REMAP Periop: a randomised, embedded, multifactorial adaptive platform trial protocol for perioperative medicine to determine the optimal enhanced recovery pathway components in complex abdominal surgery patients within a US healthcare system

INTRODUCTION

Implementation of enhanced recovery pathways (ERPs) has resulted in improved patient-centred outcomes and decreased costs. However, there is a lack of high-level evidence for many ERP elements. We have designed a randomised, embedded, multifactorial, adaptive platform perioperative medicine (REMAP Periop) trial to evaluate the effectiveness of several perioperative therapies for patients undergoing complex abdominal surgery as part of an ERP. This trial will begin with two domains: postoperative nausea/vomiting (PONV) prophylaxis and regional/neuraxial analgesia. Patients enrolled in the trial will be randomised to arms within both domains, with the possibility of adding additional domains in the future.

METHODS AND ANALYSIS

In the PONV domain, patients are randomised to optimal versus supraoptimal prophylactic regimens. In the regional/neuraxial domain, patients are randomised to one of five different single-injection techniques/combination of techniques. The primary study endpoint is hospital-free days at 30 days, with additional domain-specific secondary endpoints of PONV incidence and postoperative opioid consumption. The efficacy of an intervention arm within a given domain will be evaluated at regular interim analyses using Bayesian statistical analysis. At the beginning of the trial, participants will have an equal probability of being allocated to any given intervention within a domain (ie, simple 1:1 randomisation), with response adaptive randomisation guiding changes to allocation ratios after interim analyses when applicable based on prespecified statistical triggers. Triggers met at interim analysis may also result in intervention dropping.

ETHICS AND DISSEMINATION

The core protocol and domain-specific appendices were approved by the University of Pittsburgh Institutional Review Board. A waiver of informed consent was obtained for this trial. Trial results will be announced to the public and healthcare providers once prespecified statistical triggers of interest are reached as described in the core protocol, and the most favourable interventions will then be implemented as a standardised institutional protocol.

TRIAL REGISTRATION NUMBER

NCT04606264.

The lytB gene of Escherichia coli is essential and specifies a product needed for isoprenoid biosynthesis

LytB and GcpE, because they are codistributed with other pathway enzymes, have been predicted to catalyze unknown steps in the nonmevalonate pathway for isoprenoid biosynthesis. We constructed a conditional Escherichia coli lytB mutant and found that LytB is essential for survival and that depletion of LytB results in cell lysis, which is consistent with a role for this protein in isoprenoid biosynthesis. Alcohols which can be converted to pathway intermediates beyond the hypothesized LytB step(s) support limited growth of E. coli lytB mutants. An informatic analysis of protein structure suggested that GcpE is a globular protein of the TIM barrel class and that LytB is also a globular protein. Possible biochemical roles for LytB and GcpE are suggested.

A single-ring mitochondrial chaperonin (Hsp60-Hsp10) can substitute for GroEL-GroES in vivo

Chaperonins participate in the facilitated folding of a variety of proteins in vivo. To see whether the same spectrum of target proteins can be productively folded by the double-ring prokaryotic chaperonin GroEL-GroES and its single-ring human mitochondrial homolog, Hsp60-Hsp10, we expressed the latter in an Escherichia coli strain engineered so that the groE operon is under strict regulatory control. We found that expression of Hsp60-Hsp10 restores viability to cells that no longer express GroEL-GroES, formally demonstrating that Hsp60-Hsp10 can carry out all essential in vivo functions of GroEL-GroES.

Only the N-terminal domain of FtsK functions in cell division

Deletion of ftsK results in the inhibition of cell division, but this inhibition can be reversed by a plasmid carrying only the first approximately 17% of ftsK. The division block can be suppressed in most mutants by deletion of dacA, which codes for the D-alanine:D-alanine carboxypeptidase PBP5, or in all mutants by overexpression of ftsN. Overexpression of ftsK inhibits cell division and the formation of FtsZ rings. This division block is not due to the induction of either the SOS or the heat shock regulons.

