Solution Behavior of Glyco-Copoly(l-Glutamic Acid)s in Dilute Saline Solution.

A small series of copoly(α,l-glutamic acid/dl-allylglycine)s with the same chain length and allylglycine content (∼10 mol %) but different spatial distribution of allylglycine units was synthesized and subsequently glycosylated via thiol-ene chemistry. Dilute aqueous copolypeptide solutions (0.1 wt %, physiological saline) were analyzed by circular dichroism spectroscopy, dynamic light scattering, and cryogenic transmission electron microscopy. The copolypeptides adopted a random coil or α-helix conformation, depending on solution pH, and the glycosylated residues either distorted or enhanced the folding into an α-helix depending on their location and spatial distribution along the chain. However, regardless of their secondary structure and degree of charging, all partially glycosylated copolypeptides self-assembled into 3D spherical structures, supposedly driven by a hydrophilic effect promoting microphase separation into glucose-rich and glutamate-rich domains.

Study of the physicochemical properties of drugs suitable for administration using a lymphatic drug delivery system.

Lymph node (LN) metastasis is thought to account for 20-30% of deaths from head and neck cancer. The lymphatic drug delivery system (LDDS) is a new technology that enables the injection of drugs into a sentinel LN (SLN) during the early stage of tumor metastasis to treat the SLN and secondary metastatic LNs. However, the optimal physicochemical properties of the solvent used to carry the drug have not been determined. Here, we show that the osmotic pressure and viscosity of the solvent influenced the antitumor effect of cisplatin (CDDP) in a mouse model of LN metastasis. Tumor cells were inoculated into the proper axillary LN (PALN), and the LDDS was used to inject CDDP solution into the subiliac LN (SiLN) to treat the tumor cells in the downstream PALN. CDDP dissolved in saline had no therapeutic effects in the PALN after it was injected into the SiLN using the LDDS or into the tail vein (as a control). However, CDDP solution with an osmotic pressure of ~ 1,900 kPa and a viscosity of ~ 12 mPa⋅s suppressed tumor growth in the PALN after it was injected into the SiLN using the LDDS. The high osmotic pressure dilated the lymphatic vessels and sinuses to enhance drug flow in the PALN, and the high viscosity increased the retention of CDDP in the PALN. Our results demonstrate that optimizing the osmotic pressure and viscosity of the solvent can enhance the effects of CDDP, and possibly other anticancer drugs, after administration using the LDDS.

Radiofrequency ablation combined with conductive fluid-based dopants (saline normal and colloidal gold): computer modeling and ex vivo experiments.

BACKGROUND: The volume of the coagulation zones created during radiofrequency ablation (RFA) is limited by the appearance of roll-off. Doping the tissue with conductive fluids, e.g., gold nanoparticles (AuNPs) could enlarge these zones by delaying roll-off. Our goal was to characterize the electrical conductivity of a substrate doped with AuNPs in a computer modeling study and ex vivo experiments to investigate their effect on coagulation zone volumes. METHODS: The electrical conductivity of substrates doped with normal saline or AuNPs was assessed experimentally on agar phantoms. The computer models, built and solved on COMSOL Multiphysics, consisted of a cylindrical domain mimicking liver tissue and a spherical domain mimicking a doped zone with 2, 3 and 4 cm diameters. Ex vivo experiments were conducted on bovine liver fragments under three different conditions: non-doped tissue (ND Group), 2 mL of 0.9% NaCl (NaCl Group), and 2 mL of AuNPs 0.1 wt% (AuNPs Group). RESULTS: The theoretical analysis showed that adding normal saline or colloidal gold in concentrations lower than 10% only modifies the electrical conductivity of the doped substrate with practically no change in the thermal characteristics. The computer results showed a relationship between doped zone size and electrode length regarding the created coagulation zone. There was good agreement between the ex vivo and computational results in terms of transverse diameter of the coagulation zone. CONCLUSIONS: Both the computer and ex vivo experiments showed that doping with AuNPs can enlarge the coagulation zone, especially the transverse diameter and hence enhance sphericity.

The effect of saline versus air for cuff inflation on the incidence of high intra-cuff pressure in paediatric MicroCuff® tracheal tubes: a randomised controlled trial.

