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Biomedical subjects

J R Middleton

Publications and source records attributed to J R Middleton.

At least 19 recordsLinked to original sources
PubMed2004

Antigenic evaluation of a recombinant baculovirus-expressed Sarcocystis neurona SAG1 antigen.

Sarcocystis neurona is the primary parasite associated with equine protozoal myeloencephalitis (EPM). This is a commonly diagnosed neurological disorder in the Americas that infects the central nervous system of horses. Current serologic assays utilize culture-derived parasites as antigen. This method requires large numbers of parasites to be grown in culture, which is labor intensive and time consuming. Also, a culture-derived whole-parasite preparation contains conserved antigens that could cross-react with antibodies against other Sarcocystis species and members of Sarcocystidae such as Neospora spp., Hammondia spp., and Toxoplasma gondii. Therefore, there is a need to develop an improved method for the detection of S. neurona-specific antibodies. The sera of infected horses react strongly to surface antigen 1 (SnSAG1), an approximately 29-kDa protein, in immunoblot analysis, suggesting that it is an immunodominant antigen. The SnSAG1 gene of S. neurona was cloned, and recombinant S. neurona SAG1 protein (rSnSAG1-Bac) was expressed with the use of a baculovirus system. By immunoblot analysis, the rSnSAG1-Bac antigen detected antibodies to S. neurona from naturally infected and experimentally inoculated equids, cats, rabbit, mice, and skunk. This is the first report of a baculovirus-expressed recombinant S. neurona antigen being used to detect anti-S. neurona antibodies in a variety of host species.

Animals↗
PubMed2004

Short communication: influence of Staphylococcus aureus intramammary infection on serum copper, zinc, and iron concentrations.

The goal of the present study was to characterize changes in serum trace mineral concentrations in cattle with experimentally induced Staphylococcus aureus mastitis. Nine primiparous Holstein-Friesian cattle were challenged with approximately 150 cfu of Staph. aureus ATCC29740 by intramammary infusion on d 6, 7, and 8 of lactation. Serum Cu, Zn, and Fe concentrations were determined immediately before and at 24, 48, and 72 h after the final intramammary infusion of Staph. aureus. Infection status (cfu/mL of Staph. aureus), milk somatic cell count, and mastitis score were also determined at these times. Infection resulted in a decrease in mean serum Cu, Zn, and Fe concentrations to 89, 83, and 81% of preinfection concentrations at 24 h postchallenge. One-way analysis of variance for repeated measures demonstrated a significant change in serum zinc concentration. The reductions in trace mineral concentrations were of less magnitude than observed following experimental E. coli mastitis.

Animals↗
PubMed2002

Use of pulsed-field gel electrophoresis for detecting differences in Staphylococcus aureus strain populations between dairy herds with different cattle importation practices.

The hypothesis tested was that dairy herds which import cattle for replacement or expansion have a higher prevalence of Staphylococcus aureus mastitis and a greater number of new Staphylococcus aureus strains enter their herds than closed herds. Fifteen commercial dairy herds were divided into four groups based on cattle importation practices. Composite foremilk samples were collected at 4-monthly intervals for 1 year from all lactating cattle. Additionally, foremilk samples were collected from cattle at parturition and skin swabs were taken from the udder of primiparous heifers. All samples were cultured for Staphylococcus aureus and isolates were strain-typed using pulsed-field gel electrophoresis. Herds that purchased replacement heifers had a higher prevalence of Staphylococcus aureus mastitis than herds that purchased lactating cattle for expansion (P = 0.02). Herds that purchased replacement heifers had more total strains of Staphylococcus aureus (P = 0.01) and more new strains (P = 0.04) enter the herd than closed herds.

Animal Husbandry↗
PubMed2002

Influence of Staphylococcus aureus strain-type on mammary quarter milk somatic cell count and N-acetyl-beta-D-glucosaminidase activity in cattle from eight dairies.

The hypothesis tested was that there are differences in pathogenicity between strains of Staphylococcus aureus that cause bovine mastitis. Mammary quarter milk somatic cell count (SCC) and N-acetyl-beta-D-glucosaminidase (NAGase) activity were used as indicators of the pathogenicity of different strains of S. aureus that infect the bovine udder. Eight commercial dairy herds with a history of S. aureus in bulk tank milk cultures were studied. Initially, composite foremilk samples were collected from all lactating cattle in each herd and cultured for staphylococci. Subsequently, all cows with a coagulase-positive staphylococcal intramammary infection (IMI) at the initial sampling that were still present in the herd of origin had individual mammary quarter foremilk samples collected. Coagulase-positive staphylococcal isolates were confirmed as S. aureus using a commercial biotyping system. Staphylococcus aureus isolates were strain-typed using pulsed-field gel electrophoresis. Mammary quarter milk SCC and N-acetyl-beta-D-glucosaminidase activity were determined for each cow. The difference in mean somatic cell count and mean NAGase activity for mammary quarters infected with the same strain of S. aureus and for uninfected quarters on the same cow was calculated. One-way analysis of variance was used to assess differences between strains within a herd. Overall, no significant differences were found between strains, suggesting that the degree of udder parenchymal injury induced by S. aureus IMI is in general significantly affected by factors other than strain type.

Acetylglucosaminidase↗
PubMed2001

Management strategies to decrease the prevalence of mastitis caused by one strain of Staphylococcus aureus in a dairy herd.

