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1.
Emerg Infect Dis ; 26(1): 181-183, 2020 01.
Article in English | MEDLINE | ID: mdl-31855538

ABSTRACT

A 60-year-old man from South Korea underwent a colonoscopy. A juvenile female worm showing 3 pairs of teeth in the buccal cavity was recovered from the descending colon. Partial sequencing of the internal transcribed spacer region showed 100% identity with Ancylostoma caninum, the dog hookworm.


Subject(s)
Ancylostoma , Ancylostomiasis/epidemiology , Ancylostoma/genetics , Ancylostomiasis/diagnosis , Ancylostomiasis/parasitology , Animals , Humans , Male , Middle Aged , Phylogeny , Polymerase Chain Reaction , Republic of Korea/epidemiology , Sequence Analysis, DNA
2.
J AOAC Int ; 102(6): 1767-1773, 2019 Nov 01.
Article in English | MEDLINE | ID: mdl-30871654

ABSTRACT

Background: PCR methods are the most commonly used DNA-based identity tool in the commercial food, beverage, and natural health product markets. These methods are routinely used to identify foodborne pathogens and allergens in food. Proper validation methods for some sectors have been established, while there are none in other markets, such as botanicals. Results: A survey of the literature indicates that some validation criteria are not addressed when developing PCR tests for botanicals. Objective: We provide recommendations for qualitative real-time PCR methods for validating identity tests for botanical ingredients. Methods: These include common criteria that underpin the development and validation of rigorous tests, including (1) the aim of the validation test, (2) the applicability of different matrix variants, (3) specificity in identifying the target species ingredient, (4) sensitivity in detecting the smallest amount of the target material, (5) repeatability of methods, (6) reproducibility in detecting the target species in both raw and processed materials, (7) practicability of the test in a commercial laboratory, and (8) comparison with alternative methods. In addition, we recommend additional criteria, according to which the practicability of the test method is evaluated by transferring the method to a second laboratory and by comparison with alternative methods. Conclusions and Highlights: We hope that these recommendations encourage further publication on the validation of PCR methods for many botanical ingredients. These properly validated PCR methods can be developed on small, real-time biotechnology that can be placed directly into the supply chain ledger in support of highly transparent data systems that support QC from the farm to the fork of the consumer.


Subject(s)
Plant Preparations/analysis , Real-Time Polymerase Chain Reaction/standards , Plants/chemistry , Reproducibility of Results
3.
J Orthop Sci ; 24(4): 636-642, 2019 Jul.
Article in English | MEDLINE | ID: mdl-30606647

ABSTRACT

BACKGROUND: There are few clinical studies evaluating the relationship between lunate cysts and symptomatic ulnar impaction syndrome (UIS). The purpose of this study was to investigate the prevalence and relationship between lunate cysts and UIS by comparing data from patients with UIS against those without. MATERIALS AND METHODS: From March 2012 to January 2015, 375 patients who had undergone MRI or CT for reasons other than ulnar-sided wrist pain were classified into the 'asymptomatic group' (Group I). Thirty three patients who had been diagnosed with UIS were classified in the 'UIS group' (Group II). We determined whether any differences were present between the two groups and evaluated prognostic factors for lunate cysts. RESULTS: The prevalence of lunate cysts was significantly higher in Group II but only reached just above 50% (10.4% vs. 57.6%, p < 0.001]. Dorsal-side lunate cysts were more frequent than palmar side in Group I, while Group II had more cysts on the palmar side (74.4% vs. 52.6%, p = 0.001). Logistic regression analysis revealed that UIS and patient age was a significant factor for the presence of lunate cysts (odds ratio: 11.692, p < 0.001; odds ratio: 1.063, p < 0.001, respectively). However, positive ulnar variance or duration of symptom in Group II was not a predisposing factor for lunate cysts (odds ratio: 1.035, p = 0.598; odds ratio: 1.007, p = 0.877, respectively). CONCLUSION: Since positive ulnar variance or duration of symptom did not affect the formation of the lunate cyst and only slightly more than 50% (57.6%) of patients with UIS had a lunate cyst, it seems unlikely that these cysts are a pathognomonic finding. Surgeons can obtain some evidence from lunate cysts on radiographic exams, but care must be taken that this diagnosis is not made hastily or without due consideration.


