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Biomedical subjects

B M Aldridge

Publications and source records attributed to B M Aldridge.

At least 19 recordsLinked to original sources
PubMed2006

MHC gene configuration variation in geographically disparate populations of California sea lions (Zalophus californianus).

Major histocompatibility complex (MHC) class II DRB genotypes were examined in two geographically isolated populations of California sea lions (Zalophus californianus) (Gulf of California and California coastal Pacific Ocean). Genomic DNA from 227 California sea lions was examined using eight sequence-specific primer (SSP) pairs flanking the putative peptide-binding site. A total of 40 different Zaca-DRB genotype configurations were identified among the 227 individuals. Using SSP-PCR, significant differences were found between coastal California and Gulf of California Zalophus populations in numbers of DRB sequences per individual and configuration of sequences within individuals. Additionally, unique local patterns of MHC diversity were identified among the Midriff Island animals. These population differences are consistent with either ecologically distinct patterns of selection pressures and/or geographical isolation. The consequences of these partitioned MHC configurations at the population level are as yet unknown; however, the worldwide increase in emerging marine diseases lends urgency to their examination.

California↗
PubMed2006

Expressed MHC class II genes in sea otters (Enhydra lutris) from geographically disparate populations.

The major histocompatibility complex (MHC) is central to maintaining the immunologic vigor of individuals and populations. Classical MHC class II genes were targeted for partial sequencing in sea otters (Enhydra lutris) from populations in California, Washington, and Alaska. Sequences derived from sea otter peripheral blood leukocyte mRNAs were similar to those classified as DQA, DQB, DRA, and DRB in other species. Comparisons of the derived amino acid compositions supported the classification of these as functional molecules from at least one DQA, DQB, and DRA locus and at least two DRB loci. While limited in scope, phylogenetic analysis of the DRB peptide-binding region suggested the possible existence of distinct clades demarcated by geographic region. These preliminary findings support the need for additional MHC gene sequencing and expansion to a comprehensive study targeting additional otters.

Alaska↗
PubMed2006

Fetus in fetu in a harbor seal (Phoca vitulina richardi): histopathologic, genetic, and toxicologic analysis.

A young harbor seal (Phoca vitulina richardi), stranded on the coast of California, was found to have a 20-cm-diameter cranial cervical mass. Surgical excision revealed the subcutaneous mass to be covered in haired skin with multiple glabrous areas and structures resembling a jaw with tooth buds, eyelids, and a tail. The mass deformed the host pup's skull. Histologic examination revealed a complete vertebra in the tail, teeth in the jaw, and areas resembling tongue and larynx. Class 1 MHC sequences amplified by polymerase chain reaction from the mass and the host twin were identical. The mass was diagnosed as a fetus in fetu, a rare congenital anomaly in which 1 conjoined twin is completely enclosed in the body of the other twin. The host pup died, and no additional defects were found; however, blubber levels of persistent organic pollutants were high. The cause of the congenital anomaly in this pup is uncertain.

Animals↗
PubMed2005

Comparison of Helicobacter spp. in Cheetahs (Acinonyx jubatus) with and without gastritis.

Chronic gastritis causes significant morbidity and mortality in captive cheetahs but is rare in wild cheetahs despite colonization by abundant spiral bacteria. This research aimed to identify the Helicobacter species that were associated with gastritis in captive cheetahs but are apparently commensal in wild cheetahs. Helicobacter species were characterized by PCR amplification and sequencing of the 16S rRNA, urease, and cagA genes and by transmission electron microscopy of frozen or formalin-fixed paraffin-embedded gastric samples from 33 cheetahs infected with Helicobacter organisms (10 wild without gastritis and 23 captive with gastritis). Samples were screened for mixed infections by denaturant gel gradient electrophoresis of the 16S rRNA gene and by transmission electron microscopy. There was no association between Helicobacter infection and the presence or severity of gastritis. Eight cheetahs had 16S rRNA sequences that were most similar (98 to 99%) to H. pylori. Twenty-five cheetahs had sequences that were most similar (97 to 99%) to "H. heilmannii" or H. felis. No cheetahs had mixed infections. The ultrastructural morphology of all bacteria was most consistent with "H. heilmannii," even when 16S rRNA sequences were H. pylori-like. The urease gene from H. pylori-like bacteria could not be amplified with primers for either "H. heilmannii" or H. pylori urease, suggesting that this bacteria is neither H. pylori nor "H. heilmannii." The cagA gene was not identified in any case. These findings question a direct role for Helicobacter infection in the pathogenesis of gastritis and support the premise that host factors account for the differences in disease between captive and wild cheetah populations.

