Anaerobic bacterial response to nitric oxide stress: Widespread misconceptions and physiologically relevant responses

How anaerobic bacteria protect themselves against nitric oxide-induced stress is controversial, not least because far higher levels of stress were used in the experiments on which most of the literature is based than bacteria experience in their natural environments. This results in chemical damage to enzymes that inactivates their physiological function. This review illustrates how transcription control mechanisms reveal physiological roles of the encoded gene products. Evidence that the hybrid cluster protein, Hcp, is a major high affinity NO reductase in anaerobic bacteria is reviewed: if so, its trans-nitrosation activity is a nonspecific secondary consequence of chemical inactivation. Whether the flavorubredoxin, NorV, is equally effective at such low [NO] is unknown. YtfE is proposed to be an enzyme rather than a source of iron for the repair of iron-sulfur proteins damaged by nitrosative stress. Any reaction catalyzed by YtfE needs to be revealed. The concentration of NO that accumulates in the cytoplasm of anaerobic bacteria is unknown, but indirect evidence indicates that it is in the pM to low nM range. Also unknown are the functions of the NO-inducible cytoplasmic proteins YgbA, YeaR, or YoaG. Experiments to resolve some of these questions are proposed.

Reinforcement and a cline in mating behaviour evolve in response to secondary contact and hybridization in shield-back katydids (Orthoptera: Tettigoniidae)

In a dispersal-limited species that has evolved reproductive character displacement at a contact zone, a cline in mating behaviour may result if gene flow diffuses alleles out of the contact zone into allopatric populations. Prior work has found such a clinal pattern in the shield-back katydid Aglaothorax morsei, in which the male calling songs in a sympatric population have a displaced, short interpulse interval that increases in length with increasing distance from the contact zone. In this study, molecular phylogenetic and female preference data show that (1) sympatric populations result from secondary contact, (2) hybridization in sympatry has resulted in unidirectional mitochondrial introgression and (3) female preferences are consistent with reproductive character displacement and could generate a cline in mating behaviour. These data together suggest a history of reinforcement, generally considered rare in acoustically communicating insects; thus, Aglaothorax represents an important example of a rarely documented evolutionary process.

Enteral feeding reduces metabolic activity of the intestinal microbiome in Crohn's disease: an observational study

BACKGROUND/OBJECTIVES

Enteral feeding will induce remission in as many as 80-90% of compliant patients with active Crohn's disease (CD), but its method of action remains uncertain. This study was designed to examine its effects on the colonic microbiome.

METHODS/SUBJECTS

Healthy volunteers and patients with CD followed a regimen confined to enteral feeds alone for 1 or 2 weeks, respectively. Chemicals excreted on breath or in faeces were characterised at the start and at the end of the feeding period by gas chromatography/mass spectrometry.

RESULTS

One week of feeding in healthy volunteers caused significant changes in stool colour and deterioration in breath odour, together with increased excretion of phenol and indoles on the breath. Feeding for 2 weeks in patients with CD produced significant improvements in symptoms and a decrease in the concentration of C-reactive protein. The faecal concentrations of microbial products, including short-chain fatty acids (SCFAs), and potentially toxic substances, including 1-propanol, 1-butanol and the methyl and ethyl esters of SCFAs, showed significant falls.

CONCLUSIONS

A significant change occurs in the production of microbial metabolites after enteral feeding in both healthy volunteers and patients with CD. Many of those detected in CD are toxic and may feasibly lead to the immunological attack on the gut microbiota, which is characteristic of inflammatory bowel disease. The reduction in the production of such metabolites after enteral feeding may be the reason for its effectiveness in CD.

Implications of aligning full registration of doctors with medical school graduation: a qualitative study of stakeholder perspectives

OBJECTIVES

The Shape of Training report recommended that full registration is aligned with medical school graduation. As part of a General Medical Council-funded study about the preparedness for practice of UK medical graduates, we explored UK stakeholders' views about this proposal using qualitative interviews (30 group and 87 individual interviews) and Framework Analysis.

SETTING

Four UK study sites, one in each country.

PARTICIPANTS

185 individuals from eight stakeholder groups: (1) foundation year 1 (F1) doctors (n=34); (2) fully registered trainee doctors (n=33); (3) clinical educators (n=32); (4) undergraduate/postgraduate Deans, and Foundation Programme Directors (n=30); (5) other healthcare professionals (n=13); (6) employers (n=7); (7) policy and government (n=11); (8) patient and public representatives (n=25).

RESULTS

We identified four main themes: (1) The F1 year as a safety net: patients were protected by close trainee supervision and 'sign off' to prevent errors; trainees were provided with a safe environment for learning on the job; (2) Implications for undergraduate medical education: if the proposal was accepted, a 'radical review' of undergraduate curricula would be needed; undergraduate education might need to be longer; (3) Implications for F1 work practice: steps to protect healthcare team integration and ensure that F1 doctors stay within competency limits would be required; (4) Financial, structural and political implications: there would be cost implications for trainees; clarification of responsibilities between undergraduate and postgraduate medical education would be needed. Typically, each theme comprised arguments for and against the proposal.

CONCLUSIONS

A policy change to align the timing of full registration with graduation would require considerable planning and preliminary work. These findings will inform policymakers' decision-making. Regardless of the decision, medical students should take on greater responsibility for patient care as undergraduates, assessment methods in clinical practice and professionalism domains need development, and good practice in postgraduate supervision and support must be shared.

The global aHUS registry: methodology and initial patient characteristics

Background

Atypical hemolytic uremic syndrome (aHUS) is a rare, genetically-mediated systemic disease most often caused by chronic, uncontrolled complement activation that leads to systemic thrombotic microangiopathy (TMA) and renal and other end-organ damage.

Methods

The global aHUS Registry, initiated in April 2012, is an observational, noninterventional, multicenter registry designed to collect demographic characteristics, medical and disease history, treatment effectiveness and safety outcomes data for aHUS patients. The global aHUS Registry will operate for a minimum of 5 years of follow-up. Enrollment is open to all patients with a clinical diagnosis of aHUS, with no requirement for identified complement gene mutations, polymorphisms or autoantibodies or particular type of therapy/management.

Results

As of September 30, 2014, 516 patients from 16 countries were enrolled. At enrollment, 315 (61.0 %) were adults (≥18 years) and 201 (39.0 %) were <18 years of age. Mean (standard deviation [SD]) age at diagnosis was 22.7 (20.5) years. Nineteen percent of patients had a family history of aHUS, 60.3 % had received plasma exchange/plasma infusion, 59.5 % had a history of dialysis, and 19.6 % had received ≥1 kidney transplant. Overall, 305 patients (59.1 %) have received eculizumab.

Conclusions

As enrollment and follow-up proceed, the global aHUS Registry is expected to yield valuable baseline, natural history, medical outcomes, treatment effectiveness and safety data from a diverse population of patients with aHUS.

Trial registration

US National Institutes of Health www.ClinicalTrials.gov Identifier NCT01522183. Registered January 18, 2012.

Long-term clinical outcomes in type 1 Gaucher disease following 10 years of imiglucerase treatment

OBJECTIVE

We studied the effect of long-term alglucerase/imiglucerase (Ceredase®/Cerezyme®, Genzyme, a Sanofi company, Cambridge, MA, USA) treatment on hematological, visceral, and bone manifestations of Gaucher disease type 1 (GD1).

METHODS

The International Collaborative Gaucher Group (ICGG) Gaucher Registry identified GD1 patients treated with alglucerase/imiglucerase who had dose and clinical data at first infusion and after 10 years of follow-up. Data for hemoglobin, platelet count, organ volumes, bone pain, and bone crisis were analyzed. Tests of the null hypothesis (no change from first infusion to 10 years) were performed using t tests for within-patient absolute change in continuous measurements and McNemar/chi-square tests for change in distributions using categorical values. An alpha level of 0.05 designated statistical significance.

RESULTS

As of October 2011, 557 nonsplenectomized and 200 splenectomized patients met the inclusion criteria. The majority of GD1 patients had at least one N370S allele. Compared with nonsplenectomized patients at first infusion, splenectomized patients had lower percentages of anemia (26.0 % vs. 42.8 %) and thrombocytopenia (14.2 % vs. 76.3 %), similar percentages of moderate or severe hepatomegaly (81.2 % vs. 80.0 %), and higher percentages of bone pain (88.9 % vs. 52.4 %) and bone crises (38.3 % vs. 16.0 %). After 10 years, both groups showed significant (p < 0.05) improvements in mean hemoglobin levels, platelet count, liver, and spleen (nonsplenectomized) volumes, and bone crises. Initial dosing in both groups ranged from <15 U/kg to ≤90 U/kg every 2 weeks. After 10 years, the majority was receiving 15 to ≤45 U/kg every 2 weeks.

