PubMed Health⌕ Search

Biomedical subjects

J E Smits

Publications and source records attributed to J E Smits.

18 recordsLinked to original sources
PubMed2005

An epizootic of avian pox in endemic short-toed larks (Calandrella rufescens) and Berthelot's pipits (Anthus berthelotti) in the Canary Islands, Spain.

Between January 2002 and November 2003, 50% (n = 395) of short-toed larks (Calandrella rufescens) and 28% (n = 139) of Berthelot's pipits (Anthus berthelotti) examined on the islands of Fuerteventura and Lanzarote, Canary Islands, had gross lesions compatible with avian pox. However, Spanish sparrows (Passer hispaniolensis, n = 128) and trumpeter finches (Bucanetes githagineus, n = 228), which inhabit the same steppe habitats associated with goat husbandry, did not have poxlike lesions. Histopathology and electron microscopy confirmed poxvirus in the lesions, whereas serology using standard, fowl poxvirus-and pigeon poxvirus-based diagnostic agar gel immunodiffusion techniques was negative, likely because of the limited (74.6% pipit; 74.9% lark) similarity between the viruses in our species and fowlpox virus on which the serologic tests rely. On the basis of polymerase chain reaction analyses, the virus isolated from dried lesions of C. rufescens has 80.5% similarity with the virus isolated from A. berthelotti and 91.3% similarity with canarypox, whereas A. berthelotti poxvirus has only 80% similarity with canarypox. We have two distinct and possibly new avian poxviruses. Both poultry and the wild birds on the farms were heavily infested by fleas, which may have acted as vectors in transmission of poxvirus. Disease prevalence in these Canary Island passerines is higher than that described in song birds in Hawaii that are now threatened, endangered, or extinct. Environmental and biological factors contributing to increased disease susceptibility of these isolated populations must be investigated.

Animals↗
PubMed2002

Immune function, stress response, and body condition in arctic-breeding common eiders in relation to cadmium, mercury, and selenium concentrations.

We examined relationships between trace metal concentrations in tissues of common eider ducks (cadmium, mercury, and selenium) and selected biomarkers of health (stress response, immune function, and body condition). This study was conducted at an eider nesting colony in the Canadian arctic in 1998 and 1999. Capture-induced stress, measured as the rise in corticosterone concentrations following capture, was positively related (P=0.03) to renal cadmium concentration in 1998 when incubating eiders were sampled, but not in 1999 when prenesting eiders were sampled. Stress response was inversely related (P=0.02) to selenium concentrations in 1999. Following capture and blood sampling in 1999, eiders were placed in a flight pen on-site for eight days in order to examine immune function. Cell-mediated immunity, measured as the skin-swelling response to an intradermal injection of phytohemagglutinin-P, (PHA-P), was positively related (P=0.003) to hepatic selenium. The heterophil:lymphocyte ratio was inversely related (P=0.08) to hepatic selenium. In 1998, selenium was positively related to body mass (P=0.01), abdominal fat mass (P=0.07), kidney mass (P=0.03), and liver mass (P=0.07). In 1999, hepatic mercury was negatively related to abdominal fat mass (P=0.01), spleen mass (P=0.07) and body mass at capture (P=0.09) in prenesting eiders.

Animals↗
PubMed2002

Thyroid hormone suppression and cell-mediated immunomodulation in American kestrels (Falco sparverius) exposed to PCBs.

Exposure to environmental contaminants can induce physiological changes in animals through various mechanisms. One manifestation of subclinical toxicity from polychlorinated biphenyl (PCB) exposure is the disruption of normal immune function described in numerous species, including American kestrels (Falco sparverius). In 1998, 152 mature male and female kestrels were fed either a mixture of Aroclor 1248:1254:1260 (approximately 7 mg/kg kestrel/day) through their food items, or control diets. Offspring produced by 50 breeding pairs (thus, half received in ovo PCB exposure only) were also studied. Total and differential white blood cell counts, the phytohemagglutinin (PHA) skin response, as well as thyroid hormone levels were tested in vivo in nonbreeding adults (1998 only) and nestlings (1998 and 1999). In 1999, nestlings came from three parental groups; adults exposed in 1998, birds produced by PCB-exposed parents, and unexposed birds. In 1998, directly exposed males but not females had increased total white blood cell counts driven by lymphocytosis, plus a decreased heterophil-to-lymphocyte ratio relative to controls. PCB-exposed birds had a significantly greater response to PHA than did controls, with sex as a significant factor and plasma triiodothyonine (T(3)) as a significant covariate. Levels of T(3) were significantly depressed in PCB-exposed birds of both sexes. The 1999 nestlings (F1 generation with respect to PCB exposure) did not show any effect of parental treatment group on the PHA skin response, yet T(3) remained as a significant covariate. Immunological effects are discussed in light of the antibody-mediated immunotoxicity found in the same birds and reported previously.

