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Biomedical subjects

D B Hunter

Publications and source records attributed to D B Hunter.

At least 19 recordsLinked to original sources
PubMed2006

Avian hepatitis E virus in an outbreak of hepatitis--splenomegaly syndrome and fatty liver haemorrhage syndrome in two flaxseed-fed layer flocks in Ontario.

Two commercial layer chicken flocks that were fed a flax-based diet beginning at 28 weeks of age for the production of omega-3 fatty-acid-enriched eggs experienced increased mortality when the birds reached 37 weeks. The average weekly mortality was 0.34% over a 20-week period, with peak mortality of 0.9% for 1 week. Reduced feed consumption, reduced body weight gain and poor peak production were noticed prior to the onset of increased mortality. A total of 245 birds were necropsied and 78% of these had lesions in the liver and spleen, with 44% of those necropsied having changes consistent with hepatitis-splenomegaly syndrome, with lesions ranging from acute periportal lymphoplasmacytic hepatitis to chronic severe cholangiohepatitis with haemorrhage, vasculitis and amyloidosis. A total of 11% of the birds had lesions typical of fatty liver haemorrhagic syndrome, and 22% had lesions found in both hepatitis-splenomegaly syndrome and fatty liver haemorrhagic syndrome. No significant bacteria or viruses were recovered from samples of the liver/bile or spleen but 11 of 21 bile samples contained avian hepatitis E virus RNA detectable with a reverse transcriptase-polymerase chain reaction assay. Comparative sequence analysis found identities of 82 to 92% and 78 to 80% between the helicase and capsid protein genes, respectively, of the virus detected in this outbreak and those of other avian hepatitis E virus isolates, suggesting extensive genetic heterogeneity in avian hepatitis E viruses in Ontario flocks.

Animal Feed↗
PubMed2004

Mechanisms of strontium and uranium removal from high-level radioactive waste simulant solutions by the sorbent monosodium titanate.

High-level waste (HLW) is a waste associated with the dissolution of spent nuclear fuel for the recovery of weapons-grade material. It is the priority problem for the U.S. Department of Energy's Environmental Management Program. Current HLW treatment processes at the Savannah River Site (Aiken, SC) include the use of monosodium titanate (MST, with a similar stoichiometry to NaTi2O5 x xH2O) to concentrate strontium (Sr) and actinides. The high affinity of MST for Sr and actinides in HLW solutions rich in Na+ is poorly understood. Mechanistic information about the nature of radionuclide uptake will provide insight about MST treatment reliability. Our study characterized the morphology of MST and the chemistry of sorbed Sr2+ and uranium [U(VI)] as uranyl ion, UO2(2+), on MST, which were added (individually) from stock solutions of Sr and 238U(VI) with spectroscopic and transmission electron microscopic techniques. The local structure of sorbed U varied with loading, but the local structure of Sr did not vary with loading. Sorbed Sr exhibited specific adsorption as partially hydrated species whereas sorbed U exhibited specific adsorption as monomeric and dimeric U(VI)-carbonate complexes. Sorption proved site specific. These differences in site specificity and sorption mechanism may account forthe difficulties associated with predicting Sr and U loading and removal kinetics using MST.

Adsorption↗
PubMed2004

Retrospective evidence that the MHC (B haplotype) of chickens influences genetic resistance to attenuated infectious bronchitis vaccine strains in chickens.

Infectious bronchitis is a respiratory disease of chickens that is caused by the coronavirus infectious bronchitis virus (IBV). Virtually all broiler and layer breeder flocks are routinely vaccinated against IBV. Two hatches of 1-day-old chicks from four lines were mistakenly vaccinated for infectious bronchitis using a moderately attenuated vaccine designed for chicks of an older age. The vaccination resulted in high mortality, and chicks from three of four lines died with signs typical of infectious bronchitis. The mortality that occurred using this less-attenuated vaccine was significantly influenced by the genetic line, and the MHC (B) haplotype in chickens of three B congenic lines. B congenic chickens possessing the B*15 haplotype were resistant in contrast to chickens possessing the B*13 or B*21 haplotypes. Chicks from two further hatches of the four lines were vaccinated appropriately with a more attenuated IBV vaccine, and only limited chick mortality was seen. These retrospective data from two repeated hatches confirm earlier data indicating chicken genes influence resistance to IBV, and indicate for the first time that genes tightly linked to the B haplotype are relevant in resistance to IBV. Due to extenuating circumstances it was not possible to verify results with chicks from F2 matings. Factors that may enhance definition of the role of the B haplotype in immune response to IBV, and the desirability for further analysis of a B haplotype-linked influence on immunity to IBV are discussed.