Subject(s)
Arthralgia/complications , Arthralgia/diagnostic imaging , Bone Cysts/epidemiology , Lunate Bone , Wrist Joint , Adult , Aged , Bone Cysts/diagnostic imaging , Female , Humans , Magnetic Resonance Imaging , Male , Middle Aged , Prevalence , Retrospective Studies , Tomography, X-Ray Computed , Young Adult
5.
Korean J Gastroenterol ; 69(5): 321-324, 2017 May 25.
Article in English | MEDLINE | ID: mdl-28539039

ABSTRACT

An isolated pyogenic pancreatic abscess (IPPA) without pancreatitis is extremely rare but can occur in patients with uncontrolled diabetes. This pathologic condition poses a clinical challenge in diagnosis and management because it can be confused easily with a malignancy. Endoscopic ultrasound (EUS) may be a useful diagnostic modality for indeterminate pancreatic lesions and IPPA. Here, we report two cases with elevated carbohydrate antigen 19-9 levels and pancreatic masses on cross sectional imaging. The patients were subsequently diagnosed with IPPA by EUS. EUS-guided drainage was performed successfully and the patients' clinical symptoms and radiologic findings improved. In our experience, EUS and EUS-guided drainage are crucial steps for the diagnosis and management of patients with an indeterminate pancreatic lesion. In addition, EUS-guided drainage has excellent technical and clinical outcomes for the treatment of IPPA.


Subject(s)
Abscess/diagnosis , Pancreatic Diseases/diagnosis , Abscess/microbiology , CA-19-9 Antigen/analysis , Drainage , Endosonography , Humans , Klebsiella pneumoniae/isolation & purification , Male , Middle Aged , Pancreas/diagnostic imaging , Tomography, X-Ray Computed
6.
Knee Surg Sports Traumatol Arthrosc ; 25(6): 1951-1957, 2017 Jun.
Article in English | MEDLINE | ID: mdl-28004173

ABSTRACT

PURPOSE: The study determined the prevalence of subspinal impingement (SSI) in symptomatic and asymptomatic individuals, morphologic characteristics in symptomatic patients, and risk factors for SSI. METHODS: The study cohort consisted of 427 patients (427 hips; median age 33.4 years; range 19-50 years) with mechanical symptoms who underwent multi-detector computed tomography arthrography (symptomatic patients) and 259 control (asymptomatic) patients who underwent abdominopelvic three-dimensional CT because of a ureter stone or minor trauma. Two orthopaedic surgeons reviewed the images to evaluate the prevalence of SSI and the relationship with morphologic abnormalities. Radiologic parameters were further compared between the SSI and non-SSI groups in symptomatic patients using the Chi-squared test or two-sample t test. Variables with p values <0.10 (sex and age) were included in the multi-variate analysis. Logistic regression analysis was carried out to identify independent risk factors for SSI. RESULTS: The prevalence of SSI in symptomatic and asymptomatic patients was 65/427 (15.2%) and 40/259 (15.4%), respectively (n.s.). Structural bony abnormalities in symptomatic patients were not associated with the presence of SSI (n.s.). Binary logistic regression analysis revealed that youth (odds ratio 0.952, 95% CI 0.922-0.984) was the only significant factor for SSI. CONCLUSIONS: SSI had a similar prevalence in symptomatic and asymptomatic patients and was not rare in either group. Therefore, clinical implication of SSI in symptomatic patient should be re-evaluated through further study. LEVEL OF EVIDENCE: Level IV.


Subject(s)
Asymptomatic Diseases/epidemiology , Femoracetabular Impingement/diagnostic imaging , Femoracetabular Impingement/epidemiology , Hip Joint/diagnostic imaging , Adult , Arthrography , Asymptomatic Diseases/therapy , Cohort Studies , Female , Femoracetabular Impingement/surgery , Hip Joint/surgery , Humans , Imaging, Three-Dimensional , Male , Middle Aged , Odds Ratio , Prevalence , Risk Factors , Tomography, X-Ray Computed , Young Adult
7.
Int J Geriatr Psychiatry ; 32(10): 1079-1084, 2017 Oct.
Article in English | MEDLINE | ID: mdl-27561376

