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1.
World J Pediatr Congenit Heart Surg ; : 21501351241237955, 2024 Apr 24.
Article in English | MEDLINE | ID: mdl-38656246

ABSTRACT

Circumflex aortic arch with coarctation and anomalous origin of the left pulmonary artery from the aorta are rare cardiovascular anomalies. These conditions can lead to early pulmonary hypertension and challenging management. Early diagnosis and surgical intervention are beneficial for optimal outcome. We present a case where both anomalies coexisted and were repaired with aortic uncrossing, arch augmentation, and reimplantation of the left pulmonary artery. To our knowledge, this is the first documented instance of these anomalies coexisting and being repaired in the neonatal period.

2.
Pediatr Cardiol ; 40(1): 147-153, 2019 Jan.
Article in English | MEDLINE | ID: mdl-30196380

ABSTRACT

BACKGROUND: In 2017, the AHA published revised guidelines for the diagnosis of Kawasaki disease (KD). In the absence of compelling data supporting or refuting the utility of lack of tapering (LT) and perivascular brightness (PB), expert panel consensus removed LT and PB from consideration. We hypothesize that LT and PB are unreliable, subjective findings, non-specific to KD, which can be seen in systemic febrile illnesses without KD and in normal controls. METHODS: We performed a single-center retrospective study from 1/2008 to 12/2016. De-identified coronary artery (CA) echocardiographic clips from patients 0-10 years old were interpreted blindly by six pediatric cardiologists. Subjects were grouped as follows: (1) healthy: afebrile with benign murmur, (2) KD: IVIG treatment, 4-5 clinical criteria at presentation, (3) incomplete KD (iKD): IVIG, 1-3 clinical criteria, (4) Febrile: ≥3 days of fever, no IVIG, KD not suspected. The presence or absence of LT and PB was recorded. Inter-rater and intra-rater reliabilities were analyzed using intra-class correlation coefficient, Fleiss' Kappa and Cohen's Kappa coefficients. RESULTS: We interpreted 117 echocardiograms from healthy (27), KD (30), iKD (32), and febrile (28) subjects. Analysis showed moderate agreement in CA z score measurements. LT and PB were observed by most readers in control groups. LT exhibited fair inter-reader agreement (reliability coefficient 0.36) and PB slight inter-reader agreement (reliability coefficient 0.13). Intra-rater reliability was inconsistent for both parameters. CONCLUSIONS: LT and PB are subjective, poorly reproducible features that can be seen in febrile patients without KD and in healthy children.


Subject(s)
Coronary Vessels/diagnostic imaging , Mucocutaneous Lymph Node Syndrome/diagnostic imaging , Case-Control Studies , Child , Child, Preschool , Echocardiography , Female , Humans , Infant , Infant, Newborn , Male , Mucocutaneous Lymph Node Syndrome/classification , Reproducibility of Results , Retrospective Studies
3.
Health Secur ; 16(4): 224-238, 2018.
Article in English | MEDLINE | ID: mdl-30096247

ABSTRACT

Differentiating between illness caused by community-acquired respiratory pathogens versus infection by biothreat agents is a challenge. This review highlights respiratory and clinical features of category A and B potential biothreat agents that have respiratory features as their primary presenting signs and symptoms. Recent world events make such a reminder that the possibility of rare diseases and unlikely events can occur timely for clinicians, policymakers, and public health authorities. Despite some distinguishing features, nothing can replace good clinical acumen and a strong index of suspicion in the diagnosis of uncommon infectious diseases.


Subject(s)
Bioterrorism , Lung Diseases/diagnosis , Pneumonia/diagnosis , Biological Warfare Agents , Community-Acquired Infections/diagnosis , Humans
4.
J Perinatol ; 38(9): 1220-1226, 2018 09.
Article in English | MEDLINE | ID: mdl-29961764

