Search Results

You are looking at 61 - 70 of 193 items for :

  • Refine by Access: All Content x
Clear All

Abstract

Objective—To compare activities of interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, and matrix metalloproteinase (MMP)-3 and contents of sulfated glycosaminoglycan (S-GAG) in joint fluid obtained from dogs with hip dysplasia (HD) and clinically normal dogs, evaluate correlations among these markers in joint fluid obtained from dogs with HD, and evaluate correlations between each marker and clinical and radiographic variables.

Animals—26 dogs with HD (clinical group) and 43 clinically normal Beagles (control group).

Procedure—Joint fluid was aseptically collected from the hip joints of all dogs. For each dog in the clinical group, age, duration of lameness, radiographic osteoarthritis (OA) score, and Norberg angle in each affected joint were recorded. Activities of IL-1β, IL-6, TNF-α, and MMP-3 and S-GAG contents were measured. Values were compared between groups by use of Mann-Whitney U tests, and the Spearman rank correlation test was used to evaluate correlations among markers and between each marker and clinical or radiographic variables.

Results—Values of all markers were significantly higher for the clinical group, compared with values for the control group. There was a moderate positive correlation between lameness duration and IL-6 activity and a strong negative correlation between the Norberg angle and IL-1β activity.

Conclusions and Clinical Relevance—Analysis of our results indicated that there was a significant increase in markers of OA in dogs with HD. Activities of IL-1β and IL-6 in joint fluid of dogs with HD may be influenced by the severity of laxity in the hip joint and lameness duration, respectively. (Am J Vet Res 2005;66:2028–2033)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the activity of Kupffer cells (KC) of control neonatal pigs and neonatal pigs treated with endotoxin and to compare activity of KC with that of pulmonary alveolar macrophages (PAM).

Sample Population—Kupffer cells and PAM obtained from 24 neonatal pigs (7 to 10 days old).

Procedure—Pairs (n = 7) of littermates served as treated (lipopolysaccharide [LPS]) or untreated pigs. Pigs were euthanatized 24 hours after treatment, and cells were isolated. Cells were obtained from 10 other neonatal pigs for other assays. Functional activity of cells was evaluated by use of in vitro assays to evaluate bactericidal activity, phagocytosis, and production of superoxide anion (SOA), nitric oxide (NO), and tumor necrosis factor-α (TNF-α). Each assay was repeated on cells obtained from 4 to 6 pigs.

Results—Phagocytic activity was similar in KC and PAM, but bactericidal activity and production of SOA and TNF-α was lower in KC. Neither KC nor PAM produced NO in response to LPS stimulation. Phagocytosis, bactericidal activity, and production of SOA were enhanced for KC obtained from neonatal pigs treated with LPS. The PAM from LPS-treated neonatal pigs had similar bactericidal activity to PAM obtained from untreated pigs.

Conclusions and Clinical Relevance—Functional capacity of KC is affected by endotoxin. This provides additional information of the role the liver plays in immune surveillance. In addition, the response of KC in neonatal pigs exposed to endotoxin is of value for understanding gram-negative bacterial sepsis, which is a major cause of mortality in neonatal pigs. (Am J Vet Res 2001;62:1040–1045)

Full access
in American Journal of Veterinary Research

Abstract

Objectives—To determine concentrations of matrix metalloproteinase (MMP)-2 and -9 in synovial fluid; and mRNA expression of MMP-1, -13, and -3; interleukin[ IL]-1α and β; and tumor necrosis factor(TNF)-α in synovial membrane and articular cartilage from horses with naturally occurring joint disease.

Sample Population—Synovial fluid (n = 76), synovial membrane (59), and articular cartilage (45) from 5 clinically normal horses and 55 horses with joint disease categorized as traumatic (acute [AT] or chronic [CT]), osteochondritis dissecans (OCD), or septic (S).

Procedure—Synovial fluid gelatinase concentrations were analyzed, using zymography. Synovial membrane and articular cartilage mRNA expression for MMP-1, -3, and -13, IL-1α and β, TNF-α, type-II collagen, and aggrecan were analyzed, using quantitative reverse transcriptase-polymerase chain reaction.