ABSTRACT

OBJECTIVE: To date, data regarding the efficacy of acetylcholinesterase inhibitors in preventing postoperative delirium (POD) are inconsistent and conflicting. Older individuals with cognitive dysfunction are thought to show POD more frequently. Our aim was to study the effectiveness of rivastigmine prophylaxis on the incidence, severity, and risk factors for POD in older patients with cognitive impairment undergoing hip fracture surgery. METHODS: Of 62 older patients with cognitive impairment about to undergo surgery after a hip fracture, 31 were randomly assigned to receive a rivastigmine patch from 3 days before to 7 days after the operation (Group I), and the other 31 did not receive a rivastigmine patch (Group II). The two groups were compared with regard to incidence and severity of delirium on postoperative days 2 or 3 and 7. Multivariate logistic regression analysis was performed to assess factors associated with POD. RESULTS: Postoperative delirium occurred in five Group I patients and 14 Group II patients (p = 0.013). The mean severity of delirium in the two groups as determined by the Delirium Rating Scale was 2.2 and 6.2 respectively (p = 0.033). The odds ratio for POD was 0.259 (95% CI: 0.074-0.905, p = 0.034) after adjusting for American Society of Anesthesiologists score (p = 0.058), age (p = 0.203), and gender (p = 0.560). There were no rivastigmine-related perioperative complications. CONCLUSION: Perioperative rivastigmine patch application could reduce the occurrence of POD in older patients with low cognitive status. Copyright © 2016 John Wiley & Sons, Ltd.


Subject(s)
Cholinesterase Inhibitors/administration & dosage , Cognitive Dysfunction/complications , Delirium/prevention & control , Hip Fractures/surgery , Postoperative Complications/prevention & control , Rivastigmine/administration & dosage , Rivastigmine/therapeutic use , Administration, Cutaneous , Aged , Aged, 80 and over , Delirium/epidemiology , Female , Humans , Incidence , Male , Multivariate Analysis , Odds Ratio , Postoperative Complications/epidemiology , Prospective Studies , Risk Factors
8.
J Biol Chem ; 287(19): 16058-72, 2012 May 04.
Article in English | MEDLINE | ID: mdl-22408253

ABSTRACT

Petrobactin, a mixed catechol-carboxylate siderophore, is required for full virulence of Bacillus anthracis, the causative agent of anthrax. The asbABCDEF operon encodes the biosynthetic machinery for this secondary metabolite. Here, we show that the function of five gene products encoded by the asb operon is necessary and sufficient for conversion of endogenous precursors to petrobactin using an in vitro system. In this pathway, the siderophore synthetase AsbB catalyzes formation of amide bonds crucial for petrobactin assembly through use of biosynthetic intermediates, as opposed to primary metabolites, as carboxylate donors. In solving the crystal structure of the B. anthracis siderophore biosynthesis protein B (AsbB), we disclose a three-dimensional model of a nonribosomal peptide synthetase-independent siderophore (NIS) synthetase. Structural characteristics provide new insight into how this bifunctional condensing enzyme can bind and adenylate multiple citrate-containing substrates followed by incorporation of both natural and unnatural polyamine nucleophiles. This activity enables formation of multiple end-stage products leading to final assembly of petrobactin. Subsequent enzymatic assays with the nonribosomal peptide synthetase-like AsbC, AsbD, and AsbE polypeptides show that the alternative products of AsbB are further converted to petrobactin, verifying previously proposed convergent routes to formation of this siderophore. These studies identify potential therapeutic targets to halt deadly infections caused by B. anthracis and other pathogenic bacteria and suggest new avenues for the chemoenzymatic synthesis of novel compounds.


Subject(s)
Bacillus anthracis/metabolism , Bacterial Proteins/metabolism , Benzamides/metabolism , Biosynthetic Pathways , Carbon-Nitrogen Ligases/metabolism , Ligases/metabolism , Amino Acid Sequence , Bacillus anthracis/genetics , Bacterial Proteins/chemistry , Bacterial Proteins/genetics , Benzamides/chemistry , Biocatalysis , Carbon-Nitrogen Ligases/chemistry , Carbon-Nitrogen Ligases/genetics , Crystallography, X-Ray , Ligases/chemistry , Ligases/genetics , Models, Chemical , Models, Molecular , Molecular Sequence Data , Molecular Structure , Polyamines/chemistry , Polyamines/metabolism , Protein Binding , Protein Structure, Tertiary , Sequence Homology, Amino Acid , Siderophores/chemistry , Siderophores/metabolism , Substrate Specificity
9.
PLoS One ; 6(6): e20777, 2011.
Article in English | MEDLINE | ID: mdl-21673962