ABSTRACT

OBJECTIVE: We aimed to correlate photoplethysmographic parameters with stroke volume in infants with PDA. Photoplethysmography constitutes the optical signal in pulse oximetry. STUDY DESIGN: Stroke volume was determined echocardiographically. Pulse transit time, right hand to foot arrival time difference, and relative amplitude were measured from pulse oximeter and ECG waveforms. Photoplethysmographic parameters before and after PDA closure were compared with stroke volume. RESULTS: After PDA closure, pulse transit time to the hand and to the foot were prolonged (54.7 ± 6.7 vs 65.5 ± 9.8 ms, p < 0.001, 82.5 ± 12.8 vs 88.6 ± 10.6 ms, p = 0.03), arrival time difference decreased (27.7 ± 7.6 vs 23.1 ± 5.6 ms, p = 0.021), and relative amplitude decreased (from 2.1 ± 0.7% to 1.5 ± 0.5%, p = 0.003). The time-based photoplethysmographic parameters correlated with stroke volume. CONCLUSIONS: Photoplethysmographic waveform parameters are significantly different before and after PDA closure and the time-based parameters correlate well with stroke volume. Monitoring pulse transit time may assist in evaluation for spontaneous PDA closure or response to therapy.


Subject(s)
Ductus Arteriosus, Patent/physiopathology , Foot/physiology , Hand/physiology , Photoplethysmography , Echocardiography , Female , Humans , Infant, Extremely Low Birth Weight , Infant, Extremely Premature , Infant, Newborn , Male , Prospective Studies , Pulse Wave Analysis , Stroke Volume
7.
J Infect Dis ; 214(suppl 3): S137-S141, 2016 10 15.
Article in English | MEDLINE | ID: mdl-27651413

ABSTRACT

The concept of containment care for patients with highly hazardous infectious diseases originated in conjunction with the development of sophisticated biosafety level 4 laboratories at the US Army Medical Research Institute of Infectious Diseases in the late 1960s. Over time, the original containment facility served as a model for the development of other facilities in the United States at government and academic centers. The Ebola outbreak of 2014-2015 brought the issue of containment care into the mainstream and led to the development of such capabilities at strategic points around the country. We describe the original concepts behind development of such facilities, how the concept and acceptance has evolved over time, and how the guidelines for managing patients infected with viral hemorrhagic fevers have evolved as new information has been learned about protecting medical care providers from highly hazardous infectious pathogens.


Subject(s)
Communicable Diseases/epidemiology , Containment of Biohazards , Disease Outbreaks , Hemorrhagic Fever, Ebola/epidemiology , Hemorrhagic Fevers, Viral/epidemiology , Animals , Communicable Disease Control , Communicable Diseases/virology , Hemorrhagic Fever, Ebola/prevention & control , Hemorrhagic Fever, Ebola/virology , Hemorrhagic Fevers, Viral/prevention & control , Hemorrhagic Fevers, Viral/virology , Humans , Laboratories , Quarantine , United States/epidemiology
8.
Congenit Heart Dis ; 9(6): E179-84, 2014.
Article in English | MEDLINE | ID: mdl-23902593

ABSTRACT

The relationship between accessory pathway-mediated ventricular preexcitation and left ventricular dyssynchrony-induced dysfunction has been described in patients with Wolff-Parkinson-White (WPW) syndrome in the absence of sustained supraventricular tachycardia (SVT). Supraventricular tachycardia in infants is usually successfully suppressed with antiarrhythmic medications, but catheter ablation has ultimately been required as definitive treatment in medically resistant cases. Catheter ablation has not been described in young infants for dyssynchrony-related dilated cardiomyopathy in the absence of SVT. We describe a case of an infant with WPW who did not have sustained supraventricular tachycardia, but who developed rapid progression of ventricular dysfunction after birth. Preexcitation could not be medically suppressed but was successfully ablated. This was followed by complete resolution of ventricular dysfunction within 2 months.


Subject(s)
Cardiomyopathy, Dilated/etiology , Catheter Ablation , Wolff-Parkinson-White Syndrome/surgery , Cardiomyopathy, Dilated/diagnosis , Cardiomyopathy, Dilated/physiopathology , Echocardiography , Electrocardiography , Electrophysiologic Techniques, Cardiac , Female , Heart Failure/etiology , Heart Failure/physiopathology , Humans , Infant , Recovery of Function , Time Factors , Treatment Outcome , Ventricular Dysfunction, Left/etiology , Ventricular Dysfunction, Left/physiopathology , Ventricular Function, Left , Wolff-Parkinson-White Syndrome/complications , Wolff-Parkinson-White Syndrome/diagnosis , Wolff-Parkinson-White Syndrome/physiopathology
9.
Parkinsonism Relat Disord ; 19(12): 1164-6, 2013 Dec.
Article in English | MEDLINE | ID: mdl-24044947

