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Biomedical subjects

R S Pirie

Publications and source records attributed to R S Pirie.

At least 19 recordsLinked to original sources
PubMed2006

Comparison of IgG antibody levels to Clostridium botulinum antigens between euthanased and surviving cases of chronic grass sickness.

Serum from 12 horses suffering from chronic grass sickness (CGS) were assayed for IgG antibodies against botulinum neurotoxins C and D (BoNT/C and BoNT/D) and to a surface antigen extract of a neurotoxin negative strain of Clostridium botulinum type C. Collectively, the six surviving CGS cases demonstrated significantly higher initial IgG levels (P=0.05) against surface antigens than the six that were subsequently euthanased. The surviving animals also demonstrated higher initial IgG levels against the BoNT/C but not reaching significance (P=0.06). The two groups demonstrated no difference between IgG levels against BoNT/D. This study supports existing evidence of the involvement of C. botulinum type C in the aetiology of grass sickness.

Animals↗
PubMed2005

Cytokine profiles of peripheral blood and airway CD4 and CD8 T lymphocytes in horses with recurrent airway obstruction.

Equine recurrent airway obstruction (RAO) is thought to result from an aberrant immune response to inhaled antigens, modulated by T lymphocytes via the secretion of pro-inflammatory cytokines. However data relating to the phenotypes of the T lymphocytes present in peripheral blood and bronchoalveolar lavage fluid of RAO horses and their cytokine profiles are contradictory. The aim of this study was to further investigate the cytokine (IL-4, IL-5, IL-13 and INF-gamma) mRNA expression profile in peripheral blood lymphocytes and bronchoalveolar lavage lymphocytes from RAO and control horses, before and at 48 h after horses were exposed to hay/straw. In contrast to previous studies, cytokine expression was quantified in populations of CD4 and CD8 T lymphocytes which were purified using magnetic bead antibody cell separation. Hay/straw exposure induced clinical airway obstruction, airway neutrophilia and airway lymphocytosis in RAO horses, and, induced a mild, but significant, airway neutrophilia in controls. However, hay/straw exposure had no significant effect on peripheral blood lymphocyte or bronchoalveolar lavage lymphocyte cytokine expression in either group. In conclusion, RAO was not associated with alterations in lymphocyte cytokine expression that are consistent with Th1 or Th2 responses, but rather with a general down-regulation in expression of the measured cytokines in peripheral blood lymphocytes and bronchoalveolar lavage lymphocytes.

Airway Obstruction↗
PubMed2005

Dose responses to inhalation of endotoxin, hay dust suspension and Aspergillus fumigatus extract in horses as measured by levels and activation of matrix metalloproteinase-9.

REASONS FOR PERFORMING STUDY: Airway matrix metalloproteinases (MMPs) increase after endotoxin (LPS) exposure, but there are no reports describing dose-dependent increases or activation following exposure. OBJECTIVES: To study matrix metalloproteinase-9 (MMP-9) and -2 (MMP-2) responses in bronchoalveolar lavage fluid (BALF) from heaves-susceptible and control horses following inhalation of hay dust suspension (HDS), LPS and Aspergillus fumigatus extract (AFE). METHODS: Heaves-susceptible (n = 7) and control (n = 6) horses received inhalation challenges with 3 different doses of HDS and LPS. Heaves-susceptible horses (n = 6) also received 3 different doses of AFE and one dose of AFE depleted of endotoxin (AFE-LPS). BALF collected following inhalation challenges was analysed using gelatin zymography. Gelatinolytic bands were identified as complex, pro-MMP-9, active MMP-9, pro-MMP-2 and active MMP-2 based on molecular weights. RESULTS: Each challenge substance induced a dose-dependent elevation in gelatinolytic activity. The dose-dependency was most evident for pro-MMP-9 and total MMP-9 levels in heaves-susceptible horses following LPS challenges. CONCLUSIONS: There is a dose-dependent elevation in MMP-9 in BALF of heaves-susceptible and control horses following inhalation challenge with organic dust and some of its components, elevation being more marked in heaves-susceptible horses. Organic dust components vary in their pro-inflammatory potential. POTENTIAL RELEVANCE: This study supports the role of MMPs in the pathogenesis of heaves and highlights the potential value of protease inhibitors in attenuating the airway inflammatory response to inhaled organic dust.

