Retraction speed and chronic poststernotomy pain: A randomized controlled trial.

OBJECTIVES: Approximately 30% of patients develop chronic poststernotomy pain (CPSP) following cardiac surgery with sternal retraction. Risk factors have been described but no causal determinants identified. Investigators hypothesized that opening the sternum slowly would impart less force (and thereby less nerve/tissue damage) and translate to a reduced incidence of CPSP. The main objectives were to determine whether or not slower sternal retraction would reduce the incidence of CPSP and improve health-related quality of life. METHODS: Patients undergoing coronary artery bypass graft surgery were recruited to this randomized controlled trial. Patients were randomized to slow or standard retraction (ie, sternum opened over 15 minutes vs 30 seconds, respectively). Although the anesthesiologist and surgeon were aware of the randomization, the patients, assessors, and postoperative nursing staff remained blinded. Sternotomy pain and analgesics were measured in hospital. At 3, 6, and 12 months postoperatively, all patients completed the Medical Outcomes Survey Short Form and reported on CPSP and complications requiring rehospitalization. Thirty-day rehospitalizations and mortality were recorded. RESULTS: In total, 326 patients consented to participate and 313 were randomized to slow (n = 159) versus standard retraction (n = 154). No clinically relevant differences were detected in acute pain, analgesic consumption, or the incidence of CPSP or health-related quality of life. Although the slow group had significantly more hospitalizations at 3 and 12 months postoperatively, the reasons were unrelated to retraction speed. No differences were observed in 30-day rehospitalizations or mortality. CONCLUSIONS: All outcomes were consistent with previous reports, but no clinically significant differences were observed with retraction speed.

Multi-ancestry genome-wide analysis identifies shared genetic effects and common genetic variants for self-reported sleep duration.

Both short (≤6 h per night) and long sleep duration (≥9 h per night) are associated with increased risk of chronic diseases. Despite evidence linking habitual sleep duration and risk of disease, the genetic determinants of sleep duration in the general population are poorly understood, especially outside of European (EUR) populations. Here, we report that a polygenic score of 78 European ancestry sleep duration single-nucleotide polymorphisms (SNPs) is associated with sleep duration in an African (n = 7288; P = 0.003), an East Asian (n = 13 618; P = 6 × 10-4) and a South Asian (n = 7485; P = 0.025) genetic ancestry cohort, but not in a Hispanic/Latino cohort (n = 8726; P = 0.71). Furthermore, in a pan-ancestry (N = 483 235) meta-analysis of genome-wide association studies (GWAS) for habitual sleep duration, 73 loci are associated with genome-wide statistical significance. Follow-up of five loci (near HACD2, COG5, PRR12, SH3RF1 and KCNQ5) identified expression-quantitative trait loci for PRR12 and COG5 in brain tissues and pleiotropic associations with cardiovascular and neuropsychiatric traits. Overall, our results suggest that the genetic basis of sleep duration is at least partially shared across diverse ancestry groups.

Microgravity validation of a novel system for RNA isolation and multiplex quantitative real time PCR analysis of gene expression on the International Space Station.

The International Space Station (ISS) National Laboratory is dedicated to studying the effects of space on life and physical systems, and to developing new science and technologies for space exploration. A key aspect of achieving these goals is to operate the ISS National Lab more like an Earth-based laboratory, conducting complex end-to-end experimentation, not limited to simple microgravity exposure. Towards that end NASA developed a novel suite of molecular biology laboratory tools, reagents, and methods, named WetLab-2, uniquely designed to operate in microgravity, and to process biological samples for real-time gene expression analysis on-orbit. This includes a novel fluidic RNA Sample Preparation Module and fluid transfer devices, all-in-one lyophilized PCR assays, centrifuge, and a real-time PCR thermal cycler. Here we describe the results from the WetLab-2 validation experiments conducted in microgravity during ISS increment 47/SPX-8. Specifically, quantitative PCR was performed on a concentration series of DNA calibration standards, and Reverse Transcriptase-quantitative PCR was conducted on RNA extracted and purified on-orbit from frozen Escherichia coli and mouse liver tissue. Cycle threshold (Ct) values and PCR efficiencies obtained on-orbit from DNA standards were similar to Earth (1 g) controls. Also, on-orbit multiplex analysis of gene expression from bacterial cells and mammalian tissue RNA samples was successfully conducted in about 3 h, with data transmitted within 2 h of experiment completion. Thermal cycling in microgravity resulted in the trapping of gas bubbles inside septa cap assay tubes, causing small but measurable increases in Ct curve noise and variability. Bubble formation was successfully suppressed in a rapid follow-up on-orbit experiment using standard caps to pressurize PCR tubes and reduce gas release during heating cycles. The WetLab-2 facility now provides a novel operational on-orbit research capability for molecular biology and demonstrates the feasibility of more complex wet bench experiments in the ISS National Lab environment.