ABSTRACT

BACKGROUND: Human and animal studies, albeit not fully consistent, suggest that vitamin D may reduce risk of Parkinson's disease (PD). Ultraviolet radiation converts vitamin D precursor to the active form. This study examined the hypothesis that working outdoors is associated with a decreased risk of PD. METHODS: PD cases were enrolled from Group Health Cooperative, a health maintenance organization in the Puget Sound region in western Washington State, and the University of Washington Neurology Clinic in Seattle. Participants included 447 non-Hispanic Caucasian newly diagnosed PD cases diagnosed between 1992 and 2008 and 578 unrelated neurologically normal controls enrolled in Group Health Cooperative, frequency matched by race/ethnicity, age and gender. Subjects' amount of outdoor work was estimated from self-reported occupational histories. Jobs were categorized by degree of time spent working outdoors. A ten-year lag interval was included to account for disease latency. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by logistic regression, with adjustment for age, gender, and smoking. RESULTS: Outdoor work was inversely associated with risk of PD (outdoor only compared to indoor only): OR = 0.74, 95% CI 0.44-1.25. However, there was no trend in relation to portion of the workday spent laboring outdoors and PD risk. CONCLUSION: Occupational sunlight exposure and other correlates of outdoor work is not likely to have a substantial role in the etiology of PD.


Subject(s)
Occupations , Parkinson Disease/epidemiology , Parkinson Disease/etiology , Sunlight , Vitamin D , Adult , Aged , Aged, 80 and over , Case-Control Studies , Female , Humans , Male , Middle Aged , Ultraviolet Rays
10.
J Am Soc Echocardiogr ; 26(7): 746-55, 2013 Jul.
Article in English | MEDLINE | ID: mdl-23623591

ABSTRACT

BACKGROUND: Long-term outcome in repaired tetralogy of Fallot (TOF) is related to chronic pulmonary insufficiency (PI), right ventricular (RV) dilation, and deterioration of RV function. The aim of this study was to characterize clinical differences between restrictive and nonrestrictive RV physiology in young patients with repaired TOF. METHODS: Patients were prospectively enrolled from February 2008 to August 2009. Each had a clinic visit, brain natriuretic peptide assessment, exercise test, cardiac magnetic resonance study, and echocardiographic examination with assessment of regional myocardial mechanics. Consistent antegrade diastolic pulmonary arterial flow with atrial contraction identified restrictive RV physiology. RESULTS: Twenty-nine patients (median age, 12 years; range, 8-33 years; nine male patients) were studied. Twelve had restrictive RV physiology. The median time since initial TOF repair was 12 years (range, 5-27 years). Restrictive physiology appeared more prevalent after transannular patch repair and was not influenced by other demographic features. The restrictive group had more PI (46% vs 28%, P = .002), larger RV end-diastolic volumes (128 vs 98 mL/m(2), P = .046), but similar ejection fractions, brain natriuretic peptide levels, New York Heart Association classes, and exercise capacity. RV basal and mid free wall peak diastolic strain rate differed between groups, negatively correlating with exercise time and positively correlating with PI in patients with restrictive physiology. CONCLUSIONS: Restrictive RV physiology correlates with a larger right ventricle and increased PI after TOF repair but does not negatively affect other markers of myocardial health. Diastolic regional RV myocardial mechanics, particularly diastolic velocity and peak diastolic strain rate, differ for postoperative TOF patients with restrictive and nonrestrictive RV physiology; longitudinal study is necessary to understand the relationship of regional myocardial mechanics and patients' clinical status.


