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1.
Assays of CFTR Function In Vitro, Ex Vivo and In Vivo.
Ramalho, AS, Boon, M, Proesmans, M, Vermeulen, F, Carlon, MS, Boeck, K
International journal of molecular sciences. 2022;(3)
Abstract
Cystic fibrosis, a multi-organ genetic disease, is characterized by abnormal function of the cystic fibrosis transmembrane conductance regulator (CFTR) protein, a chloride channel at the apical membrane of several epithelia. In recent years, therapeutic strategies have been developed to correct the CFTR defect. To evaluate CFTR function at baseline for diagnosis, or the efficacy of CFTR-restoring therapy, reliable tests are needed to measure CFTR function, in vitro, ex vivo and in vivo. In vitro techniques either directly or indirectly measure ion fluxes; direct measurement of ion fluxes and quenching of fluorescence in cell-based assays, change in transmembrane voltage or current in patch clamp or Ussing chamber, swelling of CFTR-containing organoids by secondary water influx upon CFTR activation. Several cell or tissue types can be used. Ex vivo and in vivo assays similarly evaluate current (intestinal current measurement) and membrane potential differences (nasal potential difference), on tissues from individual patients. In the sweat test, the most frequently used in vivo evaluation of CFTR function, chloride concentration or stimulated sweat rate can be directly measured. Here, we will describe the currently available bio-assays for quantitative evaluation of CFTR function, their indications, advantages and disadvantages, and correlation with clinical outcome measures.
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2.
Measuring the impact of CFTR modulation on sweat chloride in cystic fibrosis: Rationale and design of the CHEC-SC study.
Zemanick, ET, Konstan, MW, VanDevanter, DR, Rowe, SM, Clancy, JP, Odem-Davis, K, Skalland, M, Mayer-Hamblett, N
Journal of cystic fibrosis : official journal of the European Cystic Fibrosis Society. 2021;(6):965-971
Abstract
BACKGROUND The Characterizing CFTR Modulated Changes in Sweat Chloride and their Association with Clinical Outcomes (CHEC-SC) study is a large epidemiologic study designed to determine the relationship between sweat chloride response and clinical outcomes in people with cystic fibrosis (CF) on commercially approved CFTR modulators. A challenge to study feasibility was capturing sweat chloride measurements before modulator initiation. We tested the hypothesis that historic sweat chloride approximated contemporary pre-modulator values to estimate CFTR modulator-induced changes, allowing a single-visit study design. METHODS GOAL and PROSPECT were multi-center prospective studies of individuals initiating ivacaftor or lumacaftor-ivacaftor. At enrollment, pre-modulator sweat chloride was measured and historic results recorded. Post-modulator sweat chloride was measured at 1, 3 and 6 months. For this analysis, differences between historic and pre-modulator sweat chloride were estimated. CFTR modulator-induced sweat chloride mean changes were compared using historic and pre-modulator sweat chloride. RESULTS Paired historic and pre-modulator sweat chloride (n=406 participants) revealed a non-significant mean change of -1.0 mmol/L (95% CI: -2.71, 0.66) over an average of 17.2 years. Calculating sweat response to ivacaftor or lumacaftor-ivacaftor using historic or pre-modulator values resulted in similar estimates of modulator response. Based on these results, the CHEC-SC study was designed with a single, post-modulator sweat chloride measurement. CONCLUSIONS Historic sweat chloride values provide a reliable estimate of pre-modulator sweat chloride for people starting on modulator therapy. The CHEC-SC study anticipates capturing approximately 5,000 sweat chloride values, providing an unprecedented understanding of sweat chloride across the CF population in the era of CFTR modulators.
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3.
Enhanced filtration performance using feed-and-bleed configuration for purification of antibody precipitates.
