Biomedical subjects

J Burger

Publications and source records attributed to J Burger.

At least 91 records · Page 5Linked to original sources

PubMed1997

Risk, mercury levels, and birds: relating adverse laboratory effects to field biomonitoring.

There is an abundance of field data on levels of mercury in a variety of organisms and there are a number of studies that demonstrate the adverse effects of mercury on laboratory animals, but few studies examine the relationship between the two. Thus it is often difficult to determine the ecological relevance of mercury concentrations found in nature, or to predict the ecosystem consequences of current levels. In this paper we review the levels in tissues that are associated with adverse effects in birds from laboratory studies and compare these with levels found in wild bird populations in the New York Bight to provide a basis for interpreting values in avian populations. We use feathers from fledgling birds which would have been fed on locally obtained food to eliminate the problem of where toxic burdens were acquired by more mobile adult birds. Laboratory studies indicate that in some species mercury levels of 1.5 ppm in eggs and/or 5 to 40 ppm in the feathers of birds are associated with adverse effects, including impaired reproduction. We report egg levels in birds that range as high as 3.8 ppm and feather levels that range as high as 10.3 ppm, although means are much lower. The levels in eggs of some wild birds in the New York Bight are within the range known to lower hatchability, embryo and chick survival, and chick weight, all variables that reduce reproductive success. Species with high egg levels include Forster's tern (Sterna forsteri) and black skimmer (Rynchops niger). Levels in feathers of some young wild birds from the New York Bight are within the range associated with reduced hatchability of eggs, behavioral abnormalities of adults, and infertility. Species with dangerously elevated mercury levels in feathers include great egret (Ardea [=Egretta] alba), snowy egret [Egretta thula), and black skimmers.

Animals↗

PubMed1997

Metal levels in mourning doves from South Carolina: potential hazards to doves and hunters.

Most game birds are found in lower trophic levels, but since such birds are harvested and consumed by humans, there is a particular need to assess their contaminant levels. In this paper, we report concentrations of mercury, lead, cadmium, selenium, manganese, and chromium in the breast feathers, liver, and muscle of mourning doves (Zenaida macroura) collected at a partially drawn-down, contaminated reactor-cooling reservoir (Par Pond) on the Department of Energy's Savannah River Site in South Carolina and at nearby agricultural fields managed as dove hunting areas. We test the hypothesis that the levels in doves are not harmful to either dove populations or humans. We also tested the simultaneous effects of collection location, year (1992, 1993), and dove age-class (hatch-year vs after hatch-year) on heavy metal and selenium levels. For all three tissues, mercury levels were nondetectable at all locations. Lead was highest in tissues from agricultural fields with prior histories of dove hunting activities. Doves at those fields were likely ingesting lead shot to a greater degree than at the recently drawn-down reservoir which was closed to public access and hunting. For other metals, Par Pond doves had equally high or higher tissue levels. For all metals, levels in doves from South Carolina were generally within the lower range of those reported in the literature, suggesting that these metals were likely to pose no health problems to these doves. Except for lead and selenium, metal levels in dove muscle that we observed were well below reference metal doses established for human intake. Lead and selenium, at the levels described here, would only be a problem if a child (not an adult) ate 120 g of dove meat every day of the year. Thus, we conclude that meat from these doves, if consumed by hunters, would not pose a risk.

Adult↗

PubMed1997

Heavy metal and selenium concentrations in feathers of egrets from Bali and Sulawesi, Indonesia.