ABSTRACT

BACKGROUND: Bacillus anthracis produces two catecholate siderophores, petrobactin and bacillibactin, under iron-limited conditions. Here, we investigate how variable iron and oxygen concentrations influence the biosynthetic output of both siderophores in B. anthracis. In addition, we describe the differential levels of transcription of select genes within the B. anthracis siderophore biosynthetic operons that are responsible for synthesis of petrobactin and bacillibactin, during variable growth conditions. METHODOLOGY/PRINCIPAL FINDINGS: Accumulation of bacillibactin in B. anthracis Sterne (34F(2)) and in a mutant lacking the major superoxide dismutase (ΔsodA1) was almost completely repressed by the addition of 20 µM of iron. In contrast, petrobactin synthesis in both strains continued up to 20 µM of iron. Accumulation of petrobactin and bacillibactin showed a slight increase with addition of low levels of paraquat-induced oxidative stress in wild type B. anthracis Sterne. Cultures grown with high aeration resulted in greater accumulation of petrobactin relative to low aeration cultures, and delayed the repressive effect of added iron. Conversely, iron-depleted cultures grown with low aeration resulted in increased levels of bacillibactin. No difference was found in overall superoxide dismutase (SOD) activity or transcriptional levels of the sodA1 and sodA2 genes between iron-depleted and iron-replete conditions at high or low aeration, suggesting that SOD regulation and iron metabolism are separate in B. anthracis. The highest transcription of the gene asbB, part of the petrobactin biosynthetic operon, occurred under iron-limitation with high aeration, but transcription was readily detectable even under iron-replete conditions and in low aeration. The gene dhbC, a member of the bacillibactin biosynthetic operon, was only transcribed under conditions of iron-depletion, regardless of growth aeration. CONCLUSION: These data suggest that bacillibactin regulation is highly sensitive to iron-concentration. In contrast, although regulation of petrobactin is less dependent on iron, it is likely subject to additional levels of regulation that may contribute to virulence of B. anthracis.


Subject(s)
Bacillus anthracis/drug effects , Bacillus anthracis/metabolism , Benzamides/metabolism , Iron/pharmacology , Oligopeptides/biosynthesis , Oxygen/pharmacology , Air , Atmosphere/chemistry , Bacillus anthracis/genetics , Bacillus anthracis/growth & development , Cell Extracts , Dose-Response Relationship, Drug , Iron/metabolism , Mutation , Oligopeptides/metabolism , Operon/genetics , Oxidation-Reduction/drug effects , Paraquat/pharmacology , Reverse Transcriptase Polymerase Chain Reaction , Siderophores/biosynthesis , Siderophores/metabolism , Superoxide Dismutase/genetics , Superoxide Dismutase/metabolism , Transcription, Genetic/drug effects
10.
J Biomech ; 43(16): 3217-21, 2010 Dec 01.
Article in English | MEDLINE | ID: mdl-20801453

ABSTRACT

We investigated the thermal effects on heart rate, hemodynamics, and response of vitelline arteries of stage-18 chicken embryos. Heart rate was monitored by a high-speed imaging method, while hemodynamic quantities were evaluated using a particle image velocimetry (PIV) technique. Experiments were carried out at seven different temperatures (36-42 °C with 1 °C interval) after 1h of incubation to stabilize the heart rate. The heart rate increased in a linear manner (r = 0.992). Due to the increased cardiac output (or heart rate), the hemodynamic quantities such as mean velocity (U(mean)), velocity fluctuation (U(fluc)), and peak velocity (U(peak)) also increased with respect to the Womersley number (Ω) in the manner r = 0.599, 0.693, and 0.725, respectively. This indicates that the mechanical force exerting on the vessel walls increases. However, the active response (or regulation) of the vitelline arteries was not observed in this study.


Subject(s)
Heart Rate/physiology , Hemodynamics/physiology , Vitelline Membrane/blood supply , Animals , Arteries/embryology , Arteries/physiology , Biomechanical Phenomena , Blood Flow Velocity/physiology , Cardiac Output/physiology , Chick Embryo , Fever/embryology , Fever/physiopathology , Temperature
11.
Microvasc Res ; 80(3): 402-11, 2010 Dec.
Article in English | MEDLINE | ID: mdl-20727902

ABSTRACT

OBJECTIVE: The primary objective of this study is to evaluate the hemodynamic and structural characteristics of the omphalo-mesenteric (vitelline) arteries in stage 18 chicken embryos. The measured results were compared with Murray's law to validate the theoretical prediction on the vascular structure. METHODS: Variation of hemodynamic parameters such as mean velocity (U(mean)), peak velocity (U(peak)) at the systolic phase, velocity fluctuations (U(fluc)) at the pulsatile frequency, and the Womersley number (Ω) were measured with respect to the geometric parameters including the bifurcation cascade level (BCL), vessel diameter (D), and distance (L) from the first bifurcation. They were assessed by using the time-resolved in vivo micro-PIV (particle image velocimetry) technique and the geometric information was obtained from the microscopic vessel images. RESULTS: The effect of "branching of the vessel" on the variation of hemodynamic characteristics is similar to those of the "increase in distance" from the first bifurcation and the "decrease in vessel diameter". The flow quantities (U(mean), U(peak) and U(fluc)) decrease due to the increase in cross-sectional area ratio (γ=1.209=(∑D(daughter)(2))/D(mother)(2)), and the Womersley number also decreases as the bifurcation cascades (Ω«1). CONCLUSION: The geometric parameters are closely related to the variation of hemodynamic characteristics. Murray's law with non-constant viscosity hypothesis would provide an insight on the two-phase nature of microvascular blood flows.