Li, Z, Chen, TH, Andini, E, Coffman, JL, Przybycien, T, Zydney, AL
Biotechnology progress. 2021;(1):e3082
Abstract
Precipitation can be used for the initial purification of monoclonal antibodies (mAbs), with the soluble host cell proteins removed in the permeate by tangential flow microfiltration. The objective of this study was to examine the use of a feed-and-bleed configuration to increase the effective conversion (ratio of permeate to feed flow rates) in the hollow fiber module to enable more effective washing of the precipitate. Experiments were performed using human serum Immunoglobulin G (IgG) precipitates formed with 10 mM zinc chloride and 7 wt% polyethylene glycol. The critical flux was evaluated as a function of the shear rate and IgG concentration, with the resulting correlation used to predict conditions that can achieve 90% conversion in a single pass with minimal fouling. Experimental data for both the start-up and steady-state performance are in good agreement with model calculations. These results were used to analyze the performance of an enhanced continuous precipitation-microfiltration process using the feed-and-bleed configuration for the initial capture / purification of a mAb product.
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4.
Usefulness of chloride levels for fluid resuscitation in patients undergoing targeted temperature management after out-of-hospital cardiac arrest.
Kong, T, Chung, YE, Lee, HS, You, JS, Chung, HS, Park, I, Chung, SP
The American journal of emergency medicine. 2021;:69-76
Abstract
OBJECTIVE Chloride is an important electrolyte in the body. In this study, we aimed to evaluate the associations between chloride levels on emergency department (ED) admission and neurologic outcomes by stratifying patients undergoing targeted temperature management (TTM) after out-of-hospital cardiac arrest (OHCA) into three groups (hyper/normo/hypochloremia); we also assessed the effect of changes in chloride levels from baseline over time on outcomes. METHODS This retrospective, observational cohort study of 346 patients was conducted between 2011 and 2019. The chloride levels were categorized as hypochloremia, normochloremia, and hyperchloremia by predetermined definitions. The primary endpoint was poor neurologic outcomes after hospital discharge. We evaluated the associations between chloride levels on ED admission and neurologic outcomes and assess the effect of changes in chloride levels over time on clinical outcomes. RESULTS On ED admission, compared with normochloremia, hypochloremia was significantly associated with unfavorable neurologic outcomes (OR, 2.668; 95% CI, 1.217-5.850, P = 0.014). Over time, unfavorable neurologic outcomes were significantly associated with increases in chloride levels in the hyperchloremia and normochloremia groups after ED admission. The rates of poor neurologic outcomes in the hyperchloremia and normochloremia groups were increased by 14.2% at Time-12, 20.1% at Time-24, and 9.3% at Time-48 with a 1-mEq/L increase in chloride levels. CONCLUSION In clinical practice, chloride levels can be routinely and serially measured cost-effectively. Thus, baseline chloride levels may be a promising tool for rapid risk stratification of patients after OHCA. For fluid resuscitation after cardiac arrest, a chloride-restricted solution may be an early therapeutic strategy.
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5.
Does Chloride Intake at the Early Phase of Septic Shock Resuscitation Impact on Renal Outcome?
Chapalain, X, Huet, O, Balzer, T, Delbove, A, Martino, F, Jacquier, S, Egreteau, PY, Darreau, C, Saint-Martin, M, Lerolle, N, et al
Shock (Augusta, Ga.). 2021;(3):425-432
Abstract
INTRODUCTION Fluid administration is one of the first lines of treatment for hemodynamic management of sepsis and septic shock. Studies investigating the effects of chloride-rich fluids including normal saline on renal function report controversial findings. METHODS This is a prospective, observational, multicenter study. Patients with septic shock, defined according to Sepsis-2 definition, were eligible. A "high-dose" of chloride was defined as a chloride intake greater than 18 g administrated within the first 48 h of septic shock management. The purpose of this study was to investigate the impact of cumulative chloride infusion within the first 48 h of septic shock resuscitation on acute kidney injury (AKI). RESULTS Two hundred thirty-nine patients with septic shock were included. Patients who received a "high-dose" of chloride had significantly higher Sequential Organ Failure Assessment score at the time of enrolment (P < 0.001). Cumulative chloride load was higher in patients requiring renal replacement therapy (RRT) (31.1 vs. 25.2 g/48 h; P < 0.005). Propensity score-weighted regression did not find any association between "high-dose" of chloride and AKI requiring RRT (OR: 0.97 [0.88-1.1]; P = 0.69). There was no association between "high-dose" of chloride and worsening kidney function at H48 (OR: 0.94 [0.83-1.1]; P = 0.42). There was also no association between "high-dose" of chloride and ICU length of stay (P = 0.61), 28-day mortality (P = 0.83), or hospital mortality (P = 0.89). CONCLUSION At the early stage of resuscitation of critically ill patients with septic shock, administration of "high-dose" of chloride (> 18 g/48 h) was not associated with renal prognosis.
