Restriction of Intravenous Fluid in ICU Patients with Septic Shock.

BACKGROUND: Intravenous fluids are recommended for the treatment of patients who are in septic shock, but higher fluid volumes have been associated with harm in patients who are in the intensive care unit (ICU). METHODS: In this international, randomized trial, we assigned patients with septic shock in the ICU who had received at least 1 liter of intravenous fluid to receive restricted intravenous fluid or standard intravenous fluid therapy; patients were included if the onset of shock had been within 12 hours before screening. The primary outcome was death from any cause within 90 days after randomization. RESULTS: We enrolled 1554 patients; 770 were assigned to the restrictive-fluid group and 784 to the standard-fluid group. Primary outcome data were available for 1545 patients (99.4%). In the ICU, the restrictive-fluid group received a median of 1798 ml of intravenous fluid (interquartile range, 500 to 4366); the standard-fluid group received a median of 3811 ml (interquartile range, 1861 to 6762). At 90 days, death had occurred in 323 of 764 patients (42.3%) in the restrictive-fluid group, as compared with 329 of 781 patients (42.1%) in the standard-fluid group (adjusted absolute difference, 0.1 percentage points; 95% confidence interval [CI], -4.7 to 4.9; P = 0.96). In the ICU, serious adverse events occurred at least once in 221 of 751 patients (29.4%) in the restrictive-fluid group and in 238 of 772 patients (30.8%) in the standard-fluid group (adjusted absolute difference, -1.7 percentage points; 99% CI, -7.7 to 4.3). At 90 days after randomization, the numbers of days alive without life support and days alive and out of the hospital were similar in the two groups. CONCLUSIONS: Among adult patients with septic shock in the ICU, intravenous fluid restriction did not result in fewer deaths at 90 days than standard intravenous fluid therapy. (Funded by the Novo Nordisk Foundation and others; CLASSIC ClinicalTrials.gov number, NCT03668236.).

Display of a naïve affibody library on staphylococci for selection of binders by means of flow cytometry sorting.

Within the field of combinatorial protein engineering there is a great demand for robust high-throughput selection platforms that allow for unbiased protein library display, affinity-based screening, and amplification of selected clones. We have previously described the development of a staphylococcal display system used for displaying both alternative-scaffolds and antibody-derived proteins. In this study, the objective was to generate an improved expression vector for displaying and screening a high-complexity naïve affibody library, and to facilitate downstream validation of isolated clones. A high-affinity normalization tag, consisting of two ABD-moieties, was introduced to simplify off-rate screening procedures. In addition, the vector was furnished with a TEV protease substrate recognition sequence upstream of the protein library which enables proteolytic processing of the displayed construct for improved binding signal. In the library design, 13 of the 58 surface-exposed amino acid positions were selected for full randomization (except proline and cysteine) using trinucleotide technology. The genetic library was successfully transformed to Staphylococcus carnosus cells, generating a protein library exceeding 109 members. De novo selections against three target proteins (CD14, MAPK9 and the affibody ZEGFR:2377) were successfully performed using magnetic bead-based capture followed by flow-cytometric sorting, yielding affibody molecules binding their respective target with nanomolar affinity. Taken together, the results demonstrate the feasibility of the staphylococcal display system and the proposed selection procedure to generate new affibody molecules with high affinity.

Piperacillin/tazobactam versus carbapenems in patients with severe bacterial infections: A systematic review with meta-analysis.

