The CcmH protein of Escherichia coli is encoded by the last gene of the ccm gene cluster required for cytochrome c maturation. A mutant in which the entire ccmH gene was deleted failed to synthesize ...both indigenous and foreign c-type cytochromes. However, deletion of the C-terminal hydrophilic domain homologous to CycH of other gram-negative bacteria affected neither the biogenesis of indigenous c-type cytochromes nor that of the Bradyrhizobium japonicum cytochrome c550. This confirmed that only the N-terminal domain containing a conserved CXXC motif is required in E. coli. PhoA fusion analysis showed that this domain is periplasmic. Site-directed mutagenesis of the cysteines of the CXXC motif revealed that both cysteines are required for cytochrome c maturation during aerobic growth, whereas only the second cysteine is required for cytochrome c maturation during anaerobic growth. The deficiency of the point mutants was complemented when 2-mercapto-ethanesulfonic acid was added to growing cells; other thiol compounds did not stimulate cytochrome c formation in these strains. We propose a model for the reaction sequence in which CcmH keeps the heme binding site of apocytochrome c in a reduced form for subsequent heme ligation.
We are attempting to resolve some of the problems encountered in measuring 8-hydroxy-2′-deoxyguanosine (8-oxodG) in human cellular DNA as a marker of oxidative stress. Samples of authentic 8-oxodG ...were distributed, and participating laboratories undertook to analyse this material within a specified period. Most HPLC procedures gave values for 8-oxodG within ±40% of the target, as did two of four GC-MS procedures, and both LC-MS-MS methods. Calf thymus DNA samples containing increasing amounts of 8-oxodG were also distributed for analysis. Fewer than half the procedures tested were able to detect the dose response; those that were successful tended to be procedures with low coefficients of variation. For the analysis of 8-oxodG in human cells, where it is likely to be present at much lower concentrations than in the calf thymus DNA, it is crucial to reduce analytical variation to a minimum; a coefficient of variation of less than 10% should be the aim, to give reasonable precision. HPLC with amperometric electrochemical detection is not recommended, as it is less sensitive than coulometric detection. Immunological detection, 32P-postlabelling and LC-MS-MS are alternative approaches to measurement of 8-oxodG in DNA that, on the grounds of precision and detection of dose response, cannot at present be recommended.
To outline the principles that direct the Veterans Affairs (VA) Quality Enhancement Research Initiative (QUERI) dedicated to diabetes quality improvement (QUERI-DM).
We discuss the VA initiatives ...aimed at improving diabetes care for veterans as well as general issues that should be considered in quality improvement initiatives. We specifically describe some of the epidemiological, statistical, and organizational issues that have guided our quality improvement (QI) programs.
The five principles that have guided the QUERI-DM process are: 1) treating clinical guidelines and goals distinct from quality standards and quality improvement priorities; 2) targeting high-risk patients and high-impact quality issues; 3) profiling processes over outcomes; 4) targeting processes that will improve patient outcomes; and 5) paying attention to the loci of practice variation.
The authors recommend that all five principles be considered when moving from practice guidelines to performance measures and QI initiatives. Targeting high-priority problems and high-risk groups can greatly improve the effectiveness and efficiency of QI interventions.
SuperCDMS is an experiment designed to directly detect weakly interacting massive particles (WIMPs), a favored candidate for dark matter ubiquitous in the Universe. In this Letter, we present ...WIMP-search results using a calorimetric technique we call CDMSlite, which relies on voltage-assisted Luke-Neganov amplification of the ionization energy deposited by particle interactions. The data were collected with a single 0.6 kg germanium detector running for ten live days at the Soudan Underground Laboratory. A low energy threshold of 170 eVee (electron equivalent) was obtained, which allows us to constrain new WIMP-nucleon spin-independent parameter space for WIMP masses below 6 GeV/c2.
Patient safety is a healthcare priority worldwide, with most hospitals engaging in activities to improve care quality, safety and outcomes. Despite these efforts, we have limited understanding of why ...quality improvement efforts are successful in some hospitals and not others. Using data collected as part of a multi-center study, we closely examined quality improvement efforts and the implementation of recommended practices to prevent central line-associated bloodstream infections (CLABSI) in U.S. hospitals. We compare and contrast the experiences among hospitals to better understand ‘how’ and ‘why’ certain hospitals were more successful with practice implementation when taking into consideration specific aspects of the organizational context. This study reveals that among a number of hospitals that focused on implementing practices to prevent CLABSI, the experience and outcomes varied considerably despite using similar implementation strategies. Moreover, our findings provide important insights about how and why different quality improvement strategies might perform across organizations with differing contextual characteristics.
What is an error? Hofer, T P; Kerr, E A; Hayward, R A
Effective clinical practice,
2000 Nov-Dec, Letnik:
3, Številka:
6
Journal Article
Recenzirano
Launched by the Institute of Medicine's report, "To Err is Human," the reduction of medical errors has become a top agenda item for virtually every part of the U.S. health care system.
To identify ...existing definitions of error, to determine the major issues in measuring errors, and to present recommendations for how best to proceed.
Medical literature on errors as well as the sociology and industrial psychology literature cited therein.
We have four principal observations. First, errors have been defined in terms of failed processes without any link to subsequent harm. Second, only a few studies have actually measured errors, and these have not described the reliability of the measurement. Third, no studies directly examine the relationship between errors and adverse events. Fourth, the value of pursuing latent system errors (a concept pertaining to small, often trivial structure and process problems that interact in complex ways to produce catastrophe) using case studies or root cause analysis has not been demonstrated in either the medical or nonmedical literature.
Medical error should be defined in terms of failed processes that are clearly linked to adverse outcomes. Efforts to reduce errors should be proportional to their impact on outcomes (preventable morbidity, mortality, and patient satisfaction) and the cost of preventing them. The error and the quality movements are analogous and require the same rigorous epidemiologic approach to establish which relationships are causal.
This study compared physician use in Ontario and the midwestern and northeastern United States for persons of different socioeconomic status and health status. The distribution of health problems ...associated with the most recent physician visit also was compared.
The design of the study was cross sectional; data derived from the 1990 Ontario Health Survey and the 1990 US National Health Interview Survey were used in analyses.
Overall, persons in Ontario averaged 19% more visits than US residents, but differences varied markedly across income and health status. At each level of health status, low- income Canadians had 25% to 33% more visits than their US counterparts. However, among higher income persons, those in excellent or very good health had 22% more visits than Americans, while those in good, fair, or poor health had 10% fewer visits than Americans. Higher visit rates in Ontario were not associated with a greater prevalence of low- priority visits.
Under the Canadian single- payer system, medical care in Ontario has been redistributed to low-income persons and the elderly. Compared with the United States, there has been a lower intensity of medical care for the sick higher income population.
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