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6.
Calixarene-based artificial ionophores for chloride transport across natural liposomal bilayer: Synthesis, structure-function relationships, and computational study.
Pilato, S, Aschi, M, Bazzoni, M, Cester Bonati, F, Cera, G, Moffa, S, Canale, V, Ciulla, M, Secchi, A, Arduini, A, et al
Biochimica et biophysica acta. Biomembranes. 2021;(10):183667
Abstract
An amphiphilic calix[6]arene, alone or complexed with an axle to form a pseudo-rotaxane, has been embedded into liposomes prepared from 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and the permeability of the membrane-doped liposomes towards Cl- ions has been evaluated by using lucigenin as the fluorescent probe. The pseudo-rotaxane promotes transmembrane transport of Cl- ions more than calix[6]arene does. Surprisingly, the quenching of lucigenin was very fast for liposomes doped with the positively charged axle alone. Molecular dynamics (MD) simulations and quantum-chemical calculations were also carried out for providing a semi-quantitative support to the experimental results.
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7.
Antimicrobial stewardship strategies in wound care: evidence to support the use of dialkylcarbamoyl chloride (DACC)- coated wound dressings.
Rippon, MG, Rogers, AA, Ousey, K
Journal of wound care. 2021;(4):284-296
Abstract
BACKGROUND Traditionally, infections are treated with antimicrobials (for example, antibiotics, antiseptics, etc), but antimicrobial resistance (AMR) has become one of the most serious health threats of the 21st century (before the emergence of COVID-19). Wounds can be a source of infection by allowing unconstrained entry of microorganisms into the body, including antimicrobial-resistant bacteria. The development of new antimicrobials (particularly antibiotics) is not keeping pace with the evolution of resistant microorganisms and novel ways of addressing this problem are urgently required. One such initiative has been the development of antimicrobial stewardship (AMS) programmes, which educate healthcare workers, and control the prescribing and targeting of antimicrobials to reduce the likelihood of AMR. Of great importance has been the European Wound Management Association (EWMA) in supporting AMS by providing practical recommendations for optimising antimicrobial therapy for the treatment of wound infection. The use of wound dressings that use a physical sequestration and retention approach rather than antimicrobial agents to reduce bacterial burden offers a novel approach that supports AMS. Bacterial-binding by dressings and their physical removal, rather than active killing, minimises their damage and hence prevents the release of damaging endotoxins. AIM: Our objective is to highlight AMS for the promotion of the judicious use of antimicrobials and to investigate how dialkylcarbamoyl chloride (DACC)-coated dressings can support AMS goals. METHOD MEDLINE, Cochrane Database of Systematic Reviews, and Google Scholar were searched to identify published articles describing data relating to AMS, and the use of a variety of wound dressings in the prevention and/or treatment of wound infections. The evidence supporting alternative wound dressings that can reduce bioburden and prevent and/or treat wound infection in a manner that does not kill or damage the microorganisms (for example, by actively binding and removing intact microorganisms from wounds) were then narratively reviewed. RESULTS The evidence reviewed here demonstrates that using bacterial-binding wound dressings that act in a physical manner (for example, DACC-coated dressings) as an alternative approach to preventing and/or treating infection in both acute and hard-to-heal wounds does not exacerbate AMR and supports AMS. CONCLUSION Some wound dressings work via a mechanism that promotes the binding and physical uptake, sequestration and removal of intact microorganisms from the wound bed (for example, a wound dressing that uses DACC technology to successfully prevent/reduce infection). They provide a valuable tool that aligns with the requirements of AMS (for example, reducing the use of antimicrobials in wound treatment regimens) by effectively reducing wound bioburden without inducing/selecting for resistant bacteria.