Administration, Oral↗
PubMed2001

Antibody-mediated immunotoxicity in American kestrels (Falco sparverius) exposed to polychlorinated biphenyls.

Antibody-mediated immune function in adult and recently fledged (30 to 33 d old) American kestrels (Falco sparverius) was examined in birds exposed directly, or only in ovo, to polychlorinated biphenyls (PCBs). In 1998, 9 mature male and 9 female kestrels were fed PCBs, whereas 9 females and 10 males served as controls. A mixture of Aroclors 1248:1254:1260 suspended in safflower oil was injected into the kestrels' food items, while in control diets only the same volume of oil was added. The dosage of PCBs was approximately 7 mg/kg kestrel/d, beginning in March 1998 and continuing for 120 d. In 1998, the antibody-mediated immune response was stimulated by immunization and booster vaccinations of the kestrels using a nonpathogenic antigen, dinitrophenol-keyhole limpet hemocyanin (DNP-KLH). In 1999, offspring from three treatment groups based upon maternal exposure to PCBs were similarly tested for their antibody response. None of these mothers was vaccinated with DNP-KLH the previous year. The maternal groups were: (1) exposed to PCBs in 1998 for 120 d, (2) exposed in ovo in 1998 (i.e., mothers were produced by PCB-exposed parents), or (3) unexposed to PCBs. Serum antibody levels were determined using an enzyme-linked immunosorbent assay (ELISA). In 1998, PCB-exposed adult females had a significantly higher antibody response than did controls, whereas adult males exposed to PCBs had significantly suppressed antibody production. For the nestlings produced in 1999, maternal treatment significantly affected antibody response. Generally, the antibody response in the nestlings was much lower than that seen in adult kestrels. Yet both male and female offspring from mothers that had been fed PCBs the previous year had significantly higher postbooster anti-DNP-KLH titers than control and in ovo-exposed maternal groups, thus mimicking the response seen in the adult females the previous year. These sex-specific responses in PCB-exposed birds provide further evidence of the endocrine-disrupting behavior of PCBs. Both suppression and stimulation of the antibody response are undesirable because this indicates that the immune system is not able to respond normally to challenges by infectious or other disease-causing agents.

Animals↗
PubMed2001

In ovo exposure to polychlorinated biphenyls: reproductive effects on second-generation American kestrels.

The reproductive success of wild birds has been affected by exposure to multiple contaminants. Reproduction of captive American kestrels (Falco sparverius) was suppressed when adult birds were exposed to dietary polychlorinated biphenyls (PCBs). In this study, the reproductive effects of in ovo exposure to PCBs is explored, along with determining effects on reproduction in second-generation birds indirectly exposed to PCBs. Reproductive changes in this subsequent generation are examined separately in male and female birds. Captive American kestrels (F. sparerius) were hatched from clutches with eggs containing environmentally relevant levels of total PCBs (34.0 microg/g whole egg WW versus 0 microg/g controls); parent birds had been fed PCB-spiked (Aroclor 1248:1254:1260) food (7 mg/kg BW day(-1)) for 100 days until their eggs hatched. In 1999, the second-generation PCB birds were paired with unexposed kestrels having reproductive experience. In ovo PCB exposure suppressed egg laying completely in 25% of PCB females and resulted in delays in clutch initiation and smaller clutch sizes for PCB male and female pairs. There was no evidence in this study of in ovo PCB treatment effects on fertility or hatching success. The decline in reproductive success was also reflected in the reduced fledging success and higher incidence of complete brood mortality of PCB nestlings. Differences between in ovo-exposed PCB males and females but not between controls were evident in reproductive success. In ovo PCB exposure appears to have had greater effects on female kestrels until clutch completion, with a greater time lag between pairing and egg laying, reduced numbers of pairs laying eggs, and smaller clutches being laid. In ovo PCB exposure has greater effects later in the breeding season on male kestrels, which had poorer hatching and fledging success relative to the PCB females. Possible behavioral and physiological mechanisms involved in these reproductive changes are discussed.

