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Biomedical subjects

F Blecha

Publications and source records attributed to F Blecha.

At least 37 records · Page 2Linked to original sources
PubMed1997

Supplemental dietary chromium does not influence ACTH, cortisol, or immune responses in young calves inoculated with bovine herpesvirus-1.

Twelve Holstein bull calves (6 to 8 wk of age) were used to determine the influence of supplemental dietary Cr on ACTH, cortisol, and immune responses of calves experimentally inoculated with bovine herpesvirus-1 (BHV-1). Calves supplemented with Cr received 3 mg Cr/d (Chromium, n = 6) of a high-Cr-yeast product. Following 53 d of treatment, all calves were fitted with jugular catheters, and blood samples were collected every 4 h into tubes containing ETDA. Twenty-four hours later, all calves were inoculated intranasally with BHV-1 (1 x 10(7) plaque-forming units in each naris). Serial blood collection continued at 4-h intervals for 6 d. Plasma was harvested, immediately frozen in liquid nitrogen, and stored at -20 degrees C. Individual rectal temperatures and urine samples were collected at the same time each day. Rectal temperatures were elevated (P < .05) on d 2, 3, 4, and 5 but were not affected by Cr treatment. Treatment with Cr did not affect secretion of ACTH, cortisol, or plasma tumor necrosis factor-alpha, although clear circadian variation in ACTH and cortisol occurred. No differences were detected in the concentrations of trace minerals excreted daily in the urine, lymphocyte proliferative response to mitogen stimulation, and neutrophil bactericidal function. The acute phase proteins, ceruloplasmin and fibrinogen, also were not affected by treatment or viral challenge. These data suggest the Cr supplementation using high-Cr yeast (3 mg/d) did not alter stress responses of calves experimentally inoculated with BHV-1.

Adrenocorticotropic Hormone↗
PubMed1996

PR-39, a proline-rich antibacterial peptide that inhibits phagocyte NADPH oxidase activity by binding to Src homology 3 domains of p47 phox.

Reactive oxygen intermediates generated by the phagocyte NADPH oxidase are critically important components of host defense. However, these highly toxic oxidants can cause significant tissue injury during inflammation; thus, it is essential that their generation and inactivation are tightly regulated. We show here that an endogenous proline-arginine (PR)-rich antibacterial peptide, PR-39, inhibits NADPH oxidase activity by blocking assembly of this enzyme through interactions with Src homology 3 domains of a cytosolic component. This neutrophil-derived peptide inhibited oxygen-dependent microbicidal activity of neutrophils in whole cells and in a cell-free assay of NADPH oxidase. Both oxidase inhibitory and direct antimicrobial activities were defined within the amino-terminal 26 residues of PR-39. Oxidase inhibition was attributed to binding of PR-39 to the p47phox cytosolic oxidase component. Its effects involve both a polybasic amino-terminal segment and a proline-rich core region of PR-39 that binds to the p47phox Src homology 3 domains and, thereby, inhibits interaction with the small subunit of cytochrome b558, p22phox. These findings suggest that PR-39, which has been shown to be involved in tissue repair processes, is a multifunctional peptide that can regulate NADPH oxidase production of superoxide anion O2-. thus limiting excessive tissue damage during inflammation.

Amino Acid Sequence↗
PubMed1996

Antibacterial activity of a synthetic peptide (PR-26) derived from PR-39, a proline-arginine-rich neutrophil antimicrobial peptide.

PR-39 is a proline-arginine-rich (PR) neutrophil antibacterial peptide originally identified and purified from the porcine small intestine. We report on the synthesis of a functional antibacterial domain of PR-39, the first 26 amino acid residues of the NH2 terminus. PR-26 was as potent as or more potent than PR-39 against enteric gram-negative bacteria. This truncated form of PR-39 potentiated neutrophil phagocytosis of Salmonella choleraesuis and decreased the level of S. typhimurium invasion into intestinal epithelial cells. Scanning electron microscopy confirmed that these peptides did not lyse cells by pore-forming mechanisms; however, they potentiated the antibacterial capabilities of a pore-forming peptide, magainin A. In addition, PR-26 was not toxic to epithelial cells at concentrations several times greater than its bactericidal concentration. These data suggest that PR-39 and its functional domain, PR-26, may potentiate the host's defense capabilities against gram-negative infections.

