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R S Hayward

Publications and source records attributed to R S Hayward.

At least 37 records · Page 2Linked to original sources
PubMed1993

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).

Bacterial Proteins↗
PubMed1993

More informative abstracts of articles describing clinical practice guidelines.

UNLABELLED: Recommendations are proposed for preparing more informative abstracts of articles describing clinical practice guidelines. Information about the development and content of guidelines should be summarized with the following structure. OBJECTIVE: a succinct statement of the objective of the guideline, including the targeted health problem, the targeted patients and providers, and the main reason for developing recommendations concerning this problem for this population. OPTIONS: principal practice options that were considered in formulating the guideline. OUTCOMES: significant health and economic outcomes identified as potential consequences of the practice options. EVIDENCE: Methods used to gather, select, and synthesize evidence, and the date of the most recent evidence obtained. VALUES: persons and methods used to assign values (relative importance) to potential outcomes of alternative practice options. BENEFITS, HARMS, AND COSTS: the type and magnitude of the main benefits, harms, and costs that are expected to result from guideline implementation. RECOMMENDATIONS: a brief and specific list of key recommendations. VALIDATION: the results of any external review, comparison with guidelines developed by other groups, or clinical testing of guideline use. SPONSORS: key persons or groups that developed, funded, or endorsed the guideline. Abstracts adhering to these recommendations could enhance readers' ability to appraise the applicability, importance, and validity of guidelines for specific providers, patients, and settings. More informative abstracts could also promote the use of more explicit methods of guideline development, more consistent reporting of guideline documents, and the more appropriate use of guidelines by clinicians.

Abstracting and Indexing↗
PubMed1992

Hypersymmetry in a transcriptional terminator of Escherichia coli confers increased efficiency as well as bidirectionality.

Rho-independent transcriptional terminators in Escherichia coli usually consist of a GC-rich region encoding a sequence which allows the nascent transcript to form a stem-loop structure, and thereby apparently causes the RNA polymerase to pause; followed by an A-rich region on the DNA template strand, whose weak pairing to the consequently U-rich 3'-tail of the transcript is believed to aid release of the RNA. Quite commonly there is additional symmetry encoding, in the RNA, an A-rich sequence complementary to the 'tail', just upstream of the GC-rich motif. It has been pointed out by others that this should allow the termination of transcription in both directions. We hypothesized that it might also increase the efficiency of termination, for example by competing with the template DNA strand so as to help 'unzip' the 3'-end of the RNA from its complementary DNA. We have tested this hypothesis by deletion analysis of the hypersymmetric alpha-operon terminator, tL17. The results show that efficiency as well as bidirectionality is indeed adversely affected by deletion of the upstream A-rich sequence.

Base Sequence↗
PubMed1992

Can patients use an automated questionnaire to define their current health status?

Patient management decisions rarely incorporate standardized health status assessments, since accurate and reliable measures are difficult and expensive to obtain. In prior research with various methods for obtaining health data from patients, it was found that physicians' acceptance of a method was improved if it provided an individualized printout. It was also determined that patients will readily complete a health status questionnaire on a computer when the computer does not look like a computer. Patients' acceptance was greatest when they were presented with a single line of large, pressure-sensitive buttons with which they could respond to questions about their health histories. Using such an instrument, the HealthQuiz, the current study found the same discrepancy rate (3%) between patients' responses to health questions presented on HealthQuiz and during interview as between their responses to questions asked during two separate interviews. Further, to ascertain health status, rules determined by an expert panel were applied to patients' responses to health questions presented on the HealthQuiz screen. It was found that the numerical health status derived from answers to the automated presentation of questions was similar to numerical health status derived by a physician after a patient-physician interview.

Aged↗
PubMed1991

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.

Cloning, Molecular↗
PubMed1991

A phenomenology of scut.

OBJECTIVE: To identify, describe, and quantify the night-call duties that residents in internal medicine call "scutwork" and to compare faculty and residents' perceptions of scutwork. DESIGN: Prospective, cross-sectional study. SETTING: General internal medicine training program at a university-affiliated tertiary care hospital. PARTICIPANTS: Forty-eight residents who spent 3 months or more on an internal medicine teaching unit during the previous year and 41 faculty members who spent 2 months or more on one of these units. INTERVENTIONS: Postcall surveys and night-call diaries were used to analyze residents' activities, to derive a definition of scutwork, and to estimate its prevalence. Residents and faculty then completed a detailed questionnaire that included ratings of the educational value, "scut content," and residents' responsibility for 20 specific tasks. MAIN RESULTS: Eighty-three percent of residents found scutwork and education to be mutually exclusive for the 20 tasks, although 20% indicated that scutwork was an appropriate task for residents. Residents' ratings of tasks as scut varied according to the context of the task. For example, obtaining routine consent from someone else's patient was considered scutwork by 98% of residents, whereas obtaining such consent from the residents's own patient was rated as scutwork by only 52% (P less than 0.01). Similarly, performing intravenous cannulation at the request of ward staff was rated as scut by 94% of residents, whereas performing cannulation at another resident's request was rated as scut by 56% (P less than 0.01). Night-time admission of a patient for an elective procedure was rated as scut by 75% of residents, whereas admission of such a patient after discussion with a faculty member was labeled scut by only 44% (P less than 0.01). Faculty ratings of such admissions did not show the same variation (24% for both). Faculty were more likely than residents to assess tasks as educational (50% compared with 26%, P less than 0.01) but were less likely to consider tasks as scutwork (47% compared with 62%, P = 0.12) or as work that should be done by nonresidents (35% compared with 46%, P greater than 0.2). CONCLUSIONS: Our results suggest that the characteristics of scutwork can be identified, that the perception of scut varies between faculty and residents, and that the context of a task often determines whether residents perceive it as scut.