Results—Synovial fluid pro-MMP-2 concentration was significantly higher in diseased joints than normal joints. Septic joints had significantly higher concentrations of pro and active MMP-9. Stromelysin-1 was expressed in ≥ 80% of synovial membrane and articular cartilage samples and was strongly influenced by age. Collagenases were rarely expressed, with MMP- 13 expressed only in diseased joints. Interleukin-1β expression was significantly higher in all OCD samples and was influenced by age. Tumor necrosis factor- α expression was significantly higher in cartilage from joints with AT and OCD. There was no correlation between MMP or cytokines and type-II collagen or aggrecan expression.

Conclusions and Clinical Relevance—Matrix metalloproteinase- 2 and -3 are abundant in naturally occurring joint disease and normal joints. Interleukin-1β and TNF-α may be important in the pathogenesis of OCD. Age affects MMP and IL-1β concentrations. (Am J Vet Res 2001;62:1467–1477)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate in situ expression of inflammatory cytokine mRNA in lymphoid tissue of swine experimentally infected with Mycobacterium avium serovar 2.

Animals—7 noninfected pigs and 7 pigs infected with M avium serovar 2.

Procedure—Expression of mRNA of inflammatory cytokines such as tumor necrosis factor α (TNFα), interleukin (IL)-1β, IL-6, and IL-8 in formalin-fixed paraffin- embedded blocks of lymphoid tissue (lymph nodes and tonsil) of swine experimentally infected with M avium serovar 2 was compared with that of noninfected pigs. Tissues were evaluated by use of morphologic localization of cytokine mRNA, using in situ hybridization at 160 days after inoculation.

Results—A noticeable increase in mRNA expression for TNFα and mild increases in mRNA expression of IL-8 and IL-1β were detected in mandibular lymph nodes from infected swine, compared with noninfected swine. Mild increase in mRNA expression for IL-6 also was observed in tonsils from infected swine. Cytokine mRNA was detected in macrophages and lymphocytes, primarily within cortical follicles and adjacent mantle zones.

Conclusions and Clinical Relevance—Expression of mRNA for inflammatory cytokines was increased in lymphoid tissue of infected swine, possibly resulting from local factors on, or secreted by, M avium. These results suggest that alterations in cytokine mRNA expression are important in the pathogenesis and clinical course of mycobacteriosis in swine. Modulation of the immune response by vaccines that selectively target cytokine expression and secretion in response to mycobacterial challenge may be effective in prevention of mycobacteriosis in swine. (Am J Vet Res 2000;61:1487–1491)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine which antimicrobials that are used to treat neonatal foals with septicemia attributable to Escherichia coli will minimize endotoxin release from bacteria and subsequent activity of inflammatory mediators while maintaining bactericidal efficacy.

Sample Population—Blood samples from 10 healthy foals.

ProcedureEscherichia coli isolates A and B were isolated from 2 septicemic foals, and minimal inhibitory concentrations (MIC) were determined for 9 antimicrobials. Five of these antimicrobials were tested in vitro at 2 and 20 times their respective MIC. Whole blood or mononuclear cells grown in tissue- culture media were incubated with 105 colonyforming units of E coli and each antimicrobial or saline (0.9% NaCl) solution. After 6 hours, number of viable bacteria remaining was determined, and supernatant was tested for endotoxin and tumor necrosis activity.

Results—Testing in whole blood was compromised by bactericidal effects of the blood itself. In mononuclear cell suspensions, each antimicrobial significantly reduced the number of viable bacteria to low or undetectable amounts. Antimicrobials did not differ significantly in efficacy of bacterial killing. Amikacin used alone or in combination with ampicillin resulted in significantly less endotoxin activity than did ampicillin, imipenem, or ceftiofur alone. There was a correlation between TNF-α and endotoxin activity.

Conclusions and Clinical Relevance—Aminoglycosides appear less likely to induce endotoxemia and TNF-α synthesis during bactericidal treatment of E coli septicemia, compared with β-lactam antimicrobials. Use of ampicillin, imipenem, or ceftiofur in the treatment of septicemic neonatal foals should be accompanied by appropriate treatment for endotoxemia. (Am J Vet Res 2002;63:660–668)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether ischemia and flunixin affect in vitro lipopolysaccharide (LPS) absorption in samples of the jejunum of horses.

