Effect of dietary mannanoligosaccharide and sodium chlorate on the growth performance, acute-phase response, and bacterial shedding of weaned pigs challenged with Salmonella enterica serotype Typhimurium.
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A 28-d experiment evaluated the growth, acute-phase response, and bacterial shedding patterns in pigs (n = 96; initially 6.8 +/- 1.3 kg) fed mannanoligosaccharides (MANNAN) and sodium chlorate (CHLORATE) before and after oral challenge with Salmonella enterica serotype Typhimurium (ST). The negative control diet contained no antimicrobial (CON), and the positive control contained carbadox (CARB; 55 ppm). Test diets contained (as-fed basis) MANNAN (1,500 ppm) or CHLORATE (800 ppm). Pigs were fed diets for 14 d and then given ST orally. Pigs fed CARB had greater ADG over the entire study than pigs from other treatments (P < 0.05). During wk 1 to 2, before ST challenge, feed intake (as-fed basis) was lower for pigs fed MANNAN and CHLORATE than pigs fed CARB (P < 0.05). During the final 2 wk, pigs fed CARB had greater feed intake than pigs on other treatments (P < 0.05). Gain/feed was greater for pigs fed CARB in the 2 wk before ST (P < 0.05); however, in wk 3 to 4 after ST, gain/feed was reduced for CON pigs compared to pigs on other treatments (P < 0.05). Serum IGF-I was decreased at 2 and 4 d after ST (P < 0.001), and, overall, IGF-I was greater in pigs fed CARB than CON or CHLORATE (P < 0.05). Serum haptoglobin concentrations were greater (P < 0.001) for all treatments at d 6 compared with d 13 after ST. Overall, haptoglobin was greater for MANNAN than for CARB and CHLORATE (P < 0.05) and tended to be increased (P < 0.06) relative to CON. Interleukin-6 was not affected by treatment or day post-ST challenge. Fecal shedding of salmonellae organisms was less for CHLORATE (P < 0.05) than all other treatments at 7 d after ST. Shedding scores decreased from d 7 to 14 after ST (P < 0.05) for the CON, CARB, and MANNAN treatments. We conclude that feeding MANNAN and CHLORATE before acute enteric disease challenge may support improved gut function as evidenced by improved gain/feed, and that CHLORATE may decrease bacterial shedding. But neither MANNAN nor CHLORATE enhanced growth relative to the absence of dietary antimicrobials, nor was either treatment as effective as CARB following ST challenge. (+info)
Alpha C protein of group B Streptococcus binds host cell surface glycosaminoglycan and enters cells by an actin-dependent mechanism.
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Group B Streptococcus (GBS) colonizes mucosal surfaces of the human gastrointestinal and gynecological tracts and causes disease in a wide range of patients. Invasive illness occurs after organisms traverse an epithelial boundary and enter deeper tissues. Previously we have reported that the alpha C protein (ACP) on the surface of GBS mediates GBS entry into ME180 cervical epithelial cells and GBS translocation across layers of these cells. We now demonstrate that ACP interacts with host cell glycosaminoglycan (GAG); the interaction of ACP with ME180 cells is inhibited if cells are pretreated with sodium chlorate, an inhibitor of sulfate incorporation, or with heparitinases. The interaction is also inhibited in the presence of soluble heparin or heparan sulfate or host cell-derived GAG. In addition, ACP binds soluble heparin specifically in inhibition and dot blot assays. After interaction with host GAG, soluble ACP enters ME180 cells and fractionates to the eukaryotic cell cytosol. These events are inhibited in cells pretreated with cytochalasin D or with Clostridium difficile toxin B. These data indicate that full-length ACP interacts with ME180 cell GAG and enters the eukaryotic cell cytosol by a mechanism that involves Rho GTPase-dependent actin rearrangements. We suggest that these molecular interactions drive ACP-mediated translocation of GBS across epithelial barriers, thereby facilitating invasive GBS infection. (+info)
Nitrate reductase activity is required for nitrate uptake into fungal but not plant cells.