Amino Acid Sequence↗
PubMed1996

Effect of molybdenum-induced copper deficiency on in vivo and in vitro measures of neutrophil chemotaxis both before and following an inflammatory stressor.

Twelve Angus x Hereford heifers (avg wt = 183.6 kg) were allotted by initial liver copper (Cu) concentrations into one of two treatments. Control (n = 6) heifers were fed a basal diet supplemented to provide a dietary Cu level of 10 ppm. Molybdenum (Mo)-induced Cu-deficient heifers (n = 6) were fed an identical basal diet supplemented with sodium molybdate (Cu:Mo ratio = 1:2.5), with dietary sulfur at .3% of the total diet. Dietary treatments were delivered for 120 d, at which time Mo-supplemented heifers were considered Cu-deficient (286 and 49 ppm liver Cu for control and Mo-induced Cu-deficient, respectively). Peripheral blood neutrophils were enumerated both before and after the administration of an inflammatory stressor, a subcutaneous injection (1.5 mL) of Freund's complete adjuvant. In vitro and in vivo measures of neutrophil chemotaxis were evaluated and the expression of two adhesion molecules, CD18 and L-selectin, were analyzed by flow cytometric procedures. Molybdenum-induced Cu deficiency increased (P < .01) the number of peripheral blood neutrophils; however, in vitro neutrophil chemotaxis was not affected. In vivo neutrophil chemotaxis tended (P < .08) to be increased in Mo-induced Cu-deficient heifers (1.55 vs 2.26 x 10(6) cells/ sponge for control and Mo-supplemented, respectively). No differences in CD18 or L-selectin expression were detected between treatments. However, CD18 expression was decreased (P < .05) in both treatments following adjuvant injection. These data suggest that Mo-induced Cu deficiency results in an increase in peripheral blood neutrophil number, without altering chemotactic ability and adhesion molecule expression.

Analysis of Variance↗
PubMed1996

The effect of molybdenum-induced copper deficiency on acute-phase protein concentrations, superoxide dismutase activity, leukocyte numbers, and lymphocyte proliferation in beef heifers inoculated with bovine herpesvirus-1.

This study was conducted to determine the effect of Cu deficiency on acute-phase protein concentrations, superoxide dismutase activity, leukocyte numbers, and lymphocyte proliferation in heifers inoculated with live bovine herpesvirus-1 (BHV-1). Hereford x Angus heifers were allotted by weight and initial liver Cu concentrations into molybdenum (Mo)-supplemented (n = 6) or control (n = 6) groups. Control heifers were fed a basal diet supplemented with Cu-sulfate to achieve a dietary concentration of 8 ppm of Cu. The Mo-supplemented heifers received the basal diet supplemented with Mo to achieve a dietary Mo:Cu ratio of 2.5:1 and with sulfur at .3% of the diet. All treatments were delivered for 129 d, when heifers were inoculated intranasally with BHV-1. To ensure adequate Cu stores before viral challenge, control heifers were given a cupric glycinate injection on d 100 of treatment. On d 129, Mo-supplemented heifers were considered Cu-deficient (liver Cu = 23.2 and 90.1 ppm for Mo-supplemented and control, respectively). Neutrophils were increased (P < .01) on d 129 in Mo-supplemented heifers. Ceruloplasmin, a copper-dependent acute-phase protein, increased (P < .01) by 48 h after challenge in control but not in Mo-supplemented heifers. Fibrinogen, an acute-phase protein not containing copper, increased by 48 h after challenge in Mo-supplemented but not in control heifers. Erythrocyte superoxide dismutase (SOD) activity was less (P < .05) in Mo-supplemented heifers on d 129. Viral challenge had no effect on SOD activity. Lymphocyte proliferative response to phytohemagglutinin stimulation was greater (P < .01) for Mo-supplemented heifers following BHV-1 challenge. No differences were detected when lymphocytes were stimulated with concanavalin-A or pokeweed mitogens. These data indicate that Cu deficiency alters the acute-phase protein response to viral infection and may affect lymphocyte responsiveness to mitogen stimulation.