Animals↗
PubMed2001

Courtship behavior of captive American kestrels (Falco sparverius) exposed to polychlorinated biphenyls.

Polychlorinated biphenyls (PCBs) adversely affect reproduction in birds. Captive adult male and female American kestrels (Falco sparverius) were studied to investigate the potential behavioral and hormonal alterations during the courtship period resulting from clinical exposure to PCBs. American kestrels ingested 7 mg/kg/body weight/bird/day of a 1:1:1 mixture of Aroclors 1248, 1254, and 1260 through their diet of day-old cockerels. The dietary dosage of Aroclors resulted in environmentally relevant total PCB residues in the eggs, averaging 34.1 microg/g wet weight (geometric mean). There was no difference between treatment and control birds in the circulating levels of total androgens (p = 0.44) or in 17 beta-estradiol (p = 0.29), one week following pairing. Male kestrels exposed to dietary PCBs exhibited significantly more sexual behaviors (p = 0.034) and flight behaviors (p = 0.026) than the control males. Sexual behaviors of male kestrels included; nest-box inspections, solicitation of copulation, the offer of food to the female, and giving the female food. The flight behaviors of the male included; flying from one perch to another and aerial display. In addition, the frequency of male sexual behaviors were correlated (r = 0.605, p = 0.001) with total PCB residues in the eggs of their mates. A concurrent study found that these same PCB-exposed kestrels experienced a delay in clutch initiation as well as a greater number of completely infertile clutches.

Animals↗
PubMed2001

Reproduction success of American kestrels exposed to dietary polychlorinated biphenyls.

While reproduction of wild birds is adversely affected by multiple environmental contaminants, we determined that polychlorinated biphenyls (PCBs) alone alter reproduction. Captive American kestrels (Falco sparverius), fed PCB-spiked (Aroclor 1248:1254:1260) food (7 mg/kg body weight/d) prior to and during the first breeding season only (100 d) laid eggs with environmentally relevant levels of total PCBs (34.0 microg/g whole egg wet wt vs 0 microg/g for controls). Reproduction changed during, not after, PCB exposure in this two-year study. The PCB-exposed pairs laid smaller clutches later in the season and laid more totally infertile clutches. Hatching success was reduced in PCB-exposed pairs, and 50% of PCB nestlings died within 3 d of hatching. Nearly 60% of PCB-exposed pairs with hatchlings failed to produce fledglings. Higher levels of total PCB residues and congeners were associated with later clutch initiation and fewer fertile eggs, hatchlings, and fledglings. We suggest that nonpersistent PCB congeners have a greater influence on reproduction than do persistent congeners.

Animals↗
PubMed2001

Bioaccumulation and toxicokinetics of 42 polychlorinated biphenyl congeners in American kestrels (Falco sparverius).

The bioaccumulation and toxicokinetics of 42 polychlorinated biphenyls (PCBs) was determined in male American kestrels exposed to an Aroclor-contaminated diet for 120 d followed by a 348-d depuration period. The birds were housed under ambient outdoor temperatures to permit normal fluctuations in body weight during the study. Whole body PCB clearance, plasma/fat distribution coefficients, and plasma PCB clearance constants were determined for individual PCBs to calibrate a two-compartment rate constant model in order to describe PCB elimination in the birds. Plasma/fat partition coefficients (K(PF)) averaged 0.0060 +/- 0.0001 for all congeners of study, were not dependent on chemical hydrophobicity, and did not change in summer versus winter sacrificed animals. Plasma clearance constants (k'pc) for PCBs were observed to be dependent on both chlorine substitution patterns and congener hydrophobicity. Polychlorinated biphenyl congeners categorized as readily cleared congeners contained vicinal meta-para hydrogen substituents on at least one phenyl ring, while slowly cleared congeners were chlorine hindered at these positions. A general equation was derived to predict plasma clearance constants for all tri- to octachlorobiphenyls based on the presence of an open meta-para site on one of the phenyl rings and from the n-octanol-water partition coefficient of the chemical. The equation was validated by comparing predicted versus measured relative biomagnification factors of PCBs determined in birds at the end of the dosing period. The two-compartment model calibrated for PCB elimination in American kestrels may be used to describe PCB toxicokinetics in wild birds provided that seasonal fluctuations in the fat content of the modeled population is known.