Acinonyx↗
PubMed2004

Immunological response to long-term transport stress in mature horses and effects of adaptogenic dietary supplementation as an immunomodulator.

REASONS FOR PERFORMING STUDY: Little information exists on the immunological effects of transport or the use of supplements to minimise transport stress. OBJECTIVES: To establish baseline ranges and evaluate immunophenotypic and functional changes associated with transport and a nutritional 'adaptogen' supplement. METHODS: Horses received either supplement (n = 10) or placebos (n = 9) during the 30 day study. After 28 days in stalls, 12 horses (6 supplement; 6 placebo) were transported for 24 h, then unloaded and recovered. Venous blood samples were collected on Days 1, 14 and 28 to establish baselines, and on Days 28, 29 and 30 to examine changes during transport and recovery. RESULTS: Transport prompted elevations (P<0.05) in cortisol concentration, neutrophil count and white blood cell counts, while lymphocyte subpopulation counts (CD3+, CD4+, CD8+, CD21+) decreased (P<0.05). Normal phenotypic lymphocyte profiles returned within 24 h of recovery. Supplement effects on immunophenotype (CD21+ and CD8+) were observed in stabled horses (P<0.05), but not in transported horses. CONCLUSIONS: These results provide insights into the immunological mechanisms associated with long-term transport. POTENTIAL RELEVANCE: The existence of a small window of immunological uncertainty follows long-term transportation, enhancing the potential risk of infectious disease in susceptible individuals.

Animals↗
PubMed2003

Regional antibody and cellular immune responses to equine influenza virus infection, and particle mediated DNA vaccination.

We have previously demonstrated that hemagglutinin (HA) gene vaccination and influenza virus infection generate protective antibody responses in equids. However, these antibody responses differ substantially in that particle mediated DNA vaccination does not induce an immunoglobulin A (IgA) response. A study was performed to investigate the regional immunoregulatory mechanisms associated with these different immune responses. Ponies were either vaccinated with equine HA DNA vaccines at skin and mucosal sites, infected with influenza virus or left untreated and influenza-specific antibody responses and protection from challenge infection was studied. In a subset of ponies, lymphocytes from peripheral blood (PBLs), nasopharyngeal mucosal tissue, or lymph nodes (LNLs) were collected for measurement of influenza virus-specific lymphoproliferative responses, local antibody production and IL-2, IL-4 and IFN-gamma mRNA production by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). DNA vaccination and influenza virus infection induced humoral immunoglobulin Ga (IgGa) and immunoglobulin Gb (IgGb) production and lymphoproliferative responses that were positively correlated with IFN-gamma mRNA production. However, there were marked differences in immune response in that only influenza infection induced an IgA response, and the regional distribution of lymphoproliferation, IFN-gamma and antibody responses. Responses to DNA vaccination occurred in PBLs and in lymph nodes draining DNA vaccination sites, while influenza virus infection induced responses in PBLs and hilar LNLs. In summary, common features of immune responses to either influenza virus infection or DNA vaccination were virus-specific IgGa, IgGb and IFN-gamma responses, which are associated with protection from infection, even when the regional distribution of these immune responses varied depending on the site of immune encounter.

Animals↗
PubMed2001

Humoral immune responses to phocine herpesvirus-1 in Pacific harbor seals (Phoca vitulina richardsii) during an outbreak of clinical disease.

Infection with phocine herpesvirus type-1 (PHV-1) has been associated with morbidity and high mortality in neonatal harbor seals (Phoca vitulina). A PHV-1 specific indirect enzyme linked immunosorbent assay (ELISA) was developed to sequentially measure the serological status of 106 harbor seal neonates admitted to a Pacific coast rehabilitation center (total number of sera tested was 371). Early in the season (February-April), the majority of pups had low serum levels of PHV-1 specific antibody. A dramatic increase in PHV-1 specific antibody, involving the majority of hospitalized pups, was observed during a 4-week period in May. This coincided with a high incidence of PHV-1 associated adrenal lesions and mortality. Although there was overall agreement between the timing of seroconversion to PHV-1 and histological evidence of PHV-1 infection, 82.4% of individual pups with adrenalitis had no evidence of a humoral response to PHV-1 at the time of their death. This suggests either a rapid disease course, or an inability to develop a humoral response in some neonatal seals.

Animals↗
PubMed1998

Effect of colostral ingestion on immunoglobulin-positive cells in calves.