Regulation of plasmid R1 replication: PcnB and RNase E expedite the decay of the antisense RNA, CopA

The replication frequency of plasmid R1 is controlled by an unstable antisense RNA, CopA, which, by binding to its complementary target, blocks translation of the replication rate-limiting protein RepA. Since the degree of inhibition is directly correlated with the intracellular concentration of CopA, factors affecting CopA turnover can also alter plasmid copy number. We show here that PcnB (PAPl-a poly(A)polymerase of Escherichia coli) is such a factor. Previous studies have shown that the copy number of ColE1 is decreased in pcnB mutant strains because the stability of the RNase E processed form of RNAI, the antisense RNA regulator of ColE1 replication, is increased. We find that, analogously, the twofold reduction in R1 copy number caused by a pcnB lesion is associated with a corresponding increase in the stability of the RNase E-generated 3' cleavage product of CopA. These results suggest that CopA decay is initiated by RNase E cleavage and that PcnB is involved in the subsequent rapid decay of the 3' CopA stem-loop segment. We also find that, as predicted, under conditions in which CopA synthesis is unaffected, pcnB mutation reduces RepA translation and increases CopA stability to the same extent.

Autoregulation of the Escherichia coli replication initiator protein, DnaA, is indirect

The expression of dnaA is autoregulated, in that transcription of the gene increases when DnaA is inactivated (and initiation of replication prevented) and decreases when DnaA is supplied in excess. However, the inactivation of DnaA does not necessarily lead to increased DnaA production, as dnaA(Ts; temperature sensitive) strains which are integratively suppressed by derivatives of the plasmid R1 do not show temperature-induced derepression. Several possible explanations for this unanticipated behaviour were considered and ruled out. We suggest here that the completion of a critical step in initiation may prevent dnaA derepression: although DnaA would be required to complete this step at oriC, DnaA(Ts) would be sufficient at the R1 origin. Autoregulation of dnaA has been attributed to the binding of DnaA at a consensus binding site in the dnaA promoter region. We show here, using reporter systems, that this DnaA-binding site is not required for the autoregulatory response. We find, further, that replacement of the chromosomal dnaA gene with one containing a mutated binding site causes no demonstrable phenotypic change: cells with the mutant gene show no disadvantage in competition with dnaA+ cells.

The coupling between ftsZ transcription and initiation of DNA replication is not mediated by the DnaA-boxes upstream of ftsZ or by DnaA

The DnaA protein of Escherichia coli is a multi-functional protein which, In addition to promoting initiation of replication, can regulate the initiation or termination of transcription of a variety of genes. It acts by binding to DNA at a defined sequence, termed a DnaA-box. Three candidate DnaA-boxes which occur within the essential cell-division genes, ftsQ and ftsA, have been hypothesized to mediate the response of the downstream ftsZ gene to intracellular levels of DnaA, and thus to couple the processes of initiation and cell division. We show here that, although transcription from promoters upstream of ftsZ is increased when initiation of chromosome replication is blocked by DnaA inactivation, this response is not mediated by the DnaA-boxes near these promoters, nor is it specific to DnaA. We show, furthermore, that mutational inactivation of the putative DnaA-binding sites in the fts region of the chromosome does not lead to impaired growth or reduced survival of cells.

The tail of a chaperonin: the C-terminal region of Escherichia coli GroEL protein

The active form of the HSP60 molecular chaperone of Escherichia coli, GroEL, is a pair of seven-membered rings. We have used site-directed mutagenesis to construct forms of the 547-amino-acid monomer truncated at the C-terminus. We show here that forms that are 520 amino acids long or longer are close to being fully functional. Removing one further amino acid, however, results in a protein, GroEL519, which retains little function. This truncated form is metabolically stable but is not recovered from the cell in particle form. When synthesized at high levels, it prevents the normal assembly of GroEL547 present in the same cell. When synthesized at low levels, it can be included, probably at low molar ratios, in particles formed by assembly-competent forms of GroEL. This can be seen as partial complementation of the temperature-sensitive mutant groEL44. We conclude that amino acid 520 is crucial for particle assembly. GroEL516 has in vivo properties similar to those of GroEL516 has in vivo properties similar to those of GroEL519, but the still shorter form, GroEL504, appears to be inactive.

