Chlorhexidine susceptibility, virulence factors, and antibiotic resistance of beta-hemolytic Escherichia coli isolated from neonatal swine with diarrhea.
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Animals↗
Biomedical subjects
R C Beier
Publications and source records attributed to R C Beier.
Impact of dietary supplemental methionine sources on sensory measurement of odor-related compounds in broiler excreta.
An experiment was conducted to detect differences in odor characteristics of broiler excreta due to utilization of different supplementary Met sources by a trained human descriptive aroma attribute sensory panel. The 5 treatment groups were no supplemental Met (control group), sodium methioninate aqueous solution, dry Met hydroxy analogue, liquid Met hydroxy analogue, and DL-Met. Two trials were conducted consisting of 5 treatment groups with 3 replications of 13 randomly distributed straight run broiler chicks per pen reared in battery cages. Starter and grower diets were formulated to contain 0.5 and 0.38% Met activity, respectively (except control group, 0.35% Met activity). Excreta were collected for 24 h in litter pans lined with aluminum foil at wk 4, 5, and 6 and analyzed by a trained sensory panel (7 people). Each panelist was given 25 g of manure heated at 27 degrees C for 5 min for sensory analysis. The 13 odor attributes used to determine differences in broiler excreta by the trained sensory panel were ammonia, dirty socks, wet poultry, fermented rotten fruit, hay, musty wet, sharp, sour, urinous, rotten eggs, irritating, pungent, and nauseating. Panelist marked intensities for each attribute ranging from 0 = none and 15 = extremely intense. Each panelist was given 2 replications of each treatment group in a random order each week (total of 10 samples per wk). All data were evaluated by ANOVA using the general linear model procedure of SAS software. No significant differences were observed in BW, feed consumption, or feed conversion among the treatments. The attributes of ammonia, wet poultry, rotten fruit, musty wet, sharp, and pungent differed (P < 0.05) across treatment groups. These findings demonstrate that supplemental Met sources significantly influence odor production in broiler excreta.
Analysis of Variance↗
The impact of supplemental dietary methionine sources on volatile compound concentrations in broiler excreta.
The impact of different Met sources on broiler fecal odor volatiles was determined by evaluating the types of sulfur compounds produced in broiler excreta. Two experiments were conducted using straight-run broiler chicks randomly distributed in battery cages, with 3 replicate pens of 16 birds each. The treatment groups were 1) dry Met hydroxy analogue (dry MetHA), 2) sodium methioninate aqueous solution (NaMet), 3) liquid Met hydroxy analogue (Liq MetHA), 4) D,L- Met, and 5) no supplemental Met (control group). The Met activities of each Met source were 52, 45.9, 88, and 98%, respectively. All diets were formulated to contain either 0.8% (experiment 1) total Met activity or 0.5% Met activity in the starter and 0.38% Met activity in the grower (experiment 2) (except the control group, 0.35% Met activity), but otherwise met NRC nutrient requirements (NRC, 1994). Diets were fed ad libitum from d 1 to 6 wk of age. There were no significant differences in BW among the treatments. All excreta were collected in litter pans lined with aluminum foil. In experiment 1, at wk 6, broiler excreta were collected for a 24-h period, and 4.5 g of broiler excreta from each treatment group was collected into 15-mL headspace vials. Samples were analyzed by gas chromatography/mass spectrometry (GC/MS). The volatile sulfur compounds that were identified and quantified in the broiler excreta were H2S, carbonyl sulfide (COS), methyl mercaptan (CH3SH), dimethyl disulfide (CH3SSCH3), and dimethyl trisulfide (CH3SSSCH3). The NaMet treatment group had significantly higher concentrations of H2S, COS, and CH3SSCH3 compared with all other treatment groups. The Liq MetHA group had significantly lower concentrations of H2S, COS, CH3SH, and CH3SSCH3 compared with the other treatment groups. The dry MetHA group significantly had the highest concentration of CH4SH. The D,L-Met treatment group had the significantly highest concentration of CH3SSSCH3 and the lowest concentration of H2S. The control group had the significantly lowest concentrations of CH3SH, CH3SSCH3, and CH3SSSCH3 compared with the other treatment groups. In experiment 2, at wk 6, an electronic nose was used to evaluate 15 air samples per treatment group. In addition, 15 air samples (containing 6 to 8 L of air in a Tedlar bag, 3 samples per treatment group) were collected for odor evaluation by a sensory panel. Electronic nose sensor data revealed that volatile compounds in broiler excreta from the control group were significantly different from the other 4 treatment groups. Evaluation of the air samples by a sensory panel determined that there was a statistically significant difference in odor threshold detection between the control group and the other treatment groups. The dilutions to threshold of control group, NaMet, dry MetHA, Liq MetHA, and D,L-Met were 350, 492, 568, 496, and 526 odor units, respectively. These findings demonstrate that dietary Met sources significantly influenced odorous volatile concentrations in broiler excreta.