BACKGROUND: Piperacillin/tazobactam or meropenem are often used to treat patients with severe bacterial infections. We aimed to compare the desirable and undesirable effects of empirical and/or definitive piperacillin/tazobactam versus carbapenems in patients with severe bacterial infections. METHODS: We searched PubMed, Embase, CENTRAL, Epistemonikos, and trial registers for randomised clinical trials of empirical and/or definitive piperacillin/tazobactam versus carbapenems in adult patients with severe bacterial infection (i.e., any bacterial infection requiring hospitalisation). The primary outcome was all-cause short-term mortality within 90 days. Secondary outcomes were all-cause long-term mortality, adverse events, quality of life, days alive without or duration of life support, secondary infections, selection of fungi or resistant bacteria, and days alive and out of hospital or hospital length of stay. We calculated relative risks (RRs) using random effects and fixed effect meta-analyses along with trial sequential analyses. RESULTS: We included 31 trials (n = 8790 patients) with overall high risk of bias. The RR for all-cause short-term mortality was 1.16 (95% confidence interval [CI]: 0.94-1.43, low certainty evidence), for adverse events 1.00 (98% CI: 0.96-1.04, moderate certainty evidence), for secondary infections 1.13 (98% CI: 0.76-1.68, very low certainty evidence), and for selection of fungi or resistant bacteria 1.61 (98% CI: 0.89-2.89, very low certainty evidence). There were no or limited data for the remaining outcomes. CONCLUSIONS: Based on very low or low certainty evidence, piperacillin/tazobactam may be associated with less favourable outcomes in patients with severe bacterial infections as compared with carbapenems, but the information size for a robust conclusion has not been reached.

Plasma MMP-1 Expression as a Prognostic Factor in Colon Cancer.

BACKGROUND: Matrix metalloproteinases (MMP) are involved in the local and distant invasiveness of colorectal cancer. This study investigates the prognostic value of circulating matrix metalloproteinase levels in patients with colon cancer. METHODS: A cohort of 152 patients was followed for more than 10 years. The correlation of plasma levels of MMP-1,-2, -7, -8, and -9 and survival was investigated. RESULTS: A high level of MMP-1 in circulating plasma was associated with a poorer prognosis in colon cancer (HR 2.0, 95% CI 1.1-3.9) in multivariate analysis regarding 5-year cancer-specific survival. This was further seen in regard of 10-year cancer-specific survival. CONCLUSIONS: Measurement of plasma MMP-1 concentration in patients planned for radical colon cancer surgery might be of importance when discussing prognosis and selection of patients for oncological treatment and postsurgery surveillance.

Thrombocytopenia in intensive care unit patients: A scoping review.

BACKGROUND: Thrombocytopenia is frequent in intensive care unit (ICU) patients and may be associated with adverse outcomes. We aimed to assess the incidence, risk factors, and outcomes associated with thrombocytopenia in adult ICU patients. METHODS: We conducted a scoping review in accordance with the Preferred Reporting Items for Systematic Review and Meta-analyses extension for Scoping Reviews (PRISMA-ScR) and the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach. We included study reports on adult ICU patients with thrombocytopenia and assessed patient-important outcomes, including mortality and health-related quality-of-life. RESULTS: We included a total of 70 studies comprising a total of 215 098 patients; 57 were cohort studies. The incidence of thrombocytopenia varied from 8 to 56 per 100 admissions (very low quality of evidence). We identified several risk factors including age, sepsis, and higher disease severity (low quality of evidence). Thrombocytopenia was associated with bleeding, use of life support, length of stay in the ICU, and increased mortality (low/very low quality of evidence). Data on platelet transfusion before invasive procedures and transfusion thresholds were limited. No studies assessed the benefits and harms of thromboprophylaxis in ICU patients with thrombocytopenia. CONCLUSIONS: Thrombocytopenia is common and associated with increased morbidity and mortality in adult ICU patients. Several risk factors for thrombocytopenia exists, but the evidence-base on management strategies, including transfusion thresholds and thromboprophylaxis in ICU patients is very limited.

Use of crystalloids and colloids in Europe per year from 2010 to 2019: Protocol for an international descriptive study.

INTRODUCTION: Intravenous (IV) fluids are widely used in everyday clinical practice. In the last two decades, several trials and clinical practice guidelines have been published on the use of different types and dosages of IV fluid. This may have led to a change in clinical practice. Thus, we aim to describe the use of IV crystalloids and colloids in Europe over a 10-year period. METHODS AND ANALYSIS: We will collect national or regional data on the use of IV crystalloids and colloids in European hospitals through companies and/or federal medical agencies that provide pharmaceutical data concerning the type and amount of fluids used from January 1st, 2010 to December 31st, 2019. We will use run charts to describe time trends in the use of fluids. CONCLUSION: This study will provide insight into the use of IV fluids in Europe between 2010 and 2019. It will enable the observation of changes over time and among the different European countries and regions. This will provide information on the extent to which landmark trials and clinical practice guidelines on fluids have affected clinical practice in Europe regarding the use of IV fluids.