Animals↗
PubMed2000

Morphological and pathological effects of cadmium ingestion on Pekin ducks exposed to saline.

This study examined the effects of simultaneous exposure to saline and cadmium (Cd) on organ mass and histology of a bird with salt glands, the Pekin duck, Anas platyrhynchos. Three mixed-sex groups, each containing 6 birds, ate duck pellets containing 0, 50, or 300 microg Cd/g, respectively, for 4 1/2 mo and drank 300 mM NaCl. Only females on the high-Cd diet lost body mass. Ingestion of Cd reduced heart mass in females. There was increased mass of Harderian and salt glands in both sexes. Mass of kidneys and liver increased only in males, and the gut mass (also length) increased more in males. Cadmium ingestion also induced (1) inflammation of renal interstitium and degenerative tubular changes, (2) marked degenerative changes in testes, (3) increased heart water content, (4) decreased cytoplasmic volume of liver cells, (5) reduced proportion of basophilic granular cells in chromaffin tissue of the adrenal glands, and (6) in the ileum, increased heterophilia in the lamina propria and, only in females, the apoptosis to mitosis ratio in crypt cells of the epithelium. The ducks' outward appearance gave no indication that ingesting large amounts of cadmium for 4 1/2 mo produced deleterious effects, but the physiological consequences were profound. Both sexes had greatly reduced gonadal mass and the males produced no sperm. The higher dietary level greatly hypertrophied the liver, kidneys, and gut only in males. The cadmium-induced changes in organs, particularly in the gonads, kidneys, and adrenal glands, should greatly impair the health and reproductive capacity of these ducks.

Animals↗
PubMed2000

Effect of cadmium on Pekin duck total body water, water flux, renal filtration, and salt gland function.

The following hypotheses were examined using Pekin ducks (Anas platyrhynchos) as a model for marine ducks: cadmium (Cd) intake affects (1) salt gland and/or kidney function of ducks and (2) osmoregulation differently in male and female ducks. Birds were fed 0, 50, or 300 microg Cd/g food. They were gradually acclimated to 450 mM NaCl and then drank 300 mM NaCl for 3 mo while salt gland secretion (SGS), glomerular filtration rate (GFR), total body water (TBW), and water flux (WF) were measured in ducks eating control and high-Cd diets. Cadmium ingestion did not markedly affect body mass, but significantly enlarged the salt glands and kidneys. Enhancement of kidney mass was greater in males. Cadmium ingestion did not affect TBW or WF, but tended to increase interstitial fluid space at the expense of intracellular fluid. Sex did not affect TBW, but males had greater WF. Birds that ate Cd diets, especially the higher Cd diet, exhibited renal tubular damage and lower GFR. Ducks that ate Cd had lower plasma sodium concentration and osmolality and, to activate SGS, required longer infusion of NaCl and larger increments

Animals↗
PubMed2000

Changes in egg composition of American kestrels exposed to dietary polychlorinated biphenyls.

Changes in the quality of eggs of birds exposed to polychlorinated biphenyls (PCBs) have been described, but have never been directly attributed to PCBs. Polychlorinated biphenyl residues in eggs have been associated with reduced reproductive success and embryonic deformities in wild birds. Egg size and composition, specifically the amount of albumen, yolk, and water in an egg, also influence the growth and viability of embryos and hatchlings, and consequently the reproductive success of birds. To deter mine whether PCB exposure of adult birds affected the size and composition of their eggs, 25 pairs of captive American kestrels (Falco sparverius) were fed a mixture of PCB-spiked (1248:1254:1260) food to give an approximate exposure of 7 mg/kg body weight/d, beginning 1 mo prior to pairing, and continuing throughout the courtship, egg-laying, and incubation periods. This dietary level in the adult female kestrels resulted in mean total PCB residues in the eggs of 34.1 microg/g wet weight (geometric mean), which is environmentally relevant. PCB residues in eggs increased with the time of female exposure to the contaminated diet and laying date. Variation in egg size within PCB clutches was significantly greater than within control clutches, although absolute egg mass and volume did not differ markedly by treatment. Only infertile eggs and only one egg per clutch were used for egg composition analysis. Yolks in the PCB-contaminated eggs were heavier, with less wet and dry albumen relative to control eggs. Water content and eggshell thickness were not significantly affected by PCB exposure. These results suggest that eggs from the PCB treatment have relatively more lipid and less protein available for embryonic development. Changes in egg composition were not associated with egg size, lay date, ambient temperature, humidity, or precipitation, which are factors known to affect these variables in bird eggs. The PCB-induced changes in egg composition described here provide insight into possible mechanisms contributing to reduced reproductive performance in wild birds exposed to PCBs.

