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phosphoserine aminotransferase, the second step-catalyzing enzyme for serine biosynthesis.as a step toward analyzing the serine biosynthetic pathway in mammals, we have studied the properties of phosphoserine aminotransferase, the second step-catalyzing enzyme. the k(m) values for 3-phosphohydroxypyruvate and l-phosphoserine are 5 and 35 microm, respectively, and those for glutamate and alpha-ketoglutarate are 1.2 and 0.8 mm, respectively. the product inhibition studies strengthened the support for a ping-pong mechanism and allowed evaluation of ki values for the four substrates. the ...199910637769
effect of ph on survival, thermotolerance, and verotoxin production of escherichia coli o157:h7 during simulated fermentation and storage.heat treatment is increasingly being introduced to fermented meat processing, since the acid tolerance properties of escherichia coli o157:h7 can permit this organism to survive traditional processing procedures. this study investigated the effect of growth ph and fermentation on the thermotolerance at 55 degrees c of e. coli o157:h7 in a model fermented meat system. e. coli o157:h7 (strain 380-94) was grown at ph 5.6 or 7.4 (18 h at 37 degrees c), fermented to ph 4.8 or 4.4 in brain heart infus ...200010643763
interventions to reduce microbiological contamination of beef variety meats.hot water and solutions of acetic acid, lactic acid, or trisodium phosphate applied by immersion or spraying, chlorine solution applied by immersion, and exposure to steam in a pasteurization system, in a cabinet, or in combination with vacuum were evaluated for their effectiveness in reducing levels of bacterial contamination on samples of beef cheek meat, large intestine, lips, liver, oxtail, and tongue. treated samples (five per treatment) and controls were analyzed for aerobic plate counts ( ...200010643768
comparison of membrane filtration rates and hydrophobic grid membrane filter coliform and escherichia coli counts in food suspensions using paddle-type and pulsifier sample preparation procedures.food suspensions prepared by pulsifier contained less debris and filtered 1.3x to 12x faster through hydrophobic grid membrane filters (hgmfs) than those prepared by stomacher 400. coliform and escherichia coli counts made by an hgmf method yielded 84 and 36 paired samples, respectively, positive by both suspending methods. overall counts of pulsificates and stomachates did not differ significantly for either analysis, though coliform counts by pulsifier were significantly higher in mushrooms an ...200010643783
inhibition of protein phosphatase-1 by clavosines a and b. novel members of the calyculin family of toxins.site-directed mutagenesis was used to investigate the mechanism of interaction between the catalytic subunit of human protein phosphatase-1 (pp-1cgamma) and members of the calyculin family of toxins. clavosines a and b are related to calyculins but are glycosylated with a trimethoxy rhamnose group. we provide experimental evidence implicating tyr-134 as an important residue in pp-1cgamma that mediates interactions with the calyculins. mutation of tyr-134 to phe, to prevent hydrogen bond formatio ...200010660582
rapid and sensitive detection of escherichia coli o157:h7 in bovine faeces by a multiplex pcr.cattle are considered the major reservoir for escherichia coli o157:h7, one of the newly emerged foodborne human pathogens of animal origin and a leading cause of haemorrhagic colitis in humans. a sensitive test that can accurately and rapidly detect the organism in the food animal production environment is critically needed to monitor the emergence, transmission, and colonization of this pathogen in the animal reservoir. in this study, a novel multiplex polymerase chain reaction (pcr) assay was ...199910664910
purification and characterization of chitin-binding proteins from the hemolymph of sweet potato hornworm, agrius convolvuli.three chitin-binding proteins (cbps: cbp9, cbp15, cbp66) were identified from the larval hemolymph of sweet potato hornworm, agrius convolvuli. two (cbp9 and cbp15) of them have been isolated and purified by gel filtration (superdex hr 75), cation-exchange chromatography (mono s), and reverse-phase chromatography (murpc pc 2.1/3). in experiments to detect cbps in hemolymph, we examined whether ionic strength and existence of bovine serum albumin in the incubation solution influenced binding affi ...199910665375
a longitudinal study of shiga-toxigenic escherichia coli (stec) prevalence in three australian diary herds.over a 12 month period, 588 cattle faecal samples and 147 farm environmental samples from three dairy farms in southeast queensland were examined for the presence of shiga-toxigenic escherichia coli (stec). samples were screened for shiga toxin gene (stx) using pcr. samples positive for stx were filtered onto hydrophobic grid membrane filters and stec identified and isolated using colony hybridisation with a stx-specific dna probe. serotyping was performed to identify serogroups commonly associa ...200010665540
cloning and expression of glycolipid transfer protein from bovine and porcine brain.glycolipid transfer protein (gltp) is a small (23-24 kda), basic protein (pi congruent with 9.0) that accelerates the intermembrane transfer of various glycolipids. here, we report the first cloning of cdnas that encode the bovine and porcine gltps. the cdna open reading frame for bovine gltp was constructed by bridge-overlapping extension polymerase chain reaction (pcr) after obtaining partial coding cdna clones by hot start, seminested, and rapid amplification of cdna ends-pcr. the cdna open r ...200010671554
subtypes of intimin among non-toxigenic escherichia coli from diarrheic calves in brazil.one hundred and five strains of escherichia coli that were isolated from calves with diarrhea in the state of são paulo, brazil, and were negative for enterotoxins and cytotoxins, were examined for the eae gene. four (3.8%) strains were positive by polymerase chain reaction (pcr) and were shown to produce intimin by using western blot with specific antiserum against the conserved n-terminal region of intimin. subtyping of the intimins was done by pcr with specific primers and by western blot wit ...200010680651
clonal turnover of enterohemorrhagic escherichia coli o157:h7 in experimentally infected cattle.a total of 401 enterohemorrhagic escherichia coli (ehec) o157:h7 isolates from two experimentally infected calves were analyzed using molecular biological methods. genetic differences detected by pulsed-field gel electrophoresis were observed between the inoculated and recovered strains as early as 1 day post inoculation. the loss of the inoculated clone was observed in one calf. replication and dissemination of the ehec o157:h7 strains that mutated in cattle may result in the diversification of ...200010689170
effect of endotoxin challenge on hepatic 5'-deiodinase activity in cattle.thyroid status is compromised in a variety of acute and chronic infections and toxin-mediated disease states. conversion of thyroxine (t4) into the metabolically active hormone, triiodothyronine (t3), is catalyzed by 5'-deiodinase (5'd). our objective was to determine the effect of endotoxin (lps) challenge with and without l-arginine (arg) infusion on hepatic activity of 5'd and plasma concentrations of t4 and t3. in a 2 x 2 factorial, beef heifers (275-310 kg b.wt.) were fed low (8% cp; 6.5 kg ...200010701770