Herons and egrets are ideal organisms to use asindicators of heavy metal exposure in an ecosystem because different speciesfeed at different levels of the food chain and live in both coastal andinland habitats. This paper reports on the concentration of heavy metals andselenium in the feathers of cattle egrets Bubulcus ibis that wereexamined from nesting and roosting sites in Bali and Sulawesi, Indonesia, andin feathers of little egrets Egretta garzetta and intermediate egretsE. intermedia from the same colony in Bali. Mercury and manganeseconcentrations were significantly higher in cattle egrets from Bali comparedto Sulawesi, but otherwise there were no significant differences. There weresignificant differences in lead, cadmium and mercury among the three egretspecies nesting on Bali: 1) the cadmium and mercury concentrations related tosize and trophic level (insectivorous cattle egrets had the lowestconcentrations, fish-eating intermediate egrets had the highestconcentrations), and 2) cattle egrets had significantly lower concentrationsof lead than the other two species. For cattle egrets, secondary flightfeathers had significantly higher levels of cadmium and mercury, and lowerlevels of manganese, than mixed breast and tertiary feathers, reflectingtemporal differences in exposure.

Animals↗

PubMed1997

Age differences in metals in the blood of herring (Larus argentatus) and Franklin's (Larus pipixcan) gulls.

Concentrations of heavy metals and selenium were measured in the blood of adult and young herring (Larus argentatus) and Franklin's (Larus pipixcan) gulls collected during the same breeding season in colonies in the New York Bight and in northwestern Minnesota, respectively. Concentrations were expected to be higher in young herring gulls collected in an urban, industrialized area, compared to young Franklin's gulls collected in a relatively pristine prairie marsh. Exposure is similar for the fledgling and adult gulls because by the time the blood of young gulls is drawn both adults and young have been eating foods from the surrounding region for two months; leading to the prediction that metal levels should be similar in adults and young. However, young Franklin's gulls had significantly higher levels of arsenic, cadmium, and manganese than adults; adults had significantly higher levels of mercury and selenium. Young herring gulls had significantly higher concentrations of arsenic and selenium, but lower levels of lead than adult herring gulls. Interspecific comparisons indicated that young Franklin's gulls had significantly higher levels of cadmium than young herring gulls, and adult Franklin's gulls had higher levels of selenium and chromium than adult herring gulls, but for all other comparisons herring gulls had higher levels of metals in their blood. Young herring gulls chicks had higher arsenic, manganese, and selenium levels and lower cadmium and lead levels in 1993 than in 1994. Overall, the levels in the two species were usually within an order of magnitude.

Aging↗

PubMed1997

Risk perception, federal spending, and the Savannah River Site: attitudes of hunters and fishermen.

This paper examines the attitudes of 285 hunters and fishermen from South Carolina about hunting and fishing, risk, environmental issues, and future land use of the Savannah River Site, We test the null hypothesis that there is no difference in hunting and fishing rates, attitudes toward the safety of fish and deer obtained from SRS, attitudes toward future land use at SRS, and perceptions of the severity of environmental problems as a function of how far respondents lived from the site. Respondents hunted or fished an average of over 40 days a year, and only half felt that the fish and deer from SRS were safe to eat. Willingness to expend federal funds was correlated with perceptions of the severity of the problem. Preferences for future land use at SRS fell into three categories: high (environmental research park, hunting, fishing, camping), medium (nuclear production, factories, preserve only), and low (nuclear waste storage, residential). There were no differences in hunting and fishing rates, ranking of the severity of environmental problems, and willingness to expend federal funds as a function of distance of residence from SRS, but attitudes toward future land use differed significantly as a function of location of residence. Those living close to SRS were more willing to have the site used for factories, residential, nuclear material production and to store nuclear wastes than those living farther from the site. Our data on recreational rates, attitudes toward future land use, and willingness to expend federal funds to solve environmental problems reiterate the importance of assessing stakeholder attitudes toward decisions regarding future land use at DOE sites.

Adult↗

PubMed1997

Methods for and approaches to evaluating susceptibility of ecological systems to hazardous chemicals.