Animals↗
Production, characterization, and cross-reactivity studies of monoclonal antibodies against the coccidiostat nicarbazin.
A cELISA was developed for the coccidiostat nicarbazin. On the basis of previous computer-assisted molecular modeling studies, p-nitrosuccinanilic acid (PNA-S) was selected as a hapten to produce antibodies to 4,4'-dinitrocarbanilide (DNC), the active component of the coccidiostat nicarbazin. Synthesis is described for the hapten [p-nitro-cis-1,2-cyclohexanedicarboxanilic acid (PNA-C)] used in a BSA conjugate as a plate coating antigen. Monoclonal antibodies (Mabs) were isolated that compete with nicarbazin, having IgM(kappa) isotype. Because of the lack of water solubility of nicarbazin, N,N-dimethylformamide (DMF) (3%, v/v) and acetonitrile (ACN) (10%, v/v) were added to the assay buffer to achieve solubility of nicarbazin and related compounds. The Nic 6 Mabs had an IC(35) value for nicarbazin of 0.92 nmol/mL, with a limit of detection of 0.33 nmol/mL. Nic 6 exhibited high cross-reactivity for PNA-S and PNA-C, and 3-nitrophenol, 4-nitrophenol, and 1-(4-chlorophenyl)-3-(4-nitrophenyl) urea. However, Nic 6 had little or no cross-reactivity with 15 other related compounds.
Animals↗
Occurrence of the toxin dehydroabietic acid in Salmonella typhimurium.
Many strains of Salmonella typhimurium studied in our lab demonstrated marked differences in the pathogenicity for guinea pig, chicken and Hela cells. As a result, a pathogenic strain of S. typhimurium, strain 9SR2, was evaluated for lipophilic components that may be associated with virulence using gas chromatography/mass spectrometry. The hydroxylated fatty acids 2-hydroxytetradecanoic acid (2-OH-14:0) and 3-hydroxytetradecanoic acid (3-OH-14:0) often present in lipid A, a potent endotoxin, were observed as their methyl esters. The cyclic fatty acids methylene-hexadecanoic acid (C17delta) and methyleneoctadecanoic acid (C19delta) also were detected. The nephrotoxic and neurotoxic diterpenoid resin acid, dehydroabietic acid, was observed for the first time from S. typhimurium in both the total lipid and diglyceride fractions and determined as its methyl ester at m/z 314.2246. Due to its previously established toxicity, dehydroabietic acid may be a factor associated with virulence of S. typhimurium.
Abietanes↗
Development of a monoclonal antibody-based cELISA for the analysis of sulfadimethoxine. 1. Development and characterization of monoclonal antibodies and molecular modeling studies of antibody recognition.
Sulfonamide antibiotics are used to treat a variety of bacterial and protozoan infections in cattle, swine, and poultry. Current residue methods for the analysis of sulfonamides in animal-based food products include bioassays, chromatographic methods (HPLC, GLC), and immunoassays. Most immunoassays have employed highly specific polyclonal antibodies. In this paper, we describe the isolation of monoclonal antibodies against sulfadimethoxine (SDM) that vary in their sensitivities and cross-reactivities against a large number of sulfonamides. The most sensitive monoclonal antibody, designated SDM-18, exhibits an IC(50) value for SDM of 1.53 ppb. Another monoclonal antibody, designated SDM-44, exhibits IC(50) values for six sulfonamides well below the established threshold level of 100 ppb for animal tissues. Molecular modeling studies of the cross-reactive drugs suggest that, depending on the monoclonal antibody, both steric and electronic features govern antibody binding. Due to the diversity of these monoclonal antibodies, it should be possible to design both compound- and class-specific monoclonal antibody-based immunoassays.
Animals↗
Development of a monoclonal antibody-based cELISA for the analysis of sulfadimethoxine. 2. Evaluation of rapid extraction methods and implications for the analysis of incurred residues in chicken liver tissue.
