Utilization of computerized clinical decision support for potentially inappropriate medications.

Background: Electronic medical record (EMR) alerts may inform point of care decisions, including the decision to prescribe potentially inappropriate medications (PIM) identified in the Beers criteria. EMR alerts may not be considered relevant or informative in the clinician context, leading to a phenomenon colloquially known as "alert fatigue." Objective: To assess the frequency of clinical interaction with EMR alerts and associated deprescribing behaviors in ambulatory settings. Methods: This is a retrospective observational study in two ambulatory clinics (the Kaye Edmonton Clinic Senior's Clinic and the Lynnwood Family Practice Clinic) in Edmonton over an observational period of 30 months. Statistical analysis was done using descriptive statistics, chi-square and regression analysis. Results: The reminder performance for interactions with the alert was 17.2% across the two clinics. The Number Needed to Remind (NNR) or mean number of alerts shown on clinician screens prior to a single interaction of any kind with the alert was 5.8. When actions were defined as a deprescribing (ie discontinuation) event that was related to the alert and that particular interaction in the EMR, the reminder performance was 1.2%, for an NNR of 82.8. Conclusion: The configuration of alerts in the EMR was not associated with a clinically detectable increase in the uptake of the Beers criteria for high hazard medications.

The practice guidelines development cycle: a conceptual tool for practice guidelines development and implementation.

PURPOSE: To develop a conceptual tool for the systematic development of cancer treatment practice guidelines. MATERIALS AND METHODS: The guidelines development tool, the Practice Guidelines Development Cycle, was derived from observing an evidence-based practice guidelines initiative at a comprehensive cancer center in Ontario, Canada, and from a literature review that uncovered barriers to guidelines development and implementation. Based on the literature findings and direct observations of how clinicians struggled with evidence-based guidelines development, we evolved a framework to incorporate clinical and administrative factors (eg, costs) into evidence-based guidelines. Use of the Practice Guidelines Development Cycle is illustrated with a clinical example (the use of adjuvant systemic therapy in good-risk, node-negative premenopausal breast cancer patients). RESULTS: The result is the Practice Guidelines Development Cycle, which consists of eight sequential steps, from topic selection to policy formulation. Independent validation of guidelines is included. The cycle products are the evidence-based recommendation, the practice guideline, and the practice policy. The main features of the cycle are emphasis on scientific evidence, acknowledgment of the roles of clinical experience and nonclinical (administrative) factors through consensus, and explicit separation of clinical and cost considerations in guidelines development. Twenty guidelines are currently in development. CONCLUSION: Attention to the barriers of guidelines development and the sociocultural nature of clinical practice, and respect for clinical experience, can lead to improved strategies for guidelines development.

Functional specialization within the alpha-subunit of Escherichia coli RNA polymerase.

The RNA polymerase core enzyme of Escherichia coli has the subunit composition alpha 2 beta beta', and when combined with one of several alternative sigma-subunits (initiation-specificity) produces holoenzyme capable of all the steps of transcription. Dimerization of the alpha-subunit and association with the beta-subunit trigger assembly of the core enzyme. Analyses of a set of deletion derivatives of rpoA (which encodes alpha) have indicated that as many as 94 carboxy-terminal amino acids (but not 153) can be removed without preventing assembly of core-like complexes in vitro. Detailed analyses of these deletion mutants have now been performed in vivo. alpha-Polypeptides truncated from the carboxy terminus to amino acid residues 235, 256 or 296 are assembled not merely into core, but also into holoenzyme-like complexes in vivo, and at least in the first two cases both of the two alpha-subunits can be replaced by the truncated versions. Nevertheless, none can complement rpoAts alleles for growth at 42 degrees C. We conclude that the domain(s) of alpha essential for the assembly of RNA polymerase (at least the major holoenzyme species) are confined to the amino-terminal 235 amino acids, while some other essential function(s) require residues close to the carboxy terminus.

A hybrid sigma subunit directs RNA polymerase to a hybrid promoter in Escherichia coli.