Acute-Phase Proteins↗
PubMed1996

Influence of lipopolysaccharide-induced immune challenge and diet complexity on growth performance and acute-phase protein production in segregated early-weaned pigs.

Segregated early-weaned pigs (initially 4.0 kg and 14 +/- 1.5 d of age) were used to quantify the effects of lipopolysaccharide (LPS)-induced immune challenge and nursery diet complexity (complex, medium, and simple) on growth performance and haptoglobin production. Three treatments of immune challenge consisted of pigs given ad libitum access to feed (control), challenged with LPS and given ad libitum access to feed (LPS-challenged), or pair-fed to receive the same amount of feed as the LPS-challenged pigs (pair-fed). The absence of interactions (P > .10) between diet complexity and immune challenge with LPS indicated that the responses were independent. Control pigs were the heaviest (P < .01), LPS-challenged the lightest (P < .01), and pair-fed intermediate in weight on d 18 after weaning. Approximately two thirds of the decreased growth of LPS-challenged pigs was due to decreased ADFI and one third was due to decreased feed efficiency (G/F). Pigs fed the complex diet were heaviest (P < .05), and pigs fed the simple diet were lightest (P < .05) on d 18 after weaning. The increased growth of pigs fed the complex compared with those fed the medium diet was due to the increased ADFI of the former. The decreased growth of pigs fed the simple diet compared with those fed the medium or complex diets was due to both decreased ADFI and G/F. The LPS-challenged pigs had increased (P < .01) haptoglobin concentrations, suggesting that inflammatory cytokine production was higher in immune-challenged pigs. These data suggest that LPS immune challenge caused decreased growth by decreasing ADFI and altering nutrient partitioning and that growth responses to diet complexity are independent of immune challenge.

Acute-Phase Proteins↗
PubMed1995

Lipopolysaccharide modulation of a CD14-like molecule on porcine alveolar macrophages.

Cluster of differentiation antigen 14 (CD14) functions as a receptor for lipopolysaccharide (LPS) LPS-binding protein (LBP) complexes. Because LPS has varying effects on CD14 expression in vitro, we evaluated CD14 expression in response to LPS with a fully differentiated macrophage phenotype, the alveolar macrophage. By using flow microfluorometric analysis and a radioimmunoassay with an anti-human CD14 monoclonal antibody (My4) that cross-reacts with porcine CD14, we found that macrophages stimulated with LPS for 24 h exhibited a two- to fivefold increase in CD14-like antigen compared with unstimulated cells. At low concentrations of LPS, up-regulation of the CD14-like antigen was dependent on serum; at higher concentrations of LPS, serum was not required. In the absence of serum a 10-fold higher dose of LPS (10 ng/ml) was required to increase CD14-like expression. In addition, LPS-induced CD14-like up-regulation correlated with secretion of tumor necrosis factor-alpha, regardless of serum concentration. Blockade with My4 antibody significantly inhibited LPS-induced tumor necrosis factor-alpha secretion at 1 ng/ml of LPS. However, inhibition decreased as we increased the LPS concentration, suggesting the existence of CD14-independent pathways of macrophage activation in response to LPS. Alternatively, My4 may have a lower affinity for the porcine CD14 antigen than LPS, which may have only partially blocked the LPS-LBP binding site at high concentrations of LPS. Therefore, these data suggest that LPS activation of porcine alveolar macrophages for 24 h increased CD14-like receptor expression. The degree of CD14-like up-regulation was related to LPS concentration, however, activation did not require the presence of serum at high concentrations of LPS.

Animals↗
PubMed1995

CD14 and other recognition molecules for lipopolysaccharide: a review.