CONCLUSION

Ten years of imiglucerase treatment results in sustainable improvements in all GD1 parameters.

Anti-α-galactosidase A antibody response to agalsidase beta treatment: data from the Fabry Registry

Agalsidase beta, a form of recombinant human α-galactosidase A (αGAL), is approved for use as enzyme replacement therapy (ERT) for Fabry disease. An immunogenic response against a therapeutic protein could potentially impact its efficacy or safety. The development of anti-αGAL IgG antibodies was evaluated in 571 men and 251 women from the Fabry Registry who were treated with agalsidase beta. Most men developed antibodies (416 of 571, 73%), whereas most women did not (31 of 251, 12%). Women were also significantly more likely to tolerize than men; whereas 18 of 31 women tolerized (58%, 95%CI: 52%-64%), only 47 of 416 men tolerized during the observation period (11%, 95% CI: 8%-15%). Patients who eventually tolerized had lower median peak anti-αGAL IgG antibody titers than patients who remained seropositive at their most recent assessment (400 versus 3200 in men, 200 versus 400 in women, respectively). Patients with nonsense mutations in the GLA gene were more likely to develop anti-αGAL IgG antibodies than patients with missense mutations. Approximately 26% of men (151 of 571) reported infusion-associated reactions (IARs), compared to 11% of women (27 of 251). Men who developed anti-αGAL IgG antibodies were more likely to experience IARs compared to those who remained seronegative. Nine percent of seronegative men and women (34 of 375) reported IARs. The majority of IARs occurred during the first 6 to 12 months of agalsidase beta treatment and decreased over time, in both seroconverted and seronegative patients.

Reducing selection bias in case-control studies from rare disease registries

BACKGROUND

In clinical research of rare diseases, where small patient numbers and disease heterogeneity limit study design options, registries are a valuable resource for demographic and outcome information. However, in contrast to prospective, randomized clinical trials, the observational design of registries is prone to introduce selection bias and negatively impact the validity of data analyses. The objective of the study was to demonstrate the utility of case-control matching and the risk-set method in order to control bias in data from a rare disease registry. Data from the International Collaborative Gaucher Group (ICGG) Gaucher Registry were used as an example.

METHODS

A case-control matching analysis using the risk-set method was conducted to identify two groups of patients with type 1 Gaucher disease in the ICGG Gaucher Registry: patients with avascular osteonecrosis (AVN) and those without AVN. The frequency distributions of gender, decade of birth, treatment status, and splenectomy status were presented for cases and controls before and after matching. Odds ratios (and 95% confidence intervals) were calculated for each variable before and after matching.

RESULTS

The application of case-control matching methodology results in cohorts of cases (i.e., patients with AVN) and controls (i.e., patients without AVN) who have comparable distributions for four common parameters used in subject selection: gender, year of birth (age), treatment status, and splenectomy status. Matching resulted in odds ratios of approximately 1.00, indicating no bias.

CONCLUSIONS

We demonstrated bias in case-control selection in subjects from a prototype rare disease registry and used case-control matching to minimize this bias. Therefore, this approach appears useful to study cohorts of heterogeneous patients in rare disease registries.

Renal outcomes of agalsidase beta treatment for Fabry disease: role of proteinuria and timing of treatment initiation

BACKGROUND

The purpose of this study was to identify determinants of renal disease progression in adults with Fabry disease during treatment with agalsidase beta.

METHODS

Renal function was evaluated in 151 men and 62 women from the Fabry Registry who received agalsidase beta at an average dose of 1 mg/kg/2 weeks for at least 2 years. Patients were categorized into quartiles based on slopes of estimated glomerular filtration rate (eGFR) during treatment. Multivariate logistic regression analyses were used to identify factors associated with renal disease progression.

RESULTS

Men within the first quartile had a mean eGFR slope of -0.1 mL/min/1.73m(2)/year, whereas men with the most rapid renal disease progression (Quartile 4) had a mean eGFR slope of -6.7 mL/min/1.73m(2)/year. The risk factor most strongly associated with renal disease progression was averaged urinary protein:creatinine ratio (UP/Cr) ≥1 g/g (odds ratio 112, 95% confidence interval (95% CI) 4-3109, P = 0.0054). Longer time from symptom onset to treatment was also associated with renal disease progression (odds ratio 19, 95% CI 2-184, P = 0.0098). Women in Quartile 4 had the highest averaged UP/Cr (mean 1.8 g/g) and the most rapid renal disease progression: (mean slope -4.4 mL/min/1.73m(2)/year).

CONCLUSIONS

Adults with Fabry disease are at risk for progressive loss of eGFR despite enzyme replacement therapy, particularly if proteinuria is ≥1 g/g. Men with little urinary protein excretion and those who began receiving agalsidase beta sooner after the onset of symptoms had stable renal function. These findings suggest that early intervention may lead to optimal renal outcomes.

Neuronopathic Gaucher disease: demographic and clinical features of 131 patients enrolled in the International Collaborative Gaucher Group Neurological Outcomes Subregistry

OBJECTIVE

To describe demographic, genetic, and clinical characteristics of patients with neuronopathic Gaucher disease (NGD).

METHODS

All patients enrolled in the Neurological Outcomes Subregistry of the International Collaborative Gaucher Group (ICGG) Gaucher Registry as of June 2007 were identified.

RESULTS

The study cohort comprised 131 patients from 17 countries who were enrolled in the Neurological Outcomes Subregistry. The onset of neurological manifestations had occurred before 2 years of age in 47% (61 out of 131 patients), 2 years of age or older in 41% (54 out of 131), and could not be ascertained in the remaining 12% (16 out of 131). The most common manifestations were inability to look to the extreme up or down (45%, 55 out of 123), abnormally slow object tracking (43%, 53 out of 123), convergent squint (36%, 44 out of 121), and ataxia (15 to 20%, 18-27 out of 117). Seizures were reported in 19 out of 122 patients (16%), and myoclonic seizures were reported in 3 out of 121 patients (2%). The most common genotypes were L444P/L444P (76 out of 108, 70%), L444P/D409H (9 out of 108, 8%), D409H/D409H (8 out of 108, 7%), and L444P/rare allele (6 out of 108, 6%); full sequencing was not performed in all patients.

CONCLUSIONS

Neurological manifestations of GD often begin to appear before the age of 2 years. The most common neurological signs and manifestations are brainstem abnormalities and fine motor dysfunction. The most common genotype is L444P/L444P.

Timing of initiation of enzyme replacement therapy after diagnosis of type 1 Gaucher disease: effect on incidence of avascular necrosis

Data from the International Collaborative Gaucher Group Gaucher Registry were analysed to assess the relationship between enzyme replacement therapy with imiglucerase (ERT) and incidence of avascular necrosis (AVN) in type 1 Gaucher disease (GD1), and to determine whether the time interval between diagnosis and initiation of ERT influences the incidence rate of AVN. All patients with GD1 enrolled in the Gaucher Registry who received ERT and did not report AVN prior to starting therapy (n = 2700) were included. The incidence rate of AVN following initiation of ERT was determined. An incidence rate of AVN of 13·8 per 1000 person-years was observed in patients receiving ERT. Patients who initiated ERT within 2 years of diagnosis had an incidence rate of 8·1 per 1000 person-years; patients who started ERT ≥2 years after diagnosis had an incidence rate of 16·6 per 1000 person-years. The adjusted incidence rate ratio was 0·59 [95% confidence interval (CI) 0·36–0·96, P = 0·0343]. Splenectomy was an independent risk factor for AVN (adjusted incidence rate ratio 2·23, 95% CI 1·61–3·08, P < 0·0001). In conclusion, the risk of AVN was reduced among patients who initiated ERT within 2 years of diagnosis, compared to initiating treatment ≥2 years after diagnosis. A higher risk of AVN was observed among patients who had previously undergone splenectomy.

Dose-response relationships for enzyme replacement therapy with imiglucerase/alglucerase in patients with Gaucher disease type 1

PURPOSE

To determine whether enzyme therapy with imiglucerase/alglucerase demonstrates dose-response relationships with doses and disease parameters used in routine clinical practice for Gaucher disease type 1 patients.