Subject(s)
Hemodynamics , Microcirculation , Vitelline Duct/blood supply , Animals , Arteries/embryology , Blood Flow Velocity , Chick Embryo , Models, Cardiovascular , Pulsatile Flow , Regional Blood Flow , Rheology
12.
J Biomech ; 42(7): 857-64, 2009 May 11.
Article in English | MEDLINE | ID: mdl-19272604

ABSTRACT

Female mosquitoes are known to have a magnificent micro-scale pumping system that can transport small quantities of blood very effectively. To understand the dynamic characteristics of blood flow inside female mosquitoes, the measurement technique that is capable of measuring instantaneous flow fields of a biological sample at micrometer scales is required. In this study, the blood-sucking flow inside a female mosquito's food canal was measured in vivo using a micro particle image velocimetry (micro-PIV) velocity field measurement technique with high-temporal resolution. The volumetric flow rate (Q) and the time-averaged feeding speed (V) based on the diameter of the food canal (D) was found to be 5.751 x 10(-3) mm3/s and 0.416 cm/s, respectively. Spectral analysis on the velocity waveform shows a clear peak at 6.1 Hz, indicating distinct pulsatile blood-sucking characteristics. The Womersley number (alpha) was about 0.117 and the velocity profile of the blood flow inside the proboscis has a parabolic Hagen-Poiseuille flow pattern when alpha is much smaller than 1.


Subject(s)
Culicidae/anatomy & histology , Culicidae/physiology , Feeding Behavior/physiology , Animals , Biomechanical Phenomena , Blood Flow Velocity , Female , Microscopy, Electron, Scanning , Sucking Behavior/physiology
13.
Proc Natl Acad Sci U S A ; 105(44): 17133-8, 2008 Nov 04.
Article in English | MEDLINE | ID: mdl-18955706

ABSTRACT

Petrobactin, a virulence-associated siderophore produced by Bacillus anthracis, chelates ferric iron through the rare 3,4-isomer of dihydroxybenzoic acid (3,4-DHBA). Most catechol siderophores, including bacillibactin and enterobactin, use 2,3-DHBA as a biosynthetic subunit. Significantly, siderocalin, a factor involved in human innate immunity, sequesters ferric siderophores bearing the more typical 2,3-DHBA moiety, thereby impeding uptake of iron by the pathogenic bacterial cell. In contrast, the unusual 3,4-DHBA component of petrobactin renders the siderocalin system incapable of obstructing bacterial iron uptake. Although recent genetic and biochemical studies have revealed selected early steps in petrobactin biosynthesis, the origin of 3,4-DHBA as well as the function of the protein encoded by the final gene in the B. anthracis siderophore biosynthetic (asb) operon, asbF (BA1986), has remained unclear. In this study we demonstrate that 3,4-DHBA is produced through conversion of the common bacterial metabolite 3-dehydroshikimate (3-DHS) by AsbF-a 3-DHS dehydratase. Elucidation of the cocrystal structure of AsbF with 3,4-DHBA, in conjunction with a series of biochemical studies, supports a mechanism in which an enolate intermediate is formed through the action of this 3-DHS dehydratase metalloenzyme. Structural and functional parallels are evident between AsbF and other enzymes within the xylose isomerase TIM-barrel family. Overall, these data indicate that microbial species shown to possess homologs of AsbF may, like B. anthracis, also rely on production of the unique 3,4-DHBA metabolite to achieve full viability in the environment or virulence within the host.