Animals↗
PubMed2005

Effect of composition and different fractions of hay dust suspension on inflammation in lungs of heaves-affected horses: MMP-9 and MMP-2 as indicators of tissue destruction.

REASONS FOR PERFORMING STUDY: Airway matrix metalloproteinases (MMPs) increase following inhalation of organic dust. The relative contribution of dust components to this elevation is unknown. OBJECTIVE: To identify components of organic dust responsible for elevated MMP levels in equine airways. METHODS: Bronchoalveolar lavage (BALF) from 7 heaves-susceptible horses, collected 6 h following inhalation challenges with saline, 2 different hay dust suspensions (HDS-1 and -2) and soluble and particulate fractions of HDS-1, were analysed for MMP-2 and -9 using SDS-page gelatin zymography. RESULTS: HDS-1 challenge increased BALF proMMP-9 and total MMP-9. HDS-1 fractions, or the particulate fraction with added lipopolysaccharide, increased BALF proMMP-9 and total MMP-9 in combination, but not when inhaled separately. HDS-2 inhalation elevated BALF complex forms, proMMP-9, active MMP-9, total MMP-9 and total MMP-2. CONCLUSIONS: The results suggest synergistic action of soluble and particulate organic dust components. The fact that HDS-1 and HDS-2 had different glucan concentrations supports a role for moulds in the activation of MMP-9. POTENTIAL RELEVANCE: Activation and release of MMPs in response to inhaled moulds are involved in the aetiopathogenesis of heaves. Endotoxin contributes to the synergistic action of the dust components, but the overall MMP response to organic dust inhalation in heaves-susceptible horses largely reflects the mould content of the dust. In the future, inhibition of MMP production and release may offer therapeutic means for treatment and prevention of heaves and recommendations for acceptable dust levels can be given.

Animals↗
PubMed2003

Diagnosis and treatment of retropharyngeal injuries in lambs associated with the administration of intraruminal boluses.

The administration of intraruminal identification boluses to a group of 76 lambs resulted in 24 (32 per cent) showing signs of pharyngeal damage. In 16 of them the bolus was found to be in the retropharyngeal region by means of a hand-held microchip scanner, radiography and endoscopy. Purulent tracts were identified in the dorsal pharynx. In 13 of the 16 lambs the surgical removal of the bolus under general anaesthesia was followed by a normal clinical recovery, although the lambs did not grow as well as similar unaffected animals; three of the 24 lambs died. The administration of a larger bolus to 10 yearling rams did not result in any clinical signs of pharyngeal damage. The most important factors influencing the occurrence of this type of injury among this group of lambs were the size and age of the lambs, the positioning of the lambs during bolus administration, the relative size of the dosing gun and bolus, and the large number of animals in the group.

Administration, Oral↗
PubMed2003

Inhaled endotoxin and organic dust particulates have synergistic proinflammatory effects in equine heaves (organic dust-induced asthma).

