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David Barnes

Publications and source records attributed to David Barnes.

16 recordsLinked to original sources
PubMed2006

Scientific research, stakeholders, and policy: continuing dialogue during research on radionuclides on Amchitka Island, Alaska.

It is increasingly clear that a wide range of stakeholders should be included in the problem formulation phase of research aimed at solving environmental problems; indeed the inclusion of stakeholders at this stage has been formalized as an integral part of ecological risk assessment. In this paper, we advocate the additional inclusion of stakeholders in the refinement of research methods and protocols and in the execution of the research, rather than just at the final communication and reporting phase. We use a large study of potential radionuclide levels in marine biota around Amchitka Island as a case study. Amchitka Island, in the Aleutian Island Chain of Alaska, was the site of three underground nuclear tests (1965-1971). The overall objective of the biological component of the study was to collect a range of marine biota for radionuclide analysis that could provide data for assessing current food safety and provide a baseline for developing a plan to monitor human and ecosystem health in perpetuity. Stakeholders, including regulators (State of Alaska), resource trustees (US Fish and Wildlife Service, State of Alaska), representatives of the Aleut and Pribilof Island communities, the Department of Energy (DOE), and others, were essential for plan development. While these stakeholders were included in the initial problem formulation and approved science plan, we also included them in the refinement of protocols, selection of bioindicators, selection of a reference site, choice of methods of collection, and in the execution of the study itself. Meetings with stakeholders resulted in adding (or deleting) bioindicator species and tissues, prioritizing target species, refining sampling methods, and recruiting collection personnel. Some species were added because they were important subsistence foods for the Aleuts, and others were added because they were ecological equivalents to replace species deleted because of low population numbers. Two major refinements that changed the research thrust were (1) the inclusion of Aleut hunters and fishers on the biological expedition itself to ensure that subsistence foods and methods were represented, and (2) the addition of a fisheries biologist on a NOAA research trawler to allow sampling of commercial fishes. Although the original research design called for the collection of biota by Aleut subsistence fishermen, and by a commercial fishing boat, the research was modified with continued stakeholder input to actually include Aleuts and a fisheries biologist on the expeditions to ensure their representation. The inclusion of stakeholders during the development of protocols and the research itself improved the overall quality of the investigation, while making it more relevant to the interested and affected parties. Final responsibility for the design and execution of the research and radionuclide analysis rested with the researchers, but the process of stakeholder inclusion made the research more valuable as a source of credible information and for public policy decisions.

Alaska↗
PubMed2006

Cell and molecular biology of SAE, a cell line from the spiny dogfish shark, Squalus acanthias.

Cartilaginous fish, primarily sharks, rays and skates (elasmobranchs), appeared 450 million years ago. They are the most primitive vertebrates, exhibiting jaws and teeth, adaptive immunity, a pressurized circulatory system, thymus, spleen, and a liver comparable to that of humans. The most used elasmobranch in biomedical research is the spiny dogfish shark, Squalus acanthias. Comparative genomic analysis of the dogfish shark, the little skate (Leucoraja erincea), and other elasmobranchs have yielded insights into conserved functional domains of genes associated with human liver function, multidrug resistance, cystic fibrosis, and other biomedically relevant processes. While genomic information from these animals is informative in an evolutionary framework, experimental verification of functions of genomic sequences depends heavily on cell culture approaches. We have derived the first multipassage, continuously proliferating cell line of a cartilaginous fish. The line was initiated from embryos of the spiny dogfish shark. The cells were maintained in a medium modified for fish species and supplemented with cell type-specific hormones, other proteins and sera, and plated on a collagen substrate. SAE cells have been cultured continuously for three years. These cells can be transfected by plasmids and have been cryopreserved. Expressed Sequence Tags generated from a normalized SAE cDNA library included a number of markers for cartilage and muscle, as well as proteins influencing tissue differentiation and development, suggesting that SAE cells may be of mesenchymal stem cell origin. Examination of SAE EST sequences also revealed a cartilaginous fish-specific repetitive sequence that may be evidence of an ancient mobile genetic element that most likely was introduced into the cartilaginous fish lineage after divergence from the lineage leading to teleosts.

Animals↗
PubMed2006

Efficacy of omega-3 fatty acids in preventing age-related macular degeneration: a systematic review.