Animals↗
PubMed2001

Comparison of two micro-analytical methods for detecting the spatial distribution of sorbed Pu on geologic materials.

Subsurface transport of groundwater contaminants is greatly influenced by chemical speciation, precipitation and sorption processes at the mineral-water interface. The retardation of contaminants is often greatest at boundaries between minerals and in fractures and pore spaces. The investigation of the spatial distribution of sorbed contaminants along these boundaries requires micro-analytical techniques. The sorption of dissolved Pu(V) on a natural zeolitic tuff from Yucca Mountain (NV, USA) was examined using microautoradiography (MAR), X-ray diffraction (XRD), electron microprobe (EM) techniques, and synchrotron-based micro-X-ray fluorescence (micro-SXRF). The tuff contained a heterogeneous distribution of zeolites and trace quantities of smectites, Fe oxides (hematite), and Mn oxides (rancieite), which are present as fracture fill and pore space materials. Micro-SXRF studies showed that Pu is mostly associated with bodies of smectite plus Mn oxides, which were typically elevated in Ce, Ga, Nb, Pb, Y, Ca, Ti, and Zn. Sorbed Pu was not associated with Fe-rich bodies, which were enriched in Cl and Rb. Results of the MAR studies were complementary to that of the micro-SXRF studies in that Pu was associated with similar elements in the tuff. Indirect detection of Pu by EM or micro-SXRF (by analyzing Ag developed on the MAR photoemulsion) was a more sensitive method for detecting lower levels of sorbed Pu than the direct detection of sorbed Pu via micro-SXRF in the absence of the photoemulsion.

Adsorption↗
PubMed2001

Avian air sac and plasma proteins that bind surface polysaccharides of Escherichia coli O2.

Some serovars of Escherichia coli, mainly O2 and O78, are responsible for air sac and systemic infections in farm-raised turkeys (Meleagris gallopavo) and chickens (Gallus gallus). We looked in air sac surface fluid from young turkeys to identify proteins that bind surface polysaccharides of pathogenic respiratory E. coli O2. Turkey air sac surface fluid was subjected to affinity chromatography on Toyopearl AF-Epoxy-650M, coupled with either lipopolysaccharide (LPS) or lipid-free polysaccharide (LFP) purified from an avian pathogenic E. coli O2 isolate. A multimeric protein termed lipid-free polysaccharide binding protein-40 (LFPBP-40) composed of six covalently associated subunits of approximately 40 kDa was isolated by elution from LFP by EDTA or L-rhamnose. An analogous protein in air sac fluid proteins bound to intact E. coli O2 and eluted with L-rhamnose or N-acetylglucosamine (GlcNAc). The N-terminal amino acid sequence of LFPBP-40 DINGGGATLPQHLYLTPDV was related to the N-terminus of fragment 3 of a partially characterized human protein possessing T cell stimulation activity in synovial membrane of rheumatoid arthritis patients. However, endogenous amino acid sequences were unrelated to other known proteins. LFPBP-40 was immunoreactively distinct from pulmonary collectins and ficolins. These studies demonstrate a novel avian respiratory soluble lectin that can bind surface polysaccharides of pathogenic E. coli responsible for respiratory disease.

Air Sacs↗
PubMed2000

Direct measurement of aluminum uptake and distribution in single cells of Chara corallina.