COVID-19 versus influenza A/B supeRInfectionS in the IntenSive care unit (CRISIS): Protocol for a Danish nationwide cohort study.

BACKGROUND: Superinfection following viral infection is a known complication, which may lead to longer hospitalisation and worse outcome. Empirical antibiotic therapy may prevent bacterial superinfections, but may also lead to overuse, adverse effects and development of resistant pathogens. Knowledge about the incidence of superinfections in intensive care unit (ICU) patients with severe Coronavirus Disease 2019 (COVID-19) is limited. METHODS: We will conduct a nationwide cohort study comparing the incidence of superinfections in patients with severe COVID-19 admitted to the ICU compared with ICU patients with influenza A/B in Denmark. We will include approximately 1000 patients in each group from the time period of 1 October 2014 to 30 April 2019 and from 10 March 2020 to 1 March 2021 for patients with influenza and COVID-19, respectively. The primary outcome is any superinfection within 90 days of admission to the ICU. We will use logistic regression analysis comparing COVID-19 with influenza A/B after adjustment for relevant predefined confounders. Secondarily, we will use unadjusted and adjusted logistic regression analyses to assess six potential risk factors (sex, age, cancer [including haematological], immunosuppression and use of life support on day 1 in the ICU) for superinfections and compare outcomes in patients with COVID-19 with/without superinfections, and present descriptive data regarding the superinfections. CONCLUSION: This study will provide important knowledge about superinfections in ICU patients with severe COVID-19.

Random epigenetic modulation of CHO cells by repeated knockdown of DNA methyltransferases increases population diversity and enables sorting of cells with higher production capacities.

Chinese hamster ovary (CHO) cells produce a large share of today's biopharmaceuticals. Still, the generation of satisfactory producer cell lines is a tedious undertaking. Recently, it was found that CHO cells, when exposed to new environmental conditions, modify their epigenome, suggesting that cells adapt their gene expression pattern to handle new challenges. The major aim of the present study was to employ artificially induced, random changes in the DNA-methylation pattern of CHO cells to diversify cell populations and consequently increase the finding of cell lines with improved cellular characteristics. To achieve this, DNA methyltransferases and/or the ten-eleven translocation enzymes were downregulated by RNA interference over a time span of ∼16 days. Methylation analysis of the resulting cell pools revealed that the knockdown of DNA methyltransferases was highly effective in randomly demethylating the genome. The same approach, when applied to stable CHO producer cells resulted in (a) an increased productivity diversity in the cell population, and (b) a higher number of outliers within the population, which resulted in higher specific productivity and titer in the sorted cells. These findings suggest that epigenetics play a previously underestimated, but actually important role in defining the overall cellular behavior of production clones.

Heterogenous treatment effects of transfusion thresholds by patient age: Post-hoc analysis of the TRISS trial.

BACKGROUND: Use of a lower haemoglobin (Hb) threshold to guide red blood cell (RBC) transfusion is now generally recommended in critically ill patients, but uncertainty remains regarding the optimal Hb threshold for RBC transfusion in patients of different ages. METHODS: We conducted a post-hoc analysis of 998 patients with septic shock and anaemia randomised to RBC transfusion at a Hb threshold of 7 g/dl [4.3 mmol/l] vs 9 g/dl [5.6 mmol/l] in the Transfusion Requirements in Septic Shock (TRISS) trial. We assessed if there were heterogeneous effects between the allocated Hb threshold and patient age categorised and on the continuous scale. The primary outcome was 1-year mortality; the secondary outcome was 90-day mortality. Both outcomes were analysed using logistic regression models and in sensitivity analyses with additional adjusting for site of enrolment, presence of haematological malignancy and the Sequential Organ Failure Assessment (SOFA) score. The secondary analyses were Kaplan-Meier curves with corresponding log-rank tests. RESULTS: We found no heterogeneity between patient age and the allocated Hb thresholds for RBC transfusion for 1-year mortality or 90-day mortality in the primary analyses. The sensitivity analyses suggested heterogeneity between age groups regarding 90-day mortality, however, this was not consistent for 1-year mortality or when assessing age on the continuous scale. CONCLUSION: In this post-hoc study of ICU patients with septic shock, we found no reliable heterogeneous effects of transfusion at a Hb threshold of 7 vs 9 g/dl according to patient age on mortality. However, due to low power, this study should only be considered as hypothesis generating.