Lipopolysaccharide (LPS) or endotoxin elicits a broad, non-specific cascade of events in vivo, resulting in secretion of a variety of potent mediators and cytokines produced primarily by activated macrophages and monocytes. The overproduction of these effector molecules, such as interleukin-1 and tumor necrosis factor-alpha, contributes to the pathophysiology of endotoxic shock. Cellular recognition of LPS involves several different molecules, including cluster of differentiation antigen CD14. A thorough understanding of the interaction of LPS with cells of the immune system is necessary before effective preventative or therapeutic measures can be designed to limit the host response to endotoxin. This review discusses the role of CD14 and other LPS-recognition molecules in LPS-mediated macrophage activation.

Acute-Phase Proteins↗
PubMed1995

Influence of recombinant bovine interleukin-1 beta and interleukin-2 in pigs vaccinated and challenged with Streptococcus suis.

An experiment was conducted to determine the adjuvanticity of recombinant bovine IL-1 beta (rBoIL-1 beta) and recombinant bovine IL-2 (rBoIL-2) administered in conjunction with a single Streptococcus suis vaccination in pigs. Sixty 4-week-old pigs were allotted to eight groups: nonvaccinated controls; vaccinated controls; rBoIL-beta at 0.1, 1, and 10 micrograms kg-1; rBoIL-2 at 2.5, 25, and 250 micrograms kg-1. All pigs (except nonvaccinated controls) were vaccinated on Day 0 with a commercial Streptococcus suis vaccine (serotypes 1 and 2). At vaccination, pigs were injected intramuscularly with their respective cytokine treatments. Pigs received additional cytokine injections on 2 consecutive days. On Day 21, all pigs were challenged intravenously with 3.2 x 10(9) colony forming units of a log phase culture of S. suis (serotype 2). The highest dose of rBoIL-1 beta exceeded the maximum tolerable dose for the cytokine; however, this dose of rBoIL-1 beta protected pigs from the S. suis challenge. Pigs administered rBoIL-1 beta at 10 micrograms kg-1 had higher antibody responses to S. suis, less severe clinical signs of the disease after challenge, better growth performance during the infection, and less severe gross pathological lesions caused by the bacteria. No pigs in this treatment group died from the bacterial challenge. These data suggest that rBoIL-1 beta (10 micrograms kg-1), administered intramuscularly for 3 consecutive days at vaccination, is more effective than a single S. suis vaccination alone in protecting pigs against a S. suis challenge.

Adjuvants, Immunologic↗
PubMed1995

Influence of dietary beta-glucan on growth performance, nonspecific immunity, and resistance to Streptococcus suis infection in weanling pigs.

Three experiments, using 344 pigs, were conducted to evaluate the influence of beta-glucan on growth performance, neutrophil and macrophage function, haptoglobin production, and resistance to Streptococcus suis challenge in weanling pigs. In Exp. 1, 144 pigs were used to evaluate the influence of .1% dietary beta-glucan in a soybean meal- or milk protein-based diet on growth performance and neutrophil function. Pigs fed beta-glucan from d 7 to 14 after weaning had lower ADFI (P < .01) and, although not significant, ADG was lower for pigs fed beta-glucan than for pigs fed control diets. However, no differences were observed in growth performance or neutrophil function for pigs fed control or diets containing beta-glucan from d 7 to 35 after weaning. Experiment 2 was a 28-d growth assay in which pigs were fed a diet with or without .1% beta-glucan, containing 7.5% spray-dried plasma protein and 25% dried whey from d 0 to 14 after weaning. Pigs then were fed corn-soybean mealbased diets containing 2.5% spray-dried blood meal and 10% dried whey. No differences in growth performance were observed. Experiment 3 was a 35-d assay to evaluate growth performance, neutrophil and macrophage function, and plasma haptoglobin concentration. Pigs were challenged on d 28 postweaning with intravenous S. suis. In Exp. 3, pigs were fed diets without or with .025 or .05% beta-glucan. Dietary beta-glucan did not influence neutrophil or macrophage function. However, pigs fed diets containing .025% beta-glucan had increased (P < .05) ADG and ADFI and were heavier (P < .05) on d 28 after weaning than pigs fed the control diet. No differences in feed efficiency (G/F) were detected between treatments. Pigs fed beta-glucan had decreased (P < .10) plasma haptoglobin on d 14, 21, and 28 after weaning. However, Fisher's Exact test revealed that more (P < .04) pigs fed a diet containing .025% beta-glucan died by d 12 after challenge with S. suis. In conclusion, these data suggest the existence of a complex interaction involving growth performance and resistance to S. suis in pigs fed .025% beta-glucan.