TOPIC: What is the evidence for efficacy of dietary and/or supplemental omega-3 fatty acids in preventing age-related macular degeneration (AMD)? CLINICAL RELEVANCE: Age-related macular degeneraion is the leading cause of blindness and vision impairment in persons older than 50 years living in North America. There is no cure for AMD, and treatment does not usually restore vision but only prevents disease progression to a modest degree. omega-3 fatty acids are considered potentially important antioxidants and are being considered as an arm of the Age-Related Eye Disease Study II clinical trial. METHODS/LITERATURE REVIEWED: Keywords were searched in Medline, Pre-Medline, Embase, and the Cochrane Library on Ovid. There was no restriction on the year or language of publication. RESULTS: There were 6 observational studies found, but the specific outcomes, exposures, and covariates studied all varied greatly. CONCLUSION: There is some clinical evidence for protection of AMD from omega-3 fatty acids. However, the results are not consistent. Hence, our conclusion is that this issue is neither clearly supported nor refuted by the present world literature. This is an intriguing and extremely important question but needs further study first with prospective cohort designs and, if positive, randomized clinical trials.

Antioxidants↗
PubMed2006

The evidence for efficacy of omega-3 fatty acids in preventing or slowing the progression of retinitis pigmentosa: a systematic review.

BACKGROUND: Studies in preterm and term human infants have suggested that a dietary supply of omega-3 fatty acids is essential for optimal visual development. Several basic science studies support the hypothesis that omega-3 fatty acids may be useful therapeutic agents for pathologies of the retina and lens. As part of a systematic review of the effect of omega-3 fatty acids on eye health, the purpose of this study was to conduct a systematic review of the scientific-medical literature to appraise and synthesize the evidence for the effects of omega-3 fatty acids in preventing the development or progression of retinitis pigmentosa. METHODS: A comprehensive search was undertaken in MEDLINE, PREMEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Global Health, and Dissertation Abstracts. Unpublished literature was sought through manual searches of reference lists of included studies and key review articles and from the files of content experts. Searches were not restricted by language of publication, publication type, or study design. Eligibility criteria were applied to screen eligible studies on two levels. Data extraction and quality assessment were performed. RESULTS: Six studies published between 1995 and 2004 met eligibility criteria in investigating the question of the possible value of omega-3 fatty acids in slowing the progression of retinitis pigmentosa. Meta-analysis was not performed because there was not enough available information for formal quantitative analysis. INTERPRETATION: There are trends in improvement of some retinitis pigmentosa outcomes with omega-3 fatty acids in the higher quality studies. Clinical research is preliminary in this field, however. Accordingly, definitive answers will require significantly more observational and interventional clinical research.

Databases, Factual↗
PubMed2006

Future-directed thinking and depression in relapsing-remitting multiple sclerosis.

BACKGROUND: Research has shown that depression is associated with a view of the future characterized by reduced anticipation of future positive experiences, but not necessarily increased anticipation of future negative experiences. The aim of the present study was to investigate how participants with relapsing-remitting multiple sclerosis (MS) anticipated their future in terms of positive and negative events. DESIGN: A mixed design compared three groups of participants on a measure of future thinking using an adapted verbal fluency paradigm. METHODS: Depressed MS participants (N=14), non-depressed MS participants (N=28) and healthy control participants (N=26) were assessed on their ability to generate future positive and negative experiences. A content analysis was also conducted on the responses generated by the MS depressed and MS non-depressed groups according to whether or not they were related to MS. RESULTS: The MS depressed group anticipated significantly fewer future positive events than the healthy control group and the MS non-depressed group. The three groups did not differ in the total numbers of anticipated future negative events, though the MS depressed group did anticipate a significantly higher proportion of MS-related negative events. CONCLUSIONS: Like depressed but physically healthy individuals, the MS depressed group was characterized by a lack of positive thoughts about the future, rather than an increased number of negative thoughts. The clinical implications of these findings are discussed along with recommendations for future research.

Adult↗
PubMed2005

10t,12c-conjugated linoleic acid inhibits lipopolysaccharide-induced cyclooxygenase expression in vitro and in vivo.

Previous data demonstrated that conjugated linoleic acid (CLA) reduced eicosanoid release from select organs. We hypothesized that one active CLA isomer was responsible for the reduced prostaglandin release and that the mechanism was through the inhibition of inducible cyclooxygenase-2 (COX-2). Here, we examined the effects of 10t,12c-CLA and 9c,11t-CLA on COX-2 protein/mRNA expression, prostaglandin E(2) (PGE(2)) production, and the mechanism by which CLA affects COX-2 expression and prostaglandin release. The COX-2 protein expression level was inhibited 80% by 10t, 12c-CLA and 26% by 9c,11t-CLA at 100 microM in vitro. PGE(2) production was decreased from 5.39 to 1.12 ng/2 x 10(6) cells by 10t,12c-CLA and from 5.7 to 4.5 ng/2 x 10(6) cells by 9c,11t-CLA at 100 microM. Mice fed 10t,12c-CLA but not 9c,11t-CLA were found to have a 34% decrease in COX-2 protein and a 43% reduction of PGE(2) release in the lung. 10t,12c-CLA reduced COX-2 mRNA expression level by 30% at 100 microM in vitro and by 30% in mouse lung in vivo. Reduced COX-2 mRNA was attributable to an inhibition of the nuclear factor kappaB (NF-kappaB) pathway by 10t,12c-CLA. These data suggested that the inhibition of NF-kappaB was one of the mechanisms for the reduced COX-2 expression and PGE(2) release by 10t,12c-CLA.