PcnB is required for the rapid degradation of RNAI, the antisense RNA that controls the copy number of ColE1-related plasmids

The replication of ColE1-related plasmids is controlled by an unstable antisense RNA, RNAI, which can interfere with the successful processing of the RNAII primer of replication. We show here that a host protein, PcnB, supports replication by promoting the decay of RNAI. In bacterial strains deleted for PcnB a stable, active form of RNAI, RNAI*, which appears to be identical to the product of 5'-end processing by RNAase E, accumulates. This leads to a reduction in plasmid copy number. We show, using a GST-PcnB fusion protein, that PcnB does not interfere with RNAI/RNAII binding in vitro. The fusion protein, like PcnB, has polyadenylating activity and is able to polyadenylate RNAI (and also another antisense RNA, CopA) in vitro.

Psychosocial performance of family physicians

This study surveyed 30 residency-trained family physicians all currently in practice to determine the nature of their psychosocial interactions with patients. In general, respondents were satisfied with the quality of their psychosocial training in residency and generally evaluated their competency on a range of psychosocial skills as adequate to excellent. Physician psychosocial competency was most strongly related to residency, but not to postresidency, behavioral science training or to psychosocial screening practices. Frequency of performing psychosocial behaviors was also related to behavioral science training, as well as to length of time in practice. Neither frequency nor self-perceived competency related to physician age, gender, patient volume, or type of practice.

The pcnB gene of Escherichia coli, which is required for ColE1 copy number maintenance, is dispensable

The pcnB gene product of Escherchia coli is required for copy number maintenance of plasmids related to ColE1 and also for that of the IncFII plasmid R1. Because PcnB is similar to the tRNA-binding protein tRNA nucleotidyltransferase, we have suggested that the protein would be required only for processes in which an RNA is a prominent regulatory component. This appears to be so; strains deleted for pcnB, although defective in ColE1 and R1 plasmid maintenance, maintain the iteron-regulated plasmids F and P1 normally. We also find that strains deleted for pcnB grow normally, demonstrating that PcnB has no essential cellular role under the conditions tested and suggesting that regulation by antisense RNAs similar to RNAI has no critical role in any essential host process. We confirm by immunological tests that PcnB is likely to be the commercially available enzyme poly(A) polymerase.

Cell division and transcription of ftsZ

For normal cell division, the ftsZ gene must be transcribed from a number of promoters that are located within the proximal upstream genes (ddlB, ftsQ, and ftsA). We show that the main promoters have identical responses to changes in growth rate, i.e., under all conditions, the frequency of transcription per septum formed is approximately constant and independent of cell size or growth rate per se. We also show that transcription from these promoters is independent of stationary-phase transcription factor sigma s.

The strongly conserved carboxyl-terminus glycine-methionine motif of the Escherichia coli GroEL chaperonin is dispensable

The universally distributed heat-shock proteins (HSPs) are divided into classes based on molecular weight and sequence conservation. The members of at least two of these classes, the HSP60s and the HSP70s, have chaperone activity. Most HSP60s and many HSP70s feature a striking motif at or near the carboxyl terminus which consists of a string of repeated glycine and methionine residues. We have altered the groEL gene (encoding the essential Escherichia coli HSP60 chaperonin) so that the protein produced lacks its 16 final (including nine gly, and five met) residues. This truncated product behaves like the intact protein in several in vitro tests, the only discernible difference between the two proteins being in the rate at which ATP is hydrolysed. GroELtr can substitute for GroEL in vivo although cells dependent for survival on the truncated protein survive slightly less well during the stationary phase of growth. Elevated levels of the wild-type protein can suppress a number of temperature-sensitive mutations; the truncated protein lacks this ability.

Proteins encoded by the Escherichia coli replication terminus region

The replication terminus region (31 to 35 min) of the Escherichia coli chromosome contains very few mapped genes (two per min) compared with the remainder of the chromosome, and much of the DNA appears dispensable. In order to determine whether, despite this, the terminus region consists of protein-coding sequences, we cloned 44 kb (1 min) of terminus region DNA (that surrounding trg at 31.4 min) and examined its ability to catalyze protein synthesis in vitro or in minicells. We were able to account for more than half the coding capacity of the cloned DNA with proteins synthesized in these systems, indicating that the sparsity of mapped genes in the terminus region does not result from a lack of identifiable coding sequences. We can therefore conclude that the terminus region is composed mainly of expressable, albeit inessential, protein-encoding genes.