Surotomycin versus vancomycin in adults with Clostridium difficile infection: primary clinical outcomes from the second pivotal, randomized, double-blind, Phase 3 trial.

BACKGROUND: The available treatment options for Clostridium difficile infection (CDI) are limited by high recurrence rates. Surotomycin was a novel bactericidal cyclic lipopeptide in development to treat CDI that demonstrated non-inferiority to vancomycin in a Phase 2 trial. OBJECTIVES: To assess surotomycin safety and clinical response (non-inferiority versus vancomycin) at the end of treatment (EOT) of CDI. Additionally, to assess surotomycin response over time and sustained response at 30-40 days post-EOT (superiority versus vancomycin). PATIENTS AND METHODS: Patients with CDI were randomized (1:1) to receive twice-daily oral surotomycin 250 mg alternating with twice-daily placebo or four-times-daily oral vancomycin 125 mg for 10 days in this Phase 3, double-blind, multicentre, international trial. Clinical response over time and sustained clinical response were monitored until the end of the trial, through a follow-up period of 30-40 days. Clinical Trial Registration: NCT01598311. RESULTS: A total of 285 and 292 patients with confirmed CDI were randomized to receive surotomycin and vancomycin, respectively. Surotomycin-associated clinical response at EOT was non-inferior to vancomycin (surotomycin/vancomycin: 83.4%/82.1%; difference 1.4%, 95% CI - 4.9, 7.6). Following treatment with surotomycin, both clinical response over time (stratified log-rank test, P = 0.277) and sustained clinical response (63.3%/59.0%; difference 4.3%, 95% CI - 3.6, 12.2) did not demonstrate superiority versus vancomycin at end of trial. Both treatments were generally well tolerated. CONCLUSIONS: Surotomycin demonstrated non-inferiority to vancomycin for CDI clinical response at EOT. Surotomycin did not demonstrate superiority to vancomycin for clinical response over time or sustained clinical response rate.

Retrograde Extrusion of Coronary Thrombus During Urgent Aortocoronary Bypass Surgery: A Case Report.

A 73-year-old man underwent urgent coronary artery bypass grafting after an acute myocardial infarction. An angiogram had revealed multivessel disease with a circumflex artery lesion suspected as the primary culprit. On separation from cardiopulmonary bypass, transesophageal echocardiography revealed a new mobile mass in the aortic root. Cardiopulmonary bypass was reinstituted and a large thrombus emanating from the left coronary ostium was surgically removed. We hypothesize that the thrombus had originated from coronary retrograde extrusion during venous grafting. This case illustrates an unusual source of emboli during coronary artery bypass grafting and emphasizes the importance of perioperative transesophageal echocardiography for the prevention of potentially catastrophic outcomes.

Cloud-based Electronic Health Records for Real-time, Region-specific Influenza Surveillance.

Accurate real-time monitoring systems of influenza outbreaks help public health officials make informed decisions that may help save lives. We show that information extracted from cloud-based electronic health records databases, in combination with machine learning techniques and historical epidemiological information, have the potential to accurately and reliably provide near real-time regional estimates of flu outbreaks in the United States.

Susceptibility of Clostridium difficile isolates from a Phase 2 clinical trial of cadazolid and vancomycin in C. difficile infection.