differential induction of complement fragment c5a and inflammatory cytokines during intramammary infections with escherichia coli and staphylococcus aureus.the prompt recruitment of neutrophils to the site of infection is essential for the defense of the bovine mammary gland against invading pathogens and is determinant for the outcome of the infection. escherichia coli is known to induce clinical mastitis, characterized by an intense neutrophil recruitment leading to the eradication of the bacteria, whereas staphylococcus aureus induces subclinical mastitis accompanied by a moderate neutrophil recruitment and the establishment of chronic mastitis. ...200010702487
catalase deficiency in staphylococcus aureus subsp. anaerobius is associated with natural loss-of-function mutations within the structural gene.degenerate oligonucleotide primers based on internal peptide sequences obtained by hplc from purified staphylococcus aureus catalase were used to locate the s. aureus and s. aureus subsp. anaerobius kat regions by pcr. southern hybridization analysis with a probe derived from a 1.1 kb pcr-amplified fragment showed that a single copy of the putative catalase gene was present in the s. aureus and s. aureus subsp. anaerobius chromosome. the nucleotide sequence of s. aureus kata revealed a 1518 bp o ...200010708385
dihydrofolate influences the activity of escherichia coli dihydrofolate reductase synthesised de novo.the folding of proteins into their native structures is known to depend on molecular chaperones. however, other ligands or cofactors which still require characterisation are also likely to influence protein folding. the intention of this study was to reveal how the folding of an enzyme, escherichia coli dihydrofolate reductase, was affected by a substrate ligand, i.e. dihydrofolate. the enzyme was synthesised by coupled transcription/translation in a bacterial cell-free system. correct folding o ...200010716630
effects of sodium fertilizers and supplements on milk production and mammary gland health.a series of experiments was conducted to investigate the effects of sodium fertilizers and supplements on the milk production and mammary health of dairy cows. in expt 1, where sodium fertilizer was applied to productive pastures consisting mainly of the natrophile perennial rye-grass, the herbage sodium content and the milk yield of cows was increased and milk somatic cell count (scc) reduced. in expt 2, which used pastures containing less productive, natrophobic grasses and broad-leaved plants ...200010717838
biosynthesis of heparin/heparan sulphate: mechanism of epimerization of glucuronyl c-5.in the biosynthesis of heparin and heparan sulphate, d-glucuronic acid residues are converted into l-iduronic acid (idoa) units by c-5 epimerization, at the polymer level. the reaction catalysed by the epimerase occurs by reversible abstraction and readdition of a proton at c-5 of target hexuronic acid residues, through a carbanion intermediate, with or without an inversion of configuration at c-5 [prihar, campbell, feingold, jacobsson, jensen, lindahl and rodén (1980) biochemistry 19, 495-500]. ...200010727403
high-throughput assay for inorganic pyrophosphatases using the cytosolic enzymes of saccharomyces cerevisiae and human as an example.this paper describes the development of a new, malachite green based, enzymatic assay for the identification of specific inhibitors of inorganic pyrophosphatase (ippase) from saccharomyces cerevisiae for antifungal drug discovery. the human ippase was used as counterscreen. the coding regions of both enzymes were amplified, cloned into a vector providing a his-tag at the c-terminus, expressed in escherichia coli, and purified by metal chelate affinity chromatography. since the complete human seq ...200010733883
the effects of preslaughter washing on the reduction of escherichia coli o157:h7 transfer from cattle hides to carcasses during slaughter.fresh bovine faeces were inoculated with a non-toxigenic, antibiotic resistant strain of escherichia coli o157:h7, spread on the rump areas of 30 heifers and allowed to dry for 24 h. ten of the cattle then entered the normal slaughter process without further treatment. the remaining cattle were washed with a powerhose for 1 min (10 animals) and 3 min (10 animals) before entering the normal slaughter process. both washing treatments removed all visible faecal materials on the live animals althoug ...200010736017
escherichia coli o26 detection from foods using an enrichment procedure and an immunomagnetic separation method.we found effective enrichment procedures for detecting escherichia coli o26 in foods using methods that are used for e. coli o157. ground beef or radish sprouts inoculated with approximately 6 colony-forming units of e. coli o26 were homogenized in 225 ml of various broths. after static incubation at 37 degrees c or 42 degrees c for 6 h or 18 h, we isolated the inoculated bacterium by plating onto rainbow agar o157 with novobiocin. in combination with the immunomagnetic separation method, e. col ...200010736019
inhibitory effects of bovine lactoferrin on the adherence of enterotoxigenic escherichia coli to host cells.adherence is an essential and prerequisite step for the colonization of mucosal surfaces by enterotoxigenic escherichia coli (etec). we studied the effect of bovine lactoferrin (blf) on the adherence of etec to human epithelial cells in vitro, and to intestinal mucosa of icr germfree mice in vivo. in the in vitro study, blf was found to inhibit the adherence of etec. this adhesion-inhibiting activity of blf was found to lessen with decreasing blf concentration, but the data obtained suggest a po ...200010737192
epidemiological study of pap genes among diarrheagenic or septicemic escherichia coli strains producing cs31a and f17 adhesins and characterization of pap(31a) fimbriae.the association of the pap operon with the cs31a and f17 adhesins was studied with 255 escherichia coli strains isolated from calves, lambs, or humans with diarrhea. the three classes of papg adhesin with different receptor binding preferences were also screened. the pap operon was associated with 50 and 36% of human strains that produced cs31a and ovine strains that produced f17, respectively. among the bovine isolates, the pap operon was detected in 61% of the cs31a-positive isolates and 72% o ...200010747134
activity of hydrolysed lactoferrin against foodborne pathogenic bacteria in growth media: the effect of edta.lactoferrin was hydrolysed with pepsin and the antimicrobial activity of the resulting hydrolysate (hlf) was studied in 1% peptone, 0.05% yeast extract, 1% glucose (pyg) medium and tryptic soy broth (tsb). hlf was effective against listeria monocytogenes, enterohaemorrhagic escherichia coli and salmonella enteritidis in pyg, however, the highest studied concentration (1.6 mg ml-1) did not inhibit growth of any of these organisms in tsb. the addition of edta enhanced the activity of hlf in tsb, i ...200010747257
a quantitative approach to classifying holstein cows based on antibody responsiveness and its relationship to peripartum mastitis occurrence.a quantitative approach was developed to classify holstein cows and heifers based on phenotypic variation of serum antibody response and to determine associations with peripartum mastitis. using an index, 136 cows and heifers were classified into high (group 1), average (group 2), or low (group 3) antibody groups following immunization with ovalbumin at wk -8, -3, and 0 relative to parturition. the ranking of groups based on the quantitative index of serum antibody response to ovalbumin were sim ...200010750107