Several rapid extraction methods were evaluated for use with a monoclonal antibody-based competitive inhibition ELISA (cELISA) to detect sulfadimethoxine (SDM) in chicken liver tissue. These methods included extraction of the samples with (1) aqueous buffer with or without ultrafiltration, (2) acetonitrile/water, (3) methanol/water, or (4) acetone. The organic extraction methods were evaluated with or without solvent evaporation prior to dilution into assay buffer for the cELISA. The aqueous-based extraction methods were compatible with the cELISA. However, of the organic extraction methods, only the acetone liver extract with solvent evaporation prior to analysis was compatible with the cELISA. The cELISA method coupled to aqueous- or acetone-based sample extraction as well as an HPLC method was evaluated for the analysis of chicken liver tissues fortified with SDM at levels from 0.2 to 0.025 ppm. Mean SDM recoveries for the HPLC method and for the cELISA method using samples prepared by aqueous extraction, aqueous extraction and ultrafiltration, or acetone extraction, evaporation, and reconstitution were 68.9, 95.7, 60.1, and 52.5%, respectively. For the analysis of samples obtained from an SDM incurred residue study, HPLC and cELISA analysis of the same organic extract gave results that were highly correlated (R(2) = 0.976; p < 0.0001). However, results obtained from the analysis of aqueous extracts by cELISA did not correlate well with those obtained by HPLC (R(2) = 0.61, p > 0. 0006). This was attributed to the coextraction of cross-reactive SDM-related residues that were not quantified by the HPLC method. The presence of these residues should be considered during data interpretation when ELISA methods coupled with rapid aqueous extraction of samples are used in SDM residue monitoring programs.
Animals↗
Molecular models for the stereochemical structures of fumonisin B1 and B2.
Assessment of the structural configuration of fumonisin B1 (FB1) and B2 (FB2) would allow better understanding of the behavior of these molecules during isolation or other handling procedures, and their interaction with binding sites or antibodies. Molecular models of the absolute configurations of FB1 and FB2 were calculated using a CAChe WorkSystemtrade mark. The electrostatic potential energy surfaces of the minimum potential energy conformations for FB1 and FB2 also were obtained. The models reveal that the backbone and acid side chains for FB1 and FB2 form a spherical globular model. The folded region forms a cage-like feature. It is this feature that suggests that these molecules may be potential chelators. The electrostatic potential surfaces show that most of the exposed surfaces of these molecules are hydrophobic in nature, and that there is a distinct difference between the electrostatic potential surfaces of the FB1 models resulting from the stereochemistry proposed by Shier et al. (1995) and Boyle and Kishi (1995a). The electrostatic surfaces clearly show a different orientation of the hydrophobic tail region of the backbone for FB2 than in the models for FB1.
Carboxylic Acids↗
Isopimpinellin is not phototoxic in a chick skin assay.
Synthetic isopimpinellin (5,8-dimethoxypsoralen), confirmed to contain as impurities only trace quantities at most of psoralen, bergapten (5-methoxypsoralen) and xanthotoxin (8-methoxypsoralen), is not phototoxic when tested in a chick skin bioassay system. These findings are at variance with earlier studies showing isopimpinellin to be phototoxic against chick skin and support the conclusion that isopimpinellin is photobiologically inactive. As recently proposed by others, the several reports of isopimpinellin photoactivity are most likely attributable to contamination by small amounts of highly active psoralens such as bergapten or xanthotoxin.
Animals↗
Pseudodipeptide analogs of the pyrokinin/PBAN (FXPRLa) insect neuropeptide family containing carbocyclic Pro-mimetic conformational components.
Three N-terminal amino acid residues of the C-terminal core pentapeptide Phe-X-Pro-Arg-Leu-NH2 (X = Gly, Ser, Thr, Val) of the pryokinin/PBAN insect neuropeptide family were replaced by nonpeptide moieties. To reestablish some of the conformational properties lost upon removal of the peptide bonds and Pro of the three amino acid residue block, carbocyclic Pro-mimetic components were incorporated into pseudodipeptide analogs. The most active analog contained a trans-DL-1,2-cyclopentanedicarboxyl carbocyclic component and proved to be over 3 orders of magnitude more potent than a simple, straight chain pseudodipeptide analog and approached the potency of the pentapeptide core in a cockroach hindgut myotropic bioassay. The pseudodipeptide analog retains a critical carbonyl residue which can participate in a hydrogen bond that stabilizes a beta-turn conformation in the active core region of the pyrokinin/PBAN peptides. This study demonstrates that knowledge of active conformation can be used to enhance the biological potency of pseudopeptide mimetic analogs of insect neuropeptides. The analogs represent a milestone in the development of pseudopeptide and nonpeptide mimetic analogs of this peptide family, which has been associated with such critical physiological processes as hindgut and oviduct contraction, pheromone biosynthesis, diapause induction, and induction of melanization and reddish coloration in a variety of insects. Mimetic analogs are potentially valuable tools to insect neuroendocrinologists studying these physiological processes and/or engaged in the development of future pest management strategies.