BACKGROUND: Equine heaves is a naturally occurring organic dust-induced asthma characterized by airway neutrophilia, mucus hypersecretion and obstructive lung dysfunction. However, the relative role of different dust components in disease severity remains unclear. OBJECTIVE: This study investigated the relative contribution of inhaled endotoxin and organic dust particulates (mainly mould spores) in inducing heaves in heaves-susceptible horses. METHODS: Control and heaves-susceptible horses received inhalation challenges with hay dust suspension (HDS) before and after lipopolysaccharide (LPS) depletion. Heaves-susceptible horses also received inhalation challenge with HDS particulates with and without the addition of LPS and were housed in two separate dusty environments during which mould and endotoxin exposure was measured. The airway inflammatory and functional response to each challenge was measured. RESULTS: Depletion of endotoxin from HDS attenuated the airway neutrophilia and abrogated the airway dysfunction induced in heaves horses by inhaled HDS. The airway response was re-established by adding back LPS to the depleted HDS, confirming that the attenuation in airway response was due specifically to endotoxin depletion. Interestingly, the magnitude of alteration in airway response following endotoxin depletion and add-back was greater than that which could be attributed solely to endotoxin per se, indicating that the LPS activity was enhanced by the other dust components. Consistent with this possibility, washed particulates harvested from HDS enhanced the airway response to inhaled LPS in heaves horses. Heaves horses given two different hay/straw challenges had a significantly different severity of airway inflammation and dysfunction, despite airborne dust and endotoxin concentrations in the horses' breathing zones being similar. CONCLUSION: Although inhaled endotoxin appears not to be the only determinant of disease severity in heaves, it does contribute significantly to the induction of airway inflammation and dysfunction. This contribution is largely via the synergistic action of inhaled endotoxin and organic dust particulates, although other soluble dust components also contribute to a lesser degree.

Animals↗
PubMed2003

Endotoxin contamination contributes to the pulmonary inflammatory and functional response to Aspergillus fumigatus extract inhalation in heaves horses.

BACKGROUND: Mould extract inhalation challenges have been used extensively in the investigation of heaves. Such challenges have induced pulmonary neutrophilic inflammation and dysfunction, consistent with, but less severe than the natural disease. However, the method of mould extract production is likely to result in endotoxin contamination. OBJECTIVE: To investigate whether insufficient dose delivery was responsible for the shortfall in response to inhaled extract compared with natural disease, and whether endotoxin contamination of mould extract contributed to the pulmonary inflammation and dysfunction. METHODS: We measured the response of six heaves horses following inhalation of saline (placebo) and three doses of Aspergillus fumigatus extract. We then compared the response of six heaves horses to A. fumigatus extract inhalation before and after lipopolysaccharide (LPS) depletion. RESULTS: Inhalation challenge with 0.5, 1.6 and 5 mg of A. fumigatus extract resulted in a significant increase in bronchoalveolar lavage fluid (BALF) neutrophil ratio when compared with saline inhalation. Only 1.6 and 5 mg extract inhalation resulted in significant lung dysfunction compared with saline. There was no significant difference between 1.6 and 5 mg extract inhalation with respect to airway neutrophil numbers or lung function, suggesting a plateau in both measured responses. LPS depletion of 1.6 mg A. fumigatus extract resulted in a significant reduction in airway neutrophil numbers and increase in arterial oxygen tension. There was no significant difference between saline and the LPS-depleted A. fumigatus extract challenges with respect to neutrophil count and lung function. The reduction in airway neutrophil numbers was greater than would be predicted by extrapolation from previously reported soluble LPS dose-response inhalation experiments. CONCLUSION: This study supports a role for other inhalants, in addition to soluble components of A. fumigatus, in the aetiopathogenesis of heaves. Also the amplification in response to LPS when inhaled with A. fumigatus extract, suggests that the role of inhaled endotoxin in the pulmonary inflammation and dysfunction in naturally occurring heaves may currently be underestimated.

Animal Feed↗
PubMed2003

Systemic concentrations of antioxidants and biomarkers of macromolecular oxidative damage in horses with grass sickness.

REASONS FOR PERFORMING STUDY: The aetiopathogenesis of equine grass sickness (EGS) is unknown. The role of free radical-mediated neuronal damage has not previously been investigated in this condition. OBJECTIVES: To investigate the potential contribution of oxidative damage and antioxidant status to neurodegeneration in EGS. METHODS: Systemic levels of surrogate biomarkers were determined in 10 horses with acute EGS and in 2 control populations; 10 healthy horses co-grazing with the 10 EGS horses at the onset of clinical disease, and 10 healthy mares grazing where EGS has not been reported. RESULTS: EGS horses had alterations in levels of several antioxidants, consistent with oxidative stress, the acute phase response and/or the secondary metabolic complications of EGS. EGS horses had elevated plasma dihydroxyphenylalanine (DOPA) levels. CONCLUSIONS: The elevated DOPA levels probably reflected a generalised disturbance of catecholamine metabolism rather than increased DOPA production via free radical-mediated oxidation of tyrosine. However, there was no evidence of systemic macromolecular oxidative damage. POTENTIAL CLINICAL RELEVANCE: Further work is required to determine whether macromolecular oxidative damage occurring at the neuronal level contributes to EGS.