The importance of colostrum for passive transfer of maternal immunoglobulin in calves is well established. Colostrum is thought to have additional generalized and antigen-specific immunomodulatory activities, of which the downregulation of endogenous immunoglobulin production is best documented. The objective of this study was to examine whether ingestion of colostrum altered the B cell subpopulations in the lymph nodes of newborn calves. Calves were fed one gallon of either fresh colostrum (Group A, n = 5), milk replacer (Group B, n = 5) or treated (frozen or irradiated) colostrum (Group D, n = 4) and were euthanized at 36-48 h. An additional 5 calves (Group C, 3 newborn and 2 mid-term fetuses) did not receive any feedings; the neonatal calves were euthanized immediately following birth. Mesenteric and regional lymph nodes from all calves were analyzed by immunocytochemistry using monoclonal antibodies recognizing bovine IgA, IgG1, IgG2, and IgM. Calves from Groups B and C (colostrum deprived, neonates, and fetuses) showed a consistent pattern of IgG1 and IgG2 positive cells scattered individually and in clusters throughout lymph node cortex, paracortex, and cortico-medullary junction. In sharp contrast, no IgG1 and IgG2 positive cells were present in the lymphoid tissues of colostrum fed calves (Groups A or D). Numbers of IgM and IgA positive cells were similarly distributed in all calf groups. These findings demonstrate that colostrum feeding reduces the number of immunoglobulin positive cells in the lymphoid tissues of newborn calves in an isotype-specific manner. This results in the elimination of IgG1 and IgG2 positive cells that are present in both fetuses and newborn calves. This effect is not eliminated by freezing or irradiation, indicating that a non-cellular, cold-stable colostral factor is responsible. Systemically distributed colostral proteins such as immunoglobulin or cytokines are the most likely mediators. The significance of this phenomenon in terms of colostral modulation of calf endogenous antibody production is discussed.

Animals↗
PubMed1998

Denaturing gradient gel electrophoresis: a rapid method for differentiating BoLA-DRB3 alleles.

The products of the BoLA-DRB3 locus are important molecules in the bovine immune response. Several techniques have been used to study and define this locus but they are generally time consuming and limited in their ability to detect novel alleles. In this study we used denaturing gradient gel electrophoresis (DGGE), and direct sequencing, for BoLA-DRB3-typing. First, modified locus-specific primers were used in polymerase chain reaction (PCR) to amplify a 240 bp fragment of exon 2 of BoLA-DRB3 from the genomic DNA of 22 cattle and one pair of twin calves. The reverse primer included a GC-rich clamp to improve the physical separation of the BoLA-DRB3 alleles by DGGE. The denaturing gradient needed to produce separation of alleles was determined using perpendicular DGGE, and this gradient was then applied to parallel denaturing gels. The optimal time for producing allele separation was determined using a time-series analysis. The bands representing individual BoLA-DRB3 alleles were excised from the gels, reamplified, and the nucleotide sequence determined using fluorescent-based automated cycle sequencing. The nucleotide sequences of the separated bands were then compared to published BoLA-DRB3 alleles. A gradient of 10-15% acrylamide combined with a 15-50% ureaformamide gradient was successfully used to separate BoLA-DRB3 alleles in all individuals examined. Nucleotide sequencing showed that the 24 animals possessed 13 BoLA-DRB3 alleles, all of which have been previously described. The BoLA-DRB3 genotypes included 20 heterozygotes and two homozygotes. Three BoLA-DRB3 alleles were seen in each of the twin calves, possibly due to leukochimerism. The technique is reliable and rapid, and avoids cloning alleles prior to nucleotide sequencing and therefore offers distinct advantages over previous techniques for BoLA-DRB3-typing.

Alleles↗
PubMed1993

Neonatal septicemia in calves: 25 cases (1985-1990).

Historical, physical, and clinicopathologic findings in 25 septicemic calves were examined to further characterize the clinical features of naturally induced bovine neonatal septicemia. Owners often reported single organ disease, but physical examination revealed multiple organ disease in more than half the calves. A third of the calves were admitted as representative of a herd problem. Laboratory findings were variable, but commonly included changes in the differential WBC count and plasma fibrinogen concentration. Low serum immunoglobulin concentrations were found in approximately half the calves. Escherichia coli was the most frequently isolated organism, but gram-positive infections were found in 10%, and polymicrobial infections in 28%, of the calves. Previous antimicrobial administration did not appear to affect culture yield. At necropsy, lesions were seen in multiple organs in most calves. The respiratory and gastrointestinal systems were most commonly affected. Few of the calves had umbilical infections. The survival rate was poor (< 12%).

Animals↗
PubMed1993

Physiologic differences between twin and single born beef calves in the first two days of life.