Differences in genetic susceptibility to hazardous chemicals affect individuals of both human and nonhuman populations. In both cases, differences in response to chemicals or general ill health result as a function of these differences in genetic susceptibility. However, ecological systems are a compilation of hundreds or even thousands of different species, resulting in structural and functional characteristics that are themselves affected by differences in susceptibility. Although individual and population differences in susceptibility to hazardous chemicals underlie effects at the community and the ecosystem level, they do not account for all differences. I propose a two-tiered approach to evaluating susceptibility to ecological systems: a general susceptibility as a function of ecosystem type (based on structure and function of that system) and a differential in susceptibility within broad ecosystem types as a function of biotic and abiotic factors. In terrestrial ecosystems, the two factors that most affect overall susceptibility are species diversity and hydrology; evaluation of the effects of hazardous chemicals involves measuring species diversity and water movement. This same methodological approach can be applied to aquatic ecosystems and to highly altered ecosystems such as agriculture, forestry, fisheries, and urbanization.

Animals↗

PubMed1997

Lead and neurobehavioral development in gulls: a model for understanding effects in the laboratory and the field.

Animals, including humans, are increasingly exposed to a variety of environmental chemicals that can cause adverse developmental neurobehavioral effects. Most studies either examine effects in the laboratory, or report levels in wild animals, but the relationship between dose, tissue levels and effects are seldom examined in one system. Establishing this relationship is particularly important for endocrine disruptors because of the current controversies regarding impacts on both humans and wildlife. In this paper we synthesize results from a 10-year research program that uses the herring gull chick as a model to examine the relationship between dose, tissue levels, and response to lead in both the laboratory and the wild; and compare levels that cause deficits to those that occur in wild populations of a number of birds. The laboratory studies show that lead affects several aspects of neurobehavioral development in herring gull chicks. There are critical periods for the effects of lead on neurobehavioral development; and there are dissociations: different behaviors have different critical periods. Response latency may be affected most when exposure occurs at one age, while accuracy of response may be affected more at a different age of exposure. Further, there is not necessarily a correlation between impairment and the recovery trajectory. The field experiments show that there are similar lead-induced neurobehavioral deficits in the wild as occur in the laboratory. However, there were important differences: recovery occurred sooner in the field compared to the laboratory; parents partially compensated for the behavioral deficits and succeeded in getting surviving chicks to a similar fledging weight as control chicks, and although survival was decreased in lead-injected chicks in the wild, it was not as low as predicted because of the protective behavior of their parents. These impairments resulted in decreases in survival, which reduced overall fledging rates for a population with lead exposure. Data on exposure levels, as indicated by lead levels in feathers of birds worldwide, suggest that some birds are at risk of neurobehavioral impairment from exposure to lead. Although the neurobehavioral deficits are subtle, and difficult to prove using only wild populations, the data from the field experiments with herring gulls clearly indicate that the deficits occur. This providers a model for studying the neurobehavioral effects of any chemicals on wild populations.

Animals↗

PubMed1997

[Detection of DNA single-copy sequences of prehistoric teeth. Site milieu as a factor for preservation of DNA].

DNA-extracts from prehistoric roots of teeth were analyzed by PCR to investigate microsatellite-systems. At the same time the x/y-chromosome specific system Amel A/B was investigated. The samples were collected from different burial conditions of similar age. Factors leading to limited DNA-degradation are given. For the first time reproducible Quadruplex-amplification on single-copy loci of prehistoric tissue was obtained in samples from the Lichtenstein-Cave, Kr. Osterode/Harz. Positive results are explained by low temperature in the burial site. In addition the results show that desiccation allows DNA-preservation but cannot protect the DNA from damage due to microbial origin. Microorganisms can destroy DNA-structures completely.

Burial↗

PubMed1996

Heavy metal and selenium levels in Franklin's Gull (Larus pipixcan) parents and their eggs.