Animals↗
PubMed2002

Cytological analysis of equine bronchoalveolar lavage fluid. Part 3: The effect of time, temperature and fixatives.

Bronchoalveolar lavage fluid (BALF) samples are often subject to time delays, possibly with temperature fluctuations, between collection and processing. The aim of this study was to evaluate the effects of time, temperature and 2 different fixatives on equine BALF cytology, in order to develop guidelines for optimal equine BALF storage conditions. Total nucleated cell count (TCC), differential cell counts (DCC), absolute cell counts (ACC), cell viability, cell morphology and bacterial growth of BALF samples stored at 4, 18 (+/- addition of formalin- or alcohol-based fixatives) and 38 degrees C were monitored serially over a 72 h period. The time taken for a significant reduction in TCC and cell viability of unfixed BALF samples decreased as the storage temperature increased. There was no diagnostically significant difference in DCC or ACC over this time-course at any temperature. Unfixed BALF samples showed significant bacterial growth by 24 h at 4 degrees C, and 8 h at 18 and 38 degrees C; and poor morphology by 48 h at 4 degrees C, 24 h at 18 degrees C and 8 h at 38 degrees C. Fixed BALF samples showed poor morphology with Leishman's stain compared to unfixed samples.

Animals↗
PubMed2002

Cytological analysis of equine bronchoalveolar lavage fluid. Part 1: Comparison of sequential and pooled aliquots.

The aim of this study was to investigate whether initial equine bronchoalveolar lavage fluid (BALF) aliquots were more representative of bronchial cytology that bronchiolar and alveolar cytology. Cell viability and total nucleated (TCC), differential (DCC) and absolute cell counts of cytocentrifuged preparations of 3 sequentially collected BALF aliquots (Aliquots 1-3) were compared with those of pooled BALF (Aliquot 4) to assess whether all aliquots were representative of the lavaged lung segment. BALF samples (n = 21) were collected from control horses (n = 5) or heaves-affected horses (n = 5). There were nonsignificant trends of increasing TCC and absolute macrophage count from Aliquot 1 to Aliquot 3 and significant differences in macrophage (P<0.05) and lymphocyte (P<0.01) DCC among aliquots of all horses; however, no linear trend in this DCC data was observed. There was a significant decrease in mast cell DCC (P<0.01) from Aliquot 1 to Aliquot 3 in control horses. Cell viability did not differ significantly among aliquots. There was no diagnostically significant difference in TCC, DCC, absolute cell counts or cell viability, among sequential and pooled BALF aliquots and, therefore, all aliquots can be considered to represent the cytology of the lavaged lung segment. This indicates that even if BALF recoveries are very low, cytological analysis of samples will be of diagnostic value.

Animals↗
PubMed2002

Cytological analysis of equine bronchoalveolar lavage fluid. Part 2: Comparison of smear and cytocentrifuged preparations.

The aim of this study was to develop a diagnostically useful smear method for preparation of equine bronchoalveolar lavage fluid (BALF) for use by practitioners. A smear method for equine BALF preparation which included the addition of serum was developed, and cell morphology, differential cell counts (DCC) and repeatability of counting DCC compared with those of cytocentrifuged BALF preparations. BALF samples (n = 21) were collected from 5 control horses and 5 heaves-susceptible horses. Smear preparations of BALF produced smaller, darker, staining cells, making cytological identification more difficult than on cytocentrifuged preparations. There was a significantly higher (P<0.01) macrophage DCC and lower lymphocyte DCC on cytocentrifuged compared to smear preparations. Mast cell and eosinophil DCC were significantly higher (P<0.05) on cytocentrifuged compared to smear preparations of BALF. Smear preparations were shown to be reliable for the cytological diagnosis of equine neutrophilic pulmonary disease and offer practitioners an alternative to sending equine BALF to a laboratory for processing and cytological analysis.