OBJECTIVES: The aim of this study was to evaluate the susceptibilities of Clostridium difficile isolates to cadazolid, a novel antibiotic for the treatment of C. difficile infection. METHODS: Ribotyping and susceptibilities were determined for C. difficile isolates from a multicentre, double-blind, Phase 2 study of oral cadazolid in patients with C. difficile infection (NCT01222702, ClinicalTrials.gov; EudraCT 2010-020941-29, European Clinical Trials Database). Patients were randomized to receive 250, 500 or 1000 mg of cadazolid twice daily or 125 mg of vancomycin four times daily, for 10 days. MICs of cadazolid, vancomycin, fidaxomicin, linezolid and moxifloxacin were determined at baseline for all patients and post-baseline for patients with clinical failure or recurrence, using the agar dilution method. RESULTS: Seventy-eight of 84 patients had an evaluable toxigenic C. difficile isolate at baseline. The most frequent PCR ribotype was 027 (15.4%). Cadazolid MICs for baseline isolates (including epidemic strain 027) ranged from 0.06 to 0.25 mg/L. Baseline cadazolid MICs were similar to those of fidaxomicin and lower than those of vancomycin, linezolid and moxifloxacin. For each clinical outcome group (clinical cure, clinical failure, sustained clinical response and clinical failure or recurrence), the baseline cadazolid MIC range was 0.06-0.25 mg/L. Mean (min-max) cadazolid faecal concentration (µg/g) on day 5 was 884 (101-2710), 1706 (204-4230) and 3226 (1481-12 600) for the doses 250, 500 and 1000 mg, respectively. CONCLUSIONS: For all cadazolid doses, the faecal concentration was in excess of several thousand-fold the MIC90 for C. difficile. The MIC of cadazolid for all C. difficile isolates, including epidemic strains, was low and in the same narrow range regardless of treatment outcome.

Surveillance and molecular characterization of non-tuberculous mycobacteria in a hospital water distribution system over a three-year period.

A three-year surveillance of non-tuberculous mycobacteria (NTM) in a hospital water distribution system was conducted at a facility located in southern Alberta. NTM was not present in any intake water samples, but was found in 106/183 (58%) of endpoint samples across 15 sites over the study period. Two different species of NTM were identified, Mycobacterium gordonae (88/183) and Mycobacterium avium (34/183); with only one strain of each M. gordonae and M. avium found. Given the sensitive nature of a healthcare facility, attention should be paid to minimize potential impact of NTM from potable water sources on patient health.

Systematic review: faecal transplantation for the treatment of Clostridium difficile-associated disease.

BACKGROUND: Management of recurrent Clostridium difficile-associated disease (CDAD), particularly in elderly patients, remains clinically challenging. Faecal transplantation (FT) may restore normal microbiota and break the cycle of recurrent CDAD. AIM: To critically appraise the clinical research evidence on the safety and effectiveness of FT compared with standard care in the treatment of patients with CDAD. METHODS: A comprehensive literature search was conducted by a research librarian to identify relevant studies published between 2000 and 2011. The Cochrane Library, PubMed, EMBASE, CINAHL, Biological Abstracts, BIOSIS Previews and Web of Science were searched using the following Medical Subject Headings (MeSH) terms and keywords, alone or in combination: Clostridium infections/Clostridium difficile/pseudomembranous/colitis/faeces/rectal/colon flora/gastrointestinal/nasogastric tube/enema/donor/transplant/infusion/bacteriotherapy/human probiotic infusion. Methodological quality of the included case series studies was assessed in terms of patient selection criteria, consecutive recruitment, prospective data collection, reporting of lost to follow-up, and follow-up rates. RESULTS: No controlled studies were found. Based on the weak evidence from seven full-text case series studies of 124 patients with recurrent/refractory CDAD, FT appears to be a safe and effective procedure. In most cases (83%) symptoms improved immediately after the first FT procedure, and some patients stayed diarrhoea free for several months or years. CONCLUSIONS: Although these results appear to be promising, the treatment effects of faecal transplantation cannot be determined definitively in the absence of a control group. Results from randomised controlled trials that compare faecal transplantation to oral vancomycin without or with a taper regimen will help to better define the role of faecal transplantation in the management of recurrent CDAD.

Caenorhabditis elegans as a host model for community-associated methicillin-resistant Staphylococcus aureus.

The nematode Caenorhabditis elegans has recently been developed as a host model for the study of Staphylococcus aureus virulence and pathogenesis. Here, the toxicity and virulence of representative clinical isolates of our methicillin-resistant S. aureus (MRSA) epidemic strains were studied using this model. The strains USA300 (associated with community infection outbreaks), USA400 (associated with sporadic community infections) and CMRSA2 (associated with both hospital and community infections), as well as the nematocidal reference strain NCTC8325, showed high nematocidal activity, both by killing the majority of the nematodes (> 90%) over 9 days, and by inhibiting second-generation nematode growth. By contrast, the typical hospital-associated MRSA strain CMRSA6, the colonization strain M92, and the non-pathogenic Staphylococcus epidermidis control strain ATCC12228 were non-toxic to the nematode, which behaved normally. The absence of nematocidal activity does not reflect lack of growth or reduced growth of the bacterial inoculum. The two non-nematocidal strains share similar genomic backgrounds, bacterial growth curve patterns and virulence gene profiles. However, the nematocidal strains each showed the same low maximum density growth curve patterns, but possessed distinct genetic profiles; no common virulence gene patterns or specific genes have been elucidated. Our findings demonstrate that community-associated MRSA strains are more pathogenic than hospital-associated MRSA in the C. elegans model and support the use of this model for studying the virulence of S. aureus strains.