phosphoaminoglycosides inhibit swi2/snf2 family dna-dependent molecular motor domains.members of the swi2/snf2 family of proteins participate in an array of nucleic acid metabolic functions, including chromatin remodeling and transcription. the present studies identify a novel strategy to specifically inhibit the functional dna-dependent adenosinetriphosphatase (atpase) motor domain common to swi2/snf2 family members. we have identified preparations of phosphoaminoglycosides, which are natural products of aminoglycoside-resistant bacteria, as inhibitors of the in vitro activities ...200010757984
formation and characterization of a single trp-trp cross-link in indolicidin that confers protease stability without altering antimicrobial activity.indolicidin is a 13-residue cationic, antimicrobial peptide-amide isolated from the cytoplasmic granules of bovine neutrophils. the unique composition of indolicidin distinguishes it from alpha-helical and beta-structured cationic peptides, because five of indolicidin's 13 residues are tryptophans: h-ile-leu-pro-trp-lys-trp-pro-trp-trp-pro-trp-arg-arg-nh(2). solid phase synthesis of indolicidin gave rise to a minor byproduct that possessed unusual fluorescence and uv absorbance properties compar ...200010766833
rapid and specific enzyme immunoassay on hydrophobic grid membrane filter for detection and enumeration of thermophilic campylobacter spp. from milk and chicken rinses.six commercially available anti-campylobacter antibodies were examined for their applicability in an enzyme immunoassay on hydrophobic grid membrane filters, both for the detection and enumeration of campylobacter spp. when a panel of nine campylobacter (seven campylobacter jejuni and two campylobacter coli) and eight non-campylobacter strains were used in a dot-blot format enzyme immunoassay to test the specificity of these antibodies, only one polyclonal antibody (biodesign) detected all campy ...200010772214
purification, cloning, expression, and mechanism of action of a novel platelet aggregation inhibitor from the salivary gland of the blood-sucking bug, rhodnius prolixus.rhodnius prolixus aggregation inhibitor 1 (rpai-1), a 19-kda protein isolated from the salivary gland of r. prolixus, was purified by strong cation exchange and reverse-phase high performance liquid chromatographies. based on 49 amino-terminal amino acid sequences of rpai-1, primers were produced to generate probes to screen an r. prolixus salivary gland cdna library. a phage containing the full-length clone of rpai-1 codes for a mature protein of 155 amino acids. rpai-1 shows sequence homology ...200010777556
identification of the f17 fimbrial subunit- and adhesin-encoding (f17a and f17g) gene variants in necrotoxigenic escherichia coli from cattle, pigs and humans.putative colonization factors of the f17 family of fimbrial adhesins have been identified in necrotoxigenic escherichia coli type 1 and type 2 (ntec1 and ntec2) from calves, pigs, and humans. the f17a and f17g gene variants, coding respectively for the major subunit and for the adhesin of the f17 fimbriae, were typed in 70 e. coli carrying f17-related sequences (15 ntec1, 51 ntec2, and four non-ntec) by colony hybridisation with gene probes derived from the different f17a gene variants (a, b, c, ...200010781731
enzyme-mediated sulfide production for the reconstitution of [2fe-2s] clusters into apo-biotin synthase of escherichia coli. sulfide transfer from cysteine to biotin.we previously showed that biotin synthase in which the (fe-s) cluster was labelled with 34s by reconstitution donates 34s to biotin [b. tse sum bui, d. florentin, f. fournier, o. ploux, a. méjean & a. marquet (1998) febs lett. 440, 226-230]. we therefore proposed that the source of sulfur was very likely the (fe-s) centre. this depletion of sulfur from the cluster during enzymatic reaction could explain the absence of turnover of the enzyme which means that to restore a catalytic activity, the c ...200010785391
specificity determinants for the pyruvate dehydrogenase component reaction mapped with mutated and prosthetic group modified lipoyl domains.efficient catalysis in the second step of the pyruvate dehydrogenase (e1) component reaction requires a lipoyl group to be attached to a lipoyl domain that displays appropriately positioned specificity residues. as substrates, the human dihydrolipoyl acetyltransferase provides an n-terminal (l1) and an inner (l2) lipoyl domain. we evaluated the specificity requirements for the e1 reaction with 27 mutant l2 (including four substitutions for the lipoylated lysine, lys(173)), with three analogs sub ...200010788482
invited review: effects of diet shifts on escherichia coli in cattle.escherichia coli o157:h7 is a pathogenic bacterium that causes acute illness in humans, but mature cattle are not affected. e. coli o157:h7 can enter the human food supply from cattle via fecal contamination of beef carcasses at slaughter. previous attempts to correlate the incidence of e. coli o157:h7 with specific diets or feeding management practices gave few statistically significant or consistent findings. however, recent work indicates that cattle diets may be changed to decrease fermentat ...200010791804
use of 8-hydroxyquinoline-beta-d-glucuronide for presumptive identification of shiga toxin-producing escherichia coli o157.8-hydroxyquinoline-beta-d-glucuronide (hqg) was used to improve the presumptive identification of shiga toxin-producing escherichia coli o157 (stec o157) on sorbitol macconkey agars (smac). advantages of hqg are (i) that it is less expensive than 5-bromo-4-chloro-3-indoxyl-glucuronide; (ii) that it is visible in normal daylight and (iii) that it does not diffuse into the agar like 4-methylumbelliferryl-beta-d-glucuronide (mug). sixteen stec o157 isolates, 91 bovine mastitis-associated e. coli is ...200010792673
isolation of repeated and self-complementary sequences from e. coli dna.we have used the single-strand specific nuclease from neurospora crassa and chromatography on methylated albumin-kieselguhr to purify and characterize repeated and self-complementary sequences from escherichia coli dna. approximately 0.5% of the genome renatures spontaneously at zero time and another 2% renatures somewhat more rapidly than the total dna. the early renaturing dna has a base composition and a tm similar to the total dna and contains on the average 100 base pairs; the self-compleme ...197410793709
some emerging food and water borne pathogens.emerging pathogens are those infective organisms whose incidence has recently increased or is likely to increase during the next two decades due to changes in demography, food habits, food technology, commerce, water sources and environmental factors. some important emerging food and water borne bacterial pathogens include listeria monocytogenes, campylobacter jejuni, yersinia enterocolitica, salmonella enteritidis, escherichia coli o157: h7, vibrio cholerae biotype e1 tor serotype 0139, vibrio ...199910810592
isolation, characterization and expression of a gra2 homologue from neospora caninum.a cdna library derived from mrna of tachyzoites of neospora caninum (nc-liverpool strain) was screened with antisera from a cow naturally infected with n. caninum. the dna sequence of 1 recombinant isolated predicted a significant protein sequence homology of the gene product to the 28 kda (gra2) antigen of toxoplasma gondii. studies on the n. caninum gene coding for this antigen demonstrated the presence of a single intron flanked by 2 exons; the gene was also highly expressed in culture-derive ...200010811279