Amino Acid Sequence↗
Calculated three dimensional structures of the fumonisin B1-4 mycotoxins.
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Carcinogens, Environmental↗
Diuretic activity of C-terminal group analogues of the insect kinins in Acheta domesticus.
A series of insect kinin analogues, AFFPWG-X, modified at the C-terminal group, were evaluated in a cricket Malpighian tubule secretion bioassay. The results were compared with activity profiles observed in a cockroach hindgut myotropic bioassay for these analogues. Although the replacement of the C-terminal amide group with a negatively charged acid leads to a precipitious drop in diuretic activity, it can be partially restored with the introduction of ester groups such as methyl or benzyl. The presence of branched chain character in the C-terminal group or a C-terminal alpha-carbon-amide distance spanning five methylene group spacers is incompatible with the receptor interaction required for biological activity. Significant diuretic activity is retained with four or fewer methylene groups in this region. C-terminal group analogues containing -SCH3, -NHCH2CH2OCH3, or -OCH2(C6H5) offered the greatest retention of diuretic activity while providing increased hydrophobicity and/or steric bulk. The data are of potential value in the development of mimetic analogues of this insect neuropeptide family. Mimetic analogues are potentially valuable tools to insect neuroendocrinologists studying diuresis and/or engaged in the development of future pest management strategies.
Amino Acid Sequence↗
Effect of lyophilization in sucrose plus dextran and rehydration in thioglycollate broth on performance of competitive exclusion cultures in broiler chicks.
Cecal bacteria grown under continuous-flow anaerobic conditions were lyophilized in skim milk (SM), Reagent 20 (R-20; sucrose and bovine serum albumin fraction V), or sucrose plus dextran (SDx), rehydrated in drinking water or thioglycollate-beef broth (TGB), and compared with fresh broth culture for control of Salmonella typhimurium enteric colonization in broiler chicks. All groups were challenged on Day 3 with 10(4) cfu of S. typhimurium per chick. Mean Salmonella colony-forming units in cecal contents of groups provided lyophilized cultures rehydrated in TGB were not different from those in groups provided fresh broth culture and were reduced (P < .05) compared with controls at 10 d of age. Likewise, groups treated with the cultured lyophilized in R-20 and SDx and rehydrated in TGB had fewer Salmonella than similar groups treated with culture rehydrated in water. The results of this study indicated that the culture was as effective when lyophilized in SDx as it was when lyophilized in SM or R-20; culture lyophilized in SDx, SM, or R-20 and rehydrated in TGB was more effective than when it was rehydrated in water for the reduction of Salmonella colonization in broiler chicks.
Animals↗
Effect of dietary lactose and cell concentration on the ability of a continuous-flow-derived bacterial culture to control Salmonella cecal colonization in broiler chickens.
The effect of dietary lactose and of cell concentration of a continuous-flow (CF) derived bacterial culture on Salmonella typhimurium cecal colonization in 10-d-old broiler chickens was examined. One-day-old chicks were provided 1) no CF culture and the control diet; 2) no culture and a 2% lactose diet; 3) CF culture (10(8) or 10(11) anaerobic cfu) and control diet; or 4) CF culture (10(8) or 10(11) anaerobic cfu) and 2 to 4% lactose diet. All groups were challenged orally with 10(4) S. typhimurium at 3 d of age. Salmonella typhimurium growth in cecal contents was significantly decreased (P < .05) at 10 d of age when 2% lactose was used in combination with CF culture containing 10(8) or 10(11) anaerobic cfu. The protection factor (log10 Salmonella control diet divided by log10 Salmonella treatment group) for these treatment groups was 2.49 and 9.26, respectively. Results indicate that birds treated with CF culture and maintained on 2% dietary lactose are protected against S. typhimurium colonization. Additionally, inoculating birds with CF culture containing a higher concentration of anaerobic colony-forming units resulted in a substantially higher protection factor.
Animals↗
Comparison of effects of chicken cecal microorganisms maintained in continuous culture and provision of dietary lactose on cecal colonization by Salmonella typhimurium in turkey poults and broiler chicks.
