bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relationships between Low Serum Cobalamin Concentrations and Methlymalonic Acidemia in Cats
Authors: Ruaux C. G. , Steiner J. M. , Williams D. A. 
Published: April 2009

Background:Serum cobalamin concentrations below reference range are a common consequence of gastrointestinal disease in cats. Serum cobalamin ≤ 100 ng/L is associated with methylmalonic acidemia.Objectives:To determine the prevalence of cobalamin deficiency, defined by elevated serum methylmalonic acid (MMA), in cats with serum cobalamin ≤ 290 ng/L, and the optimum serum cobalamin concentration to predict cobalamin deficiency in cats.Sample Set:Residual serum samples (n = 206) from cats with serum cobalamin ≤ 290 ng/L.Methods:Retrospective, observational study. Serum cobalamin and folate were measured with automated assays. Serum MMA was determined by gas chromatography‐mass spectrometry. Cobalamin deficiency was defined as serum MMA > 867 nmol/L. Sensitivity and specificity of serum cobalamin concentrations ≤290 ng/L for detecting MMA > 867 nmol/L were analyzed using a receiver‐operator characteristic curve.Results:There was a negative correlation between serum cobalamin and MMA concentrations (Spearman'sr=−0.74,P< 0.0001). The prevalence of MMA ≥ 867 nmol/L in cats with serum cobalamin ≤ 290 ng/L was 68.4%. Serum cobalamin ≤ 160 ng/L had a 74% sensitivity and 80% specificity for detecting MMA > 867 nmol/L. No significant difference in serum folate concentrations was detected between affected and unaffected cats.Conclusions and Clinical Importance:Elevated MMA concentrations, suggesting cobalamin deficiency, are common in cats with serum cobalamin ≤ 290 ng/L. Cobalamin deficiency is clinically significant, and supplementation with parenteral cobalamin is recommended for cats with gastrointestinal disease and low serum cobalamin concentrations.
Sequencing of the Von Hippel‐Lindau Gene in Canine Renal Carcinoma
Authors: Pressler B. M. , Williams L. E. , Ramos‐Vara J. A. , Anderson K. I. 
Published: April 2009

Background: Similarities in human and canine renal cell carcinoma (RCC) epidemiology and biologic behavior suggest that molecular mechanisms of tumorigenesis may be similar in both species. Approximately 75% of RCC in people are of the clear cell subtype, up to 85% of which are associated with mutation of the von Hippel‐Lindau (VHL) gene. The canine VHL coding deoxyribonucleic acid (DNA) shares 90% identity with the human VHL gene.Objective: To determine whether or not RCC in dogs are associated with VHL mutations, and if so determine the prevalence, type, and location of these mutations.Animals: Thirteen dogs with RCC, 2 dogs with primary renal sarcomas, and 10 dogs without neoplastic kidney disease.Methods: DNA was extracted from paraffin‐embedded RCC tissue; DNA extracts from paraffin‐embedded and snap‐frozen nonneoplastic canine kidneys and canine whole blood were used as negative controls. Polymerase chain reaction and sequencing of the 3 VHL exons was performed, and results compared with the accessioned canine sequence.Results: All VHL exons were amplified from 9 of 13 canine RCC samples, both renal sarcomas, 8 of 10 nonneoplastic kidney samples, and canine whole blood; only exon 2 could be amplified from 2 RCC samples. Mutations were not identified in any exons. A maximal prevalence of 33.6% for VHL mutations in canine RCC was determined.Conclusion and Clinical Importance: Although similarities between canine and human RCC merit further investigation of the dog as a model for some subtypes of renal tumors, the lower prevalence of VHL mutations suggests that oncogenesis in these 2 species differs.
Renal Disposition of Colistin in the Isolated Perfused Rat Kidney
Authors: Ma Zheng , Wang Jiping , Nation Roger L. , Li Jian , Turnidge John D. , Coulthard Kingsley , Milne Robert W. 
Published: April 2009