Animals↗
PubMed2005

Randomized placebo-controlled study of low-dose warfarin for the prevention of central venous catheter-associated thrombosis in patients with cancer.

PURPOSE: In this multicenter, randomized, placebo-controlled clinical trial, we studied whether warfarin 1 mg daily reduces the incidence of symptomatic central venous catheter (CVC) -associated thrombosis in patients with cancer. PATIENTS AND METHODS: Two hundred fifty-five patients with cancer who required a CVC for at least 7 days were randomly assigned to receive warfarin 1 mg or placebo. RESULTS: There were 11 (4.3%) symptomatic CVC-associated thromboses among 255 patients, with no difference in the incidence of symptomatic CVC-associated thrombosis between patients taking warfarin 1 mg daily (six of 130 patients; 4.6%) and patients taking placebo (five of 125 patients; 4.0%; hazard ratio, 1.20; 95% CI, 0.37 to 3.94). Warfarin had no effect on CVC life span (84 days v 63 days in control and warfarin groups, respectively; 95% confidence limit, -16 to 55 days; P = .09), and it did not affect the number of premature CVC removals (23.2% v 25.4% in control and warfarin groups, respectively; 95% confidence limit of difference -8.34 to 12.71; P = .68) or the frequency of major bleeding episodes (2% v 0% in control and warfarin groups, respectively; P = .5, Fisher's exact test). CONCLUSION: Symptomatic CVC-associated thrombosis in patients with cancer, although significant, is less common than previously reported. In this study, the administration of warfarin 1 mg daily did not reduce the incidence of symptomatic CVC-associated thrombosis in patients with cancer. However, the low rate of symptomatic CVC-associated thrombosis means that a much larger trial is required to address this issue definitively.

Adolescent↗
PubMed2005

Sentinel lymph node biopsy in N0 squamous cell carcinoma of the oral cavity and oropharynx.

OBJECTIVES: To ascertain the feasibility of sentinel lymph node (SLN) localization by preoperative lymphoscintigraphy and intraoperative gamma probe radiolocalization and to determine the predictive value of the SLN for occult metastasis of the neck in N0 squamous cell carcinoma of the oral cavity and oropharynx. DESIGN: A prospective study of 20 consecutive patients with N0 squamous cell carcinoma of the head and neck who underwent lymphoscintigraphy and SLN biopsy. INTERVENTIONS: On the day before surgery, each patient who completed the study underwent a submucosal peritumoral injection of unfiltered technetium 99m sulfur colloid followed by lymphoscintigraphy. Focal areas of radioactivity were marked on the overlying skin. The following day, the patients underwent resection of the primary tumor, elevation of subplatysmal flaps, identification and removal of the SLNs as identified by gamma probe, and complete neck dissections. RESULTS: Lymphoscintigraphy and gamma probe radiolocalization accurately identified 1 or more SLNs in all 20 patients. In 4 (20%) of the 20 patients, the SLN correctly identified metastatic disease. In no instance was the SLN negative when the lymphadenectomy specimen was positive. CONCLUSIONS: In this study, the SLN had a negative predictive value of 100%. Sentinel lymph node biopsy is feasible and appears to accurately predict the presence of occult metastatic disease. Although further study is warranted, SLN biopsy could potentially guide head and neck oncologists to the patient with N0 disease who would benefit most from selective neck dissection and prevent the morbidity of unnecessary neck dissection.

Adult↗
PubMed2005

Science, policy, and stakeholders: developing a consensus science plan for Amchitka Island, Aleutians, Alaska.

With the ending of the Cold War, the US Department of Energy is responsible for the remediation of radioactive waste and disposal of land no longer needed for nuclear material production or related national security missions. The task of characterizing the hazards and risks from radionuclides is necessary for assuring the protection of health of humans and the environment. This is a particularly daunting task for those sites that had underground testing of nuclear weapons, where the radioactive contamination is currently inaccessible. Herein we report on the development of a Science Plan to characterize the physical and biological marine environment around Amchitka Island in the Aleutian chain of Alaska, where three underground nuclear tests were conducted (1965-1971). Information on the ecology, geology, and current radionuclide levels in biota, water, and sediment is necessary for evaluating possible current contamination and to serve as a baseline for developing a plan to ensure human and ecosystem health in perpetuity. Other information required includes identifying the location of the salt water/fresh water interface where migration to the ocean might occur in the future and determining groundwater recharge balances, as well as assessing other physical/geological features of Amchitka near the test sites. The Science Plan is needed to address the confusing and conflicting information available to the public about radionuclide risks from underground nuclear blasts in the late 1960s and early 1970s, as well as the potential for volcanic or seismic activity to disrupt shot cavities or accelerate migration of radionuclides into the sea. Developing a Science Plan involved agreement among regulators and other stakeholders, assignment of the task to the Consortium for Risk Evaluation with Stakeholder Participation, and development of a consensus Science Plan that dealt with contentious scientific issues. Involvement of the regulators (State of Alaska), resource trustees (U S Fish and Wildlife Service), representatives of the Aleut and Pribilof Island communities, and other stakeholders was essential for plan development and approval, although this created tensions because of the different objectives of each group. The complicated process of developing a Science Plan involved iterations and interactions with multiple agencies and organizations, scientists in several disciplines, regulators, and the participation of Aleut people in their home communities, as well as the general public. The importance of including all parties in all phases of the development of the Science Plan was critical to its acceptance by a broad range of regulators, agencies, resource trustees, Aleutian/Pribilof communities, and other stakeholders.