Lead, cadmium, mercury, chromium, selenium, and manganese concentrations were measured in the breast feathers of 25 pairs of Franklin's Gull (Larus Pipixcan) and in their eggs from a breeding colony at Agassiz National Wildlife Refuge in Northwestern Minnesota. Metal concentrations in eggs represent metals sequestered in the egg by females at the time of egg formation; while metal concentrations in parents represent concentrations of metals in blood supply at the time of feather formation. There were no significant sexual differences in metal concentrations in feathers, assuming the male to be larger of each pair, but there were significant differences between the concentrations of metals in parents and their eggs. Eggs had significantly higher concentrations of selenium and chromium, but significantly lower concentrations of all other metals than the feathers of their parents. There were few significant correlations among metal concentrations within the egg or within the feather of females, but there were correlations for the feathers of males. Lead and cadmium in feathers were positively correlated for both males and females. Chromium concentrations in eggs were generally higher than reported in the literature. The concentrations in eggs and the feathers of females were positively correlated for mercury, and negatively correlated for chromium and manganese.

Animals↗

PubMed1996

Effect of enzyme organization on the stability of Yates-Pardee pathways.

Yates-Pardee-type metabolic pathways in a heterogeneous cell milieu are modeled as a system of coupled non-linear partial differential equations. A numerical solution to this system is described and some properties of such a physiological system are studied. Confinement with and without a membrane is considered and it is shown how confinement results in an increase in the stability of the metabolite concentrations. These results suggest that the enzyme organization may contribute to the stability of the cellular metabolism.

Cell Compartmentation↗

PubMed1996

Lead and behavioral development: parental compensation for behaviorally impaired chicks.

Lead is ubiquitous in nature, and can affect behavioral, physiological, and intellectual development in humans and other animals. We used lead-induced behavioral deficits to examine the behavior of parents and young herring gulls in the Captree, NY, gull colony. Our objectives were to determine: a) If there were differences in the behavior, weight, and survival of chicks as a function of treatment; b) if parental behavior varied as a function of treatment; and 3) if there were differences in sibling competition and parent-young conflict between experimental nests (with lead-impaired chicks and control chicks) and control nests. We injected one chick in each of 22 nests (1-2 days of age) with lead acetate (100 mg/kg in sterile water) and injected its sibling with sterile saline, and compared behavior of parents and young (from 1-21 days postinjection). We also observed behavior of parents and chicks in 12 control nests in which chicks were handled similarly but were not injected. There were significant lead-induced differences in righting response, locomotion, thermoregulation, begging, and feeding behavior in the chicks; corroborating observations from the laboratory. Lead-injected chicks were less able to compete for food with their siblings, with a resultant significant difference by weight at 16 days of age. For experimental nests in which the weight difference was great, parents engaged in divided feeding of the brood. After one parent initiated feeding, the other parent walked a short distance away and began to call to and then feed the second, smaller chick. The extra parental care resulted in increased survival for the lead-injected chicks, and in their catching up to their siblings in weight by fledging. The results of this experiment indicate that lead induces behavioral deficits and growth retardation in gulls in nature, decreases survival at young ages, and that parents compensate for these behavioral and growth deficits by brood division for feeding chicks such that by fledging the chicks are no longer at a weight and size disadvantage. Parents are, thus, able to perceive a difference in body size and/or vigor of their offspring, and to behaviorally compensate partially for the lead-induced deficits.

Animals↗

PubMed1996

The child vulnerability scale: an instrument to measure parental perceptions of child vulnerability.

Developed and validated an instrument for identifying children perceived as vulnerable. Mothers of 1,095 children, aged 4-8 years, completed interviews that included the original 12-item Child Vulnerability Scale. Eight items that correlated best with each of two major variables that contribute to vulnerability were retained in the revised scale and a cutoff score was identified for children perceived as vulnerable. The internal consistency of the revised scale was good. Using the revised scale, 10.1% of children were identified as perceived vulnerable. Children categorized as perceived vulnerable had a significant increase in behavior problems and acute medical visits. The revised Child Vulnerability Scale should be useful in providing a better understanding of the causes and effects of an important factor in child development.

Adult↗

PubMed1996

Fishing in a polluted estuary: fishing behavior, fish consumption, and potential risk.