METHODS

Analyses included all patients with Gaucher disease type 1 on enzyme therapy and with intact spleens in the large observational database of the International Collaborative Gaucher Group Gaucher Registry. Propensity scoring was used to match patients between enzyme therapy dose groups categorized as Group A (5 U to <29 U/kg/2 weeks), Group B (29 U to <48 U/kg/2 weeks), Group C (48 U to <75 U/kg/2 weeks). Hemoglobin concentration, platelet count, and hepatic and splenic volumes were assessed after initiation of enzyme therapy using nonlinear mixed effects models. The maximal effect (Emax) and half-time to Emax (T50) of enzyme therapy for each parameter were compared across dosing groups.

RESULTS

Propensity score matching resulted in three comparable groups of 122 patients each (enzyme therapy in Groups A, B, and C). Dose-response relationships were found with regard to Emax and T50 over 96 months for each disease parameter.

CONCLUSIONS

Enzyme therapy with imiglucerase/alglucerase displays a dose-dependent improvement in hematological and visceral parameters in Gaucher disease type 1 patients. Group C displayed greater treatment effects than Groups A or B. Propensity score matching and nonlinear mixed effects model analyses provide a prototype for assessment of treatment outcomes based on observational data from international rare disease registries.

A comparison of shielding calculation methods for multi-slice computed tomography (CT) systems

Currently in the UK, shielding calculations for computed tomography (CT) systems are based on the BIR-IPEM (British Institute of Radiology and Institute of Physics in Engineering in Medicine) working group publication from 2000. Concerns have been raised internationally regarding the accuracy of the dose plots on which this method depends and the effect that new scanner technologies may have. Additionally, more recent shielding methods have been proposed by the NCRP (National Council on Radiation Protection) from the USA. Thermoluminescent detectors (TLDs) were placed in three CT scanner rooms at different positions for several weeks before being processed. Patient workload and dose data (DLP: the dose length product and mAs: the tube current-time product) were collected for this period. Individual dose data were available for more than 95% of patients scanned and the remainder were estimated. The patient workload data were used to calculate expected scatter radiation for each TLD location by both the NCRP and BIR-IPEM methods. The results were then compared to the measured scattered radiation. Calculated scattered air kerma and the minimum required lead shielding were found to be frequently overestimated compared to the measured air kerma, on average almost five times the measured scattered air kerma.

Paroxetine in the first trimester and the prevalence of congenital malformations

PURPOSE

To refine a preliminary analysis identifying a possibly increased prevalence of malformations among infants born to women exposed to paroxetine in the first trimester.

METHODS

This study used data from UnitedHealthcare, a large U.S. insurer, using datasets originally for a study of bupropion in pregnancy. We identified women with a live-born delivery between January 1995 and September 2004. We classified women according to their first trimester mono- or mono/polytherapy exposure to paroxetine and other antidepressants. We confirmed malformation cases by medical record abstraction. We calculated the adjusted odds ratios (AORs) through logistic regression.

RESULTS

For paroxetine, there were 815 infants among 791 women exposed as monotherapy, and 1020 infants among 989 women exposed as mono- or polytherapy. For other antidepressants, there were 4198 infants among 4072 women exposed as monotherapy, and 4936 infants among 4767 women exposed as mono- or polytherapy. AORs for all congenital malformations associated with paroxetine were 1.89 (95%CI 1.20-2.98) for monotherapy, and 1.76 (95%CI 1.18-2.64) for mono- or polytherapy. AORs for cardiovascular malformations associated with paroxetine were 1.46 (95%CI 0.74-2.88) for monotherapy, and 1.68 (95%CI 0.95-2.97) for mono- or polytherapy.

CONCLUSIONS

These more detailed paroxetine findings confirm previous findings of analyses of these data among women exposed to all types of antidepressants. The present findings are consistent with other recent results suggesting the possibility of a modestly increased occurrence of congenital malformations following first trimester exposure to paroxetine compared to other antidepressants.

Incidence of IBS in a cohort of people with asthma

We conducted a study to examine the relation of asthma and its treatment to irritable bowel syndrome (IBS). We identified cohorts of members with and without asthma from January 1996 though June 2002 and calculated rates of IBS in both cohorts. In a nested case-control study, we calculated odds ratios for oral steroid dispensing before IBS onset. To address differential IBS detection, we conducted a quantitative sensitivity analysis. We identified 91,237 people with asthma and sample of 24,518 people without asthma. There was a 20% increase in the incidence of IBS among people with asthma (standardized morbidity ratio = 1.2; 95% CI, 1.0-1.5), and no association between oral steroids and IBS among people with asthma (OR = 1.0; 95% CI, 0.9-1.1.) Misclassification of IBS would have biased the rate ratio toward the null. We observed a small increase in IBS among people with asthma, and no association between oral steroids and IBS onset among asthma patients.

Venous Thromboembolism, Myocardial Infarction, and Stroke Among Transdermal Contraceptive System Users

OBJECTIVE

To estimate the incidence of venous thromboembolism, acute myocardial infarction, and ischemic stroke among transdermal contraceptive system users compared with users of norgestimate-containing oral contraceptives with 35 mcg ethinyl estradiol.

METHODS

We began with insurance claims data from UnitedHealthcare. We identified women exposed to the transdermal contraceptive system or norgestimate-containing oral contraceptives from April 2002 through December 2004. Outcomes were confirmed from medical records. We calculated incidence rates and age-adjusted incidence rate ratios. In a nested case-control analysis, we investigated and controlled for confounding.

RESULTS

There were 49,048 woman-years of transdermal contraceptive system exposure and 202,344 woman-years of norgestimate-containing oral contraceptives exposure. There was a more than two-fold increase in the venous thromboembolism rate (incidence rate ratio 2.2, 95% confidence interval [CI] 1.3-3.8) among transdermal contraceptive system users (20 cases, 40.8 per 100,000 woman-years) compared with norgestimate-containing oral contraceptives users (37 cases, 18.3 per 100,000 woman-years). Acute myocardial infarction occurred in three transdermal contraceptive system users compared with seven among norgestimate-containing oral contraceptives users (incidence rate ratio 1.8, 95% CI 0.5-6.8). No strokes occurred among transdermal contraceptive system users, whereas 10 occurred among norgestimate-containing oral contraceptives users. In the nested case-control analysis, after exclusions for high-risk factors, the odds ratio for venous thromboembolism was 2.4 (95% CI 1.1-5.5).

CONCLUSION

There was a more than two-fold increase in the risk of venous thromboembolism associated with use of the transdermal contraceptive system. Acute myocardial infarction and stroke occurred too rarely to ascertain precise risk estimates.

LEVEL OF EVIDENCE

II.

Bupropion in pregnancy and the prevalence of congenital malformations

PURPOSE

Reports from the GlaxoSmithKline Bupropion Pregnancy Registry suggested an increase in cardiovascular defects following exposure to bupropion during pregnancy. We conducted a study of congenital malformations among infants born to women exposed to bupropion during their first trimester.

METHODS

The study used data from UnitedHealthcare between January 1995 and September 2004. We calculated the prevalence of all congenital malformations and cardiovascular malformations associated with bupropion exposure in the estimated first trimester (1213 infants), compared with (1) other antidepressant exposure in the first trimester (4743 infants) and (2) bupropion exposure outside the first trimester (1049 infants). Malformation cases were confirmed through medical record abstraction. We calculated adjusted odds ratios (AORs) using the GEE form of logistic regression.

RESULTS

For all congenital malformations, the prevalence associated with bupropion first trimester was 23.1 per 1000 infants. The AORs were 0.95 (95%CI 0.62-1.45) and 1.00 (95%CI 0.57-1.73) in comparison to other antidepressants (prevalence 23.2 per 1000) and bupropion outside the first trimester (prevalence 21.9 per 1000), respectively. For cardiovascular malformations, the prevalence associated with bupropion first trimester was 10.7 per 1000 infants. The AORs were 0.97 (95%CI 0.52-1.80) and 1.07 (95%CI 0.48-2.40) in comparison to other antidepressants (prevalence 10.8 per 1000) and bupropion outside the first trimester (prevalence 9.5 per 1000), respectively.

CONCLUSIONS

Results do not support a hypothesis of a teratogenic effect of first trimester bupropion exposure. The prevalence of malformations associated with bupropion exposure in the first trimester was not increased relative to the comparison groups.

Migraine, fibromyalgia, and depression among people with IBS: a prevalence study

Background

Case descriptions suggest IBS patients are more likely to have other disorders, including migraine, fibromyalgia, and depression. We sought to examine the prevalence of these conditions in cohorts of people with and without IBS.