Most of the sigma (transcriptional initiation specificity) subunits of RNA polymerase, from a wide range of eubacteria, show strong elements of amino acid sequence similarity. There is evidence that two of the "conserved" regions, 2.4 and 4.2, are involved in recognition of the consensus DNA sequences centred near -10 and -35, respectively, which define promoter sites for the initiation of transcription. Since all the alternative sigma subunits of the above type function by binding to a common core polymerase enzyme in a given bacterium, it can be predicted that a hybrid sigma might be functional, and if so should permit RNA polymerase to initiate only at a correspondingly hybrid promoter. To test these predictions, a hybrid gene encoding the amino-proximal 529 amino acids of the major Escherichia coli sigma protein, sigma 70 (including region 2.4) followed by the last 82 amino acids of the heat-shock sigma protein, sigma 32 (including region 4.2) was constructed and fused to Plac on a plasmid. Major-consensus, heat-shock and hybrid promoters were fused to a chloramphenicol acetyl transferase (CAT) reporter gene on a compatible plasmid. CAT assays showed that, as predicted, a promoter with a "heat-shock" -35 consensus and a "major" -10 consensus sequence (PHM) required Plac-dependent production of the hybrid sigma (sigma 70-32) for activity in vivo. PHM then became a strong promoter. The hybrid sigma gene has potential advantages over its parents for structure-function studies.

The minus 35-recognition region of Escherichia coli sigma 70 is inessential for initiation of transcription at an "extended minus 10" promoter.

It is known that Escherichia coli promoters having the major minus 10 consensus sequence TATAAT, but lacking significant resemblance to consensus in the minus 35 region, allow transcriptional initiation in vivo and in vitro if they have an additional TGn motif immediately upstream of minus 10. To determine whether region 4.2 of sigma 70, whose normal role is sequence recognition at minus 35, is unnecessary for initiation of transcription at such "extended minus 10" promoters, we modified the sigma 70 gene so as to generate a carboxy-truncated polypeptide lacking the last 84 amino acids and therefore missing region 4.2. Our results show that both the intact and truncated sigma 70 allow purified RNA polymerase to initiate efficiently and specifically at an extended minus 10 promoter, whereas only the intact sigma 70 permits efficient initiation at normal promoters (defined by minus 35 and minus 10 hexamer sequences).

Aromatic amino acids in region 2.3 of Escherichia coli sigma 70 participate collectively in the formation of an RNA polymerase-promoter open complex.

Formation of an initiation-competent RNA polymerase-promoter complex involves DNA melting over a region of about 12 base-pairs, which includes the start site of transcription, thus enabling the template strand to base-pair with the initiating nucleoside triphosphates. By studying the effects of alanine substitutions, we have investigated the role of the aromatic amino residues in the Escherichia coli sigma(70) conserved region 2.3 in promoter strand separation. The resulting mutants were assessed for their activity in vivo in the context of a sigma(70)/sigma(32) hybrid sigma factor that could be targeted to a specific hybrid promoter in the cell. All substitutions lead to an at least twofold reduction in expression of the hybrid promoter-driven reporter gene. The in vitro assay of single substitutions indicated cold sensitivity similar to that previously observed with analogous substitutions in Bacillus subtilis sigma(A). Kinetic assays showed that these substitutions slowed the rate of open complex formation at 37 degrees C as well. RNA polymerase reconstituted with a sigma(70) containing multiple alanine substitutions readily binds to promoter DNA, but then proceeds slowly beyond the first intermediate complex on the pathway to formation of the transcription-competent complex. These data demonstrate that together the aromatic residues in region 2.3 of E. coli sigma(70) ensure that DNA strand separation proceeds efficiently, even if no individual residue may be essential for accomplishment of the process.

Role of the sigma 70 subunit of Escherichia coli RNA polymerase in transcription activation.

The role of the sigma 70 subunit of Escherichia coli RNA polymerase in transcription activation by positive transcription factors was investigated. For this purpose, we constructed a nested set of E. coli rpoD deletion mutants generating carboxy-terminally truncated sigma 70 subunits of RNA polymerase in a high-expression plasmid. The purified mutant sigma 70 subunits were reconstituted into holoenzymes and examined in vitro for their promoter selectivity. As expected, since the -35 recognition helix of sigma 70 was deleted in all cases, the mutant enzymes were unable to initiate at factor-independent promoters, except for the special case of perfect "extended minus 10" promoters, at which the need for -35 sequence recognition by RNA polymerase is replaced by recognition of additional base-pairs in the -10 region. However, two factor-dependent promoters, PhoB-dependent PpstS and cAMP receptor protein (CRP)-dependent P1gal, could be activated for transcription by different subsets of the mutant holoenzymes, although these promoters do not contain the perfect extended -10 sequences. These results establish that -35 DNA recognition by sigma 70 is not essential for these cases. Presumably it is replaced by protein-protein contacts between RNA polymerase and the activator, which in both cases is bound to the DNA in a position overlapping the -35 region. Further, the detailed results support the view that the contact and/or activation sites for these two factors may lie on the sigma 70 subunit, within a "contact site II", which extends at least from conserved region 3.2 to the upstream end of region 4.2. Moreover, as in the case of contact site I on the alpha subunit, it appears that contact site II contains various different subsites for interaction with specific class II activators, and that PhoB and CRP require distinct subsites.