Alberta↗
PubMed1991

Preventive care guidelines: 1991. American College of Physicians. Canadian Task Force on the Periodic Health Examination. United States Preventive Services Task Force.

Clinicians increasingly are urged to integrate preventive services into their clinical practices. To facilitate this process, several groups have developed practice guidelines for preventing disease in asymptomatic patients. In this paper, we compare and contrast preventive guidelines from the American College of Physicians (ACP), the Canadian Task Force on the Periodic Health Examination (CTF), the United States Preventive Services Task Force (USPSTF), and other well-known authorities. We chose these groups because they based their recommendations on explicit methods that include critical appraisal of the pertinent literature. Recommendations from these authorities usually are consistent with each other. Moreover, the ACP, CTF, and USPSTF all favor a shift away from the relatively simple classification of patients by age and sex for general preventive interventions to the more complex stratification of patients by additional risk factors and the formulation of a selective prevention strategy that is specific to each risk profile. Some guidelines, particularly the criteria used to define patients who are at increased risk for preventable disease and who should have more intensive surveillance, are difficult to interpret. Further research is needed to address some areas of disagreement and ambiguity. In addition, new tools must be developed to help physicians apply preventive guidelines, particularly those that require noting many patient-specific characteristics.

Canada↗
PubMed1990

Relapsing Clostridium difficile colitis and Reiter's syndrome.

We describe a patient with recurrent Clostridium difficile-associated colitis who suffered severe arthritis and urethritis with each of three episodes of diarrhea. Although immune complex formation was demonstrated in synovial fluid, neutralizing antibodies to C. difficile cytotoxin A and B were not found in either serum or synovial fluid. Cholestyramine did not prevent a third episode of colitis which followed the use of amikacin. This patient was HLA-B27 positive; she developed sacroiliitis, tenosynovitis, oligoarthritis, culture negative urethritis, and cervicitis. With the successful treatment of each episode of diarrhea, these additional symptoms resolved. The close temporal correlation between recurrences of C. difficile-associated colitis and these other symptoms strengthens evidence from other reports which suggests that colonic infections with C. difficile may precipitate the Reiter's syndrome. Evidence from this case does not support the contention that antibodies to C. difficile toxins are implicated in producing joint inflammation.

Antibodies, Bacterial↗
PubMed1988

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.

3-Iodobenzylguanidine↗
PubMed1987

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.

Base Sequence↗
PubMed1987

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.

DNA-Directed RNA Polymerases↗
PubMed1986

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.

DNA-Directed RNA Polymerases↗
PubMed1985

Transcription termination regions of coliphage T7 DNA: the effects of nusA1.

We report the effects in vivo of four segments of coliphage T7 DNA upon expression, from an upstream promoter, of galK in plasmids of the pKO family. Three of the segments carry the known major or putative distal terminators of host-dependent T7 early transcription. The fourth carries a novel terminator and maps in the late region of T7. We report the efficiencies of termination in these regions: evidence, based on studies with the E. coli nusA1 mutation, for an involvement of the transcription factor NusA in events at the major early and novel terminators: and the nature of the latter transcription signal.

Base Sequence↗
PubMed1985

Student-directed teaching of medical ethics at a Canadian medical school.

The medical faculty at Queen's University, Kingston, Ontario, Canada, in 1982 decided to omit the formal teaching of medical ethics from its curriculum. This decision led both students and faculty members to review the role of ethics in medical education. The outcome was the establishment of a minicourse of four three-hour sessions devoted to the examination and debate of selected ethical issues. The course was directed by students, who chose four general topics for discussion and three subtopics to be the focus in each session. They organized debates between faculty and community members from the fields of medicine, law, philosophy, and theology to be the core of instruction. The course resulted in a high level of satisfaction among the students, who felt that the issues chosen had been appropriately explored. The course, therefore, was continued in the same form by the following medical class.

Canada↗
PubMed1984

Nucleotide sequence of the rpoA-rplQ DNA of Escherichia coli: a second regulatory binding site for protein S4?

The "alpha-operon" of E.coli is a unit of regulation comprising the following known genes, mostly encoding ribosomal proteins (in order of transcription, and with their products named in brackets): rpsM (S13), rpsK (S11), rpsD (S4), rpoA (alpha-subunit of RNA polymerase), rplQ (L17). There is evidence that S4 tightly regulates all of these genes, except rpoA, by repressing translation of the polycistronic mRNA. Binding of S4 to the S13 start-site is thought to regulate the first three genes. We have extended the 'rpsD-rpoA' sequences previously determined by others, to include all of rpoA and rplQ. The rpoA-rplQ intercistronic region shows strong primary, and potential secondary structural homologies with the S4-binding sites on 16S rRNA and S13 mRNA. We suggest that S4 represses L17 translation directly.

Bacterial Proteins↗
PubMed1984

The wild-type nucleotide sequence of the rpoBC-attenuator region of Escherichia coli DNA and its implications for the nature of the rifd18 mutation.

To investigate the possibility that the unusual dominant rifampicin-resistance characteristic of the rifd18 allele of E. coli rpoB is due to a secondary, regulatory mutation, we have determined the nucleotide sequence of a 1.1 Kbp wild-type DNA fragment, including the transcriptional attenuator and translational start-site of rpoB. We have also re-investigated the previously published sequences of this region in lambda rifd18 and lambda rifd47 DNA. Our results indicate that all three sequences are identical, and reveal some errors in the published data. We discuss the basis of dominance of rifd18.

Alleles↗