a one year study of escherichia coli o157 in raw beef and lamb products.between april 1996 and march 1997 we examined 5093 samples of raw beef and lamb products for the presence of e. coli o157. samples were purchased from 81 small butchers' shops in south yorkshire. in march 1997 we also examined five samples of dried mint for the presence of e. coli o157. strains of e. coli o157 were isolated by enrichment culture in modified buffered peptone water followed by immunomagnetic separation and culture of magnetic beads onto cefixime tellurite sorbitol macconkey agar. ...200010813144
brucella abortus strain rb51 as a vector for heterologous protein expression and induction of specific th1 type immune responses.brucella abortus strain rb51 is a stable, rough, attenuated mutant widely used as a live vaccine for bovine brucellosis. our ultimate goal is to develop strain rb51 as a preferential vector for the delivery of protective antigens of other intracellular pathogens to which the induction of a strong th1 type of immune response is needed for effective protection. as a first step in that direction, we studied the expression of a foreign reporter protein, beta-galactosidase of escherichia coli, and th ...200010816476
replacement of histidine 340 with alanine inactivates the group a streptococcus extracellular cysteine protease virulence factor.streptococcus pyogenes expresses a highly conserved extracellular cysteine protease that is a virulence factor for invasive disease, including soft tissue infection. site-directed mutagenesis was used to generate a his340ala recombinant mutant protein that was made as a stable 40-kda zymogen by escherichia coli. purified his340ala protein was proteolytically inactive when bovine casein and human fibronectin were used as substrates. wild-type 28-kda streptococcal protease purified from s. pyogene ...200010816533
antimicrobial effect of herb extracts against escherichia coli o157:h7, listeria monocytogenes, and salmonella typhimurium associated with beef.the effects of plant extracts against pathogenic bacteria in vitro are well known, yet few studies have addressed the effects of these compounds against pathogens associated with muscle foods. a series of experiments was conducted to determine the effectiveness of a commercially available, generally recognized as safe, herb extract dispersed in sodium citrate (protecta one) or sodium chloride (protecta two) against escherichia coli o157:h7, salmonella typhimurium, and listeria monocytogenes asso ...200010826716
resonance raman studies of oxo intermediates in the reaction of pulsed cytochrome bo with hydrogen peroxide.cytochrome bo from escherichia coli, a member of the heme-copper terminal oxidase superfamily, physiologically catalyzes reduction of o(2) by quinols and simultaneously translocates protons across the cytoplasmic membrane. the reaction of its ferric pulsed form with hydrogen peroxide was investigated with steady-state resonance raman spectroscopy using a homemade microcirculating system. three oxygen-isotope-sensitive raman bands were observed at 805/x, 783/753, and (767)/730 cm(-)(1) for interm ...200010828985
molten globule structure of equine beta-lactoglobulin probed by hydrogen exchange.the molten globule structure of equine beta-lactoglobulin has been inferred from the hydrogen exchange protection of the backbone amide protons. in order to make it possible to measure the hydrogen exchange kinetics of the individual backbone amide protons, the uniformly (15)n-labeled recombinant protein was expressed in escherichia coli and the nmr peak assignment was obtained for most of the backbone protons. the chemical shift and noe results obtained under the condition where the protein ass ...200010835282
induction of parturition with prostaglandin f2 alpha as a possible model to study impaired reproductive performance in the dairy cow.parturitions were induced in five cows, 2 weeks before term using prostaglandin (pg) f(2alpha). two i.m. injections were performed with an interval of 24 h. all cows calved within 5 days (average 2.7 days) after the first injection of pgf(2alpha). out of five cows, four had retained fetal membranes (rfm). each animal was sampled for bacteriological examination using uterine biopsies twice a week during 42 days postpartum (pp). jugular vein blood samples were withdrawn for pgf(2alpha)-metabolite ...200010837974
expression of yeast inm1 encoding inositol monophosphatase is regulated by inositol, carbon source and growth stage and is decreased by lithium and valproate.inositol monophosphatase plays a vital role in the de novo biosynthesis of inositol and in the phosphoinositide second messenger signalling pathway. we cloned the saccharomyces cerevisiae open reading frame (orf) yhr046c (termed inm1), which encodes inositol monophosphatase, characterized the protein inm1p and analysed expression of the inm1 gene. inm1 was expressed in bacteria under the control of the lacz promoter. the purified protein has inositol monophosphatase activity that is inhibited by ...200010844654
rotavirus and concurrent infections with other enteropathogens in neonatal diarrheic dairy calves in spain.faeces samples from 218, one to 30 days old, diarrheic dairy calves in 65 dairy herds were screened for the presence of rotavirus and concurrent infections with coronavirus, cryptosporidium, f5+ escherichia coli and salmonella spp. calves were grouped according to their age as follows: 1-7, 8-14, 15-21 and 22-30 days. rotavirus infection was detected in 46.9%, 45.6%, 33.8% and 48.3% of the calves in the respective age-groups. no significant differences in the detection rate of rotavirus were fou ...200010855663
high levels of background flora inhibits growth of escherichia coli o157:h7 in ground beef.the influence of natural background flora under aerobic and anaerobic incubation on the growth of escherichia coli o157:h7 in ground beef was investigated. the background flora from eight different commercial ground beef were added to ground beef spiked with e. coli o157:h7 and stored either aerobically or anaerobically at 12 degrees c. the results showed that the presence of a large number of background bacteria in the ground meat inhibited the growth of e. coli o157:h7 both aerobically and ana ...200010857548
molecular cloning and expression of cu/zn-containing superoxide dismutase from fasciola hepatica.the cytosolic superoxide dismutase (sod) of fasciola hepatica, a causative agent of fascioliasis, was purified and characterized. the enzyme consists of two identical subunits, each with an apparent molecular mass of 17.5 kda. an analysis of the enzyme's primary structure and inhibition studies revealed that the enzyme is a copper/zinc-containing sod (cu/zn-sod). the enzyme activity was relatively stable in a broad ph range, from ph 7.0 to 10.0, and the enzyme showed maximum activity at ph 7.5. ...200010858207
the genetic diversity of predominant escherichia coli strains isolated from cattle fed various amounts of hay and grain(1).when the 16s rdna of predominant escherichia coli strains from cattle was digested with hhai and haeiii, the strains could be sub-divided into four operational taxonomic units. when genomic dna was digested with xbai, strains could be grouped into 24 pulsed-field gel electrophoresis genotypes (>95% dice similarity) and five clades (>20% dice similarity). diet (hay versus grain) and gastrointestinal compartment (rumen versus colon) did not have a large impact on diversity. however, both analyses ...200010858581