Behavioral observations and hematological, serum biochemical and blood gas measurements were made on 8 naturally occurring twin calves during the first 48 hours of life. These values were compared to similar measurements collected from 30 single born calves, born under the same calving conditions. All calves survived to at least 3 weeks of age without physically detectable disease. Although the gestational age of the twins and singles were not different, the twins had a lower mean birth weight. Calving difficulty score, time interval to standing and time interval to nursing were not different between the 2 groups. Twin calves had significantly lower rectal temperatures, arterial oxygen tensions and blood glucose concentrations than the single calves through the first 12 hours of life. Hct, Hgb concentration, and RBC were lower in twin calves throughout the 48 hour period. The N:L ratio was lower in the twins at birth. Mean serum IgG1 concentrations were lower in twins only at 24 hours whereas IgM concentrations were lower at both 24 and 48 hours in twins. Serum chemistry value differences between twin and single calves were most numerous at 24 hours of age when serum proteins, urea nitrogen, total bilirubin, sodium, chloride, and total calcium concentrations were higher in the twins and serum phosphorus concentration was lower in the twins.

Animals↗
PubMed1992

Hematologic values in newborn beef calves.

Hematologic values were determined in 35 beef calves at birth, at 24 and 48 hours, and in 22 of these calves at 3 weeks after birth. Thirty calves did not have clinical signs of disease throughout the 3-week period. Variables that changed significantly over time in these healthy calves included hematocrit, RBC count, hemoglobin concentration, mean cell volume, mean cell hemoglobin concentration, WBC count, neutrophil-to-lymphocyte ratio, and plasma total protein and serum immunoglobulin concentrations. Of the 35 calves, 5 had clinical signs of disease at 3 weeks. Comparison of hematologic values from these calves with values for healthy calves revealed significant differences at each sample collection time, although disease was not evident at the 3 early sample times. The band neutrophil count and the neutrophil-to-lymphocyte ratio differed between the 2 groups at birth. At 24 hours, the monocyte count was higher in the 5 ill calves. At 48 hours, total leukocyte, mature neutrophil, and monocyte counts, and neutrophil-to-lymphocyte ratio also were higher in the 5 calves. At 3 weeks when clinical signs of disease were detectable in the 5 calves, the total leukocyte, band neutrophil, and mature neutrophil counts, neutrophil-to-lymphocyte ratio, and plasma total protein and fibrinogen concentrations were higher.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Chronic partial obstructive urolithiasis causing hydronephrosis and chronic renal failure in a steer.

A 13-month-old Angus steer was examined with a 6-week history of lethargy, malaise and dribbling urine. Laboratory exam revealed crystalluria and poor renal function. Ultrasound revealed hydronephrosis and hydroureter. Euthanasia was chosen because of a poor prognosis for economic recovery. Necropsy demonstrated numerous calculi causing partial urethral obstruction approximately 25 cm from the end of the penis. Secondary renal changes were confirmed. Urolithiasis occurs commonly in ruminants. Secondary obstruction is usually complete with severe consequences. This is the first report of chronic partial obstructive urolithiasis resulting in endstage renal disease.

Animals↗
PubMed1989

Bovine spongiform encephalopathy in a cow in the United Kingdom.

Bovine spongiform encephalopathy (BSE) was diagnosed in a cow with a history of behavioral change, apprehension, hyperesthesia to auditory and tactile stimuli, wide-based stance, and marked hind limb hypermetria. Myoclonus involving individual muscles was observed in the shoulder region, ventral cervical region, and upper portion of the hind limb. Clonus was observed in the forelimbs. Clinicopathologic findings were normal, except for high serum globulin concentration, which was attributable mainly to an increase in the gamma-globulin fraction. Results of electroencephalography revealed almost continuous high-amplitude complexes in the occipital leads, interspersed with short runs of normal activity. There were generalized discharges, but these were not periodic. Current theory implicates the scrapie agent (prion) as the causal agent for BSE. The presence of scrapie in, and the possible entry of prion into bovine feedstuffs could result in the emergence of BSE in the United States.

Animals↗
PubMedDate not supplied

Occurrence of 14 cases of bovine spongiform encephalopathy in a closed dairy herd.

Fourteen cases of bovine spongiform encephalopathy (BSE) were diagnosed on the basis of clinical examination in a closed herd of British Friesian cows during a 9-month period from October 1987 until June 1988. The diagnosis was confirmed on histopathological examination of brain tissue from five of the six samples submitted. The main presenting clinical signs were of altered behaviour: apprehension, anxiety and hyperaesthesia. One cow was euthanized after a short period of recumbency; the remaining 13 cows were slaughtered on humane or economic grounds. No protein of animal origin had been fed to either heifers or cows in this herd during the past 5 years and there had been no direct contact with sheep. The epidemiology of BSE in this report suggests that, if the postulate of Morgan (1988) is correct, infection is ingested within the first 6 months of life and there then follows a 4-5-year period before clinical signs appear.

Animals↗