Methods

The source of data was a large U.S. health plan from January 1, 1996 though June 30, 2002. We identified all people with a medical claim associated with an ICD-9 code for IBS. A non-IBS cohort was a random sample of people with an ICD-9 code for routine medical care. In the cohorts, we identified all claims for migraine, depression, and fibromyalgia. We estimated the prevalence odds ratios (PORs) of each of the three conditions using the Mantel-Haenszel method. We conducted quantitative sensitivity analyses to quantify the impact of residual confounding and in differential outcome identification.

Results

We identified 97,593 people in the IBS cohort, and a random sample of 27,402 people to compose the non-IBS comparison cohort. With adjustment, there was a 60% higher odds in the IBS cohort of having any one of the three disorders relative to the comparison cohort (POR 1.6, 95% CI 1.5 – 1.7). There was a 40% higher odds of depression in the IBS cohort (POR 1.4, 95% CI 1.3 – 1.4). The PORs for fibromyalgia and migraine were similar (POR for fibromyalgia 1.8, 95% CI 1.7 – 1.9; POR for migraine 1.6, 95% CI 1.4 – 1.7). Differential prevalence of an unmeasured confounder, or imperfect sensitivity or specificity of outcome detection would have impacted the observed results.

Conclusion

People in the IBS cohort had a 40% to 80% higher prevalence odds of migraine, fibromyalgia, and depression.

Drug Copayment and Adherence in Chronic Heart Failure: Effect on Cost and Outcomes

STUDY OBJECTIVE

To measure the association among prescription copayment, drug adherence, and subsequent health outcomes among patients with chronic heart failure (CHF).

DESIGN

Retrospective cohort study.

DATA SOURCE

Database of a large, national health insurance plan.

PATIENTS

Patients with CHF receiving commercial and Medicare supplemental benefits.

MEASUREMENTS AND MAIN RESULTS

We estimated adherence to therapy with beta-blockers or angiotensin-converting enzyme (ACE) inhibitors in 2002 by using the medication possession ratio, an estimate of the proportion of days a patient was exposed to a drug while taking a drug regimen. For 2003, we measured the annualized total cost of health care and identified hospitalizations with a diagnostic code for CHF. We used a two-stage regression approach to model the association among copayment, adherence, and patient outcomes. For patients taking ACE inhibitors, a $10 increase in copayment was associated with a 2.6% decrease in the medication possession ratio (95% confidence interval [CI] 2.0-3.1%). This change in adherence was associated with a predicted 0.8% decrease in medical costs (95% CI -4.2-2.5%) but a predicted 6.1% increase in the risk of hospitalization for CHF (95% CI 0.5-12.0%). Among patients taking beta-blockers, a $10 increase in copayment was associated with a 1.8% decrease in the medication possession ratio (95% CI 1.4-2.2%). This change in adherence was associated with a predicted 2.8% decrease in medical costs (95% CI -5.9-0.1%) and a predicted 8.7% increase in the risk of hospitalization for CHF (95% CI 3.8-13.8%).

CONCLUSION

Among patients with CHF, higher drug copayments were associated with poorer adherence. The change was relatively small and did not affect predicted total health care costs, but it was sufficient to increase the predicted risk of hospitalization for CHF.

Microarray analysis of gene regulation by oxygen, nitrate, nitrite, FNR, NarL and NarP during anaerobic growth of Escherichia coli: new insights into microbial physiology

RNA was isolated from cultures of Escherichia coli strain MG1655 and derivatives defective in fnr, narXL, or narXL with narP, during aerobic growth, or anaerobic growth in the presence or absence of nitrate or nitrite, in non-repressing media in which both strain MG1655 and an fnr deletion mutant grew at similar rates. Glycerol was used as the non-repressing carbon source and both trimethylamine-N-oxide and fumarate were added as terminal electron acceptors. Microarray data supplemented with bioinformatic data revealed that the FNR (fumarate and nitrate reductase regulator) regulon includes at least 104, and possibly as many as 115, operons, 68 of which are activated and 36 are repressed during anaerobic growth. A total of 51 operons were directly or indirectly activated by NarL in response to nitrate; a further 41 operons were repressed. Four subgroups of genes implicated in management of reactive nitrogen compounds, NO and products of NO metabolism, were identified; they included proteins of previously unknown function. Global repression by the nitrate- and nitrite-responsive two-component system, NarQ-NarP, was shown for the first time. In contrast with the frdABCD, aspA and ansB operons that are repressed only by NarL, the dcuB-fumB operon was among 37 operons that are repressed by NarP.

Different responses to nitrate and nitrite by the model organism Escherichia coli and the human pathogen Neisseria gonorrhoeae

The ability of Escherichia coli to use both nitrate and nitrite as terminal electron acceptors during anaerobic growth is mediated by the dual-acting two-component regulatory systems NarX-NarL and NarQ-NarP. In contrast, Neisseria gonorrhoeae responds only to nitrite: it expresses only NarQ-NarP. We have shown that although N. gonorrhoeae NarQ can phosphorylate E. coli NarL and NarP, the N. gonorrhoeae NarP is unable to regulate gene expression in E. coli. Mutagenesis experiments have revealed residues in E. coli NarQ that are essential for nitrate and nitrite sensing. Chimaeric proteins revealed domains of NarQ that are important for ligand sensing.

Comparison of the structural and kinetic properties of the cytochrome c nitrite reductases from Escherichia coli, Wolinella succinogenes, Sulfurospirillum deleyianum and Desulfovibrio desulfuricans

The recent crystallographic characterization of NrfAs from Sulfurospirillum deleyianum, Wolinella succinogenes, Escherichia coli and Desulfovibrio desulfuricans allows structurally conserved regions to be identified. Comparison of nitrite and sulphite reductase activities from different bacteria shows that the relative activities vary according to organism. By comparison of both amino acid sequences and structures, differences can be identified in the monomer–monomer interface and the active-site channel; these differences could be responsible for the observed variance in substrate activity and indicate that subtle changes in the NrfA structure may optimize the enzyme for different roles.

Evolution of the soluble nitrate reductase: defining the monomeric periplasmic nitrate reductase subgroup

Bacterial nitrate reductases can be classified into at least three groups according to their localization and function, namely membrane-bound (NAR) or periplasmic (NAP) respiratory and cytoplasmic assimilatory (NAS) enzymes. Monomeric NASs are the simplest of the soluble nitrate reductases, although heterodimeric NASs exist, and a common structural arrangement of NAP is that of a NapAB heterodimer. Using bioinformatic analysis of published genomes, we have identified more representatives of a monomeric class of NAP, which is the evolutionary link between the monomeric NASs and the heterodimeric NAPs. This has further established the monomeric structural clade of NAP. The operons of the monomeric NAP do not contain NapB and suggest that other redox partners are employed by these enzymes, including NapM or NapG predicted proteins. A structural alignment and comparison of the monomeric and heterodimeric NAPs suggests that a difference in surface polarity is related to the interaction of the respective catalytic subunit and redox partner.

The incidence of abdominal and pelvic surgery among patients with irritable bowel syndrome

Rates of abdominopelvic surgery, with a particular focus on gallbladder procedures, were measured in patients with irritable bowel syndrome (IBS) (n = 108,936) and compared with those in a general population sample (n = 223,082). The patient sample was selected from persons who were members of a managed care organization during the years 1995-2000. Medical records from a randomly selected subset of IBS patients were reviewed to confirm the diagnosis. Crude and standardized rates and adjusted rate ratios for surgery were calculated. The incidence of abdominopelvic surgery, excluding gallbladder procedures, was 87% higher in patients with IBS than that for the general population. The incidence of gallbladder surgery was threefold higher in IBS patients than the general population. Patients with IBS have an increased risk for abdominopelvic and gallbladder surgery and, thus, an associated risk for experiencing morbidity and mortality associated with these surgical procedures.

Cytochrome c nitrite reductase: from structural to physicochemical analysis

The recent structural characterization of the NrfA from Escherichia coli provides a framework to rationalize the spectroscopic and functional properties of this enzyme. Analyses by EPR and magnetic CD spectroscopies have been complemented by protein-film voltammetry and these are discussed in relation to the essential structural features of the enzyme.