Animals↗
PubMed2002

Evaluation of nebulised hay dust suspensions (HDS) for the diagnosis and investigation of heaves. 2: Effects of inhaled HDS on control and heaves horses.

To evaluate inhaled hay dust suspensions (HDS) as a tool for the diagnosis and investigation of heaves, the pulmonary inflammatory and functional consequences of inhalation challenge with 3 different HDS were determined in 6 control and 7 asymptomatic heaves horses. Heaves horses given HDS challenge developed the characteristic features of heaves, including airway neutrophilia, obstructive airway dysfunction and mucus hypersecretion. While HDS challenge induced a mild airway neutrophilia in controls, the no-response threshold for controls was greater than that of heaves horses, and there was no overlap in BALF neutrophil ratio of controls and heaves horses. Furthermore, HDS challenge did not induce airway dysfunction or mucus hypersecretion in controls. Therefore, HDS challenges enabled differentiation of control and heaves horses. Interestingly, in both groups, the airway neutrophilia was a dose-dependent response rather than an 'all or nothing' response. This study suggests that HDS challenges are of value in the diagnosis and investigation of heaves.

Animals↗
PubMed2002

Evaluation of nebulised hay dust suspensions (HDS) for the diagnosis and investigation of heaves. 1: Preparation and composition of HDS.

Currently, heaves is investigated by exposing susceptible horses to dusty hay. Consequently, the response will be dependent on the organic dust content and composition of the hay. It was hypothesised that the use of a hay dust suspension (HDS) would reduce the variability of the challenge and therefore standardise experimental protocols. Furthermore, analysis of HDS would also permit further investigation of the organic dust components responsible for the response. Three hay dust suspensions (HDS-1, 2 and 3) were prepared for use in the diagnosis and investigation of heaves. HDS were produced from fine dust particles, comprising mostly fungal spores, collected from 3 batches of dusty hay. HDS-1 and 3 were analysed for endotoxin, beta-D-glucan and protein concentrations, general protease activity and enumeration and size distribution of particulates. Protease activity was mainly attributable to a 28 kDa serine protease and to 85 kDa and 160 kDa metalloproteases. The particulate and soluble components of HDS could be aerosolised by jet nebulisation. We therefore conclude that detailed analysis of HDS is possible, that such a challenge system provides a method of standardising experimental protocols and that all components of HDS (both soluble and particulate) can be delivered to the lung using standard nebulisation techniques. For the above reasons, nebulised HDS offers considerable advantages over conventional hay/straw challenge for the diagnosis and investigation of heaves.

Air↗
PubMed2002

Evaluation of nebulised hay dust suspensions (HDS) for the diagnosis and investigation of heaves. 3: Effect of fractionation of HDS.

To investigate the relative importance of inhaled particulates and soluble components in the response to inhaled hay dust suspension (HDS), heaves (previously termed chronic obstructive pulmonary disease; n = 7) and control (n = 6) horses were given inhalation challenges with whole and fractionated HDS. Fractionation was achieved by centrifugation to yield supernatant (SUP) and particulate debris. The particulates were then washed repeatedly in saline to produce a washed particulate (WP) fraction which comprised mainly fungal spores, and a wash fraction (WF) which comprised saline and soluble components washed from the surface of the particulates. Inhalation of HDS and SUP induced a significant airway neutrophilia in both groups, with the magnitude of the response being significantly greater in heaves horses. SUP induced significantly less airway neutrophilia than HDS in both groups, despite the endotoxin and protease content of HDS and SUP being comparable. WP and WF induced only a slight airway neutrophilia in heaves horses. However, a combined challenge with SUP and WP induced a neutrophilic response approaching the magnitude of that following HDS challenge, indicating that dust particulates contribute to the pulmonary recruitment of neutrophils in heaves. Consequently, inhalation challenge with HDS, which contains both particulates and soluble dust components, may be a more useful tool for the diagnosis and investigation of heaves than aqueous dust extracts, which contain only soluble components.