Guidelines, practice policies, and parameters: the case for geriatrics.

OBJECTIVE: As the population ages, the care of older persons becomes more important. At the same time, practice guidelines that provide recommendations for appropriate care are being published in greater numbers. The purpose of this work is to determine the proportion of guidelines that contain specific information about older persons. DESIGN: Through a random sample of published guidelines listed in the AMA Directory of Practice Parameters, 1992 Edition, we determined the proportion of guidelines that contain specific age-related information. We also determined if, over time, there was a difference in the proportion of practice guidelines containing information about older persons. RESULTS: 45.9% (95% CI, range 33.4-58.4) of guidelines that could conceivably pertain to older persons contain no age information; 24.6% (95% CI, range 13.8-35.4) of guidelines contain information only about persons less than 65 years of age; 29.5% (95% CI, range 18.1-41.0) of guidelines contain specific information about older persons. Moreover, there were no secular trends in the proportion of guidelines pertaining to older persons. CONCLUSIONS: Only a minority of practice guidelines contain information about older persons. Possible causes and solutions to this shortfall are discussed.

Bridges between health care research evidence and clinical practice.

Research is producing increasing amounts of important new evidence for health care, but there is a large gap between what this evidence shows can be done and the care that most patients actually receive. An important reason for this gap is the extensive processing that evidence requires before application. This article discusses a three-step model for bridging research evidence to management of clinical problems: getting the evidence straight, formulating evidence-based clinical policies, and applying evidence-based clinical policies at the right place and time. This model is purposely broad in scope and provides a framework for coordinating efforts to support evidence-based medical care. The authors' purpose is to represent the roles of health informatics in the context of the roles of all the key players, including health care researchers and practitioners, health care organizations, and the public. Health informatics has already made important contributions to bridging evidence to practice, including improving evidence retrieval, evaluation, and synthesis; new evidence-based information products; and computerized aids for facilitating the use of these products during clinical decision making. However, much more innovation and coordination are needed. The authors call for health informaticians to pay balanced attention to 1) the quality of evidence embodied in information innovations, 2) the performance of technologies and systems that retrieve, prepare, disseminate, and apply evidence, and 3) the fit of information tools to the specific clinical circumstances in which evidence is to be applied. Effective interdisciplinary teams that include health services researchers and other evidence experts, clinical practitioners, informaticians, and health care managers are needed to achieve success. Informaticians can make increasingly important contributions to the transfer of health care research by joining such teams.

Future directions for clinical practice guidelines: needs, lead agencies and potential dissemination strategies identified by Australian general practitioners.

There has been an increasing interest in developing clinical practice guidelines for general practitioners as a means of improving health outcomes. We conducted a survey of a national random sample of Australian general practitioners in May 1995 to determine their needs, preferred formats and dissemination strategies and to identify potential lead agencies for guidelines development. Of 373 eligible general practitioners, 286 (77 per cent) returned completed questionnaires. At least 50 per cent of respondents considered guidelines in angina, psychotic illness, skin cancer and attention deficit disorder as 'extremely' or 'very' useful. However, three other topics identified as areas for future guidelines development in Better health outcomes for Australians were so rated by less than half of the general practitioners surveyed. The Australian Cancer Society and the Australian Medical Association outranked nine other organisations in terms of credibility in guidelines development. Innovative formats, including computerised medical records or text, were not highly rated, consistent with our finding that only 27 respondents (9 per cent) had Internet access. Strategies nominated as likely to increase the adoption of a guideline included a personal visit by a trained nurse, a lecture about its content or a Medicare rebate being available when a patient was managed in accordance with the guideline. Public health practitioners and nominated lead agencies are encouraged to respond to these findings and recognise potential strategies to enhance the effective dissemination of guidelines. Interventional studies are required to demonstrate and allow understanding of changes in clinical practice attributable to guidelines.

Patient-specific evidence-based care recommendations for diabetes mellitus: development and initial clinic experience with a computerized decision support system.