Transcriptional regulation of a hybrid cluster (prismane) protein

HCP (hybrid-cluster protein) contains two Fe/S clusters, one of which is a hybrid [4Fe-2S-2O] cluster. Despite intensive study, its physiological function has not been reported. The Escherichia coli hcp gene is located in a two-gene operon with hcr, which encodes an NADH-dependent HCP reductase. E. coli HCP is detected after anaerobic growth with nitrate or nitrite: possible roles for it in hydroxylamine or nitric oxide reduction have been proposed. To study the regulation and role of HCP, an hcp::lacZ fusion was constructed and transformed into fnr, arcA and norR mutant strains of E. coli. Transcription from the hcp promoter was induced during anaerobic growth. Only the fnr mutant was defective in hcp expression. Nitrate- and nitrite-induced transcription from the hcp promoter was activated by the response regulator proteins NarL and NarP. Gel retardation assays were used to show that FNR (fumarate-nitrate regulation) and NarL form a complex with the hcp promoter. Transcription of the hcp-hcr operon initiates at a thymine nucleotide located 31 bp upstream of the translation-initiation codon. HCP has been overexpressed from a recombinant plasmid for physiological studies.

Nitrate and nitrite transport in Escherichia coli

Two polytopic membrane proteins, NarK and NarU, are involved in nitrate and nitrite uptake and nitrite extrusion by Escherichia coli. A third polytopic membrane protein, NirC, functions only in nitrite transport. During exponential growth, the quantity of NarU in membrane fractions was <0.01% of the quantity of NarK. During the stationary phase of growth, the ratio of NarU to NarK increased to 0.1%. However, in the exponential phase of growth, the strain expressing only NarK transports and reduces nitrate and nitrite at a rate only slightly higher than that of the strain expressing only NarU, indicating that, in a NarK+ strain, the rate of nitrate reduction is not limited by the rate of nitrate transport. By measuring nitrate and nitrite transport abilities of strains expressing only narK or expressing both narK and nirC, we hypothesized that NarK might function as a primary nitrate–nitrite antiporter. After nitrate is imported by NarK and reduced to nitrite, some nitrite is expelled from the cell and then reimported for reduction to ammonia. Two highly conserved positively charged residues, Arg-87 and Arg-303 of NarU, were shown by site-directed mutagenesis to play a key role in anion transport. This result indicates that NarU might form a single channel for nitrate and nitrite transport.

Comparison of resource utilization by patients treated with transdermal fentanyl and long-acting oral opioids for nonmalignant pain

OBJECTIVE

To quantify resource utilization and costs incurred for patients who received transdermal fentanyl as their first long-acting analgesic for non-malignant pain, and to compare these with utilization and costs for similar patients dispensed other long-acting oral opioids.

DESIGN

A retrospective matched cohort study using medical claims data from a large New England Insurer.

PATIENTS

We identified 478 patients without cancer who received transdermal fentanyl during 1995-1998. We selected patients who had no previous long-acting opioid dispensings and were enrolled during the 180 days before and 30 days following the initial dispensing. We used propensity scores to identify a matched comparison group of 478 long-acting oral opioid users.

RESULTS

Transdermal fentanyl and matched long-acting oral opioid users incurred identical median costs for outpatient medical services and prescriptions during 2 years of follow-up. A larger proportion of transdermal fentanyl patients were still taking their initial opioid analgesic at the end of the 2-year follow-up than were patients initially taking other long-acting opioids. Use of short-acting opioids tapered off more slowly among transdermal fentanyl patients than among long-acting opioid patients. In the first 6 months, the transdermal fentanyl patients had more hospital discharges than the long-acting oral opioid patients, but this difference appeared to reflect preexisting conditions.

CONCLUSIONS

Users of fentanyl transdermal system and other long-acting opioids experienced essentially identical evolution of health services utilization and costs over a 2-year period. The choice of long-acting opioid analgesia does not appear to be a determinant of future medical costs.

Algorithms to identify colonic ischemia, complications of constipation and irritable bowel syndrome in medical claims data: development and validation

PURPOSE

A challenge in the use of insurance claims databases for epidemiologic research is accurate identification and verification of medical conditions. This report describes the development and validation of claims-based algorithms to identify colonic ischemia, hospitalized complications of constipation, and irritable bowel syndrome (IBS).

METHODS

From the research claims databases of a large healthcare company, we selected at random 120 potential cases of IBS and 59 potential cases each of colonic ischemia and hospitalized complications of constipation. We sought the written medical records and were able to abstract 107, 57, and 51 records, respectively. We established a 'true' case status for each subject by applying standard clinical criteria to the available chart data. Comparing the insurance claims histories to the assigned case status, we iteratively developed, tested, and refined claims-based algorithms that would capture the diagnoses obtained from the medical records. We set goals of high specificity for colonic ischemia and hospitalized complications of constipation, and high sensitivity for IBS.

RESULTS

The resulting algorithms substantially improved on the accuracy achievable from a naïve acceptance of the diagnostic codes attached to insurance claims. The specificities for colonic ischemia and serious complications of constipation were 87.2 and 92.7%, respectively, and the sensitivity for IBS was 98.9%.

CONCLUSIONS

U.S. commercial insurance claims data appear to be usable for the study of colonic ischemia, IBS, and serious complications of constipation.

Severe vascular events in migraine patients

OBJECTIVE

To estimate rates of vascular events in relation to dispensing of triptans and ergot alkaloids among migraineurs, and to compare these rates with those of nonmigraineurs.

CONTEXT

It has been speculated that the use of triptans or ergot alkaloid drugs might increase risk of ischemic events through vasoconstriction.

DESIGN

A retrospective cohort study of 130,411 migraineurs and 130,411 age-, sex-, and health plan-matched nonmigraineurs who were members of UnitedHealthcare during 1995 through 1999. The data source for this study was Ingenix's research database containing pharmacy and medical claims for UnitedHealthcare members, and the National Death Index.

MAIN OUTCOME MEASURES

Incidence of cardiovascular and cerebrovascular events and mortality.

RESULTS

Migraineurs and nonmigraineurs had identical rates of myocardial infarction: 1.4 per 1000 person-years. Migraineurs were 67% more likely to suffer a stroke than nonmigraineurs (adjusted relative risk [RR] 1.67, 95% confidence interval [CI] 1.31-2.13), and had higher rates of unstable angina and transient ischemic attacks. There was no increase in risk of myocardial infarction with current (adjusted RR 0.80, 95% CI 0.58-1.11) or recent (adjusted RR 1.15, 95% CI 0.71-1.87) triptan use. Neither current (adjusted RR 0.90, 95% CI 0.64-1.26) nor recent (adjusted RR 0.84, 95% CI 0.46-1.55) triptan use was associated with risk of stroke. Current users of ergot alkaloids were somewhat more likely to have a stroke than other migraineurs (adjusted RR 1.49, 95% CI 0.93-2.41), but there was no dose-response relationship.

CONCLUSIONS

Use of triptans is not associated with increased risk of any ischemic events, including myocardial infarction and stroke, or mortality. Consistent with previous studies, migraineurs in general have an elevated risk of stroke, but not myocardial infarction, compared with nonmigraineurs.

Occurrence of colon ischemia in relation to irritable bowel syndrome

OBJECTIVE

In November 2000, alosetron HCl (Lotronex), a treatment for irritable bowel syndrome (IBS), was removed from the U.S. market in part because of the occurrence of colon ischemia in treated patients. Since the relation between colon ischemia and IBS is poorly understood, we evaluated the incidence of colon ischemia among people with and without IBS.

METHODS

Using medical claims data from a large health care organization in the United States, we identified 87,449 people with an IBS diagnosis between January 1995 and December 1999. We calculated age- and sex-specific incidence rates in the general population and in IBS patients.

RESULTS

There were 740 cases of colon ischemia during 8.5 million person-years of observation in 5.4 million persons. The crude incidence rate was 42.8 cases per 100,000 person-years for IBS patients. By comparison, the incidence rate was 7.2 per 100,000 person-years in the general population. After adjustment for age, sex, and calendar year, the incidence of colon ischemia in people with IBS was 3.4 times higher than in persons without (95% CI 2.6-4.5).

CONCLUSIONS

Rates of colon ischemia among patients carrying a diagnosis of IBS are substantially higher than in the general population. Colon ischemia, though unusual in IBS patients, may nonetheless constitute a distinct part of the IBS natural history. Alternatively, it may be a consequence of therapy, or a manifestation of other bowel pathology that is sometimes confused with IBS.

Risk for respiratory events in a cohort of patients receiving inhaled zanamivir: a retrospective study

BACKGROUND

Inhaled zanamivir is indicated for treatment of uncomplicated acute illness due to influenza A and B viruses in patients aged > or = 12 years who have been symptomatic for no more than 2 days.