ABSTRACTNephrotoxicity is an important limitation to the clinical use of colistin againstPseudomonas aeruginosaand other gram-negative pathogens. Previous work reported net tubular reabsorption of colistin by the kidney in vivo, but there is no knowledge of its disposition within the kidney. This study investigated the renal disposition and potential transport mechanisms of colistin in the isolated perfused rat kidney (IPK) model by perfusing with colistin sulfate alone (2 μg/ml) or in the presence of potential inhibitors (tetraethylammonium [TEA], glycine-glycine [Gly-Gly], or hydrochloric acid [HCl]) at three different concentrations. When perfused alone, the renal clearances (CLR) for colistin A and B (the major components of colistin) in control kidneys were constant and low (mean values < 0.05 ml/min throughout the perfusion). The mean clearance ratios [CR, defined as CLR/(fu× GFR), wherefuis the fraction of drug unbound in perfusate and GFR is the glomerular filtration rate] were significantly less than 1. It was concluded that there is net tubular reabsorption of colistin, and this exceeded the reabsorption of water. Less than 10% eliminated from perfusate was recovered in urine, suggesting considerable renal accumulation of colistin. The CR values for colistin were significantly increased when perfused with TEA (500 μM), Gly-Gly (833 μM), and HCl (2,500, 5,000, and 10,000 μM). It is proposed that renal reabsorption of colistin may involve organic cation transporters (inhibited by TEA) and peptide transporters (inhibited by Gly-Gly) and that the process is sensitive to the pH of urine.
First Detection of Plasmid-Encoded
bla
OXY
β-Lactamase
Authors: González-López J. J. , Coelho A. , Larrosa M. N. , Lavilla S. , Bartolomé R. , Prats G. 
Published: April 2009

ABSTRACT

Three
Klebsiella oxytoca
isolates and one
Klebsiella pneumoniae
isolate from three children admitted to the Hematology Unit of Hospital Vall d'Hebron (Barcelona, Spain) exhibited a susceptibility pattern suggesting OXY β-lactamase hyperproduction. All the isolates contained a 95-kb plasmid that harbored
bla
OXY-1
, which was transferred by electrotransformation but could not be self-transferred by conjugation. A
qnrS1
gene was also harbored in the
bla
OXY-1
-carrying plasmid. This is the first report of a plasmid-encoded OXY β-lactamase.
Prolonged Impact of Antibiotics on Intestinal Microbial Ecology and Susceptibility to Enteric
Salmonella
Infection
Authors: Croswell Amy , Amir Elad , Teggatz Paul , Barman Melissa , Salzman Nita H. 
Published: April 2009

ABSTRACT

The impact of antibiotics on the host's protective microbiota and the resulting increased susceptibility to mucosal infection are poorly understood. In this study, antibiotic regimens commonly applied to murine enteritis models are used to examine the impact of antibiotics on the intestinal microbiota, the time course of recovery of the biota, and the resulting susceptibility to enteric
Salmonella
infection. Molecular analysis of the microbiota showed that antibiotic treatment has an impact on the colonization of the murine gut that is site and antibiotic dependent. While combinations of antibiotics were able to eliminate culturable bacteria, none of the antibiotic treatments were effective at sterilizing the intestinal tract. Recovery of total bacterial numbers occurs within 1 week after antibiotic withdrawal, but alterations in specific bacterial groups persist for several weeks. Increased
Salmonella
translocation associated with antibiotic pretreatment corrects rapidly in association with the recovery of the most dominant bacterial group, which parallels the recovery of total bacterial numbers. However, susceptibility to intestinal colonization and mucosal inflammation persists when mice are infected several weeks after withdrawal of antibiotics, correlating with subtle alterations in the intestinal microbiome involving alterations of specific bacterial groups. These results show that the colonizing microbiotas are integral to mucosal host protection, that specific features of the microbiome impact different aspects of enteric
Salmonella
pathogenesis, and that antibiotics can have prolonged deleterious effects on intestinal colonization resistance.
Shiga Toxin 2 Is Specifically Released from Bacterial Cells by Two Different Mechanisms
Authors: Shimizu Takeshi , Ohta Yuko , Noda Masatoshi 
Published: April 2009