A possible role for the pcnB gene product of Escherichia coli in modulating RNA: RNA interactions

The sequence of the PcnB protein of Escherichia coli, a protein required for copy number maintenance of ColE1-related plasmids, was compared with the PIR sequence database. Strong local similarities to the sequence of the E. coli protein tRNA nucleotidyltransferase were found. Since a substrate of the latter protein, tRNA, structurally resembles the RNAs that control ColE1 copy number we believe that we may have identified a region in PcnB that interacts with these RNAs. Consistent with this idea is our observation that PcnB is required for the replication of R1, a plasmid whose replication is also regulated by a small RNA.

Identification of problems and strengths of the hospice client by clients, caregivers, and nurses. Implications for nursing

This exploratory study included instrument development as well as testing. The purpose of the study was to ascertain whether primary caregivers and hospice nurses identified the same problems and strengths of individual clients as did clients themselves. The instrument, a 27-item modified Q-sort, was based on review of literature on the concept Quality of Life. Dembo's Insider versus Outsider Perspective was the theoretical framework. Using the instrument, participants identified the problems and strengths of the client in the current time frame. Twenty consenting hospice clients, their primary caregiver, and their assigned hospice nurse were studied. No significant differences were found between clients, nurses, and caregivers when Total instrument means were compared (F = 1.38, p = 0.26). Three of the 27 items showed significant differences in the means of the three groups. Reliability coefficients showed high internal consistency on the Total instrument (0.87). Nurses and caregivers were found to identify problems and strengths of the client as perceived by the client. Findings corroborated Dembo's theory. Support of the hospice concept as the appropriate method of care for terminally ill clients was suggested.

Cloning and characterization of an Escherichia coli gene, pcnB, affecting plasmid copy number

A gene, pcnB, affecting the copy number of ColE1-related plasmids has been cloned and mapped to 3.6 min on the Escherichia coli chromosome between panD and fhu. The gene encodes a previously undescribed 48 kD protein. Several independently isolated mutants exhibiting the same phenotype, reduced copy number, have been shown to be pcnB-.

The effect of DnaA protein levels and the rate of initiation at oriC on transcription originating in the ftsQ and ftsA genes: in vivo experiments

The DnaA protein of Escherichia coli, essential for initiation at oriC, binds at a defined sequence which occurs at the chromosomal origin, near plasmid replication origins and in the promoters of the dnaA and mioC genes. This sequence also occurs at many other sites on the E. coli chromosome including three sites within the essential cell division genes ftsQ and A. Using an fts-lac fusion phage, lambda JFL100, we show here that fts gene expression responds both to reduced and increased intracellular levels of DnaA protein in a manner consistent with the hypothesis that DnaA protein regulates fts gene expression. Experiments using dnaC and dnaB-ts strains, however, suggest that DnaA control of fts transcription may be indirect, at least in part, with fts responding to the rate of initiation at oriC as well as to changes in DnaA protein level per se. It differs in this respect from dnaA gene expression which is unaffected when initiation of replication is inhibited by DnaB or DnaC inactivation. Strains integratively suppressed with pKN500 behave anomalously; neither fts nor dnaA transcription is significantly increased when DnaA is inactivated in these strains.

Packaging of transducing DNA by bacteriophage P1

P1 transduces bacterial chromosomal markers with widely differing frequencies. We use quantitative Southern hybridisations here to show that, despite this, most markers are packaged at similar levels. Exceptions are a group of markers near 2 min and another at 90 min which seem to be packaged at levels two- to threefold higher. We thus conclude that certain marker frequency variations in transduction can be explained by differences in packaging level, but that most cannot. The limited range in packaging levels suggests that P1 can initiate the packaging of chromosomal DNA from many sites. This idea is supported by our failure to find any chromosomal sequences with homology to the phage pac site and by the occurrence of hybridising bands which seem to suggest sequential packaging from a large number of specific sites. We eliminate the possibility that chromosomal DNA packaging is the result of endonucleolytic cutting by the P1 res enzyme.