role of non-o157 vtec.non-o157 vtec are typical escherichia coli that differ only in their ability to produce verocytotoxins (vt). the transmission of vtec is discussed in relation to the transmission of commensal e. coli. the emergence over the last few decades of a great variety of vtec serotypes from healthy and diseased humans and animals is described. particular attention is given to the distribution of the more important serogroups pathogenic for humans that have been described from around the world, particular ...200010880178
survival of verocytotoxigenic escherichia coli o157 in soil, water and on surfaces.cattle and sheep are major reservoirs of escherichia coli o157 and consequently these and certain other farm animals can pass out large numbers of this organism in their faeces. thus the ability of the organism to survive in faeces, on pastureland and in associated water systems has important implications for its spread to crops by direct application of manure, by irrigation with infected water or directly to man by contact with animals or contaminated soil. model systems were used to determine ...200010880181
antigenic and genetic characterization of lipoprotein lppq from mycoplasma mycoides subsp. mycoides sc.lipoprotein lppq, a predominant 48-kda antigen, and its corresponding gene, lppq, were characterized in mycoplasma mycoides subsp. mycoides sc, the etiological agent of contagious bovine pleuropneumonia. the lppq gene is specific to m. mycoides subsp. mycoides sc and was found in the type strain and in field strains isolated in europe, africa, and australia, as well as in vaccinal strains. lppq is encoded as a precursor with a consensus sequence for prokaryotic signal peptidase ii and a lipid at ...200010882657
influence of hmg-1 and adenovirus oncoprotein e1a on early stages of transcriptional preinitiation complex assembly.the tata-binding protein (tbp) in the tfiid complex binds specifically to the tata-box to initiate the stepwise assembly of the preinitiation complex (pic) for rna polymerase ii transcription. transcriptional activators and repressors compete with general transcription factors at each step to influence the course of the assembly. to investigate this process, the tbp.tata complex was titrated with hmg-1 and the interaction monitored by electrophoretic mobility shift assays. the titration produced ...200010882737
antiviral activity of shiga toxin 1: suppression of bovine leukemia virus-related spontaneous lymphocyte proliferation.human infections with shiga toxin (stx)-producing escherichia coli (stec) cause hemorrhagic colitis. the stxs belong to a large family of ribosome-inactivating proteins (rips) that are found in a variety of higher plants and some bacteria. many rips have potent antiviral activity for the plants that synthesize them. stec strains, both virulent and nonvirulent to humans, are frequently isolated from healthy cattle. interestingly, despite intensive investigations, it is not known why cattle carry ...200010899843
rotational mobility and orientational stability of a transport protein in lipid membranes.a single-cysteine mutant of the lactose transport protein lacs(c320a/w399c) from streptococcus thermophilus was selectively labeled with a nitroxide spin label, and its mobility in lipid membranes was studied as a function of its concentration in the membrane by saturation-transfer electron spin resonance. bovine rhodopsin was also selectively spin-labeled and studied to aid the interpretation of the measurements. observations of spin-labeled proteins in macroscopically aligned bilayers indicate ...200010920009
chalcone and stilbene synthases expressed in eucaryotes exhibit reduced cross-reactivity in vitro.chalcone synthase (chs) and stilbene synthase (sts) catalyze different cyclization reactions of the common tetraketide to give different products, naringenin chalcone and resveratrol, respectively. we have previously observed in vitro cross-reaction of chs and sts overexpressed in escherichia coli, resveratrol production by chs and chalcone production by sts. when expressed in eucaryotic cells, or in e. coli as thioredoxin-fusion proteins, chs and sts exhibited reduced cross-reaction. sts refold ...200010923839
inhibition of six serine proteinases of the human coagulation system by mutants of bovine pancreatic trypsin inhibitor.a series of 12 bovine pancreatic trypsin inhibitor variants mutated in the p(4) and p(3) positions of the canonical binding loop containing additional k15r and m52l mutations were used to probe the role of single amino acid substitutions on binding to bovine trypsin and to the following human proteinases involved in blood clotting: plasmin, plasma kallikrein, factors x(a) and xii(a), thrombin, and protein c. the mutants were expressed in escherichia coli as fusion proteins with the le1413 hydrop ...200010930417
p64k meningococcal protein as immunological carrier for weak immunogens.previously, the p64k meningococcal protein, an antigen of 64 kda expressed in escherichia coli, has been extensively characterized. we have successfully conjugated several synthetic peptides and meningococcal group c polysaccharide to p64k. in three out of four model peptides, the murine humoral immune response against the homologous peptide, evaluated after three doses of conjugate, was higher in the animals immunized with the coupled peptide than in those that received free peptide. the fourth ...200010931377
isolation of shiga toxin-producing escherichia coli including o157:h7 strains from dairy cattle and beef samples marketed in calcutta, india. 200010933264
coupling efficacy and selectivity of the human mu-opioid receptor expressed as receptor-galpha fusion proteins in escherichia coli.two constructs encoding the human micro-opioid receptor (hmor) fused at its c terminus to either one of two galpha subunits, galpha(o1) (hmor-galpha(o1)) and galpha(i2) (hmor-galpha(i2)), were expressed in escherichia coli at levels suitable for pharmacological studies (0.4-0.5 pmol/mg). receptors fused to galpha(o1) or to galpha(i2) maintained high-affinity binding of the antagonist diprenorphine. affinities of the micro-selective agonists morphine, [d-ala(2),n-me-phe(4),gly(5)-ol]enkephalin (d ...200010936202
enterohaemorrhagic escherichia coli o157:h7 target peyer's patches in humans and cause attaching/effacing lesions in both human and bovine intestine.enterohaemorrhagic escherichia coli (ehec) constitute a significant risk to human health worldwide, and infections, particularly with serogroup o157:h7, are associated with consumption of a variety of food and water vehicles, particularly food of bovine origin. ehec cause acute gastroenteritis, bloody diarrhoea, and haemorrhagic colitis; up to 10% of cases develop severe complications, including the haemolytic uraemic syndrome, with a 5% case fatality. a virulence characteristic of enteropathoge ...200010940275
expression and characterization of e. coli-produced soluble, functional human dihydroorotate dehydrogenase: a potential target for immunosuppression.human dihydroorotate dehydrogenase (hudhodh) is essential for de novo biosynthesis of pyrimidines and the target of two immunosuppressive drugs, brequinar and the leflunomide metabolite a77-1726 (chen et al., 1992; davis et al., 1996). using a t7 rna polymerase expression system, we produced hudhodh as a fusion protein containing an amino-terminal decahistidine tag. escherichia coli growth and expression conditions were optimized to enhance hudhodh solubility and to permit purification of the en ...199910941801