Subject(s)
Bacterial Proteins/chemistry , Benzamides/metabolism , Hydro-Lyases/chemistry , Hydroxybenzoates/metabolism , Animals , Bacillus anthracis/genetics , Bacillus anthracis/metabolism , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Crystallography, X-Ray , Hydro-Lyases/genetics , Hydro-Lyases/metabolism , Hydrogen-Ion Concentration , Hydroxybenzoates/chemistry , Mice , Models, Molecular , Operon , Protein Conformation , Shikimic Acid/analogs & derivatives , Shikimic Acid/chemistry , Shikimic Acid/metabolism , Structure-Activity Relationship
14.
Pest Manag Sci ; 64(2): 172-7, 2008 Feb.
Article in English | MEDLINE | ID: mdl-18069650

ABSTRACT

BACKGROUND: A number of synthetic fungicides are not effective when confronted by oomycete pathogens because many fungicide targets are absent from oomycetes. Moreover, resistance to fungicides has already arisen in oomycete species, and thus development of new, effective and safe compounds for use in oomycete disease control is necessary. RESULTS: Zoospore lysis began at 10 microg mL(-1) of thiobutacin, and most of the zoospores were collapsed at 50 microg mL(-1). Thiobutacin also revealed inhibitory activity against the cyst germination and hyphal growth of Phytophthora capsici at 50 microg mL(-1). Treatment with thiobutacin exhibited protective activity against development of Phytophthora disease on pepper plants. CONCLUSION: The authors verified in vitro antioomycete activity of thiobutacin against P. capsici and its control efficacy against Phytophthora blight in vivo. This is the first report to demonstrate in vivo antioomycete activity of the novel antibiotic thiobutacin against P. capsici infection.


Subject(s)
Anti-Bacterial Agents/pharmacology , Butyrates/pharmacology , Phytophthora/drug effects , Alanine/analogs & derivatives , Alanine/pharmacology , Anti-Bacterial Agents/chemistry , Bacteria/drug effects , Butyrates/chemistry , Capsicum/microbiology , Dose-Response Relationship, Drug , Fungi/drug effects , Molecular Structure
15.
Physiol Meas ; 28(10): 1149-62, 2007 Oct.
Article in English | MEDLINE | ID: mdl-17906384

ABSTRACT

The hemodynamic characteristics of blood flow are important in the diagnosis of circulatory diseases, since such diseases are related to wall shear stress of cardiovascular vessels. In chicken embryos at early stages of development, it is possible to directly visualize blood flow inside blood vessels. We therefore employed a micro-PIV technique to assess blood flow in extraembryonic venous and arterial blood vessels of chicken embryos, using red blood cells (RBCs) as tracers and obtaining flow images of RBCs using a high-speed CMOS camera. The mean velocity field showed non-Newtonian flow characteristics. The blood flow in two venous vessels merged smoothly into the Y-shaped downstream vein without any flow separation or secondary flow. Vorticity was high in the inner regions, where the radius of curvature varied greatly. A periodic variation of temporally resolved velocity signals, due to beating of the heart, was observed in arterial blood vessels. The pulsating frequency was obtained by fast Fourier transform analysis using the measured velocity data. The measurement technique used here was useful in analyzing the hemodynamic characteristics of in vivo blood flow in chicken embryos.


Subject(s)
Extraembryonic Membranes/blood supply , Rheology/methods , Animals , Arteries/physiology , Chick Embryo , Erythrocytes , Regional Blood Flow , Time Factors , Veins/physiology
16.
Biochemistry ; 46(13): 4147-57, 2007 Apr 03.
Article in English | MEDLINE | ID: mdl-17346033

ABSTRACT

Recently, iron acquisition and, more specifically, enzymes involved in siderophore biosynthesis have become attractive targets for discovery of new antibiotics. Accordingly, targeted inhibition of the biosynthesis of petrobactin, a virulence-associated siderophore encoded by the asb locus in Bacillus anthracis, may hold promise as a potential therapy against anthrax. This study describes the biochemical characterization of AsbC, the first reported 3,4-dihydroxybenzoic acid-AMP ligase, and a key component in the biosynthesis of DHB-spermidine (DHB-SP), the first isolable intermediate in petrobactin biosynthesis. AsbC catalyzes adenylation to the corresponding AMP ester of the unusual precursor 3,4-dihydroxybenzoate, in addition to benzoate substrates bearing hydrogen bond-donating substituents at the para and meta positions on the phenyl ring. In a second reaction, AsbC catalyzes transfer of the activated starter unit to AsbD, an aryl carrier protein similar to acyl and peptidyl carrier proteins that function in fatty acid, polyketide, and nonribosomal peptide biosynthesis. A third protein, AsbE, is shown to be responsible for condensation of 3,4-dihydroxybenzoyl-AsbD with spermidine, providing the DHB-spermidine arms that are linked to citrate for assembly of petrobactin. On the basis of the selective substrate profile of AsbC, a nonhydrolyzable analogue of 3,4-DHB-AMP was synthesized and shown to effectively inhibit AsbC function in vitro.