Transductional analysis of chromosome replication time

Following transduction of exponentially growing cultures of Escherichia coli with phage P1, cells with recombinant phenotype begin to increase in number after an initial lag of about one generation time. We show that transductants for markers located at different positions on the chromosome begin to increase at different times, in reverse order to that in which they are replicated. The period over which this happens is equal in duration to the time taken to replicate the chromosome and we have used this relationship to calculate the C-period of E. coli K12 growing at 30 degrees C. We exclude transduction-induced filamentation as the cause of the initial lag and suggest that the lag may result from the way in which donor DNA is inherited.

A DNA fragment containing the groE genes can suppress mutations in the Escherichia coli dnaA gene

An 8.2 kb fragment of E. coli chromosomal DNA, when cloned in increased copy number, suppresses the dnaA46 mutation, and an abundant protein of about 68 kd (60 kd when measured by us), encoded by the fragment, is essential for the suppression (Takeda and Hirota 1982). Mapping experiments show that the fragment originates from the 94 min region of the chromosome. It encodes several proteins but only one abundant polypeptide of the correct size, the product of the groEL gene. Suppression by the fragment is allele specific; those mutations which map to the centre of the gene are suppressed. Other initiation mutants including dnaA203, dnaA204, dnaA508, dnaAam, dnaC, dnaP and dnaB252 are not suppressed. Most suppressed strains are cold-sensitive suggesting an interaction between the mutant proteins (or their genes) and the suppressing protein or proteins.

Reduction of marker discrimination in transductional recombination

The recovery of phage P1 mediated transductants varies with the marker selected in a manner which cannot be fully accounted for by dosage differences in the donor gene population. This variation in transduction frequency is due primarily to recombinational discrimination in the recipient cell. We show here that increasing the intracellular level of recA protein, which might be expected to increase the contribution of recF mediated events to recombinant formation, decreases this discrimination slightly, and that replacing recBC mediated recombination by a recF dependent process, augmented by an additional, as yet uncharacterized mutation, dramatically reduces recombinational discrimination. We conclude that although recBC mediated transductional recombination is selective, recombination which relies on recF need not be so. We also show that UV-damaged DNA can be successfully recombined in the absence of the recB product (even in sbcB+ cells) and that eliminating exonuclease I (the sbcB product) facilitates the recombination of heavily irradiated DNA.

Escherichia coli minichromosomes containing the pSC101 partitioning locus are stably inherited

The par region of pSC101, required in cis to promote its stable inheritance, was joined, in combination with the tetr determinant of pBR325, to large and small minichromosomes. These hybrid minichromosomes were examined for stability and found to be no more stable than their parent minichromosomes. Indeed, one recombinant plasmid, pEH21, showed reduced stability, which was not attributable to a reduced copy number. Neither pEH21 nor pEH22, a plasmid composed of the same DNA arranged differently, was stabilized by the presence of a Par+ pSC101 derived replicon in the same cell. We conclude that the par region of pSC101 does not stabilize minichromosomes.

The variation in frequency with which markers are transduced by phage P1 is primarily a result of discrimination during recombination

The efficiency of recovery of P1 transductants is marker dependent and normally varies over a 25-fold range. UV irradiation of either transducing lysates for recipient cells results in a selective stimulation of the transduction of markers which are normally transduced poorly. As a result the range in frequency of transduction is reduced to about 3-fold and resembles the gene frequency distribution expected in the donor cells. We conclude that P1 transducing lysates are likely to contain a random sample of donor DNA but that the recombination system of the recipient cell exhibits a preference for the DNA of some regions over that of others. Damage to DNA presumably overrides this specificity.

Deoxyribonucleic acid and outer membrane: strains diploid for the oriC region show elevated levels of deoxyribonucleic acid-binding protein and evidence for specific binding of the oriC region to outer membrane

We have recently reported that part of the chromosomal deoxyribonucleic acid (DNA) of Escherichia coli is associated with the outer membrane fraction and that an outer membrane protein having a molecular weight of 31,000 probably is involved in this association (H. Wolf-Watz and A. Norqvist, J. Bacteriol. 140:43-49, 1979). We have now found that F' merodiploid strains containing two copies of the DNA between bglB and ilv have increased levels of this protein and an increased amount of DNA in their outer membranes. Increased levels of the protein are also found when lambda asn phage, containing at 1.5-megadalton fragment of DNA located to the right of the uncA uncB genes but to the left of oriC, are induced. It therefore seems that this 1.5-megadalton fragment of DNA either codes for or binds to the 31,000-dalton outer membrane protein. Hybridization studies utilizing DNA found to be bound to outer membrane and DNA isolated from a specialized transducing phage lambda asn 132 revealed that at least 5 to 10% of outer membrane DNA has a DNA sequence homologous with a chromosomal segment carried by this oriC-containing phage.