Animals—12 horses.

Procedure—Horses were anesthetized, a midline celiotomy was performed, and the jejunum was located. Two 30-cm sections of jejunum (60 cm apart) were selected. One segment was designated as control tissue; ischemia was induced in the other segment for 120 minutes. Horses were then euthanatized. Mucosa from each jejunal segment was mounted on Ussing chambers and treated with or without flunixin. Tissues from 6 horses were used to assess permeability to radiolabeled LPS; mucosal samples from the remaining 6 horses were incubated with fluorescent-labeled LPS (FITC-LPS) and examined histologically. Production of tumor necrosis factor-α (TNF-α) and production of LPS-binding protein (LBP) were assessed as indicators of mucosal response to LPS.

Results—Ischemia significantly increased mucosal permeability to LPS, but by 180 minutes, the mucosa was not more permeable than control tissue. Flunixin treatment adversely affected intestinal barrier function throughout the experiment but did not result in increased mucosal permeability to LPS. Compared with control tissues, LBP production was increased by ischemia and reduced by exposure to LPS. In ischemic tissue, FITC-LPS entered the lamina propria but TNF-α was produced on the mucosal side only, indicating little response to the absorbed LPS.

Conclusions and Clinical Relevance—Ischemia increased LPS passage across equine jejunal mucosa. Flunixin delayed mucosal recovery but did not exacerbate LPS absorption. Evaluation of the clinical importance of flunixin-associated delayed mucosal recovery requires further in vivo investigation. (Am J Vet Res 2004;65:1377–1383)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine the amount of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) activity in alveolar macrophages in response to Actinobacillus pleuropneumoniae (APP) by determining nitric oxide (NO) and prostaglandin E2 (PGE2) concentrations.

Sample Population—Freshly isolated porcine alveolar macrophages.

Procedure—Alveolar macrophages were incubated for 48 hours with APP (1 × 104 colony-forming units/mL), interleukin-1β (IL-1β; 5 U/mL), tumor necrosis factor-α (TNF-α; 500 U/mL), interferon-γ (IFN-γ; 100 U/mL), or lipopolysaccharide (LPS; 10 µg/mL). In a second experiment, alveolar macrophages were incubated with fresh medium (negative control), APP alone, or APP with 1 of the following: IL-1β, TNF-α, or IFN-γ. In a third experiment, alveolar macrophages were incubated with fresh medium (negative control), LPS (positive control), APP alone, or APP with 1 of the following: an iNOS inhibitor (3.3µM), a COX-2 inhibitor (10µM); or both the iNOS and COX-2 inhibitors. Supernatant was obtained at 0, 3, 6, 9, 12, 24, and 48 hours after treatment for determination of NO and PGE2 production.

Results—The addition of APP to alveolar macrophages resulted in significant increases in NO and PGE2 production. The addition of APP and IFN-γ synergistically induced NO production. Inhibition of iNOS and COX-2 decreased NO and PGE2 production, respectively.

Conclusions and Clinical Relevance—In vitro activation of alveolar macrophages by APP results in increased production of NO and PGE2. Nitric oxide and PGE2 production appears to be largely dependent on iNOS and COX-2 activity. Pharmacologic modulation of iNOS and COX-2 activity may represent a therapeutic target for pigs with pleuropneumonia. (Am J Vet Res 2003;64:1514–1518)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine functional characteristics of monocytes obtained from cows with subclinical infection with Mycobacterium avium subsp paratuberculosis (MAP) that may have predisposed those cows to becoming infected with MAP.

Sample Population—Monocytes obtained from 5 uninfected cows and 5 cows subclinically infected with MAP in a herd with a high prevalence of paratuberculosis (ie, Johne's disease).

Procedures—Monocytes from uninfected and subclinically infected cows were incubated with MAP for 2, 6, 24, 72, or 96 hours. Variables measured included expression of tumor necrosis factor-α (TNF-α), interleukin (IL)-10, IL-12, transforming growth factor-β, and suppressor of cytokine signaling-3 (SOCS-3); apoptosis of monocytes; acidification of phagosomes; and killing of MAP.