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The ability to transport net nitrate was conferred upon transformant cells of the non-nitrate-assimilating yeast Pichia pastoris after the introduction of two genes, one encoding nitrate reductase and the other nitrate transport. It was observed that cells of this lower eukaryote transformed with the nitrate transporter gene alone failed to display net nitrate transport despite having the ability to produce the protein. In addition, loss-of-function nitrate reductase mutants isolated from several nitrate-assimilating fungi appeared to be unable to accumulate nitrate. Uptake assays using the tracer (13)NO(3)(-) showed that nitrate influx is negligible in cells of a nitrate reductase null mutant. In parallel studies using a higher eukaryotic plant, Arabidopsis thaliana, loss-of-function nitrate reductase strains homozygous for both NIA1 insertion and NIA2 deletion were found to have no detectable nitrate reductase mRNA or nitrate reductase activity but retained the ability to transport nitrate. The reasons for these fundamental differences in nitrate transport into the cells of representative members of these two eukaryotic kingdoms are discussed. (+info)
Evaluation of the pharmacokinetics and pharmacodynamics of intravenous lansoprazole.
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AIM: To compare the pharmacokinetics and pharmacodynamics of lansoprazole 30 mg administered intravenously in 0.9% NaCl or in polyethylene glycol, or orally. METHODS: Twenty-nine subjects received lansoprazole orally on days 1-7 and intravenous lansoprazole in NaCl on days 8-14. Blood samples were collected on days 1, 7, 8 and 14. Fasting basal acid output and pentagastrin-stimulated maximal acid output were determined on days -1, 8, 9 and 15. Thirty-six different subjects received one of four regimen sequences: intravenous lansoprazole in NaCl, intravenous in polyethylene glycol, per orally, or intravenous placebo, each for 5 days. Twenty-four hour intragastric pH was recorded on days 1 and 5. RESULTS: Intravenous and per oral lansoprazole for 7 days produced equivalent basal acid output and maximal acid output suppression. Pharmacokinetics and mean pH values with intravenous lansoprazole in NaCl or polyethylene glycol were equivalent. Both produced mean pH and percentages of time pH above 3, 4, 5 and 6 that were significantly greater than did per orally. CONCLUSIONS: Intravenous lansoprazole inhibits acid secretion as effectively in NaCl as in polyethylene glycol, and its onset of action is faster than per oral lansoprazole. (+info)
A novel efflux-recapture process underlies the mechanism of high-density lipoprotein cholesteryl ester-selective uptake mediated by the low-density lipoprotein receptor-related protein.
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OBJECTIVE: To determine the mechanism of low-density lipoprotein (LDL) receptor-related protein (LRP)-mediated selective uptake of high-density lipoprotein (HDL)-derived cholesteryl esters (CE). METHODS AND RESULTS: Apolipoprotein E (apoE) and heparin sulfate proteoglycans are required for LRP-mediated selective uptake in adipocytes. Furthermore, 2-deoxyglucose and NaN(3) abolish this process, indicating that cellular energy is required. LRP-mediated selective uptake is also abolished by monensin or when clathrin-mediated internalization is inhibited (using hypotonic, K(+)-free medium or hyperosmolar sucrose), clearly implicating receptor endocytosis. The receptor-associated protein (RAP), an inhibitor of ligand binding to LRP, reduced the transport of CE into an intracellular compartment but not into the plasma membrane. Remarkably, the CE that is ultimately transported by LRP first enters the plasma membrane then undergoes apoE-mediated CE efflux before being recaptured and internalized by LRP. CONCLUSIONS: According to this "efflux-recapture" model, LRP contributes to selective uptake because it recovers CE that would normally be lost by efflux mediated by apoE. In adipocytes, the LDL receptor-related protein contributes to selective uptake when it recaptures and internalizes HDL-derived cholesteryl esters that are otherwise lost by apoE-mediated efflux. This novel "efflux-recapture" process explains some conflicting observations of selective uptake and underscores the bi-directional nature of efflux. (+info)
Metabolic primers for detection of (Per)chlorate-reducing bacteria in the environment and phylogenetic analysis of cld gene sequences.