BACKGROUND: adherence with evidence-based recommendations for chronic disease management is often suboptimal. Providing patient-specific reminders at the time of clinical encounters has the potential to improve this situation. A necessary prerequisite for providing such reminders, however, is to have an efficient means of acquiring patient information that can be matched to an underlying knowledge base. The decision support system: we have developed a computer-based, self-administered questionnaire for diabetes care. The questionnaire assesses numerous diabetes-related topics. Patients complete the questionnaire using a touchscreen interface, and their responses are then matched to evidence-based guidelines so that patient-specific care suggestions can be provided for both the patients and their health care professionals. The guidelines are derived from a database of abstracts of studies of diabetes care that are screened for scientific merit and clinical relevance, supplemented by recommendations from diabetes organizations. EVALUATION: initial evaluation of the system included an assessment of the agreement of responses to the automated questionnaire with responses to similar questions administered during a structured, personal interview. Overall agreement was 92.5% and the majority of disagreements were minor. More recently, patients aged 18-69 years have been completing the automated questionnaire before appointments at a diabetes clinic. The average time required has been 10.9 min and a mean of 3.0 recommendations have been provided per patient. Patient and health care practitioner satisfaction with the questionnaire and the patient-specific feedback have been high. CONCLUSIONS: evidence-based patient-specific diabetes care recommendations can be provided using a self-administered computer-based questionnaire.

I-131 metaiodobenzylguanidine uptake in a parathyroid adenoma.

We describe a patient with multicentric small bowel carcinoids, severe hypertension, primary hyperparathyroidism, and multiple parathyroid adenomas. Intense uptake of I-131 metaiodobenzylguanidine (MIBG) occurred in a parathyroid adenoma. There was no biochemical evidence of catecholamine secretion by the tumor but elevated serum levels of parathyroid hormone were demonstrated. We suspect that occasional parathyroid adenomas, like other APUDomas, may give false positive results when MIBG imaging is used to search for pheochromocytomas. This observation supports the inclusion of the parathyroid chief cells in the amine precursor uptake and decarboxylation (APUD) cell system.

Direct evidence for autogenous regulation of the Escherichia coli genes rpoBC in vivo.

We have fused the rpoBC genes to the strong controllable promoter PL in phage lambda while deleting most of the intercistronic regulatory DNA and ribosomal protein genes upstream of rpoB. Induction of a lysogen carrying the recombinant prophage gave rise to a 2-3-fold oversynthesis of beta beta' in the cell whereas rpoBC-mRNA levels rose by at least 10-fold. Similar observations were made when these sequences were present in the prophage, indicating that the removal of DNA sequences up to 26 base pairs before rpoB does not affect post-transcriptional autogenous regulation of beta beta' synthesis. Overexpression of beta beta' also autogenously regulated the synthesis of the beta polypeptide from the chromosome in two strains carrying electrophoretic mobility mutations in rpoB. S1 nuclease mapping experiments indicated that this regulation was also post-transcriptional, and confirmed that phage beta-mRNA synthesis exceeded chromosomal beta-mRNA synthesis by 20-fold. The provision of excess beta alone in the cell caused autoregulation of chromosomal beta, but not beta' synthesis, indicating that beta and beta' are regulated independently.

Direct evidence for rifampicin-promoted readthrough of the partial terminator tL7 in the rpoBC operon of Escherichia coli.

The RNA polymerase subunits beta and beta' of Escherichia coli, encoded by the genes rpoB and rpoC, are co-transcribed with four 50 S ribosomal protein genes, rplKAJL. After treatment with the antibiotic rifampicin a partial uncoupling of rpoBC from rplKAJL transcription occurs. We have been investigating the role played in uncoupling by tL7, an 80% efficient terminator of transcription present in the 319 bp intercistronic space between rplL and rpoB, using S1 nuclease mapping of transcripts produced in vivo in normal (rpoBC haploid) strains. Our results show directly that rifampicin stimulates readthrough of tL7 on the chromosome by approximately twofold, an effect sufficient to explain the observed increase in beta beta' protein synthesis. We also provide preliminary evidence for the map position of PL7, and show that both this and P beta, two very weak promoters which might in principle be activated by rifampicin, are not in fact stimulated by the drug.

Transcriptional termination at a fully rho-independent site in Escherichia coli is prevented by uninterrupted translation of the nascent RNA.