The dairy herd at Washington State University had an outbreak of mastitis caused by a single strain of Staphylococcus aureus. The outbreak strain, termed novel, could not be controlled with routine contagious mastitis pathogen control procedures (incidence, 3.4 infections/100 cow months; peak prevalence > 22%). Our objective was to implement mastitis control measures that would decrease the incidence and prevalence of intramammary infection (IMI) caused by S aureus in the herd. The following intervention strategies were successfully implemented: strict segregation of cattle with IMI caused by S aureus, intensified culling of cattle with multiple-quarter IMI caused by S aureus, and inducing cessation of lactation of infected quarters in single-mammary-quarter infected cattle. One year after implementation of these control measures, incidence of IMI caused by S aureus was 0.35 infections/100 cow months, and prevalence had decreased from 20 to 8%.

Animals↗
PubMed2001

Technical note: Therapeutic cessation of lactation of Staphylococcus aureus-infected mammary quarters.

The objective of the present study was to compare the ability of chlorhexidine and povidone-iodine to cause cessation of lactation in Staphylococcus aureus-infected mammary quarters, assess milk production in the treated quarter in the subsequent lactation, and evaluate whether microbiological cure was obtained. Fourteen mid- to late-lactation Holstein-Friesian dairy cattle from the Washington State University dairy herd with single mammary quarter S. aureus intramammary infections were studied. Cows were randomly assigned to one of two treatment groups, povidone-iodine or chlorhexidine. Cows in the povidone-iodine group were infused with 120 ml of 5% povidone-iodine solution (0.5% iodine) after complete milk-out. Chlorhexidine-treated cows were infused with a proprietary chlorhexidine suspension after two milkings 24 h apart. Treated mammary quarters were not milked for the rest of the lactation. Milk production from each mammary quarter (kg of milk/quarter) was measured using in-line volume flow meters for 5 consecutive days before treatment and again at the start of the subsequent lactation. Povidoneiodine caused permanent cessation of lactation in the treated quarter, whereas 71% of the chlorhexidine-treated mammary quarters returned to function in the subsequent lactation. Hence, if the primary objective is to eliminate the mammary quarter from lactation, and thereby presumably lower the risk of herdmates acquiring new S. aureus intramammary infection, then povidone-iodine appears to be the best of the two methods. No difference in total milk production between lactation one and two in either group was found, suggesting that permanent loss of a quarter was not detrimental to overall milk production.

Animals↗
PubMed1998

Outbreak of mastitis caused by one strain of Staphylococcus aureus in a closed dairy herd.

The Washington State University dairy experienced an outbreak of intramammary infections (IMI) caused by Staphylococcus aureus during autumn 1993 through summer 1995. The outbreak was believed to be a result of transmission of 1 strain of S aureus in a herd that historically had excellent control of contagious mastitis. Control practices included strict hygiene at time of milking and preferential culling of cows infected with S aureus. Mastitis caused by Streptococcus agalactiae was not found in this herd. Despite excellent control practices, the strain of S aureus caused a new infection rate of approximately 3% of the herd per month. Moreover, a second strain of S aureus, isolated from a cow with mastitis, was introduced into the herd experimentally, and it failed to transmit disease. The outbreak of S aureus mastitis in this herd was eventually controlled by maintaining a program of strict milking time hygiene, by intensifying the program of preferentially culling infected cows, and by segregating cows with S aureus IMI in a separate pen and milking these infected cows last.

Animals↗
PubMed1998

Conservative management of a ruptured gastrocnemius muscle in a male llama.

Rupture of the gastrocnemius muscle was diagnosed in an obese llama using physical examination and ultrasound imaging. Conservative therapy consisting of the use of a cast to immobilize the affected limb permitted the muscle to heal. Only mild, residual gait abnormalities were observed on follow-up examination.

Animals↗
PubMed1995

Corticosteroid-induced asthma: a manifestation of limited hyperinfection syndrome due to Strongyloides stercoralis.

Inadequate therapeutic response to parenteral corticosteroids in patients with acute bronchial asthma is infrequent. We report four patients whose bronchial asthma symptoms worsened after treatment with parenteral corticosteroids. All had larvae of Strongyloides stercoralis in the stool. The new attack or the exacerbation of asthma appeared to be precipitated by systemic corticosteroid administration. The paradoxic therapeutic response of asthma to glucocorticoides was the major pulmonary manifestation of Strongyloides superinfection; there was no evidence of other organ involvement. Individuals with new onset of bronchial asthma or worsening of asthmatic episodes concurrent with the use of systemic corticosteroids should have thorough investigation for possible superinfection due to Strongyloides stercoralis. This is particularly important for patients who have resided in areas where intestinal helminthic infections are endemic. Discontinuance of steroid therapy or reduction in dosage of parenteral steroids appears necessary. Treatment with thiabendazole appears to be effective in patients with limited hyperinfection syndrome.

Acute Disease↗
PubMed1991

Oral candidiasis as a marker of acute retroviral illness.

All reported clinical characteristics of acute retroviral illness with the human immunodeficiency virus (HIV) are nonspecific. Signs and symptoms described are associated with a variety of acute infections. We report the cases of three patients in whom the acute retroviral illness was characterized by transient oral candidiasis and unexplained high lactate dehydrogenase values, with or without transient pulmonary infiltrate, in the context of an acute febrile illness. The clinical findings correlated with a severe reduction in the number of CD4 cells. We believe that thrush could be a marker of acute retroviral infection, as it is not a feature of any other heterophil-negative mononucleosis-like syndrome. We propose that in any patient having transient thrush and acute viral syndrome, the possibility of HIV infection should be aggressively pursued serologically, regardless of the patient's HIV risk status, provided that the usual causes of candidiasis (eg, diabetes mellitus, antibiotic use, and dentures) can be excluded.

Adult↗