Quantitative information on the uptake and distribution of Al at the cellular level is required to understand mechanisms of Al toxicity, but direct measurement of uptake across the plasma membrane has remained elusive. We measured rates of Al transport across membranes in single cells of Chara corallina using the rare (26)Al isotope, an emerging technology (accelerator mass spectrometry), and a surgical technique for isolating subcellular compartments. Accumulation of Al in the cell wall dominated total uptake (71-318 microgram m(-2) min(-1)), although transport across the plasma membrane was detectable (71-540 ng m(-2) min(-1)) within 30 min of exposure. Transport across the tonoplast was initially negligible, but accelerated to rates approximating uptake across the plasma membrane. The avacuolate protoplasm showed signs of saturation after 60 min, but continued movement across the plasma membrane was supported by sequestration in the vacuole. Saturation of all compartments was observed after 12 to 24 h. Accumulation of Al in the cell wall reflected variation in [Al(3+)] induced by changes in Al supply or complexing ligands, but was unaffected by pH. In contrast, transport across the plasma membrane peaked at pH 4.3 and increased when [Al(3+)] was reduced by complexing ligands. Cold temperature (4 degrees C) reduced accumulation in the cell wall and protoplasm, whereas 2,4-dinitrophenol and m-chlorocarbonylcyanidephenyl hydrazone increased membrane transport by 12- to 13-fold. Our data suggest that the cell wall is the major site of Al accumulation. Nonetheless, membrane transport occurs within minutes of exposure and is supported by subsequent sequestration in the vacuole. The rapid delivery of Al to the protoplasm suggests that intracellular lesions may be possible.

2,4-Dinitrophenol↗
PubMed2000

Hygiene at winter bird feeders in a southwestern Ontario city.

To further understand the source of the epidemic of salmonellosis in some species of birds using bird feeders in southern Ontario in the winter of 1997-1998, 124 bird feeder stations were examined for their state of hygiene and for Salmonella on 5 occasions during the winter of 1999 in a city of 100,000 people in southwestern Ontario. No Salmonella were isolated from feed contaminated with feces recovered from the feeders. Squirrel-proof feeders were significantly less contaminated with feces than were other feeder types (hopper, platform, silo), which did not differ significantly in their hygiene scores. Contamination of squirrel-proof feeders increased significantly through the course of the study, but other feeder types showed no significant change. Hygiene was poorer if feeders were maintained equally by both male and female household members, particularly as they grew older, but no age or gender effect was observed if only one person was largely responsible for maintaining the feeders. We concluded that winter bird feeder stations in a southern Ontario city were not contaminated with Salmonella but that bird feeder stations could be designed better to reduce fecal contamination of feed.

Animals↗
PubMed1999

Observations on pigeon circovirus infection in Ontario.

Subclinical pigeon circovirus infection was diagnosed in 1-day-old to 6-week-old birds from a loft with no history of clinical disease. Pigeons from other lofts presented with various illnesses and were found at necropsy to be concurrently infected with pigeon circovirus.

Animals↗
PubMed1998

X-ray imaging and microspectroscopy of plants and fungi.

X-ray fluorescence microscopy and microspectroscopy with micrometre spatial resolution and unprecedented capabilities for the study of biological and environmental samples are reported. These new capabilities are a result of both the combination of high-brilliance synchrotron radiation and high-performance X-ray microfocusing optics and the intrinsic advantages of X-rays for elemental mapping and chemical-state imaging. In this paper, these capabilities are illustrated by experimental results on hard X-ray phase-contrast imaging, X-ray fluorescence (XRF) imaging and microspectroscopy of mycorrhizal plant roots and fungi in their natural hydrated state. The XRF microprobe is demonstrated by the simultaneous mapping of the elemental distributions of P, S, K, Ca, Mn, Fe, Ni, Cu and Zn with a spatial resolution of approximately 1 x 3 micron and with an elemental sensitivity of approximately 500 p.p.b. Microspectroscopy with the same spatial resolution is demonstrated by recording near-edge X-ray absorption (XANES) spectra of Mn at a concentration of approximately 3 p.p.m.

Journal Article↗
PubMed1997

Mortality in fledgling great horned owls from black fly hematophaga and leucocytozoonosis.

Black fly feeding alone and in concert with Leucocytozoon spp. infection caused mortality in fledgling great horned owls (Bubo virginianus) in the Yukon, Canada 1990 to 1991. These mortalities occurred during a year of food shortage corresponding with a decline in the population of snowshoe hare (Lepus americanus), the main prey for great horned owls. We hypothesize an interaction between food availability and the consequences of host-parasite interactions.

Anemia↗
PubMed1997

Cutaneous mycoses in chameleons caused by the Chrysosporium anamorph of Nannizziopsis vriesii (Apinis) Currah.

