologic and serum biochemical variables by use of data derived from free-ranging bottlenose dolphins (Tursiops truncatus) and examine potential variation in distributions of clinicopathologic values related to sampling sites' geographic locations.

Animals: 255 free-ranging bottlenose dolphins.

Procedures: Data from samples collected during multiple bottlenose dolphin capture-release projects conducted at 4 southeastern US coastal locations in 2000 through 2006 were combined to determine reference intervals for 52 clinicopathologic variables.

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Photo-identification surveys conducted between 2002 and 2005 were used to determine dolphin home ranges and site fidelity within the Indian River Lagoon (IRL), Florida. The IRL was divided into six segments based on hydrodynamics and geographic features for purposes of characterization. Among the 615 dolphins with identifiable dorsal fins, 339 had > or =6 sightings and were used in segment and linear range analyses.

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We present prevalence of Bartonella spp. for multiple cohorts of wild and captive cetaceans. One hundred and six cetaceans including 86 bottlenose dolphins (71 free-ranging, 14 captive in a facility with a dolphin experiencing debility of unknown origin, 1 stranded), 11 striped dolphins, 4 harbor porpoises, 3 Risso's dolphins, 1 dwarf sperm whale and 1 pygmy sperm whale (all stranded) were sampled.

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Objective: To conduct health assessments and compare outcomes in 2 populations of Atlantic bottlenose dolphins. Design-Repeated cross-sectional study.

Animals: 171 Atlantic bottlenose dolphins.

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Monsanto produced two distinct variants of Aroclor 1254. The late-production variant resulted from a change in Monsanto's manufacturing process in the early 1970s. Previous literature had reported that the late-production variant was produced from 1974 to 1976, but subsequent work has identified a sample known to be obtained in 1972.

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Our abilities to assess health risks to free-ranging dolphin populations, to treat live-stranded or captive dolphins, and to evaluate the risks of disease transmission between humans and dolphins have suffered from a lack of basic information on microorganisms associated with normal, presumably healthy free-ranging individuals. In order to provide these data, we sampled free-ranging bottlenose dolphins (Tursiops truncatus) off Florida, Texas, and North Carolina during 1990-2002. Blowhole and anal/fecal samples yielded 1,871 bacteria and yeast isolates and included 85 different species or groups of organisms.

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The objective of this study was to establish reference baseline data for hematologic, biochemical, and cytologic findings in apparently healthy Atlantic bottlenose dolphins (Tursiops truncatus) inhabiting the Indian River Lagoon, Florida, USA. Sixty-two dolphins were captured, examined, and released during June 2003 and June 2004. Mean, standard deviation, and range were calculated for each parameter, and values for which published data were available, were close to or within the ranges previously reported for free-ranging bottlenose dolphins.

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Ryanodine receptor isoforms are expressed in both excitable and nonexcitable tissues where they form microsomal Ca2+ release channels broadly involved in shaping cellular signaling. In this report, we provide a detailed structure-activity relationship (SAR) for polychlorinated biphenyl (PCB) congeners and metabolites necessary for enhancing ryanodine receptor type 1 (RyR1) activity using [3H]ryanodine ([3H]Ry) binding analysis. The 2,3,6-Cl PCB configuration is most important for optimal recognition by the RyR1 complex and/or critical for sensitizing its activation.

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Each environmental exposure matrix contains a unique mixture of PCB congeners. Since several congener types have multiple and distinct biological actions, it is important to characterize congener profiles in exposure sources. The Fox River Environment and Diet Study (FRIENDS) is assessing the human health effects of consumption of PCB-contaminated fish from the Fox River in northeastern Wisconsin.

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Background: Different PCB congeners and different mixtures of congeners have been demonstrated to have different biological actions. More complete characterization of congener profiles in exposure sources may assist in predicting health outcomes.

Methods: Thirty-six (36) polychlorinated biphenyl (PCB) congeners were measured by gas chromatography isotope-dilution mass spectrometry (IDMS) in 314 serum samples from Native Americans in Wisconsin, Michigan and Minnesota.

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Fat, ear skin and trunk skin were collected from mice exposed to PCB-contaminated soil for PCB specific congener analysis. The soil had been retrieved from a Superfund site prior to remediation. Mice were exposed to either contaminated soil or control soil for 4 weeks.

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Concentrations of polychorinated biphenyls (PCBs) and other organochlorine contaminants (OCs) were measured in blubber collected from live bottlenose dolphins (Tursiops truncatus) at three sites along the United States Atlantic coast. Dolphins were sampled via surgical biopsy during capture-release studies near Charleston, South Carolina and Beaufort, North Carolina. Additional animals were sampled using remote biopsy techniques in estuarine waters near Charleston and from the Indian River Lagoon, Florida.

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Polychlorinated biphenyl compounds (PCBs) are global environmental contaminants that cause disruption of the endocrine system in humans and wildlife. Recently, we reported that acute exposures to ortho-PCB congeners 95 (2,3,6-2',5') or 101 (2,4,5,-2',5') causes changes in the performance of the hypothalamo-pituitary-thyroid (HPT)-axis in developing rats through mechanism(s) not yet clear. The functionality of the HPT-axis was evaluated by using the thyrotropin releasing hormone (TRH) test following acute exposure to PCBs 95 or 101.

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Humans are always exposed to mixtures of polychlorinated biphenyls (PCBs), so assessment of their health effects is complicated. Because the original sources are relatively standard mixtures that change in predictable ways while traversing the environment, there is substantial uniformity in the congener mixtures people carry. To the extent that concentrations are highly correlated, measuring multiple congeners within correlated groups would be unnecessary and estimation of separate biologic effects would be impossible.

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Chlorinated aromatic contaminants are active in carcinogenic processes within the skin and may have the potential to modulate ultraviolet radiation (UV)-induced skin carcinogenesis. Exposure to a complex environmental PCB/PCDD/PCDF mixture (polychlorinated biphenyls/polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans) during the irradiation phase of photocarcinogenesis was associated with significant (P < or = 0.001) reductions in papilloma incidence and squamous cell carcinoma multiplicity at irradiated skin sites.

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High levels of polychlorinated biphenyls (PCBs) have been reported in the tissues of some species of marine mammals. The high concentrations are of concern because a growing body of experimental evidence links PCBs to deleterious effects on reproduction, endocrine homeostasis, and immune system function. Much of the recent research has focused on determining the exposure of marine mammal populations to PCBs, but very little effort has been devoted to the actual risk assessments that are needed to determine the expected impacts of the documented exposures.

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Background: Reductions in cholinergic function occur in Alzheimer disease (AD) and dementia with Lewy bodies and correlate with cognitive decline. However, whether such alterations appear in early-stage disease is unclear.

Objective: To examine the timing of cholinergic deficits in AD and dementia with Lewy bodies.

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Coplanar polychlorinated biphenyls (PCBs) cause adverse effects in developing and adult animals. Less is known about the effects of nonplanar ortho-substituted PCBs. We investigated the effects of 2 nonplanar PCB congeners, 95 (2,3,6-2',5'-penta CB) or 101 (2,4,5-2',5'-penta CB), and estradiol on selected endocrine parameters.

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