NT-pro-BNP as marker for cardiac strain that may be caused by high-output arteriovenous shunting in a haemodialysis patient. A case report.

BACKGROUND: An arteriovenous fistula (AVF) is the first choice when considering access for haemodialysis (HD). When a forearm AVF fails an upper arm AVF is a frequent subsequent dialysis access option. The latter may cause cardiac strain. NT-pro-B-type natriuretic peptide (NT-NT-proBNP) is a marker used to estimate volume overload and cardiac strain. This case report shows the benefit of using longitudinal individual follow-up of pre-dialysis NT-proBNP in clinical practice to detect changes in cardiac condition that may be due to high-output AVF. CASE PRESENTATION: An 18 years old patient performed HD via an upper arm AVF before he was admitted to our unit. NT-proBNP was above the upper detection level of 70,000 ng/L. Echocardiography revealed a left-ventricular cardiac insufficiency. Interdialytic weight gain (IDWG) was above 5%. He was instructed to lower fluid intake and IDWG towards 2%. Four months later NT-proBNP surpassed 70,000 ng/L again. Flow in the brachial artery was at 3034 ml/min. Reconstructive surgery of the AVF did not reduce flow and NT-proBNP in the long run. Clinically, he worsened to NYHA class III-IV. It was decided to close the upper arm AVF and to replace it with a lower arm AVF leading to a reduced artery flow of 1344 mL/min. The clinical condition successively recovered and NT-proBNP decreased to 7000 ng/L. CONCLUSIONS: Pre-dialysis NT-proBNP should be considered as a suitable routine marker for cardiac strain such as caused by high-output AVF besides variables such as IDWG. Brachial artery flow besides AVF flow measurement is helpful.

Results of renal artery revascularization in the post-ASTRAL era with 4 years mean follow-up.

Purpose: To investigate contemporary results of percutaneous transluminal renal angioplasty (PTRA).Materials and Methods: A multicentre retrospective study analysing all patients treated with PTRA for primary symptomatic renal artery stenosis (RAS) between 2010 and 2013 at four tertiary centres. Procedures during the preceding four years were counted to evaluate for change in PTRA frequency.Results: The number of PTRA procedures decreased by approximately 50% from 2006 to 2013. Patients treated in the post-ASTRAL period (n = 224) had a significant reduction in mean systolic pressure (168 to 146 mmHg, p < 0.01), diastolic pressure (84 to 76 mmHg, p < 0.01), number of anti-hypertensive drugs (3.54 to 3.05, p < 0.01), and anti-hypertensive treatment index (21.75 to 16.92, p < 0.01) compared to before PTRA. These improvements were maintained at one year and at the last clinical evaluation after a mean follow-up of 4.31 years. Renal function increased transiently without sustained improvement, or deterioration, during later follow-up. Thirteen patients (5.8%) eventually required dialysis, nine of these had eGFR <20 ml/min/1.73 m2 before PTRA. There was no difference in outcomes between subgroups differentiated by different indications for PTRA.Conclusion: The frequency of PTRA has decreased, indicating a higher threshold for invasive treatment of RAS in recent years. The reduction in blood pressures, the reduced need for anti-hypertensive medication, and stabilization of renal function over time suggest a clinical benefit for most patients who are now being treated with PTRA.

Bleeding and thrombosis in intensive care patients with thrombocytopenia-Protocol for a topical systematic review.