A dermatophyte-like fungus was isolated from skin biopsies of three different species of captive chameleon in which fungal elements had been observed by histologic examination. An adult Parson's chameleon (Chamaeleo parsonii) presented with vesicles that became crusty brown lesions on the limbs and body. Skin biopsies revealed fungal hyphae in the affected epidermis and underlying dermis. The lesions regressed fully after oral administration of itraconazole. An adult jewel chameleon (Chamaeleo lateralis) from the same private collection presented with localized black skin lesions and died while being treated with itraconazole. A pulmonary granuloma was also present in this chameleon at autopsy. Cultures obtained from skin and lung lesions yielded the same fungus. A third isolate was obtained from a skin biopsy of a Jackson's chameleon (Chamaeleo jacksoni) with deep ulcerative cutaneous lesions located at the base of the tail. The fungus, in all three cases, has been identified as the Chrysosporium anamorph of Nannizziopsis vriesii, a poorly known ascomycetous species recorded previously from the skin of a lizard and from soil, on the basis of its keratinolytic activity, resistance to cycloheximide, strongly restricted growth at 37 degrees C, formation of clavate or pyriform single-celled or two-celled aleurioconidia, and alternate and fission arthroconidia.

Administration, Oral↗
PubMed1993

Nursing disease in mink: clinical and postmortem findings.

One hundred fifty lactating mink on one ranch in southern Ontario were monitored over the lactation period in 1989 for evidence of clinical disease, and serial blood samples were collected for biochemical analysis. Antemortem blood samples were collected and necropsies performed on the 17 females that developed nursing disease and on 17 controls matched to the same stage of lactation and on ten nonlactating controls. Twenty-two additional nursing disease cases were selected from seven ranches in the following year and processed similarly. The clinical signs typically observed in affected females were sudden onset lethargy and anorexia followed by dehydration, ataxia, and a reluctance to move. The major clinical-pathologic findings were a marked increase in serum osmolality and total protein, urea nitrogen, creatinine, phosphorus, glucose, and potassium concentrations and a decrease in sodium and chloride concentration. In addition, the animals were acidotic, there was a reduction in the urine specific gravity, and the hemogram was consistent with a stress response. Emaciation and dehydration were the only pathologic changes consistently present in cases of nursing disease and not in controls. In almost all cases, bacteria were not cultured from the liver, spleen, and mammary gland, but Campylobacter jejuni was cultured from the intestinal contents of 15/17 affected mink and 2/5 controls. Aleutian disease virus antibody was not present in any of the affected mink. Lipid vacuoles in hepatocytes and renal tubular epithelium, hypertrophy of cells in the adrenal cortex, and pulmonary congestion and atelectasis were present in both diseased females and controls, as were various sporadic inflammatory lesions. Nursing disease may result from energy depletion due to lactation. All lactating females are affected by this process; clinical disease reflects the terminal physiologic decompensation of the most susceptible individuals.

Adrenal Cortex↗
PubMed1988

A source of cutaneous maternal semiochemicals in the mink?

Unique hypertrophic apocrine sweat glands are described in the neck, perineal and inguinal skin of mink kits. These glands enlarge after birth, only to regress rapidly and become vestigal by weaning. No similar phenomenon has been recognized before in mammals. Behavioral studies indicate a possible role for the glandular secretion in maternal recognition of the young.

Animals↗
PubMed1987

Use of equine chorionic gonadotrophin in female mink.

This study was comprised of three trials to determine the effects of equine chrionic gonadotrophin (eCG) on induction of sexual receptivity in female mink that had failed to mate by late in the breeding season. In the first trial one ovary was removed from unmated mink, which were then injected with 100 IU eCG. This treatment induced ovarian activity, including ovulation in the remaining ovary. In the second experiment, mink that had not been observed to mate were treated with 100 IU eCG or saline, resulting in mating of 10 11 of the eCG-treated animals, compared to 5 11 controls. Litter sizes were larger in mink in the control group, suggesting that eCG interfered with some phase of the reproductive process. In the third trial, 226 mink that had failed to mate until late in the breeding season were treated with 100 IU eCG. Of the 191 that subsequently mated, 99 produced litters, but litter sizes were reduced slightly from those observed in the remainder of the herd that bred without hormone treatment prior to March 20. Neonatal kit loss per female whelping was greater in mink treated with eCG. It is concluded that eCG treatment will induce mating in mink that refuse to mate, but this treatment results in reduced whelping success and greater neonatal kit loss. Its utility may be restricted to salvage situations where large numbers of mink fail to mate.

Journal Article↗