Proton pump inhibitors increase significantly the risk of Clostridium difficile infection in a low-endemicity, non-outbreak hospital setting.

BACKGROUND: Proton pump inhibitors (PPI) have been linked to higher risk of Clostridium difficile infection (CDI). The relevance of this association in hospitals with low disease activity, where an outbreak strain is nondominant, has been assessed in relatively few studies. AIM: To assess the association of PPI and CDI in a setting of low disease activity. METHODS: A retrospective cohort study was conducted at two hospitals. Patients admitted for > or = 7 days receiving antibiotics were included. Demographics, exposure to PPI, antibiotics and other drugs in relation to diagnosis of CDI were assessed by univariate and multivariate analyses. RESULTS: Of 14 719 patients, 149 (1%) first episode CDI were documented; PPI co-exposure increased CDI [1.44 cases/100 patients vs. 0.74 cases/100 non-exposed (OR: 1.96, 95% CI: 1.42-2.72)]. By logistic regression, PPI days (adjusted OR: 1.01 per day, 95% CI: 1.00-1.02), histamine-2 blockers, antidepressants, antibiotic days, exposure to medications, age, admission service and length of admission were significant predictors. CONCLUSIONS: A statistically significant increase in CDI was observed in antibiotic recipients who received PPI, but the absolute risk increase is modest. In settings of with low rates of CDI, the benefit of PPI therapy outweighs the risk of developing CDI. These data support programmes to decrease inappropriate use of PPI in hospitalized patients.

Clinical outcomes, safety, and pharmacokinetics of OPT-80 in a phase 2 trial with patients with Clostridium difficile infection.

OPT-80, a novel, minimally absorbed macrocycle, is a candidate treatment option for Clostridium difficile infection (CDI) based on cure without recurrence of CDI in the hamster challenge model, good in vitro activity against C. difficile, and relative sparing of commensal gram-negative anaerobes. In this open-label, dose-ranging clinical trial, 48 evaluable subjects were randomized to receive either 50, 100, or 200 mg of OPT-80 orally every 12 h for 10 days as treatment for mild to moderately severe CDI. OPT-80 was well tolerated by all subjects. Plasma concentrations were below the lower limit of quantitation in almost one-half of patients and typically

Bloodstream infection-associated sepsis and septic shock in critically ill adults: a population-based study.

BACKGROUND: Few studies have investigated the epidemiology of sepsis and septic shock in a large population and none have been from Canada. The objective of this study was to define the epidemiology of bloodstream infection (BSI)-associated sepsis and septic shock among all critically ill patients in a large, fully integrated health region in Canada. PATIENTS AND METHODS: All critically ill adults admitted to multidisciplinary intensive care units (ICU) in the Calgary Health Region during May 1, 1999 to April 30, 2000 were included. Clinical, microbiologic and outcome information was obtained from regional databases. RESULTS: We surveyed 1981 patients having at least one ICU admission. Systemic inflammatory response syndrome (SIRS) was diagnosed in 92%, BSI-associated sepsis (BSI with SIRS) in 6% and BSI-associated septic shock (BSI with SIRS and hypotension) in 3%; respective hospital mortality rates were 36%, 40% and 49%. The most common BSI etiologies were Staphylococcus aureus, Escherichia coli and Streptococcus species; only one isolate (1%) was highly antibiotic resistant. Independent risk factors for death among patients with SIRS included age (>or= 65), hypothermia (< 35 degrees C), and higher APACHE II and TISS scores. A surgical diagnosis was associated with decreased mortality risk. Neither a positive blood culture nor hypotension at presentation independently predicted death. CONCLUSION: Knowledge of the epidemiology of these syndromes is important for assessing the burden of disease and providing background information for investigating new therapies.

Identification, purification, and characterization of iminodiacetate oxidase from the EDTA-degrading bacterium BNC1.