BACKGROUND: Thrombocytopenia is a common condition in critically ill patients in the intensive care unit (ICU). It is associated with prolonged stay in the ICU, increased transfusion requirements, risk of bleeding and mortality. The evidence regarding the use of prophylactic platelet transfusion and thrombosis prophylaxis in patients with thrombocytopenia in the ICU is unknown. To direct future research, we aim to assess the current evidence regarding prophylactic platelet transfusion and thrombosis prophylaxis on patient-important benefits and harms in the ICU population. METHODS: We will conduct a topical systematic review of all study designs (ie no study design will per se be excluded from the proposed review) in accordance with the Preferred Reporting Items for Systematic and Meta-Analyses (PRISMA) statements. We will include studies on adult patients in the ICU where the incidence of thrombocytopenia and the predefined outcome measures, including mortality, quality-of-life, thrombotic events and haemorrhagic events are reported. We will provide descriptive analyses of the included studies/trials, ie no meta-analyses will be conducted, and the quality of evidence will be assessed according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. CONCLUSION: The outlined topical systematic review will provide important data on the benefits and harms of prophylactic platelet transfusion and thrombosis prophylaxis in ICU patients with thrombocytopenia and provide estimates on the rate of thrombocytopenia in this vulnerable population.

Empirical metronidazole for patients with severe bacterial infection: A systematic review with meta-analysis and trial sequential analysis.

BACKGROUND: Metronidazole is the preferred empirical anti-anaerobic agent for patients with suspected anaerobic infection. The balance between benefits and harms of empirical metronidazole is unclear. We aimed to assess patient-important benefits and harms of empirical metronidazole vs placebo/no treatment in adult patients with severe bacterial infection of any origin. METHODS: We conducted a systematic review with meta-analysis and trial sequential analysis of randomized clinical trials assessing empirical metronidazole vs placebo/no treatment in adult hospitalized patients with severe bacterial infection. The review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement, the Cochrane Handbook and the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) methodology. A protocol and statistical analysis plan was published prior to conducting the review. RESULTS: We included a total of nine trials (n = 1753 patients), all of which were adjudicated as having high risk of bias. We found no difference in the primary outcome mortality within 90 days (relative risk 1.56, 95% confidence interval 0.39-6.25). Fewer patients receiving metronidazole had secondary infections (relative risk 0.43, 95% CI: 0.27-0.68). Trial sequential analysis indicated high risk of random errors due to lack of data, and the quality of evidence was very low for all outcomes. CONCLUSIONS: There is low quantity and quality of evidence supporting the use of empirical metronidazole in adult patients with severe bacterial infections of any origin, and no firm evidence for benefit or harm.

Lower vs higher transfusion threshold in septic shock patients of different ages: A study protocol.

BACKGROUND: Current evidence indicates that it is safe to use a lower haemoglobin (Hb) threshold for red blood cell (RBC) transfusion as compared to a higher Hb-threshold. However, the recent Transfusion Requirements in Cardiac Surgery (TRICS-3) trial reported a significant interaction between patient age and the effect of lower vs higher Hb-thresholds for RBC transfusion. The interaction between patient age and transfusion strategy appears to differ between trials. METHODS: This is the protocol and statistical analysis plan for a post hoc analysis of the Transfusion Requirements in Septic Shock (TRISS) trial. We will assess the effect of a lower vs a higher Hb-threshold for RBC transfusion in patients of different ages with septic shock. The primary and secondary outcomes are 1-year mortality and 90-day mortality respectively. We will assess age divided into six age groups and as a continuous variable and present baseline characteristics and odds ratios derived from both simple and adjusted (for the Sequential Organ Failure Assessment score, haematological malignancy, age and trial site) logistic regression models and P-values for the test-of-interaction. Furthermore, we will compare outcomes according to Hb-threshold in each age group using Kaplan-Meier curves and log-rank tests. DISCUSSION: The outlined study will make a detailed assessment of potential interaction of patient age with transfusion strategy in patients with septic shock. This may inform future trials on the benefits and harms of RBC transfusion.

Use of red blood cells in Danish intensive care units: A population-based register study.