overexpression, purification, and characterization of bacillus subtilis n-acetylmuramoyl-l-alanine amidase cwlc.n-acetylmuramoyl-l-alanine amidase cwlc of bacillus subtilis was overproduced in escherichia coli and purified 21-fold. the amidase hydrolyzed type a cell walls such as b. subtilis. the amidase bound slightly to the microbacterium lacticum cell wall (type b), but did not entirely hydrolyze it. the presence of calcium or magnesium ion increased the resistance of the amidase to heat denaturation.200010945275
a pollen-specific novel calmodulin-binding protein with tetratricopeptide repeats.calcium is essential for pollen germination and pollen tube growth. a large body of information has established a link between elevation of cytosolic ca(2+) at the pollen tube tip and its growth. since the action of ca(2+) is primarily mediated by ca(2+)-binding proteins such as calmodulin (cam), identification of cam-binding proteins in pollen should provide insights into the mechanisms by which ca(2+) regulates pollen germination and tube growth. in this study, a cam-binding protein from maize ...200010956642
immunological aspects of pregnancy-associated glycoproteins.the incidence of severe cases of acute e. coli mastitis in dairy cows is highest during early lactation. this phenomenon has been associated with a decreased function and decreased numbers of circulating polymorphonuclear neutrophil leukocytes (pmn). the cause of this impaired function and decreased number is poorly understood. stress, hormonal and metabolic alterations around parturition and the onset of lactation may play a role in this phenomenon. several molecules, such as cortisol and beta- ...200010959437
contribution of dps to acid stress tolerance and oxidative stress tolerance in escherichia coli o157:h7.an escherichia coli o157:h7 dps::npti mutant (frik 47991) was generated, and its survival was compared to that of the parent in hcl (synthetic gastric fluid, ph 1.8) and hydrogen peroxide (15 mm) challenges. the survival of the mutant in log phase (5-h culture) was significantly impaired (4-log(10)-cfu/ml reduction) compared to that of the parent strain (ca. 1.0-log(10)-cfu/ml reduction) after a standard 3-h acid challenge. early-stationary-phase cells (12-h culture) of the mutant decreased by c ...200010966408
cattle can be a reservoir of sorbitol-fermenting shiga toxin-producing escherichia coli o157:h(-) strains and a source of human diseases.using the immunomagnetic separation procedure, we isolated sorbitol-fermenting (sf) shiga toxin-producing escherichia coli (stec) o157:h(-) strains from two patients, one with hemolytic-uremic syndrome and the other with diarrhea, and from a dairy cow epidemiologically associated with the patients. the phenotypic and genotypic characteristics of all isolates were identical or closely related. moreover, the bovine isolate showed a clonal relatedness to sf stec o157:h(-) strains isolated from pati ...200010970407
fad insertion is essential for attaining the assembly competence of the dihydrolipoamide dehydrogenase (e3) monomer from escherichia coli.dihydrolipoamide dehydrogenase (e3) from escherichia coli, an fad-linked homodimer, can be fully reconstituted in vitro following denaturation in 6 m guanidinium chloride. complete restoration of activity occurs within 1-2 h in the presence of fad, dithiothreitol, and bovine serum albumin. in the absence of fad, the dihydrolipoamide dehydrogenase monomer forms a stable folding intermediate, which is incapable of dimerization. this intermediate displays a similar tryptic resistance to the native ...200010970889
shiga-toxin-producing escherichia coli in faeces of healthy dairy cows, sheep and goats: prevalence and virulence properties.the prevalence of shiga-toxin-producing escherichia coli (stec) in healthy dairy ruminants was investigated between 1996 and 1998 by a multiplex polymerase chain reaction (mpcr) technique. a total of 13 552 e. coli colonies from 726 cows, 28 sheep and 93 goats out of 112 randomly selected dairy farms in hessia, germany were analysed. stec strains were recovered from 131 (18.0%) cows, nine (32.1%) sheep and 70 (75.3%) goats. further characterization of the stec isolates showed that 89 (0.66% of t ...200010972729
frequency of shiga toxin-producing escherichia coli in cattle at a breeding farm and at a slaughterhouse in japan.to investigate the frequency of shiga toxin-producing escherichia coli (stec) infected calves at a breeding farm and cattle at a slaughterhouse in tohoku area of japan, the polymerase chain reaction (pcr) was used for detection of genes for shiga toxin(s). the fecal samples from a total of 204 calves and 306 cattle were examined. the prevalence rates in calves less than 2 months of age, cattle 2-8 months of age, and adults greater than 1 year of age were 39.4, 78.9, and 40.8%, respectively. dete ...200010973705
evaluation of 1.6% phenol as a premilking and postmilking teat dip in preventing new bovine intramammary infections.we evaluated the effectiveness of a 1.6% phenol-based teat dip using both a teat skin assay and natural exposure field trial. a teat skin assay was conducted to ascertain the concentration of phenol + phenate to be used in the field study. one percent and 0.5% iodine, and 0.5, 1.1, and 1.6% phenol + phenate were compared using escherichia coli and staphylococcus aureus. logarithmic reductions for s. aureus were 2.2 and 2.8 for 0.5 and 1% iodine, and 1.3, 2.1, and 2.8 for 0.5, 1.1, and 1.6% pheno ...200010984151
plasmid-mediated florfenicol resistance encoded by the flor gene in escherichia coli isolated from cattle.a florfenicol resistance gene almost identical to flor of salmonella enterica serovar typhimurium dt104 was detected on 110- to 125-kb plasmids in escherichia coli isolates of animal origin. analysis of the flor gene flanking regions of one of the plasmids showed that they were different from those encountered in s. enterica serovar typhimurium dt104.200010991873
g-protein sensitivity of ligand binding to human dopamine d(2) and d(3) receptors expressed in escherichia coli: clues for a constrained d(3) receptor structure.human dopamine d(2) and d(3) receptors were expressed in chinese hamster ovary (cho) and escherichia coli cells to compare their ligand binding properties in the presence or absence of g-proteins and to analyze their ability to interact with g(i/o)-proteins. binding affinities of agonists (dopamine, 7-oh-dpat, pd128907, lisuride) and antagonists/inverse agonists (haloperidol, risperidone, domperidone, spiperone, raclopride, nemonapride), measured using [(125)i]iodosulpride and [(3)h]7-oh-dpat, w ...200010991990
assessment of the in vitro and in vivo genotoxicity of thalomid (thalidomide).thalomid is the fda-approved commercial formulation of thalidomide currently used in the us to treat erythema nodosum leprosum, a complication of leprosy. the genotoxicity of thalomid thalidomide was assessed in the ames reverse mutation, as52/xprt mammalian cell forward gene mutation, and mouse bone marrow micronucleus assays. the ames and as52 assays were performed with and without s9. in the ames, salmonella typhimurium strains ta1535, 1537, 98, 100, and 102 and escherichia coli strain wp2 uv ...200010992277
hydrolysis of beta-galactosyl ester linkage by beta-galactosidases.p-hydroxybenzoyl beta-galactose (phb-gal) was synthesized chemically to examine the hydrolytic activity of beta-galactosyl ester linkage by beta-galactosidases. the enzyme from penicillium multicolor hydrolyzed the substrate as fast as p-nitrophenyl beta-galactoside (pnp-gal), a usual substrate with a beta-galactosidic linkage. the enzymes from escherichia coli and aspergillus oryzae hydrolyzed phb-gal with almost the same rates as pnp-gal. the enzymes from bacillus circulans, saccharomyces frag ...200010993159