People make subjective judgments about hazards relying on what they know and feel. These risk perceptions may be based on accurate or inaccurate information and are often optimistically biased. The existence of uncertainties in the evaluation of many environmental hazards effects how risks are perceived. This paper examines fish consumption and risk perception of urban fishermen in the New York/New Jersey estuary, in areas where there were consumption advisories. We interviewed 318 fishermen and crabbers in the Arthur Kill, Raritan Bay, and New Jersey shore. Fish were eaten an average of at least four times per month in all regions, but fishermen in the Arthur Kill fished most frequently, averaging over eight times per month. Although 60% of fishermen and crabbers in the Arthur Kill reported hearing warnings about consuming fish caught in these waters, 70% of fishermen and 76% of crabbers said they are their catch. Significantly fewer fishermen in the Bay and Shore regions had heard warnings (28% and 30%, respectively), and more reported consuming their catch (88% and 82%, respectively). In all regions, most people thought that the fish were safe to eat, many believing they were "fresher" than store bought fish. Thus, most people ignored the consumption advisories in effect for these waters. Some of these people are consuming high quantities of fish and crabs, and thus are exposed to potentially deleterious levels of contaminants. In general, people failed to consider the possibility of chronic effects and did not perceive that this enjoyable, familiar pastime could be hazardous. Further, fishermen generally had great confidence in their own knowledge, which proved to be inaccurate in many cases, and often expressed distrust in the information source (government). Clearly, simply issuing consumption advisories is insufficient to promote risk-reducing behavior.

Animals↗

PubMed1995

Eggshell thickness in marine birds in the New York Bight--1970s to 1990s.

Maintaining eggshell thickness is critical for birds, as thin eggshells result in breakage during incubation, with subsequent hatching failure. Beginning in the 1960s, eggshell thickness has been used as a biomarker of exposure to chlorinated hydrocarbon pesticides, as a measure of avian population health, and as a predictor of potential reproductive failures. In this study, eggs were collected from four coastal bird species nesting in the New York Bight (Cedar Beach, NY to Barnegat Bay, NJ) in the early 1970s, early 1980s, and early 1990s, and eggshell thickness was measured. We tested the hypothesis that decreasing use of chlorinated hydrocarbons, and subsequent decreased levels of these pollutants in the New York Bight estuarine food web, should have resulted in increased eggshell thickness from the 1970s to the 1990s. Most of the variation in eggshell thickness was explained by decade and species. Eggshell thickness increased from the early 1970s (or the 1980s for some species) to the early 1990s for all four species examined: common tern (Sterna hirundo), Roseate tern (S. dougallii), least tern (S. antillarum), and black skimmer (Rynchops niger). For common terns and black skimmers, eggshell thickness increased by nearly 50% from the 1970s to the 1990s, whereas in the smallest species, the least tern, eggshell thickness increased only by 12%. In the 1990s, least terns with the smallest eggs had the thinnest eggshells, and black skimmers with larger eggs had the thickest eggshells.

Animals↗

PubMed1995

Heavy metal and selenium concentrations in eggs of herring gulls (Larus argentatus): temporal differences from 1989 to 1994.

Concentrations of five metals and selenium in the eggs of herring gulls (Larus argentatus) were examined at a breeding colony on western Long Island, New York from 1989 to 1994. There were significant yearly differences in lead, cadmium, mercury, selenium, chromium, and manganese. Chromium and cadmium were significantly higher in 1993 compared to the other years. Lead levels were highest in 1989, and were uniformly lower in the succeeding four years. Manganese showed no clear pattern. Selenium concentrations decreased from 1991 through 1994, whereas mercury increased from 1992 through 1994. Generally, concentrations of cadmium were similar to those reported for avian eggs from elsewhere; mercury and lead were within the range, but were at the high end; and chromium concentrations were higher than elsewhere. For all years combined, there was a positive correlation between lead and cadmium concentrations and between chromium and manganese, and a negative correlation between lead and mercury concentrations. In conclusion, egg contents can be used to monitor heavy metal concentrations, but consecutive years must be examined because concentrations can vary significantly among years. Ideally, data are needed for more than three years before trends, or lack thereof, can be determined.

