Summary Background Antimicrobial stewardship is advocated to improve the quality of antimicrobial use. We did a systematic review and meta-analysis to assess whether antimicrobial stewardship ...objectives had any effects in hospitals and long-term care facilities on four predefined patients' outcomes: clinical outcomes, adverse events, costs, and bacterial resistance rates. Methods We identified 14 stewardship objectives and did a separate systematic search for articles relating to each one in Embase, Ovid MEDLINE, and PubMed. Studies were included if they reported data on any of the four predefined outcomes in patients in whom the specific antimicrobial stewardship objective was assessed and compared the findings in patients in whom the objective was or was not met. We used a random-effects model to calculate relative risk reductions with relative risks and 95% CIs. Findings We identified 145 unique studies with data on nine stewardship objectives. Overall, the quality of evidence was generally low and heterogeneity between studies was mostly moderate to high. For the objectives empirical therapy according to guidelines, de-escalation of therapy, switch from intravenous to oral treatment, therapeutic drug monitoring, use of a list of restricted antibiotics, and bedside consultation the overall evidence showed significant benefits for one or more of the four outcomes. Guideline-adherent empirical therapy was associated with a relative risk reduction for mortality of 35% (relative risk 0·65, 95% CI 0·54–0·80, p<0·0001) and for de-escalation of 56% (0·44, 0·30–0·66, p<0·0001). Evidence of effects was less clear for adjusting therapy according to renal function, discontinuing therapy based on lack of clinical or microbiological evidence of infection, and having a local antibiotic guide. We found no reports for the remaining five stewardship objectives or for long-term care facilities. Interpretation Our findings of beneficial effects on outcomes with nine antimicrobial stewardship objectives suggest they can guide stewardship teams in their efforts to improve the quality of antibiotic use in hospitals. Funding Dutch Working Party on Antibiotic Policy and Netherlands National Institute for Public Health and the Environment.
Lipoarabinomannan (LAM), a component of the Mycobacterium tuberculosis (MTB) cell wall, is detectable in the urine of MTB infected patients with active tuberculosis (TB). LAM-specific antibodies ...(Igs) have been developed by a variety of traditional and recombinant methods for potential use in a rapid diagnostic test (RDT). We evaluated the analytical performance of the TB LAM Igs to identify pairs that offer superior performance over existing urine LAM tests. We assessed 25 new and 4 existing Igs in a matrixed format using a multiplex electrochemiluminescence-based liquid immunoassay. A total of 841 paired Ig combinations were challenged with in vitro cultured LAM (cLAM) derived from MTB strains representing diverse phylogenetic lineages, alongside urinary LAM (uLAM) from the urine of adults with active pulmonary TB. Analytical sensitivity of down-selected Ig pairs was determined using MTB Aoyama-B cLAM, while diagnostic accuracy was determined using clinical samples. When testing cLAM, the reactivity of Ig pairs was similar across MTB lineages 1-4 but lineage 5:6 had significantly more reactivity among Ig pairs. Overall, 41 Ig pairs had a strong binding affinity to cLAM, as compared to the reference pair of S4-20/A194-01, and 28 Ig pairs therein exhibited a strong affinity for both cLAM and uLAM. Retrospective testing on clinical urine specimens demonstrated varying sensitivities (12-80%) and specificities (14-100%). The five top pairs had a similar analytical limit of detection to the reference pair but in four instances, the sensitivity and specificity with clinical uLAM samples was poor. Overall, epitopes presented by uLAM are different from cLAM, which may affect antibody performance when testing uLAM in patient samples. Several new Ig pairs had similar ranges of high sensitivity to cLAM but overall, there were no new candidate Ig pairs identified in this round of screening with increased performance with uLAM as compared to an existing optimal pair.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We have explored a series of trisubstituted acridine-peptide conjugates for their ability to recognize and discriminate between DNA quadruplexes derived from the human telomere, and the c-kit and ...N-ras proto-oncogenes. Quadruplex affinity was measured as the peptide sequences were varied, together with their substitution position on the acridine, and the identity of the C-terminus (acid or amide). Surface plasmon resonance measurements revealed that all compounds bound to the human telomeric quadruplex with sub-micromolar affinity. Docking calculations from molecular modelling studies were used to model the effects of substituent orientation and peptide sequence. Modelling and experiment were in agreement that placement of the peptide over the face of the acridine is detrimental to binding affinity. The highest degrees of selectivity were observed towards the N-ras quadruplex by compounds capable of forming simultaneous contacts with their acridine and peptide moieties. The ligands that bound best displayed quadruplex affinities in the 1-5 nM range and at least 10-fold discrimination between the quadruplexes studied.