OBJECTIVE

The primary objective of this study was to estimate the incidence of adverse respiratory events among zanamivir-treated patients under conditions of usual care.

METHODS

The Ingenix research database includes insurance claims for all dispensations, inpatient and outpatient services, and procedures including the associated diagnoses and costs for a subset of all enrolled UnitedHealthcare members. We identified all persons with a dispensation of zanamivir recorded between October 1, 1999, and April 30, 2000. We captured medical and pharmaceutical claims data for the 6 months before the dispensation to obtain information about comorbidities, overall health status, and respiratory events. Medical and hospital record abstraction and clinical review served to confirm inpatient/emergency department (ED) events. We also examined the records of an approximately 10% random sample of patients treated for a potential respiratory event in an outpatient/ physician office visit during the 10-day follow-up period. Respiratory events not sufficiently severe to result in medical care were not captured in this study.

RESULTS

A total of 5498 eligible zanamivir dispensations contributed by 5450 patients (2911 females, 2539 males; mean age, 38.8 years), with 40 confirmed inpatient/ED respiratory events, were included in the study. Of these 40 events, 31 were pneumonia, bronchitis, or exacerbations of existing chronic respiratory disease; none required intubation or ventilation. No events occurred on the dispensation date. The overall risk for an inpatient/ ED respiratory event was 0.7 per 100 episodes (95% CI, 0.5-1.0). Seven events of wheezing or shortness of breath were not an obvious extension of the original influenza-like illness or of a complicating bronchitis (risk = 0.13 per 100 episodes; 95% CI, 0.06-0.26).

CONCLUSIONS

No immediate or severe bronchoconstrictive responses occurred among 5498 zanamivir dispensations. The overall risk for any respiratory event was low, and none was sufficiently severe to suggest respiratory failure.

The effect of zanamivir treatment on influenza complications: a retrospective cohort study

BACKGROUND

Complications of influenza are a major cause of morbidity and mortality during the influenza season. Clinical trials of zanamivir have reported a reduced incidence of influenza complications among high-risk patients.

OBJECTIVES

This retrospective study sought to determine whether the use of zanamivir lowers the risk of acute influenza complications in a broader population, based on an analysis of claims data from a large managed care organization.

METHODS

Medical and pharmacy health insurance claims data from October 1, 1999, through April 30, 2000, were compiled for UnitedHealthcare members in 19 states. All patients with a diagnosis of influenza (International Classification of Diseases, Ninth Revision, Clinical Modification diagnostic code 487.xx) associated with a physician visit were identified. From these, all patients were selected who had received zanamivir on the same day as the diagnosis of influenza. The propensity score matching technique was used to identify a comparison group with similar health service utilization and comorbidities who received a diagnosis of influenza but no antiviral therapy. Follow-up started the day after the influenza diagnosis and continued for 21 days.

RESULTS

From the 43,741 patients originally identified, 2341 were selected who received a simultaneous diagnosis of influenza and a prescription for zanamivir. The untreated comparator group numbered 2337. Fewer zanamivir patients than untreated patients were hospitalized for complications, and the absolute risks were low (0.6% and 1.0%, respectively; risk ratio [RR], 0.58; 95% CI, 0.30-1.12). Zanamivir-treated patients had an excess of outpatient visits (16.9% vs 14.5%; RR, 1.16; 95% CI, 1.02-1.33) and antibiotic use (16.3% vs 14.8%; RR, 1.10; 95% CI, 0.97-1.26), although the RRs were modest.

CONCLUSIONS

In the setting of a large managed care plan, patterns of influenza complications were similar in zanamivir-treated and untreated patients with a diagnosis of influenza. The results of this study are in contrast to those of published clinical trials reporting a reduction in the risk of influenza complications in zanamivir-treated patients.

Pharmacokinetics and endometrial tissue concentrations of enrofloxacin and the metabolite ciprofloxacin after i.v. administration of enrofloxacin to mares

Enrofloxacin was administered i.v. to five adult mares at a dose of 5 mg/kg. After administration, blood and endometrial biopsy samples were collected at regular intervals for 24 h. The plasma and tissue samples were analyzed for enrofloxacin and the metabolite ciprofloxacin by high-pressure liquid chromatography. In plasma, enrofloxacin had a terminal half-life (t(1/2)), volume of distribution (area method), and systemic clearance of 6.7 +/- 2.9 h, 1.9 +/- 0.4 L/kg, and 3.7 +/- 1.4 mL/kg/min, respectively. Ciprofloxacin had a maximum plasma concentration (Cmax) of 0.28 +/- 0.09 microg/mL. In endometrial tissue, the enrofloxacin Cmax was 1.7 +/- 0.5 microg/g, and the t(1/2) was 7.8 +/- 3.7 h. Ciprofloxacin Cmax in tissues was 0.15 +/- 0.04 microg/g and the t(1/2) was 5.2 +/- 2.0 h. The tissue:plasma enrofloxacin concentration ratios (w/w:w/v) were 0.175 +/- 0.08 and 0.47 +/- 0.06 for Cmax and AUC, respectively. For ciprofloxacin, these values were 0.55 +/- 0.13 and 0.58 +/- 0.31, respectively. We concluded that plasma concentrations achieved after 5 mg/kg i.v. are high enough to meet surrogate markers for antibacterial activity (Cmax:MIC ratio, and AUC:MIC ratio) considered effective for most susceptible gram-negative bacteria. Endometrial tissue concentrations taken from the mares after dosing showed that enrofloxacin and ciprofloxacin both penetrate this tissue adequately after systemic administration and would attain concentrations high enough in the tissue fluids to treat infections of the endometrium caused by susceptible bacteria.

Roles of NapF, NapG and NapH, subunits of the Escherichia coli periplasmic nitrate reductase, in ubiquinol oxidation

The nap operon of Escherichia coli K-12, encoding a periplasmic nitrate reductase (Nap), encodes seven proteins. The catalytic complex in the periplasm, NapA-NapB, is assumed to receive electrons from the quinol pool via the membrane-bound cytochrome NapC. Like NapA, B and C, a fourth polypeptide, NapD, is also essential for Nap activity. However, none of the remaining three polypeptides, NapF, G and H, which are predicted to encode non-haem, iron-sulphur proteins, are essential for Nap activity, and their function is currently unknown. The relative rates of growth and electron transfer from physiological substrates to Nap have been investigated using strains defective in the two membrane-bound nitrate reductases, and also defective in either ubiquinone or menaquinone biosynthesis. The data reveal that Nap is coupled more effectively to menaquinol oxidation than to ubiquinol oxidation. Conversely, parallel experiments with a second set of mutants revealed that nitrate reductase A couples more effectively with ubiquinol than with menaquinol. Three further sets of strains were constructed with combinations of in frame deletions of ubiCA, menBC, napC, napF and napGH genes. NapF, NapG and NapH were shown to play no role in electron transfer from menaquinol to the NapAB complex but, in the Ubi+Men- background, deletion of napF, napGH or napFGH all resulted in total loss of nitrate-dependent growth. Electron transfer from ubiquinol to NapAB was totally dependent upon NapGH, but not on NapF. NapC was essential for electron transfer from both ubiquinol and menaquinol to NapAB. The results clearly established that NapG and H, but not NapF, are essential for electron transfer from ubiquinol to NapAB. The decreased yield of biomass resulting from loss of NapF in a Ubi+Men+ strain implicates NapF in an energy- conserving role coupled to the oxidation of ubiquinol. We propose that NapG and H form an energy- conserving quinol dehydrogenase functioning as either components of a proton pump or in a Q cycle, as electrons are transferred from ubiquinol to NapC.

Prevalence of serious eosinophilia and incidence of Churg-Strauss syndrome in a cohort of asthma patients

BACKGROUND

Some leukotriene receptor antagonists, such as zafirlukast and montelukast, have been associated with systemic eosinophilia, with interest focused on Churg-Strauss syndrome (CSS).

OBJECTIVE

To calculate the background incidence rate of CSS and prevalence of eosinophilia among people with asthma who have not used leukotriene receptor antagonists.

METHODS

We conducted a cohort study in the setting of three geographically diverse UnitedHealthcare health plans. We identified 36,230 people who received a diagnosis of asthma during the period October 1994 through September 1997. We identified 241 potential cases from the claims data. Using a standardized hospital record abstract form, nurses abstracted relevant clinical data from the hospital charts of potential cases. We applied several a priori case definitions to the abstracted clinical data and computed incidence rates of CSS among patients with asthma. We additionally used these data to compute the prevalence of serious eosinophilia.