Alaska↗
PubMed2003

Coral record of increased sediment flux to the inner Great Barrier Reef since European settlement.

The effect of European settlement on water quality in the Great Barrier Reef of Australia is a long-standing and controversial issue. Erosion and sediment transport in river catchments in this region have increased substantially since European settlement, but the magnitude of these changes remains uncertain. Here we report analyses of Ba/Ca ratios in long-lived Porites coral from Havannah Reef--a site on the inner Great Barrier Reef that is influenced by flood plumes from the Burdekin river--to establish a record of sediment fluxes from about 1750 to 1998. We find that, in the early part of the record, suspended sediment from river floods reached the inner reef area only occasionally, whereas after about 1870--following the beginning of European settlement--a five- to tenfold increase in the delivery of sediments is recorded with the highest fluxes occurring during the drought-breaking floods. We conclude that, since European settlement, land-use practices such as clearing and overstocking have led to major degradation of the semi-arid river catchments, resulting in substantially increased sediment loads entering the inner Great Barrier Reef.

Agriculture↗
PubMed2003

Targeting thalamic nuclei is not sufficient for the full anti-absence action of ethosuximide in a rat model of absence epilepsy.

Absence epilepsy is characterised by recurrent periods of physical and mental inactivity coupled to bilateral, synchronous spike and wave discharges (SWDs) on the electroencephalogram. The mechanism of action of ethosuximide (ETX), a drug specific for absence seizures, is believed to involve a reduction in the low threshold T-type Ca(2+) current in thalamocortical and nucleus reticularis thalami (NRT) neurones, although other electrophysiological data have questioned this. Here, we employed a genetic rat model of absence seizures to investigate the effects of directly administering ETX to the thalamus.SWDs were immediately and substantially reduced (approximately 90%) by systemic administration of ETX (177-709 micromol/kg), or by bilateral microinfusion into the thalamus of the GABA(B) antagonist, CGP 36742 (5-27 nmol per side). However, infusion of ETX (1-200 nmol per side) into the ventrobasal complex or the NRT resulted in a reduction of SWDs that was delayed (30-60 min) and less marked (approximately 50%). Administration of ETX (0.2 mM to 1M) to a greater volume of thalamus by reverse microdialysis also produced significant but delayed reduction of SWDs at concentrations >1mM. Only at 5mM were seizures significantly reduced (approximately 70%) within 30 min of administration. These results suggest that targeting of the thalamus alone may be insufficient for an immediate and full anti-absence action for ETX. Concomitant or exclusive actions in the cortex remain a possibility.

Animals↗
PubMed2002

The long-term survival and causes of death in patients who survive at least 1 year after liver transplantation.

BACKGROUND: The purpose of this study was to examine the long-term survival and causes of death in patients who survive the first year after liver transplantation. METHODS: The focus of the analysis was 433 patients who survived for at least 1 year after liver transplantation between November 1, 1984, and December 31, 2001. A total of 586 liver transplants were performed in 542 patients during this time period. The overall 1-, 5-, and 10-year survivals and the 5- and 10-year survivals for those patients who lived for a year were analyzed on the basis of Kaplan-Meier survival estimates. Factors examined included diagnosis, sex, age, and retransplantation. The causes of death were also analyzed. RESULTS: The overall 1-, 5-, and 10-year survivals were 85%, 73%, and 55%, respectively. The 5- and 10-year survivals for those patients who lived for a year were 86% and 65%, respectively. Fifty-one percent of the causes of late death were graft-related, 71% from recurrent primary disease. Cardiovascular events and de novo malignancies were responsible for 65% of the nongraft-related deaths. CONCLUSIONS: The long-term survival in patients who survive for the first year after liver transplantation is excellent. Recurrent primary disease is responsible for the majority of graft-related deaths. Cardiovascular events and de novo malignancy cause most of the nongraft-related deaths.

Adolescent↗