Subject(s)
Cardiomyopathy, Restrictive/diagnosis , Postoperative Complications/diagnosis , Tetralogy of Fallot/surgery , Adolescent , Adult , Cardiomyopathy, Restrictive/physiopathology , Child , Echocardiography , Exercise Test , Female , Humans , Magnetic Resonance Imaging , Male , Postoperative Complications/physiopathology , Prospective Studies , Statistics, Nonparametric , Tetralogy of Fallot/physiopathology , Treatment Outcome
11.
Pediatr Cardiol ; 34(6): 1314-20, 2013 Aug.
Article in English | MEDLINE | ID: mdl-23389098

ABSTRACT

This study aimed to determine whether quantification of subpulmonary stenosis (SPS) in tetralogy of Fallot (TOF) in the second-trimester fetus can predict postnatal clinical outcome measured by pulmonary valve size and/or timing or type of intervention. The study retrospectively identified fetuses with TOF from 1998 to 2010 diagnosed at 26 weeks gestation or earlier. The data evaluated included pre- and postnatal pulmonary valve z-scores (PVZ). To quantify fetal SPS, the authors created a novel index, the SPS/DAO ratio, a ratio of the minimum infundibular diameter to the descending aorta diameter (DAO). Multiple linear regression was used to predict postnatal PVZ from prenatally determined parameters, including SPS/DAO. Fetal parameters were analyzed by logistic regression for association with postnatal outcomes, namely, timing of surgery (<1 month), used as a surrogate for severity, and type of surgery [transannular patch (TAP) vs valve sparing surgery]. A total of 23 fetuses met the inclusion criteria. The mean gestational age was 21.8 ± 1.9 weeks (range, 16.6-25.4 weeks). There was excellent correlation between predicted and measured PVZ (r = 0.82; p < 0.0001) using the following derived equation: -3.68 + (0.91 × prenatal PVZ) - (4.44 × SPS/DAO) - 3.19 (prenatal PVZ × SPS/DAO). An SPS/DAO value lower than 0.5 had 100 % sensitivity and 56 % specificity for repair before the age of 1 month, and a value lower than 0.47 had 100 % sensitivity and 75 % specificity for TAP repair. Prenatal PVZ and the SPS/DAO ratio at 26 weeks gestation or earlier can reliably predict postnatal PVZ in fetuses with TOF. Quantification of SPS with the SPS/DAO ratio identifies patients who may require early intervention secondary to disease severity and may predict the type of repair, thereby influencing prenatal counseling.


Subject(s)
Fetal Diseases/diagnostic imaging , Pulmonary Subvalvular Stenosis/diagnostic imaging , Tetralogy of Fallot/diagnostic imaging , Ultrasonography, Prenatal/methods , Diagnosis, Differential , Female , Follow-Up Studies , Gestational Age , Humans , Predictive Value of Tests , Pregnancy , Pregnancy Trimester, Second , Prognosis , Retrospective Studies
12.
Pediatr Cardiol ; 34(8): 2030-3, 2013.
Article in English | MEDLINE | ID: mdl-23179424

ABSTRACT

Uncontrolled/untreated maternal hyperthyroidism has been associated with fetal tachycardia. We report a case of right-ventricular (RV) hypertrophy with pericardial effusion related to untreated maternal Graves' disease. A 33-year-old G4P1021 woman with uncontrolled Graves' disease presented at 29 weeks gestation with abdominal pain and vaginal bleeding. Fetal echocardiogram showed severe RV hypertrophy and a pericardial effusion. The infant was born prematurely, and initial transthoracic echocardiogram showed severe RV hypertrophy and a small pericardial effusion. The infant had clinical findings consistent with congenital thyrotoxicosis and was treated for this. Follow-up imaging at 4 weeks showed improvement of the cardiac hypertrophy and pericardial effusion. This article describes the presentation of fetal RV hypertrophy with congenital thyrotoxicosis and underscores the importance of screening for this prenatally in mothers with uncontrolled or untreated hyperthyroidism.