Microbial degradation of synthetic chelating agents, such as EDTA and nitrilotriacetate (NTA), may help immobilizing radionuclides and heavy metals in the environment. The EDTA- and NTA-degrading bacterium BNC1 uses EDTA monooxygenase to oxidize NTA to iminodiacetate (IDA) and EDTA to ethylenediaminediacetate (EDDA). IDA- and EDDA-degrading enzymes have not been purified and characterized to date. In this report, an IDA oxidase was purified to apparent homogeneity from strain BNC1 by using a combination of eight purification steps. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a single protein band of 40 kDa, and by using size exclusion chromatography, we estimated the native enzyme to be a homodimer. Flavin adenine dinucleotide was determined as its prosthetic group. The purified enzyme oxidized IDA to glycine and glyoxylate with the consumption of O2. The temperature and pH optima for IDA oxidation were 35 degrees C and 8, respectively. The apparent Km for IDA was 4.0 mM with a kcat of 5.3 s(-1). When the N-terminal amino acid sequence was determined, it matched exactly with that encoded by a previously sequenced hypothetical oxidase gene of BNC1. The gene was expressed in Escherichia coli, and the gene product as a C-terminal fusion with a His tag was purified by a one-step nickel affinity chromatography. The purified fusion protein had essentially the same enzymatic activity and properties as the native IDA oxidase. IDA oxidase also oxidized EDDA to ethylenediamine and glyoxylate. Thus, IDA oxidase is likely the second enzyme in both NTA and EDTA degradation pathways in strain BNC1.

Randomized, double-blind, multicenter trial comparing clinafloxacin with imipenem as empirical monotherapy for febrile granulocytopenic patients.

In a double-blind, multicenter trial, 541 febrile granulocytopenic patients were randomized to receive either intravenous (iv) clinafloxacin (200 mg every 12 h) or i.v. imipenem (500 mg every 6 h) as empirical monotherapy. More baseline pathogens were susceptible to clinafloxacin (259 [99%] of 262 organisms) than to imipenem (253 [95%] of 265; P=.03). Initial favorable clinical response rates for clinafloxacin (88 [32%] of 272 patients) and imipenem (89 [33%] of 269) were similar. After addition of other antimicrobial agents, overall response rates were 259 (95%) of 272 for clinafloxacin and 251 (93%) of 269 for imipenem. During the study, only 13 clinafloxacin (5%) and 18 imipenem (7%) recipients died. Both drugs were generally well tolerated. Drug-related skin rash occurred more often with clinafloxacin (11% vs. 6%; P=.07), whereas nausea (2% vs. 5%; P=.16), Clostridium-difficile-associated diarrhea (3% vs. 8%; P=.02), and seizures (0% vs. 2%; P=.06) occurred more often with imipenem. These results suggest that clinafloxacin and imipenem have similar efficacy as empirical monotherapy in febrile granulocytopenic patients.

HIV postexposure prophylaxis for children and adolescents.

HIV postexposure prophylaxis (PEP) is now a well-established part of the management of health care workers after occupational exposures to HIV. Use of PEP for adults exposed to HIV after sexual contact or injection drug use in nonoccupational settings remains controversial with limited data available. There is even less information available concerning HIV PEP for children and adolescents after accidental needlestick injuries or sexual assault. The objective was to describe the current practice of and associated problems with HIV PEP for children and adolescents at an urban academic pediatric emergency department. A retrospective review of all children and adolescents offered HIV PEP between June 1997-June 1998 was conducted. Ten pediatric and adolescent patients were offered HIV PEP, six patients after sexual assault, four patients after needle stick injuries. There were two small children 2 and 3 years of age and eight adolescents. Of these 10 patients, eight were started on HIV PEP. The regimens used for PEP varied; zidovudine, lamivudine, and indinavir were prescribed for in seven patients and zidovudine, lamivudine, and nelfinavir for one other. All 10 patients were HIV negative by serology at baseline testing and all available for follow-up testing (5 of 10) remained HIV negative at 4 to 28 weeks. Only two patients completed the full course of 4 weeks of antiretroviral therapy. Financial concerns, side effects, additional psychiatric and substance abuse issues as well as the degree of parental involvement influenced whether PEP and clinical follow-up was completed. HIV PEP in the nonoccupational setting for children and adolescents presents a medical and management challenge, and requires a coordinated effort at the initial presentation to the health care system and at follow-up. The difficulties encountered in the patients in our series need to be considered before initiating prophylaxis. A provisional management approach to HIV PEP in children and adolescents is proposed.

Comparison of higher-dose intradermal hepatitis B vaccination to standard intramuscular vaccination of healthcare workers.