short communication: survival of escherichia coli o157:h7 in dairy cattle drinking water.cattle drinking water from two dairy farms was used in a study to determine the survival characteristics of the bacterial pathogen escherichia coli o157:h7 and wild-type e. coli. the e. coli o157:h7 inoculum consisted of a consortium of isolates obtained from dairy cattle. fresh manure was used as the source for the wild-type e. coli. in the water source from farm 1 the pathogens were present at both 5 and 15 degrees c during the 16-d duration of the study. in the water source from farm 2, the p ...200011003233
comparison between the growth of yersinia enterocolitica, listeria monocytogenes, escherichia coli o157:h7 and salmonella spp. in ground beef packed by three commercially used packaging techniques.growth of the pathogens yersinia enterocolitica, listeria monocytogenes, escherichia coli o157:h7 and strains of salmonella were compared in ground beef packed in modified atmospheres of 60% co2/40% n2/0.4% co (high co2/low co mixture), 70% o2/30% co2 (high o2 mixture) and in chub packs (stuffed in plastic casings). the ground beef was inoculated with rifampicin-resistant or nalidixic acid/streptomycin-resistant strains of the pathogens (final concentration 10(2) - 10(3) bacteria/g) and stored a ...200011020041
the isolation of enterohaemorrhagic escherichia coli o111:h- from australian cattle. 200011022293
interactions of the nadp(h)-binding domain iii of proton-translocating transhydrogenase from escherichia coli with nadp(h) and the nad(h)-binding domain i studied by nmr and site-directed mutagenesis.using the purified nadp(h)-binding domain of proton-translocating escherichia coli transhydrogenase (eciii) overexpressed in (15)n- and (2)h-labeled medium, together with the purified nad(h)-binding domain from e. coli (eci), the interface between eciii and eci, the nadp(h)-binding site and the influence on the interface by nad(p)(h) was investigated in solution by nmr chemical shift mapping. mapping of the nadp(h)-binding site showed that the nadp(h) substrate is bound to eciii in an extended c ...200011027139
one-step purification of the recombinant catalytic subunit of pyruvate dehydrogenase phosphatase.a facile one-step affinity chromatographic purification of the recombinant catalytic subunit (pdpc) of bovine pyruvate dehydrogenase phosphatase (pdp) to near homogeneity is described. pdpc binds in the presence of ca(2+) to the inner lipoyl domain (l2) of the dihydrolipoamide acetyltransferase component (e2) of the mammalian pyruvate dehydrogenase complex. the affinity column consists of a glutathione s-transferase (gst)-l2 fusion protein bound to glutathione-sepharose 4b beads. an extract of t ...200011035961
characterization of shiga toxin-producing escherichia coli strains isolated from calves in poland.fecal samples from 67 3-5-months-old calves with diarrhea were screened for the presence of shiga toxin-producing escherichia coli (stec). several accessory virulence factors genes were also tested. among 192 e. coli isolates tested, 15 (7.6%) were found to harbour the shiga toxin 1 or 2 (stx1 or stx2) genes. the stx2-carrying samples were further subtyped by pcr for the stx2c, stx2d, and stx2e toxin variants. it was shown that stx2-positive bacteria mainly possessed the stx2c shiga toxin type g ...200011038128
in vitro incorporation of nascent molybdenum cofactor into human sulfite oxidase.we were able to reconstitute molybdopterin (mpt)-free sulfite oxidase in vitro with the molybdenum cofactor (moco) synthesized de novo from precursor z and molybdate. mpt-free human sulfite oxidase apoprotein was obtained by heterologous expression in an escherichia coli mutant with a defect in the early steps of mpt biosynthesis. in vitro reconstitution of the purified apoprotein was achieved using an incubation mixture containing purified precursor z, purified mpt synthase, and sodium molybdat ...200111042213
the escherichia coli pii signal transduction protein regulates the activities of the two-component system transmitter protein nrii by direct interaction with the kinase domain of the transmitter module.the pii signal transduction protein regulates the transcription of nitrogen-regulated genes by controlling the kinase and phosphatase activities of nrii. we used a cross-linking approach to study the interaction of the t-loop of the pii protein with nrii. cross-linking of pii to nrii required atp and 2-ketoglutarate, allosteric effectors known to control pii activity, and was not affected by the presence of excess nonspecific proteins such as bovine serum albumin. the purified cross-linked speci ...200011063581
host defense function in neutrophils from the american bison (bison bison).selected host defense functions of neutrophils isolated from american bison (bison bison) were characterized and compared with those of cattle (bos taurus). bison neutrophils had a robust chemotactic response to both il-8 and ltb(4), with maximal responses occurring at 10(-7) m (il-8) and 10(-8) m (ltb(4)). the magnitude of the chemotactic response to il-8 was similar in bison and bovine neutrophils (except at 10(-7) m il-8, where bison had a stronger response). in response to ltb(4), bison neut ...200011064290
survival of escherichia coli o157 in faeces of experimentally infected rats and domestic pigeons.in order to evaluate the role of some synanthropic animals in the spreading of escherichia coli o157, laboratory rats and domestic pigeons were experimentally infected per os with e. coli o157. rats infected with 10(5) colony forming units (cfu) (n = 5) and 10(9) cfu (n = 5) shed e. coli o157 for 2 +/- 1.7 d and 9.8 +/- 1.3 d, respectively. in the faeces of infected rats stored at 4 degrees c in a moist environment, at 4 degrees c in a dry environment or at 20 degrees c in a moist environment, e ...200011069635
reconstitution of mitochondrial processing peptidase from the core proteins (subunits i and ii) of bovine heart mitochondrial cytochrome bc(1) complex.mature core i and core ii proteins of the bovine heart mitochondrial cytochrome bc(1) complex were individually overexpressed in escherichia coli as soluble proteins using the expression vector pet-i and pet-ii, respectively. purified recombinant core i and core ii alone show no mitochondrial processing peptidase (mpp) activity. when these two proteins are mixed together, mpp activity is observed. maximum activity is obtained when the molar ratio of these two core proteins reaches 1. this indica ...200111073949
milk leucocyte population patterns in bovine udder infection of different aetiology.this study compared the different leucocyte populations in milk from udders infected with different mastitic pathogens and in different stages of infection. milk samples were collected from quarters free of intramammary infection, acutely infected with escherichia coli or staphylococcus aureus and chronically infected with s. aureus, coagulase-negative staphylococci (cns) or streptococcus dysgalactiae. udder bacteriological status was confirmed after three consecutive bacteriological examination ...200011075546
antitumor interaction of short-course endostatin and ionizing radiation.the purpose of this study was to evaluate whether endostatin, an antiangiogenic cleavage fragment of collagen xviii, enhances the antitumor effects of ionizing radiation (ir). endostatin was injected to coincide with fractionated radiotherapy.200011079167