Subject(s)
Hyperthyroidism/complications , Hypertrophy, Right Ventricular/etiology , Infant, Premature, Diseases/etiology , Pericardial Effusion/etiology , Pregnancy Complications , Adult , Echocardiography , Female , Follow-Up Studies , Humans , Hyperthyroidism/blood , Hypertrophy, Right Ventricular/diagnostic imaging , Hypertrophy, Right Ventricular/embryology , Infant, Newborn , Infant, Premature , Infant, Premature, Diseases/diagnostic imaging , Male , Pericardial Effusion/diagnostic imaging , Pericardial Effusion/embryology , Pregnancy , Prenatal Exposure Delayed Effects , Thyrotropin/blood , Ultrasonography, Prenatal
13.
Congenit Heart Dis ; 6(1): 18-27, 2011.
Article in English | MEDLINE | ID: mdl-21269409

ABSTRACT

OBJECTIVE: The study aims to evaluate and compare self-reported and parent proxy-reported quality of life (QOL) in pediatric patients with repaired tetralogy of Fallot (TOF) and determine relationships with residual disease. DESIGN: QOL was prospectively evaluated in children/adolescents with repaired TOF and parents' proxy report using the Pediatric Quality of Life Inventory Generic Core and Cardiac Module scales. The scores were compared with published self and parent proxy-reported normative data for children considered healthy, chronically ill, and with congenital heart disease. Recent clinical data were reviewed for correlations between QOL and residual disease severity. RESULTS: Twenty child-parent pairs were assessed at median age of 10.9 years (range 8.4-18.7 years). Self-report was higher than parent proxy report. Compared with peers, self-reported QOL was higher than for chronically ill children (overall QOL 85 vs. 77, P= 0.007) and similar to healthy children (85 vs. 83, P= 0.44), while proxy report by parent was similar to parents of chronically ill children (overall QOL 77 vs. 74, P= 0.035). Despite moderate pulmonary regurgitation (mean 35%) and right ventricular dilation (mean 114 mL/m(2) ), 76% had a New York Heart Association class of 1, normal B-natriuretic peptide (24 pg/mL), reasonable exercise tolerance VO(2) max% predicted (mean 77%), and preserved right ventricular ejection fraction (mean 58%, range 44-80%). Overall QOL positively correlated with child's VO(2) max% predicted, when reported by child (r = 0.47, P < 0.05) and parent proxy (r = 0.63, P < 0.05). CONCLUSIONS: QOL in children/adolescents with repaired TOF is not proportional to the severity of their residual disease. Self-reported QOL appears similar to healthy peers while parent proxy reported lower QOL. For both children and parents, QOL positively correlated with the child's exercise capacity. Therefore, comprehensive follow-up should include cardiac rehabilitation and psychosocial evaluation to ensure an active lifestyle, improve health perception, and prevent later acquired heart disease.


Subject(s)
Cardiac Surgical Procedures , Peer Group , Quality of Life , Tetralogy of Fallot/therapy , Adolescent , Case-Control Studies , Child , Emotions , Exercise Tolerance , Female , Humans , Magnetic Resonance Imaging , Male , Parents/psychology , Prospective Studies , Pulmonary Circulation , Self Report , Social Behavior , Stroke Volume , Surveys and Questionnaires , Tetralogy of Fallot/diagnosis , Tetralogy of Fallot/physiopathology , Tetralogy of Fallot/psychology , Treatment Outcome , Ventricular Function, Right , Wisconsin
14.
J Obstet Gynaecol Can ; 28(6): 519-525, 2006 Jun.
Article in English | MEDLINE | ID: mdl-16857120

ABSTRACT

OBJECTIVE: To assess the overall success of sling procedures and surgical sling release in achieving urinary continence and voiding function in women with stress urinary incontinence. METHODS: We reviewed the charts of 107 patients with stress urinary incontinence who had a two-team abdominal-vaginal fascial sling procedure performed between January 2000 and December 2003. Data reviewed included the patients' medical history, demographic data, findings on physical examination, urodynamic studies, operative report, and findings at visits 6 weeks, 6 months, and 12 months after surgery. Patients with sling releases were followed up to assess pelvic organ prolapse, uroflowmetry, and post-void residual urine volume, and to complete the quality of life questionnaire IIQ-7. RESULTS: At one year after pubovaginal sling surgery, 82.1% of patients were cured of stress urinary incontinence. The majority (85.1%) of patients did not develop postoperative voiding dysfunction. Only 5.6% of those who did develop postoperative voiding dysfunction required surgical sling release. Sling release resolved the post-sling voiding dysfunction in three out of five patients. CONCLUSION: Pubovaginal sling surgery is a highly successful strategy for the management of stress urinary incontinence and has a low rate of postoperative voiding dysfunction. Surgical sling release may resolve post-sling voiding dysfunction.