ABSTRACT

Shiga toxin 1 (Stx1) is located in the periplasmic fraction, while Stx2 is found in the extracellular fraction, suggesting that enterohemorrhagic
Escherichia coli
(EHEC) contains a specific Stx2 release system. Both
stx
1
and
stx
2
are found within the late operons of Stx-encoding phages. Stx2 production is greatly induced by mitomycin C, suggesting that
stx
2
can transcribe from the late phage promoter of the Stx2-encoding phage. However, the Stx1 promoter adjacent to
stx
1
is a dominant regulatory element in Stx1 production. With the deletion of phage lysis genes of the Stx2-encoding phage, Stx2 remains in the bacterial cells. Further, we demonstrate that the Stx2-encoding phage, but not the Stx1-encoding phage, is spontaneously induced at extremely low rates. These results indicate that spontaneously specific Stx2-encoding phage induction is involved in specific Stx2 release from bacterial cells. Furthermore, to examine whether another system for specific Stx2 release is present in EHEC, we analyze the
stx
-replaced mutants. As expected, Stx2 derived from the Stx1 promoter is located in both the extracellular and cell-associated fractions, while mutant Stx2 (B subunit, S31N) derived from the Stx1 promoter is found only in the cell-associated fraction. These results indicate that EHEC has another Stx2 release system that strictly recognizes the serine 31 residue of the B subunit. Overall, we present evidence that specific Stx2 release from bacterial cells is involved in both the Stx2-encoding phage induction system and another Stx2 release system.
Cellular Tumor Necrosis Factor, Gamma Interferon, and Interleukin-6 Responses as Correlates of Immunity and Risk of Clinical
Plasmodium falciparum
Malaria in Children from Papua New Guinea
Authors: Robinson Leanne J. , D'Ombrain Marthe C. , Stanisic Danielle I. , Taraika Jack , Bernard Nicholas , Richards Jack S. , Beeson James G. , Tavul Livingstone , Michon Pascal , Mueller Ivo , Schofield Louis 
Published: April 2009

ABSTRACT

The role of early to intermediate
Plasmodium falciparum
-induced cellular responses in the development of clinical immunity to malaria is not well understood, and such responses have been proposed to contribute to both immunity and risk of clinical malaria episodes. To investigate whether
P. falciparum
-induced cellular responses are able to function as predictive correlates of parasitological and clinical outcomes, we conducted a prospective cohort study of children (5 to 14 years of age) residing in a region of Papua New Guinea where malaria is endemic Live, intact
P. falciparum
-infected red blood cells were applied to isolated peripheral blood mononuclear cells obtained at baseline. Cellular cytokine production, including production of interleukin-2 (IL-2), IL-4, IL-6, IL-10, tumor necrosis factor (TNF) (formerly tumor necrosis factor alpha), and gamma interferon (IFN-γ), was measured, and the cellular source of key cytokines was investigated. Multicytokine models revealed that increasing
P. falciparum
-induced IL-6 production was associated with an increased incidence of
P. falciparum
clinical episodes (incidence rate ratio [IRR], 1.75; 95% confidence interval [CI], 1.20 to 2.53), while increasing
P. falciparum
-induced TNF and IFN-γ production was associated with a reduced incidence of clinical episodes (IRR for TNF, 0.55 [95% CI, 0.38 to 0.80]; IRR for IFN-γ, 0.71 [95% CI, 0.55 to 0.90]). Furthermore, we found that monocytes/macrophages and γδ-T cells are important for the
P. falciparum
-induced production of IL-6 and TNF. Early to intermediate cellular cytokine responses to
P. falciparum
may therefore be important correlates of immunity and risk of symptomatic malaria episodes and thus warrant detailed investigation in relation to the development and implementation of effective vaccines.
The Arginine Catabolic Mobile Element Is Not Associated with Enhanced Virulence in Experimental Invasive Disease Caused by the Community-Associated Methicillin-Resistant
Staphylococcus aureus
USA300 Genetic Background
Authors: Montgomery Christopher P. , Boyle-Vavra Susan , Daum Robert S. 
Published: April 2009

ABSTRACT

USA300 has become the predominant community-associated methicillin (meticillin)-resistant
Staphylococcus aureus
(CA-MRSA) genetic background in most U.S. communities. The reasons for the dominance of this genetic background are unclear, but the presence of the recently identified arginine catabolic mobile element (ACME) in the USA300 genome has been advocated as one possibility. CA-MRSA clinical isolates (USA300) differing in the presence or absence of ACME and a USA300 wild-type/ACME deletion mutant pair were analyzed for in vitro expression of global regulatory genes and production of virulence factors. The virulence of these isolates was compared in rodent models of necrotizing pneumonia and skin infection. There was no significant difference in the expression of selected genes mediating virulence (
hla
,
lukSF-PV
,
agr
,
saeRS
) among the isolates tested, regardless of the presence of ACME. There was a higher abundance of α-hemolysin in culture supernatants among ACME-positive isolates than among ACME-negative isolates, but there was no significant difference in the levels of protein A. The presence of ACME was not associated with increased virulence in a rat model of necrotizing pneumonia, as assessed by mortality, in vivo bacterial survival, and severity of lung pathology. Nor was the presence of ACME associated with increased dermonecrosis in a model of skin infection. We conclude that ACME is not necessary for virulence in rodent models of CA-MRSA USA300 pneumonia or skin infection.
Processing of
Pseudomonas aeruginosa
Exotoxin A Is Dispensable for Cell Intoxication
Authors: Morlon-Guyot Juliette , Méré Jocelyn , Bonhoure Anne , Beaumelle Bruno 
Published: April 2009