Individual proteins are synthesized continuously throughout the Escherichia coli cell cycle

The pattern of synthesis of about 750 individual polypeptides was followed throughout the cell cycle of Escherichia coli B/r. Samples taken at different times in the cell cycle exhibited the same pattern of protein synthesis. No protein could be identified that was synthesized at different rates during different parts of the cell cycle.

Evidence that F' lac replicates asynchronously during the cell cycle of Escherichia coli B/r

The replication of F' lac was studied in exponentially growing cultures of E. coli B/r. The cells were pulse induced for the synthesis of beta-galactosidase and their DNA pulse labelled with 3H thymidine. The cells were then separated into age classes by centrifugation through a sucrose gradient in a zonal rotor. Plasmide replication was measured in each age fraction by three methods: the rate at which beta-galactosidase could be induced, the amount of label incorporated into CCC plasmid DNA which had been separated from chromosomal DNA on agarose gels, and the amount of label incorporated into plasmid DNA which had been separated from chromosomal DNA by ultracentrifugation through CsCl-EtBr gradients. All these methods gave the same result, that replication of F' lac occurs in cells of all ages and is not confined to a part of the cell cycle.

The frequency of P1 transduction of the genes of Escherichia coli as a function of chromosomal position: preferential transduction of the origin of replication

The frequencies with which the generalized transducing phage P1 transduced 26 selected markers on the E. coli. chromosome were measured. The frequencies were found to vary relative to argH+ = 1 from a maximum of 6.8 near the origin of replication to a minimum of 0.23 for a marker not far from the terminus. The low frequencies obtained for some markers were shown not to result from poor expression under the selective conditions employed. When plotted as a function of marker position on the chromosome the frequencies were found to exhibit a series of peaks and troughs which correspond to those in gene density noted by Bachmann et al. (1976). The possible relationship of these results to the structure of the E. coli chromosome and to the mechanism of generalized transduction are discussed.

Strains of Escherichia coli diploid for the chromosomal origin of DNA replication

F' strains of E. coli have been isolated which are merodiploid for various chromosomal segments between 66 and 78 minutes. Strains diploid for the chromosomal DNA between the genes bgl and mtl grow slowly, have a reduced DNA/mass and an increased cell size. These properties could result if the chromosomal replication origin and a second, extrachromosomal, copy of the origin (located in this case on the F') were to compete for a substance required to initiate replication. We therefore suggest that these strains are diploid for the chromosomal origin of replication and that, therefore, the origin is located between bgl and mtl, that is between 71 and 73 minutes on the E. coli chromosome.

Origin and direction of replication of the chromosome of E. coli B-r

The origin and direction of replication of the E. coli B/r chromosome has been determined by comparing gene frequencies in P1-transducing lysates prepared on cultures growing at different rates. The gene frequencies found are consistent with the idea that replication of the chromosome is dichotomous in rapidly growing B/r. The origin was found to be between 40 and 55 min on the E. coli genetic map with replication proceeding in a clockwise direction. Markers near the origin behaved anomalously.

Evidence for polarity of chromosome replication in F- strains of Escherichia coli

The inducibility of three enzymes (β-galactosidase, tryptophanase and D-serine deaminase) has been measured at various times during the cell cycles of three strains ofEscherichia coli(K12 58–161 F−, B/r F–and 15T−). In each strain sharp increases in inducibility of these enzymes occurred at characteristic periods in each cell cycle. Such increases depend on DNA replication and therefore probably reflect synchronized gene replication. It is inferred that chromosome replication in these F−strains is sequential from a fixed origin.

Infection with F′Lack+results in an extra period of increase in inducibiity of β-galactosidase in each cell cycle. It is concluded that the F′ episome replicates once in each cell cycle at a time soon after cell separation.