BACKGROUND: Red blood cell (RBC) transfusion is common in the intensive care unit (ICU). Recent trials have shown that a restrictive transfusion strategy is safe in most patients, and recent guidelines recommend such a strategy in most ICU patients. It is unknown if this has translated into a change in clinical practice. METHODS: We conducted a population-based register study of RBC transfusions in ICUs in the Danish Capital Region between 1st of January 2011 and 31st of December 2016 by linking data from the regional blood bank and the Danish Intensive Care Database. We used crude data and run- and control-charts to analyse changes in the number of RBC transfusions. RESULTS: We included 27 835 ICU admissions of which 6936 received 40 889 RBC units. The crude use was 36.2 RBC units per one-hundred patient bed-days in 2011 vs 29.8 in 2016. The run-chart analysis did not confirm a change in the total use of RBC units in all ICUs combined, and we observed no change in the proportion of transfused patients or in the use of RBCs among transfused patients. Sensitivity analyses showed decreased use of RBC units in two general ICUs, and a reduced use of RBC units among medical ICU patients. CONCLUSIONS: In this population-based register study, we did not with certainty observe changes over time in the use of RBC transfusions in all patients in all ICUs in the Danish Capital Region. A reduction in RBC use may have occurred in some general ICUs and in medical ICU patients.

Piperacillin/tazobactam vs carbapenems for patients with bacterial infection: Protocol for a systematic review.

INTRODUCTION: Early empirical broad-spectrum antimicrobial therapy is recommended for patients with severe infections, including sepsis. ß-lactam/ß-lactamase inhibitor combinations or carbapenems are often used to ensure coverage of likely pathogens. Piperacillin/tazobactam is proposed as a carbapenem-sparing agent to reduce the incidence of multidrug-resistant bacteria and superinfections. In the recently published MERINO trial, increased mortality from piperacillin/tazobactam was suggested in patients with bacteraemia with resistant Escherichia coli or Klebsiella species. Whether these findings also apply to empirical piperacillin/tazobactam in patients with other severe infections, including sepsis, is unknown. We aim to assess the benefits and harms of empirical and definitive piperacillin/tazobactam vs carbapenems for patients with severe bacterial infections. METHODS AND ANALYSIS: This protocol has been prepared according to the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols statement, the Cochrane Handbook and the Grading of Recommendations, Assessment, Development, and Evaluation approach. We will include randomised clinical trials assessing piperacillin/tazobactam vs carbapenems in patients with severe bacterial infections of any origin. The primary outcome will be all-cause short-term mortality ≤ 90 days. Secondary outcomes will include all-cause long-term mortality > 90 days, adverse events, quality of life, use of life support, secondary infections, antibiotic resistance, and length of stay. We will conduct meta-analyses, including pre-planned subgroup and sensitivity analyses for all assessed outcomes. The risk of random errors in the meta-analyses will be assessed by trial sequential analysis.

Conservative vs liberal fluid therapy in septic shock (CLASSIC) trial-Protocol and statistical analysis plan.

INTRODUCTION: Intravenous (IV) fluid is a key intervention in the management of septic shock. The benefits and harms of lower versus higher fluid volumes are unknown and thus clinical equipoise exists. We describe the protocol and detailed statistical analysis plan for the conservative versus liberal approach to fluid therapy of septic shock in the Intensive Care (CLASSIC) trial. The aim of the CLASSIC trial is to assess benefits and harms of IV fluid restriction versus standard care in adult intensive care unit (ICU) patients with septic shock. METHODS: CLASSIC trial is an investigator-initiated, international, randomised, stratified, and analyst-blinded trial. We will allocate 1554 adult patients with septic shock, who are planned to be or are admitted to an ICU, to IV fluid restriction versus standard care. The primary outcome is mortality at day 90. Secondary outcomes are serious adverse events (SAEs), serious adverse reactions (SARs), days alive at day 90 without life support, days alive and out of the hospital at day 90 and mortality, health-related quality of life (HRQoL), and cognitive function at 1 year. We will conduct the statistical analyses according to a pre-defined statistical analysis plan, including three interim analyses. For the primary analysis, we will use logistic regression adjusted for the stratification variables comparing the two interventions in the intention-to-treat (ITT) population. DISCUSSION: The CLASSIC trial results will provide important evidence to guide clinicians' choice regarding the IV fluid therapy in adults with septic shock.