ABSTRACT

Exotoxin A is a major virulence factor of
Pseudomonas aeruginosa
. This toxin binds to a specific receptor on animal cells, allowing endocytosis of the toxin. Once in endosomes, the exotoxin can be processed by furin to generate a C-terminal toxin fragment that lacks the receptor binding domain and is retrogradely transported to the endoplasmic reticulum for retrotranslocation to the cytosol through the Sec61 channel. The toxin then blocks protein synthesis by ADP ribosylation of elongation factor 2, thereby triggering cell death. A shorter intracellular route has also been described for this toxin. It involves direct translocation of the entire toxin from endosomes to the cytosol and therefore does not rely on furin-mediated cleavage. To examine the implications of endosomal translocation in the intoxication process, we investigated whether the toxin required furin-mediated processing in order to kill cells. We used three different approaches. We first fused to the N terminus of the toxin proteins with different unfolding abilities so that they inhibited or did not inhibit endosomal translocation of the chimera. We then assayed the amount of toxin fragments delivered to the cytosol during cell intoxication. Finally we used furin inhibitors and examined the fate and intracellular localization of the toxin and its receptor. The results showed that exotoxin cytotoxicity results largely from endosomal translocation of the entire toxin. We found that the C-terminal fragment was unstable in the cytosol.
Effects of Amino Acid Substitutions at Conserved and Acidic Residues within Region 1.1 of
Escherichia coli
ς
70
Authors: Bowers Christina Wilson , McCracken Andrea , Dombroski Alicia J. 
Published: April 2009

ABSTRACT

Amino acid substitutions in
Escherichia coli
ς
70
were generated and characterized in an analysis of the role of region 1.1 in transcription initiation. Several acidic and conserved residues are tolerant of substitution. However, replacement of aspartic acid 61 with alanine results in inactivity caused by structural and functional thermolability.
Synthesis of Triacylglycerols by the Acyl-Coenzyme A:Diacyl-Glycerol Acyltransferase Dga1p in Lipid Particles of the Yeast
Saccharomyces cerevisiae
Authors: Sorger Daniel , Daum Günther 
Published: April 2009

ABSTRACT

The terminal step of triacylglycerol (TAG) formation in the yeast
Saccharomyces cerevisiae
is catalyzed by the enzyme acyl-CoA:diacylglycerol acyltransferase (DAGAT). In this study we demonstrate that the gene product of
YOR245c
, Dga1p, catalyzes a major yeast DAGAT activity which is localized to lipid particles. Enzyme measurements employing a newly established assay containing radioactively labeled diacylglycerol (DAG) as a substrate and unlabeled palmitoyl-CoA as a cosubstrate revealed a 70- to 90-fold enrichment of DAGAT in lipid particles over the homogenate but also a 2- to 3-fold enrichment in endoplasmic reticulum fractions. In a
dga1
deletion strain, the DAGAT activity in lipid particles is dramatically reduced, whereas the activity in microsomes is affected only to a minor extent. Thus, we propose the existence of DAGAT isoenzymes in the microsomal fraction. Furthermore, we unveiled an acyl-CoA-independent TAG synthase activity in lipid particles which is distinct from Dga1p and the phosphatidylcholine:DAGAT Lro1p. This acyl-CoA-independent TAG synthase utilizes DAG as an acceptor and free fatty acids as cosubstrates and occurs independently of the acyl-CoA synthases Faa1p to Faa4p. Based on lipid analysis of the respective deletion strains, Lro1p and Dga1p are the major contributors to total cellular TAG synthesis, whereas other TAG synthesizing systems appear to be of minor importance. In conclusion, at least three different pathways are involved in the formation of storage TAG in the yeast.
Effects of Lipoprotein Biogenesis Mutations on Flagellar Assembly in
Salmonella
Authors: Dailey Frank E. , Macnab Robert M. 
Published: April 2009