Aging↗
PubMed1995

Stress-associated concentrations of plasma cortisol cannot account for reduced lymphocyte function and changes in serum enzymes in lambs exposed to restraint and isolation stress.

Lambs were used to evaluate the effect of stress-associated plasma concentrations of cortisol on measures of immune function. Lambs given restraint and isolation stress (RIS) were isolated from visual and tactile contact with other lambs for 6 h on three consecutive days. Additional lambs were infused with cortisol (CORT) to increase plasma concentrations similar to those in lambs subjected to RIS. Control lambs (CON) were undisturbed. On the 1st and 3rd d of the experiment, plasma was obtained hourly during treatment for quantification of cortisol and ACTH. Blood mononuclear cells were obtained 24 h before the 1st d of treatment and daily at the conclusion of treatment for responses to phytohemagglutinin (PHA), concanavalin A (Con A), and pokeweed mitogen (PWM); for production of interleukin 2 (IL2); and for identification of cells expressing major histocompatibility complex class II antigens (MHCII). Combined fitted profiles of cortisol in RIS and CORT lambs differed (P < .005) from those in CON on both days evaluated. Fitted profiles of cortisol were similar between RIS and CORT lambs on the 1st d of treatment but differed (P < .005) on the 3rd d. Combined fitted profiles of ACTH from CON and CORT lambs differed from those of RIS lambs on both days of treatment (P < .005). Lymphocyte responses to PHA (P < .01), Con A (P < .01), and PWM (P < .07) were less in RIS than in CON but did not differ between CON and CORT. Treatment did not affect IL2 or MHCII. Increased plasma cortisol measured during RIS cannot alone account for reduced lymphocyte proliferative responses.

Adrenocorticotropic Hormone↗
PubMed1995

Effect of copper depletion and repletion on lymphocyte blastogenesis and neutrophil bactericidal function in beef heifers.

Thirty-two beef heifers were used to examine the effect of dietary copper depletion and repletion on neutrophil and lymphocyte functions. Heifers allotted to the control group (C+; n = 8) were fed a basal roughage/concentrate diet with Cu-sulfate supplementation (Cu > or = 8 ppm). To induce a Cu deficiency (depletion phase d 0 to 60), treated (T; n = 24) heifers received a diet supplemented with sulfur (.3% of diet) and sodium molybdate to achieve a Cu:Mo ratio of 1:1.5. Liver biopsies were collected on d 0, 27, and 60. Despite random allocation, T heifers had lower initial liver Cu concentrations (P < .01) than C+ heifers. At the start of the repletion phase (d 0, equal to d 60 of depletion), treated heifers were allotted by liver Cu concentration to three treatments (n = 8/treatment): Cu sulfate (S; Cu = 10 ppm), Cu proteinate (P; Cu = 10 ppm), or a negative control (C-) that remained on Mo and S supplementation. During the repletion phase, livers were biopsied on d 0, 14, and 45. By d 45, both S and P heifers had greater (P < .05) liver Cu concentrations than C- heifers. For both depletion and repletion phases, no treatment differences were detected in liver Mo or S concentrations. Jugular blood was collected on d 0, 27, and 55 of the depletion phase and d 0, 13, and 42 of the repletion phase. Neutrophils were isolated and incubated with Staphylococcus aureus to determine neutrophil bactericidal capacity (NBC).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Influence of interleukin-1 on neutrophil function and resistance to Streptococcus suis in neonatal pigs.