Subject(s)
Bacillus anthracis/metabolism , Benzamides/metabolism , Nucleotidyltransferases/isolation & purification , Bacillus anthracis/enzymology , Carrier Proteins/isolation & purification , Carrier Proteins/metabolism , Cloning, Molecular , Nucleotidyltransferases/antagonists & inhibitors , Nucleotidyltransferases/metabolism , Substrate Specificity
17.
J Am Soc Mass Spectrom ; 18(5): 842-9, 2007 May.
Article in English | MEDLINE | ID: mdl-17331739

ABSTRACT

Siderophores are high-affinity iron-chelating ligands produced by microorganisms to scavenge vital Fe(3+) from the environment. Thus, siderophores constitute potential therapeutic targets and their structural determination is important for exploiting their therapeutic value. Here, the virulence-associated siderophore petrobactin from Bacillus anthracis was characterized with electron capture dissociation (ECD). Fragmentation of doubly protonated petrobactin was investigated and compared to sustained off-resonance irradiation collision-activated dissociation (SORI CAD) and infrared multiphoton dissociation (IRMPD) of both the singly and doubly protonated species. These experiments demonstrate that ECD provides additional information (complementary bond cleavages) on the structure of petrobactin compared to both SORI CAD and IRMPD. Furthermore, complexes of petrobactin with divalent (Ca(2+), Fe(2+), and Co(2+)) and trivalent (Fe(3+) and Ga(3+)) metal cations were also subjected to SORI CAD and ECD. Again, most structural information was obtained from the ECD spectra. However, significant differences were found in both SORI CAD and ECD of metal complexes, dependent on the nature of the metal ion. Intriguingly, unique behavior, consistent with a recently proposed solution-phase structure, was observed for the highly preferred Fe(3+)-petrobactin complex.


Subject(s)
Bacillus anthracis/chemistry , Benzamides/chemistry , Electrons , Organometallic Compounds/chemistry , Photons , Siderophores/chemistry , Bacillus anthracis/metabolism , Benzamides/metabolism , Cations/chemistry , Infrared Rays , Siderophores/metabolism , Spectrometry, Mass, Electrospray Ionization , Spectroscopy, Fourier Transform Infrared , Tandem Mass Spectrometry
18.
J Bacteriol ; 189(11): 3996-4013, 2007 Jun.
Article in English | MEDLINE | ID: mdl-17384197

ABSTRACT

Microarray analyses were conducted to evaluate the paraquat-induced global transcriptional response of Bacillus anthracis Sterne (34F(2)) to varying levels of endogenous superoxide stress. Data revealed that the transcription of genes putatively involved in metal/ion transport, bacillibactin siderophore biosynthesis, the glyoxalase pathway, and oxidoreductase activity was perturbed most significantly. A B. anthracis mutant lacking the superoxide dismutase gene sodA1 (Delta sodA1) had transcriptional responses to paraquat similar to, but notably larger than, those of the isogenic parental strain. A small, unique set of genes was found to be differentially expressed in the Delta sodA1 mutant relative to the parental strain during growth in rich broth independently of induced oxidative stress. The bacillibactin siderophore biosynthetic genes were notably overexpressed in Sterne and Delta sodA1 cells after treatment with paraquat. The bacillibactin siderophore itself was isolated from the supernatants and lysates of cells grown in iron-depleted medium and was detected at lower levels after treatment with paraquat. This suggests that, while transcriptional regulation of these genes is sensitive to changes in the redox environment, additional levels of posttranscriptional control may exist for bacillibactin biosynthesis, or the enzymatic siderophore pipeline may be compromised by intracellular superoxide stress or damage. The Delta sodA1 mutant showed slower growth in a chelated iron-limiting medium but not in a metal-depleted medium, suggesting a connection between the intracellular redox state and iron/metal ion acquisition in B. anthracis. A double mutant lacking both the sodA1 and sodA2 genes (Delta sodA1 Delta sodA2) was attenuated for growth in manganese-depleted medium, suggesting a slight level of redundancy between sodA1 and sodA2, and a role for the sod genes in manganese homeostasis.