Animals↗

PubMed1995

Behavior effects of lead exposure on different days for gull (Larus argentatus) chicks.

Lead exposure early in life affects behavioral, physiologic, and intellectual development in humans and other animals. In this article, we examine the effects of temporal differences in lead exposure on early development in herring gulls (Larus argentatus). Each of 72 1-day-old herring gull chicks was randomly assigned to one of six treatment groups to receive a lead nitrate concentration of 100 micrograms/g at age 2 or at age 6, a similar cumulative dose evenly divided on days 2, 4, and 6, or matched-volume saline injections on the same days. Behavioral tests were performed (some at 2- and others at 5-day intervals) to examine locomotion, balance, righting response, thermoregulation, and visual cliff. Most variation in weight was explained by testing age, although treatment affected weight gain for the lead-6 gulls, particularly after 20 days. Although treatment influenced balance and locomotion, the effect was small. The lead-6 birds were unable to remain on an incline as long as the lead-2, lead-246, and control birds. The overall score for balance improved with age for controls, showed little change for the lead-2 and lead-2-4-6 gulls, but showed a decrease in performance for the lead-6 birds. On the thermoregulation test, the lead-6 birds performed less well under both low- and high-temperature test conditions. Although the lead-2-4-6 birds had a lower score on the visual cliff tests than the other groups, the lead-6 gulls showed a significant delay in response and gave significantly fewer calls then the other groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Growth and behavioral effects of early postnatal chromium and manganese exposure in herring gull (Larus argentatus) chicks.

Organisms in marine environments are exposed to chromium and manganese, yet little is known of the effects of these metals on physiology and behavior. In this article we examine the effects of chromium and manganese on early neurobehavioral development in herring gulls, Larus argentatus. Each of 36 2-day-old herring gull chicks was randomly assigned to one of three treatment groups to receive either chromium nitrate (25 mg/kg), manganese acetate (50 mg/kg), or a control dose of sterile saline solution. The trios were not siblings, but were matched by age and weight. Behavioral tests examined food-begging, balance, locomotion, righting response, recognition, thermoregulation, and perception. There were significant differences in begging behavior by 5 days postinjection, and there were significant differences in weight gain throughout development until 50 days of age, when the experiment was terminated. Behavioral tests, administered from 18-48 days postinjection, indicated significant differences between control and the exposed groups for time to right themselves; thermoregulation behavior; and performance on a balance beam, inclined plane, actual cliff, and visual cliff (although not all components varied significantly). Of the 14 behavioral measures with significant differences, control birds performed best on 12.

Analysis of Variance↗

PubMed1995

Effects of varying temporal exposure to lead on behavioral development in herring gull (Larus argentatus) chicks.

In humans and other animals, lead exposure in infants and young animals affects anatomic, physiologic, behavioral, and intellectual development. Yet it is largely unknown whether the effects occur gradually or are more pronounced if exposure occurs at particular stages. In this article we examine the effects of temporal differences in lead exposure on early behavioral development in herring gulls (Larus argentatus). We randomly assigned 64 1-2-day-old gull chicks to one of four treatment groups to receive a lead acetate dose at age 6 days (100 micrograms/g) or 12 days (50 or 100 micrograms/g), or to receive matched volume saline injections on the same days. Behavioral tests were performed at 2-5-day intervals to examine locomotion, balance, righting response, thermoregulation, and visual cliff. Flight behavior was examined at fledging. Results were compared with previously studied exposures at 2, 4, and 6 days of age. Righting response and balance were disrupted immediately after exposure, regardless of the timing of exposure. Thermoregulatory, visual cliff, and individual recognition behavior were more affected by exposure at 2-6 days, and there was little effect with exposure at 12 days. These results confirm the existence of critical periods for certain behaviors to lead exposure in developing herring gulls.

Aging↗