Lipoarabinomannan (LAM), a component of the Mycobacterium tuberculosis (MTB) cell wall, is detectable in the urine of MTB infected patients with active tuberculosis (TB). LAM-specific antibodies ...(Igs) have been developed by a variety of traditional and recombinant methods for potential use in a rapid diagnostic test (RDT). We evaluated the analytical performance of the TB LAM Igs to identify pairs that offer superior performance over existing urine LAM tests. We assessed 25 new and 4 existing Igs in a matrixed format using a multiplex electrochemiluminescence-based liquid immunoassay. A total of 841 paired Ig combinations were challenged with in vitro cultured LAM (cLAM) derived from MTB strains representing diverse phylogenetic lineages, alongside urinary LAM (uLAM) from the urine of adults with active pulmonary TB. Analytical sensitivity of down-selected Ig pairs was determined using MTB Aoyama-B cLAM, while diagnostic accuracy was determined using clinical samples. When testing cLAM, the reactivity of Ig pairs was similar across MTB lineages 1-4 but lineage 5:6 had significantly more reactivity among Ig pairs. Overall, 41 Ig pairs had a strong binding affinity to cLAM, as compared to the reference pair of S4-20/A194-01, and 28 Ig pairs therein exhibited a strong affinity for both cLAM and uLAM. Retrospective testing on clinical urine specimens demonstrated varying sensitivities (12-80%) and specificities (14-100%). The five top pairs had a similar analytical limit of detection to the reference pair but in four instances, the sensitivity and specificity with clinical uLAM samples was poor. Overall, epitopes presented by uLAM are different from cLAM, which may affect antibody performance when testing uLAM in patient samples. Several new Ig pairs had similar ranges of high sensitivity to cLAM but overall, there were no new candidate Ig pairs identified in this round of screening with increased performance with uLAM as compared to an existing optimal pair.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Over 500 million people worldwide are affected by diabetes mellitus, a chronic disease that leads to high blood glucose levels and causes severe side effects. The predominant biological marker for ...diagnosis of diabetes is glycated haemoglobin (GHb). In human blood the predominant reducing sugar, glucose, irreversibly conjugates onto accessible amine groups within Hb. Most methods for diagnosis and monitoring of diabetes selectively detect N-terminal glycation at Val-1 on the β-globin chain, but not glycation at other sites. Detection of other glycated epitopes of GHb has the potential to provide new information on the extent, duration and timing of elevated glucose, facilitating personalised diagnosis and intelligent diabetic control. In this work, a new anti-GHb Fab antibody (Fab-1) specific for haemoglobin A1c (HbA1c) with nanomolar affinity was discovered via epitope-directed immunisation and phage display. A single chain variable fragment (scFv) antibody derived from Fab-1 retained affinity and specificity for HbA1c, and affinity was enhanced tenfold upon addition of an enhanced green fluorescent protein tag. Both the scFv and Fab-1 recognised an epitope within HbA1c that was distinct from β-Val-1, and our data suggest that this epitope may include glycation at Lys-66 in the β-globin chain. To our knowledge, this is the first report of an scFv/Fab anti-glycated epitope antibody that recognises a non-A1c epitope in GHb, and confirms that fructosamine attached to different, discrete glycation sites within the same protein can be resolved from one another by immunoassay.
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•Diabetes diagnostics are limited by a small range of detectable glycation products.•Epitope-directed immunisation and phage display yielded novel anti-HbA1c antibodies.•A single-chain variable fragment antibody was designed with nanomolar affinity.•A tenfold enhancement of affinity was seen upon addition of green fluorescent protein.•Antibody binds glycated epitope in haemoglobin that is distinct from A1c epitope.
The peptidoglycan layer of
Staphylococcus aureus
contains a (Gly)
5
cross-link which is not found in other bacteria, and which could be used to develop a specific immunoassay for detection of
S. ...aureus
in MRSA infections. A semi-synthetic route was used to prepare the
S. aureus
peptidoglycan precursor UDPMurNAc-
l
-Ala--
d
-Glu-
l
-Lys(Gly)
5
-
d
-Ala-
d
-Ala, which was covalently attached to carrier protein bovine serum albumin
via
the UDP nucleotide. Serum raised using this antigen showed specificity for chemically immobilised peptidoglycan monomer containing (Gly)
5
, using an ELISA immunoassay. ELISA assays using 0.1 or 1.0 g samples of cell walls prepared from two MRSA strains and one penicillin-sensitive
S. aureus
strain, and from three other bacteria, showed the highest response against cell walls containing (Gly)
5
, with a particularly high response against cell walls from one MRSA strain. Competition assays to investigate antibody selectivity demonstrated that the antibody response could be most effectively antagonised using ligands containing (Gly)
5
. These data demonstrate that it is possible to generate antibodies with high affinity and selectivity for the (Gly)
5
containing monomer in
S. aureus
peptidoglycan, that could be used to develop an immunoassay for
S. aureus
.