We have examined the possibility that translation reading through a fully rho-independent transcriptional terminator in Escherichia coli might prevent termination, as already established for rho-dependent terminators. Plasmids were constructed with and without interposition of the rho-independent coliphage T7 'early' terminator between a promoter and galK. Our constructions ensured either that there was no upstream translation, or that translation (initiated at the galE ribosome binding site) stopped upstream of, or at the normal position (the T7 gene 1.3 stop codon) with respect to, the transcriptional terminator; or else downstream of both this stop codon and the terminator. Our galactokinase enzyme and mRNA measurements on strains harbouring these plasmids indicate that 'readthrough translation' eliminates transcriptional termination at the T7 site. This effect is suppressed if the rate of ribosome movement is reduced with fusidic acid.

New genes and promoters suggested by the DNA sequence near the end of the coliphage T7 early operon.

We have employed the dideoxynucleotide chain-terminating method to determine the nucleotide sequence of T7 DNA between the physical map positions 18.9% and 19.8%. The most striking features of this sequence are two perfect 21-basepair repeats, each of which appears to contain a promoter for late transcription. In each case the promoter sequence incorporates a putative translational terminator on its left (5'-side of the "sense" strand), and overlaps a potential ribosome-binding site on its right. The region probably lies immediately distal to the early operon, and may contain two short, hitherto unreported protein-coding sequences.

Cloning of DNA of the rpoBC operon from the chromosome of Escherichia coli K12.

We provide evidence that, in terms of transcriptional organisation, the rpoBC operon carried by lambdarifd 18 accurately represents the corresponding region of the E. coli K12 chromosome. A restriction fragment of E. coli K12 chromosomal DNA carrying the genes rpoBC (encoding the beta and beta' subunits of RNA polymerase) and rplL (coding for ribosomal proteins L7/L12) was cloned in a lambda vector, and the resulting phage tested for gene expression. In common with the corresponding fragment of lambdarifd 18 DNA, the chromosomal fragment has no strong promoter for rplL or rpoBC transcription. Another new phage was constructed by adding, to the restriction fragment carrying the rplL rpoBC structural genes from lambdarifd 18, a sequence from the E. coli K12 chromosome which includes a promoter for these genes. As in lambdarifd 18 itself, this promoter is shared with rplJ but not with rplKA. The properties of the latter phage also show that the dominant rifampicin-resistance characteristic of lambdarifd 18 results from more than one mutation.

Bacterial RNA polymerases: structural and functional relationships.

The essential role of DNA-dependent RNA polymerases in gene expression and the fact that the multimeric species are highly conserved throughout nature makes these enzymes a particular fascinating area of study. Here we shall review the conservation of structures and their relationship to function, especially in the multimeric eubacterial RNA polymerases, paying particular attention to the ß core subunit and to recent studies of σ-factors of both the σ (70) and σ (54) families. We shall conclude with a brief consideration of phage-encoded RNA polymerases and phage-mediated modification of the host enzyme, and of the evolution of RNA-synthesising enzymes.

Over-synthesis and instability of sigma protein in a merodiploid strain of Escherichia coli.

We have used two different methods to study the rates of RNA polymerase subunit synthesis in haploid Escherichia coli K12, and a KLF10 rPOB, C+ merodiploid derivative, when grown in glucose-minimal medium at 37 degrees C. Our results indicate that the haploid strain produces beta, beta', alpha and sigma in the molar ratios 1.01:0.99: less than or equal to 2.90:0.26; and that all these subunits are reasonably stable during subsequent growth. The merodiploid produces alpha at the same rate as the haploid, beta and beta' at a 42% higher rate, and sigma at twice the rate. Some 40% of the newly synthesised beta and beta' is degraded within one hour; the residuum is as stable as in the haploid. Alpha is stable throughout. By contrast, sigma is subject to a marked and continuous turnover in the merodiploid. These results are discussed in terms of gene dosage and regulatory effects.

Non-coordinate expression of the neighbouring genes rplL and rpoB,C of Escherichia coli.

The operon rpoB,C of Escherichia coli codes for the RNA polymerase subunits beta and beta'. rpoB procedes rpoC in the direction of transcription. The nearest characterised gene to rpoB on the chromosome is rplL, which codes for the ribosomal proteins L7/12. rplL appears to be transcribed in the same direction as rpoB,C, and it has been suggested that all three genes may lie in a single operon. The drug rifampicin induces increased production of beta and beta' in suitable strains of E. coli. We show here that alpha and sigma are also induced, whereas synthesis of L7/12 is not detectably affected.