Subject(s)
Urinary Incontinence, Stress/surgery , Urologic Surgical Procedures/methods , Female , Humans , Middle Aged , Postoperative Complications/epidemiology , Retrospective Studies , Treatment Failure , Treatment Outcome , Urethral Obstruction/epidemiology , Urologic Surgical Procedures/adverse effects
15.
Environ Health Perspect ; 114(3): 460-5, 2006 Mar.
Article in English | MEDLINE | ID: mdl-16507472

ABSTRACT

Children's exposure to arsenic and chromium from playground equipment constructed with chromated copper arsenate (CCA)-treated wood is a potential concern because of children's hand-to-mouth activity. However, there exists no direct measure of Cr levels on the hands of children after playing in such playgrounds. In this study we measured both soluble and total Cr on the hands of 139 children playing in playgrounds, eight of which were constructed with CCA-treated wood and eight of which were not. Children's age and duration of play were recorded. The hands of each child were washed after play with 150 mL deionized water, which was collected in a bag and subsequently underwent analysis of Cr and 20 other elements, using inductively coupled plasma mass spectrometry. Total average Cr on the hands of 63 children who played in CCA playgrounds was 1,112 +/- 1,089 ng (median, 688; range 78-5,875). Total average Cr on the hands of 64 children who played in non-CCA playgrounds was 652 +/- 586 ng (median, 492; range 61-3,377). The difference between the two groups is statistically significant (p < 0.01). Cr levels were highly correlated to both Cu (r = 0.672) and As (r = 0.736) levels in CCA playgrounds (p < or = 0.01), but not non-CCA playgrounds (r = 0.252 and 0.486 for Cu and As, respectively). Principal-component analysis indicates that Cr, Cu, and As are more closely grouped together in CCA than in non-CCA playgrounds. These results suggest that the elevated levels of Cr and As on children's hands are due to direct contact with CCA wood.


Subject(s)
Chromium/analysis , Environmental Pollutants/analysis , Play and Playthings , Arsenates , Arsenic/analysis , Canada , Child , Child, Preschool , Copper/analysis , Environmental Exposure/analysis , Environmental Monitoring , Hand , Humans , Silicon Dioxide/analysis , Soil/analysis , Wood
16.
Environ Health Perspect ; 112(14): 1375-80, 2004 Oct.
Article in English | MEDLINE | ID: mdl-15471728

ABSTRACT

Increasing concerns over the use of wood treated with chromated copper arsenate (CCA) in playground structures arise from potential exposure to arsenic of children playing in these playgrounds. Limited data from previous studies analyzing arsenic levels in sand samples collected from CCA playgrounds are inconsistent and cannot be directly translated to the amount of children's exposure to arsenic. The objective of this study was to determine the quantitative amounts of arsenic on the hands of children in contact with CCA-treated wood structures or sand in playgrounds. We compared arsenic levels on the hands of 66 children playing in eight CCA playgrounds with levels of arsenic found on the hands of 64 children playing in another eight playgrounds not constructed with CCA-treated wood. The children's age and duration of playtime were recorded at each playground. After play, children's hands were washed in a bag containing 150 mL of deionized water. Arsenic levels in the hand-washing water were quantified by inductively coupled plasma mass spectrometry. Our results show that the ages of the children sampled and the duration of play in the playgrounds were similar between the groups of CCA and non-CCA playgrounds. The mean amount of water-soluble arsenic on children's hands from CCA playgrounds was 0.50 microg (range, 0.0078-3.5 microg). This was significantly higher (p < 0.001) than the mean amount of water-soluble arsenic on children's hands from non-CCA playgrounds, which was 0.095 microg (range, 0.011-0.41 microg). There was no significant difference in the amount of sand on the children's hands and the concentration of arsenic in the sand between the CCA and non-CCA groups. The higher values of arsenic on the hands of children playing in the CCA playgrounds are probably due to direct contact with CCA-treated wood. Washing hands after play would reduce the levels of potential exposure because most of the arsenic on children's hands was washed off with water. The maximum amount of arsenic on children's hands from the entire group of study participants was < 4 microg, which is lower than the average daily intake of arsenic from water and food.