OBJECTIVE: To compare the immunogenicity of hepatitis B vaccine administered via intradermal (ID) versus intramuscular (IM) route. METHODS: Subjects chose either to specify the route of immunization or to undergo random allocation to vaccination by the ID (0.15 mL) or the IM (1.0 mL) route. Yeast-derived recombinant hepatitis B vaccine was given at 0, 30, and 180 days. Hepatitis B surface antibody (HBsAb) and hepatitis B core antibody (HBcAb) were measured by microparticle enzyme immunoassay. RESULTS: 763 subjects were enrolled. Baseline screening identified 65 subjects (8%) who were positive for HBsAb or HBcAb. Vaccination was completed by 590 (85%) of 698 enrollees (370 ID, 220 IM). Seroconversion rates (geometric mean titers [GMT]>0 IU/mL HBsAb) for those vaccinated ID were 99% and 96% for screening at 9 months and 1 year post-vaccination, respectively; subjects vaccinated intramuscularly had similar rates of 95% and 96%. Seropositivity rates (GMT > or = 10 IU/mL HBsAb) showed a similar pattern, with 95%, 92%, and 73% at 9 months and 1 and 2 years, respectively, for those vaccinated ID, and 94%, 93%, and 81% for those having IM vaccination. GMT for HBsAb was significantly higher for individuals vaccinated IM than for those vaccinated ID (P<.0001). The GMT ratio for the IM and ID routes decreased over time, being 9.3 at 9 months, 7.8 at 1 year, and 5.9 at 2 years. An unanticipated side effect of intradermal vaccination was skin discoloration at injection sites, which persisted for at least 2 years postvaccination. Two thirds (112/166) of respondents reported that they would have selected the ID route despite the discoloration. CONCLUSIONS: Higher-dose ID vaccination (3 vs 1 microg per injection) uses one sixth of the dose required for standard IM vaccination. It is a cost-effective way to vaccinate populations against hepatitis B virus, but the long-term efficacy of the ID route must still be investigated.

"I knew we would win": hindsight bias for favorable and unfavorable team decision outcomes.

This study examined hindsight bias for team decisions in a competitive setting in which groups attempted to outperform each other. It was anticipated that, because of self-serving mechanisms, individuals would show hindsight bias only when decision outcomes allowed them to take credit for their own team's success or to downgrade another team for being unsuccessful. MBA students playing a market simulation game made hindsight estimates regarding the likelihood that either their own or another team would perform well. Consistent with a self-serving interpretation, when decision outcomes were favorable individuals evaluating their own team, but not those evaluating another, showed hindsight bias. When outcomes were unfavorable individuals evaluating their own team did not show hindsight bias, but those evaluating another team did. Discussion focuses on implications of hindsight bias in team decision-making settings.

Evidence for a chemiosmotic model of dehalorespiration in Desulfomonile tiedjei DCB-1.

Desulfomonile tiedjei DCB-1, a sulfate-reducing bacterium, conserves energy for growth from reductive dehalogenation of 3-chlorobenzoate by an uncharacterized chemiosmotic process. Respiratory electron transport components were examined in D. tiedjei cells grown under conditions for reductive dehalogenation, pyruvate fermentation, and sulfate reduction. Reductive dehalogenation was inhibited by the respiratory quinone inhibitor 2-heptyl-4-hydroxyquinoline N-oxide, suggesting that a respiratory quinoid is a component of the electron transport chain coupled to reductive dehalogenation. Moreover, reductive dehalogenation activity was dependent on 1, 4-naphthoquinone, a possible precursor for a respiratory quinoid. However, no ubiquinone or menaquinone could be extracted from D. tiedjei. Rather, a UV-absorbing quinoid which is different from common respiratory quinones in chemical structure according to mass spectrometric and UV absorption spectroscopic analyses was extracted. ATP sulfurylase, adenosine phosphosulfate reductase, and desulfoviridin sulfite reductase, enzymes involved in sulfate reduction, were constitutively expressed in the cytoplasm of D. tiedjei cells grown under all three metabolic conditions. A periplasmic hydrogenase was detected in cells grown under reductive-dehalogenating and pyruvate-fermenting conditions. A membrane-bound, periplasm-oriented formate dehydrogenase was detected only in cells grown with formate as electron donor, while a cytoplasmic formate dehydrogenase was detected in cells grown under reductive-dehalogenating and pyruvate-fermenting conditions. Results from dehalogenation assays with D. tiedjei whole-cell suspensions and cell extracts suggest that the membrane-bound reductive dehalogenase is cytoplasm oriented. The data clearly demonstrate an enzyme topology in D. tiedjei which produces protons directly in the periplasm, generating a proton motive force by a scalar mechanism.