the effect of different grain diets on fecal shedding of escherichia coli o157:h7 by steers.three groups of six yearling steers (three rumen fistulated plus three nonfistulated) fed one of three different grain diets (85% cracked corn, 15% whole cottonseed and 70% barley, or 85% barley) were inoculated with 10(10) cfu of escherichia coli o157:h7 strain 3081, and the presence of the inoculated strain was followed in the rumen fluid and feces for a 10-week period. e. coli o157:h7 was rapidly eliminated from the rumen of the animals on all three diets but persisted in the feces of some an ...200011079685
molecular cloning of nadph-cytochrome p450 oxidoreductase from silkworm eggs. its involvement in 20-hydroxyecdysone biosynthesis during embryonic development.using rt-pcr, a cdna fragment of nadph-cytochrome p450 oxidoreductase from silkworm, bombyx mori, was cloned from three-day-old nondiapause eggs. race was used to isolate the ends of the dna. the full-length cdna obtained was composed of 3471 bp with an open reading frame encoding a protein of 687 amino-acid residues with a relative molecular mass of 77 700. the protein, fused with glutathione s-transferase, was expressed in escherichia coli and purified to homogeneity. the fused protein not onl ...200011082204
a functional water channel protein in the pathogenic bacterium brucella abortus.the gene for a new bacterial aquaporin, aqpx, was cloned from the pathogenic gram-negative bacterium brucella abortus. the gene was mapped on the large chromosome of b. abortus. it is flanked by one upstream and two downstream copies of the brucella repeated sequence bru-rs. prediction from the nucleotide sequence indicated that the protein is a member of the mip family, which comprises channels for water and/or solute transport. expression in xenopus oocytes and cryoelectron microscopy of esche ...200011101683
dimer formation by a "monomeric" protein.dimeric proteins can arise by the swapping of structural domains between monomers. the prevalence of this occurrence is unknown. ribonuclease a (rnase a) is assumed to be a monomer near physiological conditions. here, this hypothesis is tested and found to be imprecise. the two histidine residues (his12 and his119) in the active site of rnase a arise from two domains (s-peptide and s-protein) of the protein. the h12a and h119a variants have 10(5)-fold less ribonucleolytic activity than does the ...200011106177
results of a longitudinal study of the prevalence of escherichia coli o157:h7 on cow-calf farms.to describe the frequency and distribution of escherichia coli o157:h7 in the feces and environment of cow-calf herds housed on pasture.200011108182
ca(2+)-binding proteins in the retina: from discovery to etiology of human disease(1).examination of the role of ca(2+)-binding proteins (cabps) in mammalian retinal neurons has yielded new insights into the function of these proteins in normal and pathological states. in the last 8 years, studies on guanylate cyclase (gc) regulation by three gc-activating proteins (gcap1-3) led to several breakthroughs, among them the recent biochemical analysis of gcap1(y99) mutants associated with autosomal dominant cone dystrophy. perturbation of ca(2+) homeostasis controlled by mutant gcap1 ...200011108966
coenzyme q is an obligatory cofactor for uncoupling protein function.uncoupling proteins (ucps) are thought to be intricately controlled uncouplers that are responsible for the futile dissipation of mitochondrial chemiosmotic gradients, producing heat rather than atp. they occur in many animal and plant cells and form a subfamily of the mitochondrial carrier family. physiological uncoupling of oxidative phosphorylation must be strongly regulated to avoid deterioration of the energy supply and cell death, which is caused by toxic uncouplers. however, an h+ transpo ...200011117751
lactate dehydrogenase release assay from vero cells to distinguish verotoxin producing escherichia coli from non-verotoxin producing strains.the vero cell assay presently used for virulence testing of verotoxigenic escherichia coli (vtec) requires at least 48-96 h where cytotoxicity effects are examined under a microscope. here, a complimentary rapid assay was developed that measures endogenous lactate dehydrogenase (ldh) release from vero or hep-2 cells as an indicator of cytotoxicity. toxin preparations from 24 vtec strains induced 36-89% ldh from vero cells and 15-62% ldh from hep-2 cells in 12-16 h. a verotoxin-positive but enter ...200111118652
in situ hybridization method for studies of cell wall deficient m. paratuberculosis in tissue samples.cell wall deficient forms of mycobacteria may be important in the pathogenesis of crohn's disease and sarcoidosis. however, no method has been available to localize this type of organisms in tissue sections. we developed an in situ hybridization method for the demonstration of mycobacterium paratuberculosis spheroplasts (cell wall deficient forms) in paraffin embedded tissue sections.m. paratuberculosis spheroplasts were prepared by treatment with glycine and lysozyme. pieces of beef were inject ...200011118736
tumor necrosis factor-alpha and nitrite/nitrate responses during acute mastitis induced by escherichia coli infection and endotoxin in dairy cows.concentrations of tumor necrosis factor-alpha (tnf-alpha) and of no(x) (sum of nitrite and nitrate as indicators of endogenous nitric oxide production) in milk and blood plasma were measured in three mastitis models in dairy cows in early lactation. escherichia coli p4:o37 bacteria or endotoxin o111:b4 were administered into both left quarters of 12 and 6 cows, respectively. six of the e. coli-infected cows were treated with a bactericidal antibiotic (enrofloxacin; bayer ag, leverkusen, germany) ...200011118787
multiple restraints to the unfolding of spermidine nucleoids from escherichia coli.bacterial dna is largely localized in compact bodies known as nucleoids. the structure of the bacterial nucleoid and the forces that maintain its dna in a highly compact yet accessible form are largely unknown. in the present study, we used urea to cause controlled unfolding of spermidine nucleoids isolated from escherichia coli to determine factors that are involved in nucleoid compaction. isolated nucleoids unfolded at approximately 3.2 m urea. addition of pancreatic rnase reduced the urea con ...200011121306
identification of escherichia coli recovered from milk of sows with coliform mastitis by random amplified polymorphic dna (rapd) using standardized reagents.a standardized-reagents commercial kit for random amplified polymorphic dna (rapd) analysis was used for typing 58 escherichia coli strains that were recovered from the milk of sows, having coliform mastitis, within a single swineherd in sweden. previously, the 58 e. coli strains were characterized serologically and profiled biochemically. they were also evaluated for their serum resistance and their ability to adhere to fibronectin and bovine fetal fibroblasts. the rapd analysis was fast, easil ...200011126575
relationship between intra-uterine bacterial contamination, endotoxin levels and the development of endometritis in postpartum cows with dystocia or retained placenta.a study was conducted to investigate the relationship between intra-uterine bacterial contamination, endotoxin levels and the development of endometritis in cows that experienced a dystocia or retained their placenta. fifteen healthy cows, 31 cows with retained placenta (rp) and 13 cows that had dystocia were clinically examined 1 or 2 days after parturition when a uterine swab for bacteriological examination was taken. in addition, plasma and uterine lochia samples were collected to determine l ...200011131320
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