Results—Monocytes from infected cows had greater expression of IL-10 and SOCS-3 at 2 hours of coincubation with MAP and lower expression of TNF-α and IL-12 when results for all incubation times were combined. Monocytes from infected cows had a greater capacity to acidify phagosomes. No differences were observed in the rate of apoptosis or capacity of monocytes to kill MAP organisms.

Conclusions and Clinical Relevance—Monocytes obtained from cows with subclinical infection with MAP had upregulated expression of IL-10 and SOCS-3 within the first 2 hours after exposure to MAP organisms. Although this did not inhibit acidification of phagosomes, apoptosis of monocytes, or attenuation of the capacity to kill MAP organisms, it may have attenuated the capacity of mononuclear phagocytes to initiate inflammatory and adaptive immune responses. (Am J Vet Res 2005;66:1114–1120)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine the effects of continuous low-dose infusion of lipopolysaccharide (LPS) on the expression of E-selectin and intercellular adhesion molecule-1 (ICAM-1) mRNA and neutrophil accumulation in the lungs, liver, spleen, small intestine, and pancreas in dogs.

Animals—11 healthy adult Beagles.

Procedure—Dogs received a continuous infusion of a low dose (10 µg/kg/h, IV) of LPS ( Escherichia coli055:B5) or saline (0.9% NaCl) solution (20 mL/kg/h, IV) for 8 hours. Activity levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) and the number of WBCs in circulation were examined before and 1, 2, 4, and 8 hours after the onset of LPS infusion. Expression of E-selectin and ICAM-1 mRNA and the number of neutrophils in each tissue were examined.

Results—After the onset of LPS infusion, serum TNF-α and IL-1β activities transiently increased. Thereafter, IL-6 activity increased, and high IL-6 activity was maintained throughout the experiment. In dogs in the LPS group, expression of E-selectin mRNA increased only in the lungs, and expression of ICAM-1 mRNA increased in the lungs and liver; the number of neutrophils in the tissue increased in the lungs and liver.

Conclusions and Clinical Relevance—Results suggested that expression of E-selectin and ICAM-1 mRNA increased during sepsis, particularly in the lungs and liver, and that this increase was associated with neutrophil accumulation. Hence, inhibiting the activation of endothelial cells in the lung and liver may decrease organ damage caused by accumulated neutrophils and help regulate multiple-organ dysfunction. (Am J Vet Res 2005;66:1259–1266)

Full access
in American Journal of Veterinary Research

SUMMARY

The antibiotic polymyxin B sulfate is a cationic polypeptide with a unique cyclical configuration and distinct cationic characteristics. In this investigation, polymyxin H was evaluated to determine its ability to prevent synthesis of lactic acid and tumor necrosis factor-α (tnf-α) by lipopolysaccharide-stimulated strain RAW 264.7 macrophage-like cell populations. In this context, gradient concentrations of polymyxin B were formulated in the presence of fixed concentrations of lipopolysaccharide fractions from Escherichia coli (B4:0111), E coli (J5), Klebsiella pneumoniae, Pseudomonas aeruginosa. Salmonella minnesota, and S typhimurium (Re). Quantitation of tnf-α was established by the application of a tissue culture-based biological assay system, using the WEHI 164 clone 13 indicator cell line. Investigations also included evaluation of the ability of gradient concentrations of lipopolysaccharide fractions from E coli (B4:0111), E coli Q5), K pneumoniae, P aeruginosa, S minnesota, and S typbimurium (Re) to form a complex with polymyxin B. This was established through application of high-performance thin-layer chromatography techniques. On the basis of the known molecular characteristics of lipopolysaccharide, its lipid A-core subfractions, and polymyxin B, these results imply that cytoprotective properties of polymyxin B are attributable to direct interaction and subsequent complex formation. More specifically, the mechanism by which polymyxin B exerts affinity for lipopolysaccharide fractions is proposed to occur through attractive ionic interactions established between the cationic diami-nobutyric acid residues of polymyxin B and the mono- or diphosphate group(s) of the lipid A-corc moiety. It is highly probable that this molecular phenomenon is accompanied by hydrophobic interactions established between the terminal methyloctanoyl or methylheptanoyl groups of polymyxin B and the saturated carbon chains of the lipid A-core subfraction of lipopolysaccharide fractions

Free access
in American Journal of Veterinary Research