We prepare UDPMurNAc-decapeptide peptidoglycan precursor found in
S. aureus
(MRSA), and report the detection of the staphylococcal peptidoglycan monomer and staphylococcal cell walls using antibodies raised to this antigen.
MurM and MurN are tRNA-dependent ligases that catalyze the addition of the first (l-Ala/l-Ser) and second (l-Ala) amino acid onto lipid II substrates in the biosynthesis of the peptidoglycan layer of ...Streptococcus pneumoniae. We have previously characterized the first ligase, MurM (Lloyd, A. J., Gilbey, A. M., Blewett, A. M., De Pascale, G., El Zoeiby, A., Levesque, R. C., Catherwood, A. C., Tomasz, A., Bugg, T. D., Roper, D. I., and Dowson, C. G. (2008) J. Biol. Chem. 283, 6402–6417). In order to characterize the second ligase MurN, we have developed a chemoenzymatic route to prepare the lipid II-Ala and lipid II-Ser substrates. Recombinant MurN enzymes from penicillin-resistant (159) and -sensitive (Pn16) S. pneumoniae were expressed and purified as MBP fusion proteins and reconstituted using a radiochemical assay. MurN ligases from strains 159 and Pn16 both showed a 20-fold higher catalytic efficiency for lipid II-l-Ala over lipid II-l-Ser, with no activity against unmodified lipid II, and similar kinetic parameters were measured for MurN from penicillin-resistant and penicillin-sensitive strains. These results concur with the peptidoglycan analysis of S. pneumoniae, in which the major cross-link observed is l-Ala-l-Ala. The combined action of ligases MurM and MurN is therefore required in order to rationalize the high level of dipeptide cross-links in penicillin-resistant S. pneumoniae, with ligase MurM showing the major difference between penicillin-resistant and penicillin-sensitive strains.
G-quadruplex DNA-specific ligands were generated using a combinatorial selection of tetrapeptides which were then conjugated to a hemicyanine scaffold. The heterocycle enhanced peptide binding ...affinity by ∼1000-fold to give ligands with near micromolar affinity and >40-fold discrimination for quadruplex DNA over duplex.
UDPMurNAc-L-Ala-gamma-D-Glu-X-D-Ala-DAla (X = L-Lys or m-DAP) is the cytoplasmic precursor for the lipid-linked cycle of bacterial peptidoglycan biosynthesis, consisting of at least four enzymatic ...reactions, which are targets for antibacterial agents. Fluorescent derivatives of the UDPMurNAc-pentapeptide labelled at the 3rd, 4th, and 5th position of the peptide chain were prepared chemoenzymatically, in order to study the reactions catalysed by enzymes in this cycle. Derivatives labelled on the epsilon-amino group of the 3rd amino acid (N-dansyl, N-fluorescamine and N-phthalaldehyde) were prepared by chemical modification. Two methods were developed for preparation of analogues of UDPMurNAc-pentapeptide containing D-cysteine at position 4 or 5: either by MurF-catalysed ligation of the UDPMurNAc-tripeptide to synthetic D-Ala-D-Cys or D-Cys-D-Ala dipeptides; or by enzymatic synthesis of D-Ala-D-Cys by ligase VanD. D-Cys-containing UDPMurNAc-pentapeptides were labelled with pyrene maleimide, to give 4-pyrene and 5-pyrene labelled derivatives. The fluorescent UDPMurNAc-pentapeptides were processed as substrates by Escherichia coli MraY or E. coli membranes, giving 1.5-150-fold changes in fluorescence upon transformation to lipid intermediate I. Subsequent processing to lipid intermediate II gave rise only to small changes in fluorescence. Pyrene-labelled lipid intermediates I and II can be generated using Micrococcus flavus membranes, enabling the study of the later lipid-linked steps.
We have recently described an engineered zinc finger protein (Gq1) that binds with high specificity to the intramolecular G-quadruplex formed by the human telomeric sequence 5‘-(GGTTAG)5-3‘, and that ...inhibits the activity of the enzyme telomerase in vitro. Here we report site-directed mutagenesis, biophysical, and molecular modeling studies that provide new insights into quadruplex recognition by the zinc finger scaffold. We show that any one finger of Gq1 can be replaced with the corresponding finger of Zif268, without significant loss of quadruplex affinity or quadruplex versus duplex discrimination. Replacement of two fingers, with one being finger 2, of Gq1 by Zif268 results in significant impairment of quadruplex recognition and loss of discrimination. Molecular modeling suggests that the zinc fingers of Gq1 can bind to the human parallel-stranded quadruplex structure in a stable arrangement, whereas Zif268−quadruplex models show significantly weaker binding energy. Modeling also suggests that an important role of the key protein finger residues in the Gq1−quadruplex complex is to maintain Gq1 in an optimum conformation for quadruplex recognition.
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