Subject(s)
Arsenic/analysis , Environmental Exposure , Environmental Pollutants/analysis , Play and Playthings , Arsenates/analysis , Case-Control Studies , Child , Child, Preschool , Female , Hand , Humans , Male , Solubility , Wood
17.
FEMS Microbiol Lett ; 228(2): 211-6, 2003 Nov 21.
Article in English | MEDLINE | ID: mdl-14638426

ABSTRACT

The csbX gene of Azotobacter vinelandii was regulated in an iron-repressible manner from a divergent promoter upstream of the catecholate siderophore biosynthesis (csb) operon and was predicted to encode an efflux pump of the major facilitator superfamily. Other proteins that were most similar to CsbX were encoded by genes found in the catecholate siderophore biosynthesis operons of Aeromonas hydrophila and Stigmatella aurantiaca. Inactivation of csbX resulted in 57-100% decrease in the amount of catecholates released when compared to the wild-type in iron-limited medium. CsbX was most important for the export of the high affinity chelator protochelin with the majority of the catecholates released by csbX mutants being the protochelin intermediates azotochelin and aminochelin.


Subject(s)
Azotobacter vinelandii/genetics , Azotobacter vinelandii/metabolism , Bacterial Proteins/genetics , Catechols/metabolism , Genes, Bacterial , Siderophores/metabolism , Amino Acid Motifs , Amino Acid Sequence , Bacterial Proteins/chemistry , Bacterial Proteins/physiology , Biological Transport , DNA, Bacterial/chemistry , DNA, Bacterial/isolation & purification , Gene Expression Regulation, Bacterial/drug effects , Gene Order , Iron/pharmacology , Membrane Proteins/chemistry , Membrane Proteins/genetics , Membrane Proteins/physiology , Molecular Sequence Data , Mutagenesis, Insertional , Restriction Mapping , Sequence Analysis, DNA , Sequence Homology, Amino Acid
18.
Microbiology (Reading) ; 147(Pt 2): 483-490, 2001 Feb.
Article in English | MEDLINE | ID: mdl-11158365

ABSTRACT

Azotobacter vinelandii UWD is a mutant of strain UW that is defective in the respiratory oxidation of NADH. This mutation causes an overproduction of polyhydroxyalkanoates (PHAs), as polyester synthesis is used as an alternative electron sink. Since PHAs have potential for use as natural, biodegradable plastics, studies of physiology related to their production are of interest. Alginate production by this strain is limited to < 11 microg (mg cell protein)(-1), which permits high efficiency conversion of carbon source into PHA. However, < or = 400 microg (mg cell protein)(-1) was formed when UWD cells were oxygen-limited and in the stationary phase of growth. Alginate formation was fuelled by PHA turnover, which was coincident with the synthesis of alkyl resorcinols, under conditions of exogenous glucose limitation. However, alginate production was a phenotypic and reversible change. Alginate production was stopped by interruption of algD with Tn5lacZ. LacZ activity in UWD was shown to increase in stationary phase, while LacZ activity in a similarly constructed mutant of strain UW did not. Transcription of algD in strain UWD started from a previously identified RpoD promoter and not from the AlgU (RpoE) promoter. This is because strain UWD has a natural insertion element in algU. Differences between strain UW and UWD may reside in the defective respiratory oxidation of NADH, where the NADH surplus in strain UWD may act as a signal of stationary phase. Indeed, a backcross of UW DNA into UWD generated NADH-oxidase-proficient cells that failed to form alginate in stationary phase. Evidence is also presented to show that the RpoD promoter may be recognized by the stationary phase sigma factor (RpoS), which may mediate alginate production in strain UWD.


Subject(s)
Alginates/metabolism , Azotobacter vinelandii/growth & development , Azotobacter vinelandii/metabolism , Hydroxybutyrates/metabolism , Polyesters/metabolism , Azotobacter vinelandii/genetics , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Base Sequence , Carbohydrate Dehydrogenases/genetics , Carbohydrate Dehydrogenases/metabolism , Culture Media , Glucuronic Acid , Hexuronic Acids , Molecular Sequence Data , Oxygen/pharmacology , Promoter Regions, Genetic , Sigma Factor/metabolism , Transcription, Genetic
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