RESULTS

Incidence rates of definite CSS among asthma patients ranged from zero (90% confidence interval 0.0 to 23.0) to 67 (90% confidence interval 22.5 to 160.6) cases per 1,000,000 person-years, depending on the definition used. All patients who met the criteria for CSS expressed symptoms consistent with mild asthma.

CONCLUSIONS

This report is the first direct measurement of the incidence rate of CSS among asthma patients. We believe that the prevalence and incidence information that we report is a useful description of population rates in the United States for these conditions.

Overproduction, purification and novel redox properties of the dihaem cytochrome c, NapB, from Haemophilus influenzae

The napB gene of the pathogenic bacterium Haemophilus influenzae encodes a dihaem cytochrome c, the small subunit of a heterodimeric periplasmic nitrate reductase similar to those found in other bacteria. In order to obtain sufficient protein for biophysical studies, we aimed to overproduce the recombinant dihaem protein in Escherichia coli. Initial expression experiments indicated that the NapB signal peptide was not cleaved by the leader peptidase of the host organism. Apocytochrome was formed under aerobic, semi-aerobic and anaerobic growth conditions in either Luria--Bertani or minimal salts medium. The highest amounts of apo-NapB were produced in the latter medium, and the bulk was inserted into the cytoplasmic membrane. The two haem groups were covalently attached to the pre-apocytochrome only under anaerobic growth conditions, and with 2.5 mM nitrite or at least 10 mM nitrate supplemented to the minimal salts growth medium. In order to obtain holocytochrome, the gene sequence encoding mature NapB was cloned in-frame with the E. coli ompA (outer membrane protein A) signal sequence. Under anaerobic conditions, NapB was secreted into the periplasmic space, with the OmpA signal peptide being correctly processed and with both haem c groups attached covalently. Unless expressed in the DegP-protease-deficient strain HM125, some of the recombinant NapB polypeptides were N-terminally truncated as a result of proteolytic activity. Under aerobic growth conditions, co-expression with the E. coli ccm (cytochrome c maturation) genes resulted in a higher yield of holocytochrome c. The pure recombinant NapB protein showed absorption maxima at 419, 522 and 550 nm in the reduced form. The midpoint reduction potentials of the two haem groups were determined to be -25 mV and -175 mV. These results support our hypothesis that the Nap system fulfils a nitrate-scavenging role in H. influenzae.

Research and development to improve naval shipboard waste management using a compact closed-loop-controlled waste incinerator

Research has been conducted into the application of forced acoustics for enhancing the performance of a pyrolyzed waste afterburner configured as a dump combustor. Subscale studies showed that acoustic forcing of an air jet entering a dump chamber could trigger the formation of coherent vortices generated by entrainment of ambient gases. Subsequent studies showed that combustible gases could be introduced into the coherent vortices, and with additional modulation this configuration would lead to an enhanced combustion rate with low emissions of pollutants. The acoustically forced burner concept was scaled up to practical levels and tested as an afterburner on a commercial waste incinerator operating in pyrolysis mode. Results show that the afterburner can promote both compactness, due to the rapid combustion rate, and low pollutant emissions resulting from enhanced mixing prior to combustion.

Suppression of FNR-dependent transcription activation at the Escherichia coli nir promoter by Fis, IHF and H-NS: modulation of transcription initiation by a complex nucleo-protein assembly

Expression from the Escherichia coli nir promoter is co-dependent on both the FNR protein (an anaerobically triggered transcription activator) and the NarL or NarP proteins (transcription activators triggered by nitrite and nitrate). Under anaerobic conditions, FNR binds to a site centred between positions -41 and -42, activating transcription of the nir operon. In previous work, we showed that this activation is suppressed by the binding of Fis protein, and at least one other protein, to sequence elements located upstream of the nir promoter. We proposed that the binding of NarL or NarP to a site centred between positions -69 and -70 counteracts this suppression, resulting in increased transcription in response to nitrite or nitrate. Here we have further investigated the different proteins that downregulate the nir promoter. We show that the nir promoter is repressed by three DNA binding proteins, Fis, IHF and H-NS. We demonstrate that, in addition to binding to its previously characterized upstream site located at position -142, Fis also binds to a second downstream site located at position +23. A second suppressing factor is IHF, that binds to a site located at position -88. Finally, the nucleoid associated protein, H-NS, preferentially binds to upstream sequences at the nir promoter and represses promoter activity. The association of Fis, IHF and H-NS suggests that nir promoter DNA is sequestrated into a highly ordered nucleo-protein structure that represses FNR-dependent transcription activation. NarL and NarP can relieve both IHF- and Fis-mediated repression, but are unable to counteract H-NS-mediated repression.

Identification of transcription activators that regulate gonococcal adaptation from aerobic to anaerobic or oxygen-limited growth

Analysis of the Neisseria gonorrhoeae DNA sequence database revealed the presence of two genes, one encoding a protein predicted to be 37. 5% identical (50% similar) in amino acid sequence to the Escherichia coli FNR protein and the other encoding a protein 41% and 42% identical (54 and 51% sequence similarity) to the E. coli NarL and NarP proteins respectively. Both genes have been cloned into E. coli and insertionally inactivated in vitro. The mutated genes have been transformed into gonococci and recombined into the chromosome. The fnr mutation totally abolished and the narP mutation severely diminished the ability of gonococci to: (i) grow anaerobically; (ii) adapt to oxygen-limited growth; (iii) initiate transcription from the aniA promoter (which directs the expression of a copper-containing nitrite reductase, AniA, in response to the presence of nitrite); and (iv) reduce nitrite during growth in oxygen-limited media. The product of nitrite reduction was identified to be nitrous oxide. Immediately upstream of the narL/narP gene is an open reading frame that, if translated, would encode a homologue of the E. coli nitrate- and nitrite-sensing proteins NarX and NarQ. As transcription from the aniA promoter was not activated during oxygen-limited growth in the presence of nitrate, the gonococcal two-component regulatory system is designated NarQ-NarP rather than NarX-NarL. As far as we are aware, this is the first well-documented example of a two-component regulatory system working in partnership with a transcription activator in pathogenic neisseria. A 45 kDa c-type cytochrome that was synthesized during oxygen-limited, but not during oxygen sufficient, growth was identified as a homologue of cytochrome c peroxidases (CCP) of other bacteria. The gene for this cytochrome, designated ccp, was located, and its regulatory region was cloned into the promoter probe vector pLES94. Transcription from the ccp promoter was repressed during aerobic growth and induced during oxygen-limited growth and was totally FNR dependent, suggesting that the gonococcal FNR protein is a transcription activator of at least two genes. However, unlike AniA, synthesis of the CCP homologue was insensitive to the presence of nitrite during oxygen-limited growth.

Uptake of metabolites by gonococci grown with lactate in a medium containing glucose: evidence for a surface location of the sialyltransferase

Promotion of uptake of essential metabolites is a possible reason for the general stimulation of gonococcal metabolism which is caused by lactate (1 mM) in a defined medium containing glucose (5 mM). However, although uptake of(14)C adenine by gonococci [strain BS4(agar)] held for 4 or 7 min at 37 degrees C in Hanks balanced salt solution was increased for lactate treated gonococci compared with control organisms, uptake of(14)C glucose and(14)C proline under these conditions was unaffected. Hence, there is no evidence that lactate produces general stimulation of metabolite uptake. Unlike the other metabolites, cytidine 5'-monophospho-(14)CN-acetyl neuraminic acid (CMP-(14)CNANA), the substrate for sialylation of gonococcal lipopolysaccharide (LPS), was adsorbed in substantial quantities by gonococci held on ice for 6 min. Also, the increase in uptake of CMP-(14)CNANA at 37 degrees C over that adsorbed at 0 degrees C was much smaller (less than two-fold) than for the other compounds (4-30-fold). The substantial adsorption at 0 degrees C suggested a surface receptor for CMP-(14)CNANA. It is probably the sialyltransferase because a sialyltransferase deficient mutant, JB1, did not absorb CMP-(14)CNANA at 0 degrees C or take it up at 37 degrees C, in contrast to its parent strain, F62, which behaved similarly to strain BS4 (agar). This supports previous evidence for a surface location of the sialyltransferase. There was a small increase in adsorption of CMP-(14)CNANA in lactate treated gonococci indicating a slight increase in the surface enzyme. This could enhance LPS sialylation and hence affect pathogenicity.