Administration, Oral↗
PubMed1999

Validation of immunotoxicology techniques in passerine chicks exposed to Oil Sands tailings water.

Avian species, through their trophic relationships, may represent ideal indicators for assessing environmental health. In this study several assays of immune function in young passerines are validated and compared. From 6 to 10 days of age, zebra finch nestlings (Taeniopygia guttata) were given daily oral doses of Oil Sands tailings water (CT), an immunosuppressant dexamethasone, or phosphate-buffered saline. At 9-10 days of age, a phytohemagglutinin (PHA) skin test of immune function was conducted; at 11 days of age, five chicks from each group were euthanized for gross and histopathologic examination of immune system organs. The remaining birds were vaccinated with sheep red blood cells (srbc) to evaluate antibody-mediated immunity. The main findings were that in 10-day-old nestlings, T lymphocytes were sensitive to PHA stimulation, while B lymphocytes were unable to respond to srbc; that hematocrit was approximately 30% lower than in mature birds; that precision of leucocrit determination was heavily technique-dependent; that endogenous steroids increased the total leucocrit, while exogenous steroids increased heterophil and decreased lymphocyte counts, thus increasing H:L; that dexamethasone exposure temporarily reduced growth rate; that CT exposure stimulated germinal cell development in the bursa of Fabricius; and that dexamethazone and CT exposure were associated with decreased splenic white pulp formation.

Animals↗
PubMed1999

Pathological and physiological responses of ring-necked pheasant chicks following dietary exposure to the fungus Metarhizium flavoviride, a biocontrol agent for locusts in Africa.

Metarhizium flavoviride, a fungal pathogen of grasshoppers and locusts, appears to be an effective, non-chemical insecticide (mycoinsecticide) for control of grasshoppers and locusts. This study, conducted during June and July, 1997, examined the pathogenic potential of this entomopathogenic fungus to non-target avian species that encounter infected insect prey items or contaminated food sources. Ring-necked pheasant (Phasianus colchicus) chicks were exposed to one of three diets, (spore-coated feed, infected insects, or untreated feed), either from 4 to 9 days of age, or, from 35 to 40 days of age. Necropsies were conducted on birds 10 days and 46 days old, respectively. Neither consumption of infected insects, nor of spore-coated feed, resulted in pathological changes, or significant changes in weight, growth rate, behavior, or mortality rate. Histological examination of organs indicated either no changes related to treatment, or normal tissue responses to antigenic challenge.

Analysis of Variance↗
PubMed1998

Health of tree swallows (Tachycineta bicolor) nesting in pesticide-sprayed apple orchards in Ontario, Canada. II. Sex and thyroid hormone concentrations and testes development.