Levels of matrix metalloproteinases differ in plasma and serum - aspects regarding analysis of biological markers in cancer.

BACKGROUND: There are inconsistencies in the use of serum or plasma when analysing the matrix metalloproteinases (MMPs) as diagnostic or prognostic markers. The purpose of this study was to compare the concentration of MMP-1, -2, -7, -8, -9 and -13 in serum vs plasma samples. METHODS: Blood samples were obtained from sixty-five men and women. Samples were analysed for levels of MMPs in corresponding citrate plasma and serum. RESULTS: All MMPs expressed higher concentration in serum compared with plasma (P<0.01). There were no differences between genders. CONCLUSIONS: Present study demonstrated significant differences regarding concentrations of some MMPs using plasma vs serum. We conclude that future studies regarding MMPs as biological markers in cancer should consider the use of citrate plasma instead of serum.

A new prodrug form of Affibody molecules (pro-Affibody) is selectively activated by cancer-associated proteases.

Affinity proteins have advanced the field of targeted therapeutics due to their generally higher specificity compared to small molecular compounds. However, side effects caused by on-target binding in healthy tissues are still an issue. Here, we design and investigate a prodrug strategy for improving tissue specificity of Affibody molecules in future in vivo studies. The prodrug Affibody (pro-Affibody) against the HER2 receptor was constructed by fusing a HER2-specific Affibody (ZHER2) to an anti-idiotypic Affibody (anti-ZHER2). The linker was engineered to comprise a substrate peptide for the cancer-associated matrix metalloprotease 1 (MMP-1). The hypothesis was that the binding surface of ZHER2 would thereby be blocked from interacting with HER2 until the substrate peptide was specifically hydrolyzed by MMP-1. Binding should thereby only occur where MMP-1 is overexpressed, potentially decreasing on-target toxicities in normal tissues. The pro-Affibody was engineered to find a suitable linker and substrate peptide, and the different constructs were evaluated with a new bacterial display assay. HER2-binding of the pro-Affibody was efficiently masked and proteolytic activation of the best variant yielded over 1,000-fold increase in apparent binding affinity. Biosensor analysis revealed that blocking of the pro-Affibody primarily affected the association phase. In a cell-binding assay, the activated pro-Affibody targeted native HER2 on cancer cells as opposed to the non-activated pro-Affibody. We believe this prodrug approach with proteolytic activation is promising for improving tissue specificity in future in vivo targeting applications and can hopefully be extended to other Affibody molecules and similar affinity proteins as well.

Expanding the zinc-finger recombinase repertoire: directed evolution and mutational analysis of serine recombinase specificity determinants.

The serine recombinases are a diverse family of modular enzymes that promote high-fidelity DNA rearrangements between specific target sites. Replacement of their native DNA-binding domains with custom-designed Cys2-His2 zinc-finger proteins results in the creation of engineered zinc-finger recombinases (ZFRs) capable of achieving targeted genetic modifications. The flexibility afforded by zinc-finger domains enables the design of hybrid recombinases that recognize a wide variety of potential target sites; however, this technology remains constrained by the strict recognition specificities imposed by the ZFR catalytic domains. In particular, the ability to fully reprogram serine recombinase catalytic specificity has been impeded by conserved base requirements within each recombinase target site and an incomplete understanding of the factors governing DNA recognition. Here we describe an approach to complement the targeting capacity of ZFRs. Using directed evolution, we isolated mutants of the ß and Sin recombinases that specifically recognize target sites previously outside the scope of ZFRs. Additionally, we developed a genetic screen to determine the specific base requirements for site-specific recombination and showed that specificity profiling enables the discovery of unique genomic ZFR substrates. Finally, we conducted an extensive and family-wide mutational analysis of the serine recombinase DNA-binding arm region and uncovered a diverse network of residues that confer target specificity. These results demonstrate that the ZFR repertoire is extensible and highlights the potential of ZFRs as a class of flexible tools for targeted genome engineering.