Novel growth characteristics and high rates of nitrate reduction of an Escherichia coli strain, LCB2048, that expresses only a periplasmic nitrate reductase

Escherichia coli strain LCB2048 is a double mutant defective in the synthesis of the two membrane-associated nitrate reductases A and Z. This strain can grow anaerobically on a non-fermentable carbon source, glycerol, in the presence of nitrate even in media supplemented with high concentrations of tungstate. This growth was totally dependent upon a highly active, periplasmic nitrate reductase (Nap). Due to the presence of a previously unreported narL mutation, synthesis of the periplasmic nitrate reductase by this strain was induced during anaerobic growth by nitrate. We have also demonstrated that methyl viologen is an ineffective electron donor to Nap: its use leads to an underestimation of the contribution of Nap activity to the rate of nitrate reduction in vivo.

Parathyroid hormone activates mitogen-activated protein kinase in opossum kidney cells

Many G protein-coupled receptor agonists activate p42/p44 mitogen-activated protein kinase (MAPK), using signaling pathways that are a function of receptor, G protein-coupled, and effector complement. In opossum kidney (OK) cells, activation of endogenous PTH receptors caused a time- (peak within 15-30 min, sustained for approximately 2 h) and dose-dependent (EC50 approximately 3 x 10(-10) M) activation of MAPK. Immunoblot analysis with an activation- specific MAPK antibody indicated that PTH activated both p42 and p44 MAPK. Epidermal growth factor (EGF) also activated p42 and p44MAPK in a time- (peak at 5 min, return to basal within 2 h) and dose-dependent (EC50 approximately 3 ng/ml) fashion. PTH-dependent MAPK activation was mimicked by the protein kinase C activator (PKC) phorbol myristate acetate (PMA), and the protein kinase A activators 8 bromo-cAMP (8-Br-cAMP) and forskolin but was not affected by pertussis toxin pretreatment. PMA or 8-Br-cAMP pretreatment blocked MAPK activation by reexposure to each kinase activator but caused no significant reduction in MAPK activation by PTH. MAPK activation by PTH, EGF, and 8-Br-cAMP was inhibited by the MAPK kinase inhibitor PD98059 and an EGF receptor (EGFR)-selective inhibitor tyrphostin AG1478. AG1478 also blocked MAPK activation by insulin-like growth factor-1 and platelet-derived growth factor. EGF and PTH caused time- and AG1478-sensitive phosphorylation of the EGFR, but EGFR desensitization did not affect MAPK activation by PTH. EGF, PMA, and low doses of PTH (10(12) to 10(-9) M) stimulated while 8-Br-cAMP and high doses of PTH (10(-8) to 10(-6) M) inhibited [3H]thymidine uptake. These data demonstrate that PTH activates MAPK and suggest that PKC, protein kinase A, and the EGFR play roles in PTH signaling. The biphasic effect of PTH on DNA synthesis suggests that MAPK activation by the hormone leads to distinct cellular responses.

Microbial reduction of technetium by Escherichia coli and Desulfovibrio desulfuricans: enhancement via the use of high-activity strains and effect of process parameters

Escherichia coli and Desulfovibrio desulfuricans reduce Tc(VII) (TcO(4)(-)) with formate or hydrogen as electron donors. The reaction is catalyzed by the hydrogenase component of the formate hydrogenlyase complex (FHL) of E. coli and is associated with a periplasmic hydrogenase activity in D. desulfuricans. Tc(VII) reduction in E. coli by H(2) and formate was either inhibited or repressed by 10 mM nitrate. By contrast, Tc(VII) reduction catalyzed by D. desulfuricans was less sensitive to nitrate when formate was the electron donor, and unaffected by 10 mM or 100 mM nitrate when H(2) was the electron donor. The optimum pH for Tc(VII) reduction by both organisms was 5.5 and the optimum temperature was 40 degrees C and 20 degrees C for E. coli and D. desulfuricans, respectively. Both strains had an apparent K(m) for Tc(VII) of 0.5 mM, but Tc(VII) was removed from a solution of 300 nM TcO(4)(-) within 30 h by D. desulfuricans at the expense of H(2). The greater bioprocess potential of D. desulfuricans was shown also by the K(s) for formate (>25 mM and 0.5 mM for E. coli and D. desulfuricans, respectively), attributable to the more accessible, periplasmic localization of the enzyme in the latter. The relative rates of Tc(VII) reduction for E. coli and D. desulfuricans (with H(2)) were 12.5 and 800 micromol Tc(VII) reduced/g biomass/h, but the use of an E. coli HycA mutant (which upregulates FHL activities by approx. 50%) had a similarly enhancing effect on the rate of Tc reduction. The more rapid reduction of Tc(VII) by D. desulfuricans compared with the E. coli strains was also shown using cells immobilized in a hollow-fiber reactor, in which the flow residence times sustaining steady-state removal of 80% of the radionuclide were 24.3 h for the wild-type E. coli, 4.25 h for the upregulated mutant, and 1.5 h for D. desulfuricans.

Essential roles for the products of the napABCD genes, but not napFGH, in periplasmic nitrate reduction by Escherichia coli K-12

The seven nap genes at minute 47 on the Escherichia coli K-12 chromosome encode a functional nitrate reductase located in the periplasm. The molybdoprotein, NapA, is known to be essential for nitrate reduction. We now demonstrate that the two c-type cytochromes, the periplasmic NapB and the membrane-associated NapC, as well as a fourth polypeptide, NapD, are also essential for nitrate reduction in the periplasm by physiological substrates such as glycerol, formate and glucose. None of the three iron-sulphur proteins, NapF, NapG or NapH, are essential, irrespective of whether the bacteria are grown anaerobically in the presence of nitrate or fumarate as a terminal electron acceptor, or by glucose fermentation. Mutation of napD resulted in the total loss of Methyl Viologen-dependent nitrate reductase activity of the molybdoprotein, NapA, consistent with an earlier suggestion by others that NapD might be required for post-translational modification of NapA.

Competition between Escherichia coli strains expressing either a periplasmic or a membrane-bound nitrate reductase: does Nap confer a selective advantage during nitrate-limited growth?

The physiological role of the periplasmic nitrate reductase, Nap, one of the three nitrate reductases synthesized by Escherichia coli K-12, has been investigated. A series of double mutants that express only one nitrate reductase were grown anaerobically in batch cultures with glycerol as the non-fermentable carbon source and nitrate as the terminal electron acceptor. Only the strain expressing nitrate reductase A grew rapidly under these conditions. Introduction of a narL mutation severely decreased the growth rate of the nitrate reductase A strain, but enhanced the growth of the Nap(+) strain. The ability to use nitrate as a terminal electron acceptor for anaerobic growth is therefore regulated primarily by the NarL protein at the level of transcription. Furthermore, the strain expressing nitrate reductase A had a substantial selective advantage in competition with the strain expressing only Nap during nitrate-sufficient continuous culture. However, the strain expressing Nap was preferentially selected during nitrate-limited continuous growth. The saturation constants for nitrate for the two strains (which numerically are equal to the nitrate concentrations at half of the maximum specific growth rate and therefore reflect the relative affinities for nitrate) were estimated using the integrated Monod equation to be 15 and 50 microM for Nap and nitrate reductase A respectively. This difference is sufficient to explain the selective advantage of the Nap(+) strain during nitrate-limited growth. It is concluded that one physiological role of the periplasmic nitrate reductase of enteric bacteria is to enable bacteria to scavenge nitrate in nitrate-limited environments.

The periplasmic nitrate reductase from Escherichia coli: a heterodimeric molybdoprotein with a double-arginine signal sequence and an unusual leader peptide cleavage site

The periplasmic nitrate reductase, NapA, from Escherichia coli was identified as a 90 kDa molybdoprotein which comigrated during polyacrylamide gel electrophoresis with the di-haem c-type cytochrome, NapB. The DNA sequence of the 5' end of the napA gene and the N-terminal amino acid sequences of both NapA and NapB were determined. The 36 residue leader peptide for NapA includes the double-arginine motif typical of proteins to which complex redox cofactors are attached in the cytoplasm prior to targeting to the periplasm. The pre-NapA leader sequence is both unexpectedly long and, unless two successive proteolysis steps are involved, is cleaved at the unprecedented sequence G-Q-Q-. Nap activity was suppressed during growth in the presence of tungstate and was absent from a mutant unable to synthesise the molybdopterin cofactor.