ABSTRACT

Flagellar assembly requires the expression of a large number of flagellum-specific genes. However, mutations in a number of other genes in
Salmonella
and
Escherichia coli
have been shown to have pleiotropic effects that affect flagellar assembly. FlgH (the L-ring subunit of the flagellar basal body) is a lipoprotein whose modification is important for L-ring assembly. We therefore tested whether the lack of motility of
Salmonella
mutants defective in lipoprotein biogenesis is a result of inability to modify FlgH. Our results show that temperature-sensitive apolipoprotein
N
-acyltransferase [
lnt
(Ts)] mutants are nonflagellate at 42°C. However, the flagellar assembly defect occurs at a much earlier step in the pathway than L-ring assembly. These mutants failed to assemble even an MS ring, presumably because of the observed decrease in transcription of
fliF.
In contrast, temperature-sensitive diacylglycerol transferase [
lgt
(Ts)] mutants were motile at 42°C, provided the strains carried an
lpp
(Braun lipoprotein) mutation to permit growth. We have isolated second-site mutants from an
lgt
(Ts)
lpp
+
strain that grow but are nonflagellate at 42°C. Thus, lipoprotein biogenesis is a factor that is important for flagellar assembly.
Molecular Characterization and Transcriptional Analysis of
adhE2
, the Gene Encoding the NADH-Dependent Aldehyde/Alcohol Dehydrogenase Responsible for Butanol Production in Alcohologenic Cultures of
Clostridium acetobutylicum
ATCC 824
Authors: Fontaine Lisa , Meynial-Salles Isabelle , Girbal Laurence , Yang Xinghong , Croux Christian , Soucaille Philippe 
Published: April 2009

ABSTRACT

The
adhE2
gene of
Clostridium acetobutylicum
ATCC 824, coding for an aldehyde/alcohol dehydrogenase (AADH), was characterized from molecular and biochemical points of view. The 2,577-bp
adhE2
codes for a 94.4-kDa protein.
adhE2
is expressed, as a monocistronic operon, in alcohologenic cultures and not in solventogenic cultures. Primer extension analysis identified two transcriptional start sites 160 and 215 bp upstream of the
adhE2
start codon. The expression of
adhE2
from a plasmid in the DG1 mutant of
C. acetobutylicum
, a mutant cured of the pSOL1 megaplasmid, restored butanol production and provided elevated activities of NADH-dependent butyraldehyde and butanol dehydrogenases. The recombinant AdhE2 protein expressed in
E. coli
as a
Strep
-tag fusion protein and purified to homogeneity also demonstrated NADH-dependent butyraldehyde and butanol dehydrogenase activities. This is the second AADH identified in
C. acetobutylicum
ATCC 824, and to our knowledge this is the first example of a bacterium with two AADHs. It is noteworthy that the two corresponding genes,
adhE
and
adhE2
, are carried by the pSOL1 megaplasmid of
C. acetobutylicum
ATCC 824.
NolX of
Sinorhizobium fredii
USDA257, a Type III-Secreted Protein Involved in Host Range Determination, Is Localized in the Infection Threads of Cowpea (
Vigna unguiculata
[L.] Walp) and Soybean (
Glycine max
[L.] Merr.) Nodules
Authors: Krishnan Hari B. 
Published: April 2009

ABSTRACT

Sinorhizobium fredii
USDA257 forms nitrogen-fixing nodules on soybean (
Glycine max
[L.] Merr.) in a cultivar-specific manner. This strain forms nodules on primitive soybean cultivars but fails to nodulate agronomically improved North American cultivars. Soybean cultivar specificity is regulated by the
nolXWBTUV
locus, which encodes part of a type III secretion system (TTSS). NolX, a soybean cultivar specificity protein, is secreted by TTSS and shows homology to HrpF of the plant pathogen
Xanthomonas campestris
pv. vesicatoria. It is not known whether NolX functions at the bacterium-plant interface or acts inside the host cell. Antibodies raised against
S. fredii
USDA257 NolX were used in immunocytochemical studies to investigate the subcellular localization of this protein. Immunostaining of paraffin-embedded sections of developing soybean and cowpea (
Vigna unguiculata
[L.] Walp) nodules revealed localization of NolX in the infection threads. Protein A-gold immunocytochemical localization studies utilizing affinity-purified NolX antibodies revealed specific deposition of gold particles in the fibrillar material inside infection threads. Similar immunogold localization studies failed to detect NolX in thin sections of mature soybean and cowpea nodules. The results from this study indicate that NolX is expressed in planta only during the early stages of nodule development.