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Natural attenuation of the environmental contaminant perchlorate is a cost-effective alternative to current removal methods. The success of natural perchlorate remediation is dependent on the presence and activity of dissimilatory (per)chlorate-reducing bacteria (DPRB) within a target site. To detect DPRB in the environment, two degenerate primer sets targeting the chlorite dismutase (cld) gene were developed and optimized. A nested PCR approach was used in conjunction with these primer sets to increase the sensitivity of the molecular detection method. Screening of environmental samples indicated that all products amplified by this method were cld gene sequences. These sequences were obtained from pristine sites as well as contaminated sites from which DPRB were isolated. More than one cld phylotype was also identified from some samples, indicating the presence of more than one DPRB strain at those sites. The use of these primer sets represents a direct and sensitive molecular method for the qualitative detection of (per)chlorate-reducing bacteria in the environment, thus offering another tool for monitoring natural attenuation. Sequences of cld genes isolated in the course of this project were also generated from various DPRB and provided the first opportunity for a phylogenetic treatment of this metabolic gene. Comparisons of the cld and 16S ribosomal DNA (rDNA) gene trees indicated that the cld gene does not track 16S rDNA phylogeny, further implicating the possible role of horizontal transfer in the evolution of (per)chlorate respiration. (+info)
Disposable diaper to collect urine samples from young children for pyrethroid pesticide studies.
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Disposable diapers are widely used in the US and many other areas in the world; therefore, they are ideal media for urine collection for measurement of young children's exposure to pesticides. However, disposable diapers normally contain polyacrylate polymers that make the extraction and analysis of urine very difficult. The objectives of this paper were to evaluate whether disposable diapers that contain polyacrylate granules can be extracted using salt solutions, and whether they can be used for the collection and quantitative measurements of selected urinary pyrethroid pesticide metabolites and creatinine. The storage stability of the metabolites and creatinine in a wet diaper at body temperature and at refrigeration temperature was also evaluated. Salt solutions including calcium chloride dihydrate, magnesium sulfate, ammonium acetate, and sodium chloride solutions were tested for efficiency of polymer shrinkage. Pyrethroid metabolites 3-(2,2-dichlorovinyl)-2,2-dimethyl-(1-cyclopropane) carboxylic acid (DCCA), 3-(2,2-dibromovinyl)-2,2,dimethyl-(1-cyclopropane) carboxylic acid (DBCA) and 3-phenoxybenzoic acid (3-PBA) were analyzed using LC/MS/MS and evaluated for recoveries in the urine released from the diapers. The study found calcium chloride dihydate to be satisfactory in releasing urine and metabolites from the polymers. The percent recoveries for the three tested pyrethroid metabolites were mostly in the range of 65-130. The percent recoveries for creatinine were in the range of 71-133. The detection limit for each of the three metabolites was 0.1 microg/l. The pyrethroid metabolites and creatinine were stable on the diaper for at least 72 h. We concluded from this study that calcium chloride dihydrate can successfully release urine and metabolites from polyacrylate-containing diapers, and the method is promising for studies of pyrethroid metabolites. (+info)
Hot spot for a large deletion in the 18- to 19-centisome region confers a multiple phenotype in Salmonella enterica serovar Typhimurium strain ATCC 14028.
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Loss of the Salmonella MsbB enzyme, which catalyzes the incorporation of myristate destined for lipopolysaccharide in the outer membrane, results in a strong phenotype of sensitivity to salt and chelators such as EGTA and greatly diminished endotoxic activity. MsbB- salmonellae mutate extragenically to EGTA-tolerant derivatives at a frequency of 10(-4) per division. One of these derivatives arose from inactivation of somA, which suppresses sensitivity to salt and EGTA. Here we show that a second mode of MsbB- suppression is a RecA-dependent deletion between two IS200 insertion elements present in Salmonella enterica serovar Typhimurium strain ATCC 14028 but not in two other wild-type strains, LT2 and SL1344, which lack one of the IS200 elements. This deletion occurs spontaneously in wild-type and MsbB- strain 14028 salmonellae and accounts for about one-third of all of the spontaneous suppressors of MsbB- in strain 14028. It spans the region corresponding to 17.7 to 19.9 centisomes, which includes somA, on the sequenced map of Salmonella LT2 (136 ORFs in that strain; ATCC 14028 and other strains showed variability in this region). In addition to conferring EGTA resistance correlated with somA, the deletion confers a MacConkey galactose resistance phenotype on MsbB- Salmonella, indicating that at least one additional gene (distinct from somA) within the deletion is responsible for this phenotype. In the wild type, the deletion mutant grows with normal exponential growth rate in Luria broth but is chlorate resistant and does not grow on citrate agar. The deletion strains have lost hydrogen sulfide production, nitrate reductase activity, and gas production from glucose fermentation. (+info)