Animals↗
PubMed2002

Inhalation of organic dusts and lipopolysaccharide increases gelatinolytic matrix metalloproteinases (MMPs) in the lungs of heaves horses.

We report the effects of mouldy hay/straw exposure, inhaled hay dust suspension (HDS) and inhaled lipopolysaccharide (LPS) on bronchoalveolar lavage fluid (BALF) gelatinolytic matrix metalloproteinase (MMP) levels and degree of activation in healthy (n = 6) and heaves- (previously termed chronic obstructive pulmonary disease) affected (n = 6 or 7) horses. Gelatinolytic MMPs in BALF were quantified by zymography, and gelatinases were shown by Western immunoblotting to be MMP-2 and MMP-9. Hay/straw and HDS challenges increased BALF total gelatinolytic activity only in heaves horses, with the majority of gelatinolytic activity comprising pro- and active MMP-9. The 5 h duration hay/straw challenge increased BALF gelatinolytic MMP activity in heaves horses at 5 and 24 h after the start of this challenge, with activity returning to baseline by Day 4. In contrast to hay/straw and HDS challenges, LPS inhalation increased BALF gelatinolytic MMP activity in both groups. For all challenges, absolute BALF neutrophil counts were highly significantly correlated (P<0.0001) with levels of proMMP-9 and active MMP-9, but not with levels of MMP-2 (P>0.05). As gelatinolytic MMPs are pro-inflammatory agents, they may contribute to lung dysfunction and tissue destruction in heaves horses exposed to airborne organic stable dusts.

Animals↗
PubMed2001

Pulmonary and systemic effects of inhaled endotoxin in control and heaves horses.

To investigate whether inhaled endotoxin contributes to airway inflammation and dysfunction in stabled horses, control (n = 6) and asymptomatic heaves (previously termed chronic obstructive pulmonary disease)-susceptible (n = 7) horses were given inhalation challenges with 20, 200 and 2,000 microg of soluble Salmonella typhimurium Ra60 lipopolysaccharide (LPS). LPS inhalation induced a dose-dependent neutrophilic airway inflammatory response in both groups. Inhalation with 2,000 microg of LPS also induced detectable lung dysfunction in the heaves group. LPS inhalation did not alter clinical score, tracheal secretion volume or airway reactivity in either group. The no-response thresholds were lower for the heaves group (<20 microg for airway inflammation; 200 to 2,000 microg for lung dysfunction) than for the control group (20 to 200 microg for airway inflammation; >2,000 microg for lung dysfunction). To enable comparison of these threshold levels with airborne endotoxin concentrations in stables, horses also received a 5 h duration hay/straw challenge, during which the total and respirable airborne endotoxin concentrations were determined. Comparison of the effects of acute LPS inhalation and hay/straw challenges suggest that inhaled endotoxin is not the sole cause of heaves. However, it is likely that it contributes to airway inflammation, both in heaves horses in concert with other inhalants, and in normal horses when they are exposed to high levels in poor stable environments.

Air↗
PubMed2000

Endoscopic and bacteriological findings in a chronic outbreak of strangles.

Recently there has been increased awareness of the role of the carrier state in propagating Streptococcus equi var equi (S equi) infections (strangles), although the anatomical location of the organisms in chronic carriers has not been consistently established. This case report describes a chronic strangles outbreak in a riding school, that was monitored over six months by repeated clinical and endoscopic guttural pouch examinations. All asymptomatic horses that had positive S equi cultures on nasal swabs or guttural pouch lavages were found to have lesions in their guttural pouches. These lesions included empyema, chondroids and previously undescribed chronic discharging lesions on the floor of the medical compartment of the guttural pouches. These observations further support previous studies indicating the importance of investigating the guttural pouches in horses suspected to be asymptomatic carriers of this organism.

Animals↗