Nonspecific immunity is usually lower in neonates than adults. Consequently, enhancing the neonate's nonspecific immune capability may be beneficial for the health and growth performance of young animals. We conducted two experiments in which neonatal pigs were injected with recombinant bovine interleukin-1 beta (rBoIL-1 beta) at 9 to 11 days of age. Three consecutive daily injections of rBoIL-1 beta increased neutrophil and monocyte numbers, which remained elevated until the animals were challenged with Streptococcus suis at 19 days of age. Neutrophil bactericidal activity was greater in interleukin-1-treated pigs than in saline-injected controls. At lower ratios of effector to target cells, neutrophil-mediated, antibody-dependent cellular cytotoxicity was increased in neonates treated with IL-1. However, natural killer cell activity and neutrophil production of superoxide anion were not affected by treatment with IL-1. Expression of CD18 was increased transiently on neutrophils from IL-1-treated pigs at 15 days of age. Severity of the streptococcal infection was less in pigs that were treated with IL-1 at 9 to 11 days of age. These data suggest that IL-1 treatment in neonates may augment nonspecific immune function and disease resistance.

Animals↗
PubMed1994

Identification of a proline-arginine-rich antibacterial peptide from neutrophils that is analogous to PR-39, an antibacterial peptide from the small intestine.

Neutrophil nonoxidative defense mechanisms include several low molecular weight antimicrobial peptides. We have isolated a proline-arginine-rich antibacterial peptide from porcine neutrophils. This cationic, low molecular weight peptide has a very high degree of identity (97%) to a bactericidal peptide, PR-39, that has been found in the porcine small intestine. Isolation of the same antimicrobial peptide from both neutrophils and cells of the small intestine in the same species is unique and suggests an important role for this protein in innate immune defenses.

Amino Acid Sequence↗
PubMed1994

Workshop studies on monoclonal antibodies reactive against porcine myeloid cells.

Investigators from eight laboratories analyzed the reactivity of 22 monoclonal antibodies (mAb) against porcine myeloid cells. Based on binding data, clustering analysis and inhibition studies, workshop mAb 74-22-15 (003) and 6F3 (007) were assigned a swine workshop cluster number 3 (SWC3). These mAb recognized macrophages and neutrophils; neutrophils; a monocyte/macrophage-specific mAb was not identified by this workshop.

Animals↗
PubMed1994

Competitive binding analysis of monoclonal antibodies reactive with porcine alveolar macrophages using anti-CD14 and anti-CD18.

Four monoclonal antibodies (mAb) from the myeloid subset panel of the First International Swine CD Workshop (74-22-15, DH59B, PM16-6, and MUC21A) were analyzed using competitive inhibition studies with anti-human CD14 (My4) and anti-human/anti-porcine CD18 (MHM23) on porcine alveolar macrophages. Results suggested that none of the mAb tested recognized CD14 or CD18 on porcine alveolar macrophages. Additionally, the cross-reactivity of My4 with porcine alveolar macrophages was established.

Animals↗
PubMed1994

Vitamin concentration and function of leukocytes from dairy calves supplemented with vitamin A, vitamin E, and beta-carotene in vitro.

Blood neutrophils and pulmonary alveolar macrophages, isolated from calves at 3 and 6 wk of age, were cultured in medium without added vitamins or supplemented with 100 micrograms/dl of vitamin A, 1000 micrograms/dl of vitamin E, 100 micrograms/dl of vitamin A plus 1000 micrograms/dl of vitamin E, or .25 micrograms/dl of beta-carotene plus 1000 micrograms/dl of vitamin E. Macrophage bactericidal activity improved with supplementation of vitamins A plus E compared with supplementation of beta-carotene plus E or vitamin E at wk 3. Neutrophil bactericidal activity decreased with all vitamin E treatments at wk 3 and with vitamins E or A plus E at wk 6. Neutrophil phagocytosis improved at wk 3 with supplementations of vitamins A, E, and A plus E. The chemotactic index improved with beta-carotene and vitamin E compared with vitamin E alone at wk 3 and at wk 6 with vitamin E compared with vitamin A and control treatments. Retinol content of neutrophils varied at wk 3, but, by wk 6, cells supplemented with vitamins A, E, or A plus E had greater retinol concentrations than control cells. Neutrophil alpha-tocopherol concentrations at wk 3 increased from those of controls with supplementation of vitamin E or beta-carotene and vitamin E, but, at wk 6, vitamin E-supplemented cells were different only from vitamin A-supplemented cells. These data suggest that optimal plasma concentrations of vitamins A and E exist for leukocyte function.

Animal Feed↗