A mixed bacterial culture derived from the cecal contents of an adult broiler chicken was maintained in continuous-flow culture and tested for effectiveness in Salmonella colonization reduction in broiler chicks and turkey poults. Day-old chicks and poults in two separate experiments were divided into four groups and provided a standard corn-soybean diet with: 1) no culture, no lactose (control); 2) 5% dietary lactose; 3) broth culture by crop gavage; 4) culture by crop gavage and 5% lactose. All groups were challenged orally on Day 3 with 10(4) Salmonella typhimurium. At 10 and 21 d of age the chicks provided culture and lactose had significantly (P < .05) fewer Salmonella per gram of cecal contents than controls. Poults provided culture by gavage and lactose also had significantly (P < .05) fewer Salmonella per gram of cecal contents than control poults, but the number was 100- to 1,000-fold higher than that of the chicks provided the same treatment. The percentage of Salmonella cecal-culture-positive chicks provided culture and lactose was significantly reduced at 10 and 21 d of age in both experiments compared with controls, but the percentage of cecal-culture-positive poults was significantly different from controls only at 21 d in one of the two experiments. Chicks provided culture and lactose had significantly fewer Salmonella colony-forming units per gram and significantly fewer cecal-culture-positive birds than poults provided culture and lactose in both experiments. The results indicate that cultures of cecal bacteria that effectively reduce Salmonella colonization in broiler chicks may not be as effective for reduction of Salmonella colonization in turkey poults.
Animals↗
Resistance against Salmonella enteritidis cecal colonization in Leghorn chicks by vent lip application of cecal bacteria culture.
Leghorn chicks were treated with cultures of cecal bacteria from adult chickens by crop gavage, upper body spray, or vent lip application on the day of hatch. The chicks were challenged orally with 10(4) Salmonella enteritidis (SE) at 3 d of age and evaluated for SE cecal colonization at 10 d of age. The concentration of volatile fatty acids (VFA) in the cecal contents was determined on the day after culture treatment and at 10 d of age. Compared with controls, SE colonization was significantly decreased in each of the treatment groups. Vent lip application of a single .05-mL drop of cecal bacteria culture resulted in resistance against SE challenge comparable to crop gavage or spray treatment with .5 mL of culture. Resistance to SE challenge was directly associated with the concentrations of total VFA and propionic acid in the cecal contents of the treated chicks on the day after culture treatment. The results indicated that cecal bacteria from adult chickens that increase SE colonization resistance may rapidly become established in the ceca of newly hatched chicks following contact with the vent lips.
Administration, Rectal↗
Effect of cecal cultures lyophilized in skim milk or reagent 20 on Salmonella colonization in broiler chicks.
Mixed cultures of cecal bacteria that were grown under continuous flow anaerobic conditions were prepared as lyophilized powder in skim milk or Reagent 20 (R-20; a mixture containing sucrose and bovine serum albumin fraction V) and compared with broth cultures for reduction of Salmonella typhimurium enteric colonization. Day old broiler chicks were provided a standard corn-soybean diet with: 1) no culture, (control); 2) broth culture administered by crop gavage; 3) broth culture added to the drinking water; 4) culture lyophilized in skim milk and added to drinking water; 5) culture lyophilized in skim milk in gelatin capsules and force-fed; 6) culture lyophilized in R-20 and added to drinking water; and 7) culture lyophilized in R-20 in gelatin capsules and force-fed. All groups were challenged on Day 3 with 10(4) cfu of S. typhimurium per chick. Culture by crop gavage, culture in the drinking water, skim milk powder in capsules, and R-20 powder in the water and in capsules significantly (P < .05) reduced mean Salmonella colony-forming units in cecal contents by 3.21 to 5.26 log10 units at 10 d of age. Likewise, the number of cecal-culture-positive chicks in the same groups was significantly less than controls with reductions of 27 to 67%. The numbers of Salmonella per gram of cecal contents and the percentage of cecal-culture-positive chicks in the skim milk powder in the drinking water group were not different from control chicks in one of two experiments.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Isolation of the major component in white snakeroot that is toxic after microsomal activation: possible explanation of sporadic toxicity of white snakeroot plants and extracts.
Tremetone, the major toxic component in white snakeroot (Eupatorium rugosum Houtt) extracts, was isolated following an in vitro bioactivity assay. Microsomal activation was required to produce a product toxic to murine melanoma (B16F1) cells as well as five other mammalian cell cultures. The metabolic activation product(s) of tremetone is suspected to be responsible for the toxic activity of the plant. Tremetone is also smoothly converted to dehydrotremetone in the plant and cell free homogenates, and readily decomposes to dehydrotremetone in extracts. Dehydrotremetone is not toxic even after microsomal activation. The efficient conversion of tremetone to dehydrotremetone may explain why white snakeroot plant material and extracts have varied activities, and why a previous claim that tremetone was responsible for the toxic activity of white snakeroot was withdrawn. Rayless goldenrod extracts show the same toxic activity as white snakeroot and the toxic activity of rayless goldenrod is most likely due to tremetone.
Animals↗