Subject(s)
Bacillus anthracis/drug effects , Mutation , Paraquat/pharmacology , Superoxides/metabolism , Transcription, Genetic/drug effects , Bacillus anthracis/genetics , Bacillus anthracis/metabolism , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Benzamides/metabolism , Chromatography, Liquid , Esters/metabolism , Gene Expression Regulation, Bacterial/drug effects , Herbicides/pharmacology , Homeostasis , Iron/metabolism , Mass Spectrometry , Oligonucleotide Array Sequence Analysis , Oligopeptides/metabolism , Oxidative Stress , Reverse Transcriptase Polymerase Chain Reaction , Siderophores/metabolism , Superoxide Dismutase/genetics , Superoxide Dismutase/metabolism
19.
J Bacteriol ; 189(5): 1698-710, 2007 Mar.
Article in English | MEDLINE | ID: mdl-17189355

ABSTRACT

The asbABCDEF gene cluster from Bacillus anthracis is responsible for biosynthesis of petrobactin, a catecholate siderophore that functions in both iron acquisition and virulence in a murine model of anthrax. We initiated studies to determine the biosynthetic details of petrobactin assembly based on mutational analysis of the asb operon, identification of accumulated intermediates, and addition of exogenous siderophores to asb mutant strains. As a starting point, in-frame deletions of each of the genes in the asb locus (asbABCDEF) were constructed. The individual mutations resulted in complete abrogation of petrobactin biosynthesis when strains were grown on iron-depleted medium. However, in vitro analysis showed that each asb mutant grew to a very limited extent as vegetative cells in iron-depleted medium. In contrast, none of the B. anthracis asb mutant strains were able to outgrow from spores under the same culture conditions. Provision of exogenous petrobactin was able to rescue the growth defect in each asb mutant strain. Taken together, these data provide compelling evidence that AsbA performs the penultimate step in the biosynthesis of petrobactin, involving condensation of 3,4-dihydroxybenzoyl spermidine with citrate to form 3,4-dihydroxybenzoyl spermidinyl citrate. As a final step, the data reveal that AsbB catalyzes condensation of a second molecule of 3,4-dihydroxybenzoyl spermidine with 3,4-dihydroxybenzoyl spermidinyl citrate to form the mature siderophore. This work sets the stage for detailed biochemical studies with this unique acyl carrier protein-dependent, nonribosomal peptide synthetase-independent biosynthetic system.


Subject(s)
Bacillus anthracis/metabolism , Benzamides/metabolism , Bacillus anthracis/growth & development , Base Sequence , Chromatography, High Pressure Liquid , Genetic Complementation Test , Iron/metabolism , Mass Spectrometry , Molecular Sequence Data , Mutation , Operon
20.
J Agric Food Chem ; 54(8): 3041-6, 2006 Apr 19.
Article in English | MEDLINE | ID: mdl-16608228

ABSTRACT

The actinomycete strain LS-A24 active against some plant fungal and oomycete pathogens was isolated from a soil sample of the Sunghwan Lake in Korea. The cell wall composition and spore shape of strain LS-A24 were LL-diaminopimelic acid and spiral type, respectively. On the basis of the physiological and biochemical characteristics and 16S ribosomal DNA sequence analysis, strain LS-A24 was identical to Streptomyces roseoflavus. An antifungal and antioomycete antibiotic was isolated from LS-A24 using various chromatographic procedures. The molecular formular of the antibiotic was determined to be C(28)H(26)N(4)O(3), and on the basis of the NMR data, the antibiotic was confirmed to be staurosporine, 2,3,10,11,12,13-hexahydro-10R-methoxy-9S-methyl-11R-methylamino-9S,13R-epoxy-1H,9H-diindolo[1,2,3-gh:3',2',1'-lm]pyrrolo[3,4-j][1,7]benzodiazonin-1-one. Staurosporine completely inhibited the mycelial growth of Colletotrichum orbiculare, Phytophthora capsici, Rhizoctonia solani, Botrytis cinerea, and Cladosporium cucumerinum with minimum inhibitory concentration (MIC) values of 1-50 microg/mL for MICs. Staurosporine also was active against Saccharomyces cerevisiae, Bacillus subtilis ssp. subtilis, and Xanthomonas vesicatoria. Staurosporine and the commercial fungicide metalaxyl inhibited the development of Phytophthora blight on pepper plants. However, the control efficacy of staurosporine against the Phytophthora disease was somewhat less than that of metalaxyl. This is the first study to isolate staurosporine from S. roseoflavus and demonstrate its in vitro and in vivo antioomycete activity against P. capsici.


Subject(s)
Fungicides, Industrial/pharmacology , Oomycetes/drug effects , Staurosporine/isolation & purification , Staurosporine/pharmacology , Streptomyces/chemistry , Magnetic Resonance Spectroscopy , Phylogeny , Plants/microbiology , Soil Microbiology , Staurosporine/chemistry , Streptomyces/classification
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