To investigate the effects of pesticides on wild birds, sex (17beta-estradiol; testosterone) and thyroid (triiodothyronine (T3) hormone concentrations, body mass, and testes mass were measured and the development of testes was evaluated in wild tree swallows (Tachycineta bicolor) nesting in four sprayed apple orchards and three nonsprayed sites in southern Ontario, Canada, in 1995-1996. In orchards, birds were exposed to asmany as 11 individual spray events and five sprays of mixtures of chemicals. Residues of organochlorine pesticides, PCBs, lead, and arsenic concentrations were low and not variable among sites except p,p'-DDE concentrations, which ranged from 0.36 to 2.23 microg/g wet weight in eggs. These persistent compounds were not correlated with any endocrine response measured in tree swallows. In 16-d-old male tree swallow chicks, body mass and concentrations of 17beta-estradiol (estradiol), testosterone, and T3 in plasma showed no significant differences between sprayed and nonsprayed groups and among sites within those groups. However, T3 concentrations were slightly elevated in the sprayed group compared to the nonsprayed group, and there was a significant and positive correlation between T3 and the number of mixtures of sprays applied during egg incubation through chick rearing. In 16-d-old female chicks, there were no significant differences among spray treatments or sites and no correlations with spray exposure for testosterone, estradiol, or T3 in plasma. Body mass was correlated positively with T3 and negatively with estradiol but showed no differences among spray exposure groups or sites. Histology of testes of 16-d-old male chicks indicated there were no significant differences among sprayed and nonsprayed birds in testes mass, area, or diameter, or the presence of Leydig cells in the interstitium, the distribution of the Sertoli cells, or the occurrence of heterophils in the testicular interstitium. For the percentage of spermatogonia present on the basement membrane, there were significant differences among sites, but these differences were not specifically associated with spray exposure. However, there was a marginally significant trend between increasing occurrence of a disrupted Sertoli cell population on the seminiferous tubular basement membranes as the number of mixtures of pesticides sprayed during chick rearing increased. In adult male and female parent tree swallows, there were no differences in hormone concentrations between birds from sprayed and nonsprayed sites. Nor were there any significant correlations between the concentration of any hormone and collection date, body mass, or any type of spray exposure for adults. The correlations between increasing pesticide exposure and abnormal thyroid hormone and testes development in male chicks indicate that further reductions of pesticide use in orchards may benefit the health of birds that nest there. However, it is unclear which of these pesticides or spray mixtures are responsible for these effects, and this needs to be examined in future studies.

Animals↗
PubMed1996

Immunotoxicity studies in mink (Mustela vison) chronically exposed to dietary bleached kraft pulp mill effluent.

The immunotoxic potential of bleached kraft pulp mill effluent (BKME) to cell-mediated immunity in mink (Mustela vison) was investigated October 1993 through May 1994. For 26 weeks, 20 mink were fed a diet based upon fish caught within 6 km downstream of a bleached kraft mill in Saskatchewan, Canada. Water for this group contained 25% softwood-run BKME. Twenty control mink were fed nutritionally matched diets based upon fish from lakes receiving no municipal or industrial effluent and tap water. Using in vitro and in vivo immunotoxicity assays, the proliferative response of mink peripheral blood mononuclear cells (PBMC) to mitogens was optimal, at 72 hr with 10 micrograms/ml Concanavalin A, 1/80 dilution pokeweed mitogen, and 1/80 dilution phytohemagglutinin. Bacterial cell wall Escherichia coli lipopolysaccharide did not stimulate mitosis of the mink PBMC. No difference (P < 0.05) in PBMC proliferation was seen between the control and BKME-exposed mink with any of the mitogens used. Delayed type hypersensitivity (DTH), a cell mediated response, was assessed in mink vaccinated with live bacille Calmette-Guérin (BCG) and then challenged by intradermal toe web injection with 200 micrograms of sonicated BCG approximately 6 weeks later. The DTH response in the BKME-exposed mink was impaired based upon assessment using skin thickness measurements, histopathological assessment and image analyzer technology. This decreased response is evidence for suboptimal immune function associated with BKME exposure, which could affect the competitive fitness of piscivorous mammals naturally exposed to BKME.

Animal Feed↗
PubMed1996

Assessment of humoral immune response in mink (Mustela vison): antibody production and detection.

A method for investigating the humoral immune response in mink (Mustela vison) was developed between October 1993 and March 1994. Protein A, 1:8000 dilution, had a high affinity for mink immunoglobulin, while anti-ferret (Mustela putorius) antibody, 1:200 dilution, had a weaker affinity. Four adult mink were immunized with a hapten, dinitrophenol (DNP), conjugated to a large carrier protein, keyhole limpet hemocyanin (KLH), and received two boosters at 3-week intervals. This provoked a strong T-lymphocyte dependent humoral immune response. An indirect enzyme linked immunosorbent assay (ELISA) was used to quantify the antibody produced. All mink had undetectable anti-DNP-KLH antibody in the pre-immune sera, with antibody levels increasing post-immunization, and peaking after the first or second booster.

Adjuvants, Immunologic↗