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8.
The association between serum chloride levels and chronic kidney disease progression: a cohort study.
Khatri, M, Zitovsky, J, Lee, D, Nayyar, K, Fazzari, M, Grant, C
BMC nephrology. 2020;(1):165
Abstract
BACKGROUND Limited data suggest serum chloride levels associate with mortality in heart failure, chronic kidney disease (CKD), and pulmonary arterial hypertension. Randomized trials have also shown that administration of crystalloid intravenous fluids with lower chloride concentration may have better renal outcomes. However, chloride has not been studied longitudinally for CKD progression. METHODS We used a prospective cohort of subjects with stage 3 and 4 CKD recruited from a nephrology clinic at a single medical center. Linear regression, linear regression with generalized estimating equations, and Cox proportional hazards models were created for outcomes of overall change in estimated glomerular filtration rate (eGFR), longitudinal changes in eGFR, and time to > 30% decline in eGFR, respectively. Baseline chloride was modeled continuously and categorically, and models were adjusted for potential confounders. RESULTS Median follow-up was 1.7 years. Baseline median age was 72 years and median eGFR was 35.7 mL/min/1.73m2. In multivariable analysis, higher serum chloride associated with worsened eGFR decline. Every 1 mEq/L increase in chloride associated with an overall eGFR decline of 0.32 mL/min/1.73m2 (p = 0.003), while the difference in eGFR decline in the highest quartile of chloride was 3.4 mL/min/1.73m2 compared to the lowest quartile (p = 0.004). No association between serum chloride and time to 30% decline in eGFR was observed in multivariable analysis (hazard ratio 1.05 per 1 mEq/L increase in serum chloride, p = 0.103). CONCLUSIONS In CKD patients, higher serum chloride associated with a modestly steeper rate of eGFR decline, and may be a useful biomarker to predict CKD progression. Further studies are needed to determine causality.
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9.
What biologists want from their chloride reporters - a conversation between chemists and biologists.
Zajac, M, Chakraborty, K, Saha, S, Mahadevan, V, Infield, DT, Accardi, A, Qiu, Z, Krishnan, Y
Journal of cell science. 2020;(2)
Abstract
Impaired chloride transport affects diverse processes ranging from neuron excitability to water secretion, which underlie epilepsy and cystic fibrosis, respectively. The ability to image chloride fluxes with fluorescent probes has been essential for the investigation of the roles of chloride channels and transporters in health and disease. Therefore, developing effective fluorescent chloride reporters is critical to characterizing chloride transporters and discovering new ones. However, each chloride channel or transporter has a unique functional context that demands a suite of chloride probes with appropriate sensing characteristics. This Review seeks to juxtapose the biology of chloride transport with the chemistries underlying chloride sensors by exploring the various biological roles of chloride and highlighting the insights delivered by studies using chloride reporters. We then delineate the evolution of small-molecule sensors and genetically encoded chloride reporters. Finally, we analyze discussions with chloride biologists to identify the advantages and limitations of sensors in each biological context, as well as to recognize the key design challenges that must be overcome for developing the next generation of chloride sensors.
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10.
Females with Cystic Fibrosis Demonstrate a Differential Response Profile to Ivacaftor Compared with Males.
Secunda, KE, Guimbellot, JS, Jovanovic, B, Heltshe, SL, Sagel, SD, Rowe, SM, Jain, M
American journal of respiratory and critical care medicine. 2020;(8):996-998