The use of cuffed tracheal tubes in paediatric anaesthesia is now common. The use of nitrous oxide in anaesthesia risks excessive tracheal tube cuff pressures, as nitrous oxide can diffuse into the cuff during the course of surgery. The aim of this single-centre, prospective, randomised controlled trial was to compare the effect of saline versus air for the inflation of tracheal tube cuffs on the incidence of excessive intra-operative cuff pressure in children undergoing balanced anaesthesia with nitrous oxide. Children (age ≤ 16 y) were randomly allocated to receive either saline (saline group) or air (air group) to inflate the cuff of their tracheal tube. The pressure in the tracheal tube cuff was measured during surgery and brought down to the initial inflation level if it breached a safe limit (25 cmH2 O). Post-extubation adverse respiratory events were noted. Data from 48 patients (24 in each group), aged 4 months to 16 y, were analysed. The requirement for reduction in intra-cuff pressure occurred in 1/24 patients in the saline group, compared with 16/24 patients in the air group (p < 0.001). The incidence of extubation-related adverse events was similar in the saline and air groups (15/24 vs. 13/24, respectively; p = 0.770). The use of saline to inflate the cuff of paediatric cuffed tubes reduces the incidence of high intra-cuff pressures during anaesthesia. This may provide a pragmatic extra safety barrier to help reduce the incidence of excessive tracheal cuff pressure when nitrous oxide is used during paediatric anaesthesia.

Aluminium release and fluid warming: provocational setting and devices at risk.

BACKGROUND: Fluid warming, recommended for fluid rates of > 500 ml h-1, is an integral part of patient temperature management strategies. Fluid warming devices using an uncoated aluminium containing heating element have been reported to liberate aluminium resulting in critical aluminium concentrations in heated fluids. We investigated saline solution (0.9%), artificially spiked with organic acids to determine the influence of fluid composition on aluminium release using the uncoated enFlow® device. Additionally, the Level1® as a high volume fluid warming device and the ThermoSens® device were investigated with artificial spiked fluid at high risk for aluminum release and a clinically used crystalloid solution. RESULTS: Saline solution spiked with lactate more than acetate, especially at a non neutral pH, led to high aluminium release. Next to the enFlow® device, aluminium release was observed for the Level1® device, but not for the coated ThermoSens®-device. CONCLUSION: Uncoated aluminium containing fluid warming devices lead to potentially toxic levels of aluminium in heated fluids, especially in fluids with non-neutral pH containing organic acids and their salts like balanced electrolyte solutions.

Immersion of Achilles tendon in phosphate-buffered saline influences T1 and T2 * relaxation times: An ex vivo study.

Robust mapping of relaxation parameters in ex vivo tissues is based on hydration and therefore requires control of the tissue treatment to ensure tissue integrity and consistent measurement conditions over long periods of time. One way to maintain the hydration of ex vivo tendon tissue is to immerse the samples in a buffer solution. To this end, various buffer solutions have been proposed; however, many appear to influence the tissue relaxation times, especially with prolonged exposure. In this work, ovine Achilles tendon tissue was used as a model to investigate the effect of immersion in phosphate-buffered saline (PBS) and the effects on the T1 and T2* relaxation times. Ex vivo samples were measured at 0 (baseline), 30 and 67 hours after immersion in PBS. Ultrashort echo time (UTE) imaging was performed using variable flip angle and echo train-shifted multi-echo imaging for T1 and T2* estimation, respectively. Compared with baseline, both T1 and T2* relaxation time constants increased significantly after 30 hours of immersion. T2* continued to show a significant increase between 30 and 67 hours. Both T1 and T2* tended to approach saturation at 67 hours. These results exemplify the relevance of stringently controlled tissue preparation and preservation techniques, both before and during MRI experiments.

Extraction of bioimpedance phase information from its magnitude using a non-uniform Kramers-Kronig transform.

A novel non-uniform Kramers-Kronig Transform algorithm for bioimpedance phase extraction is proposed and tested in this work. The algorithm error is studied and compared with a previously proposed phase extraction technique, also based on the Kramers-Kronig transform. Results using simulated datasets and experimental datasets confirm the excellent performance of the algorithm.

Specific and non-specific interactions between metal cations and zwitterionic alanine tripeptide in saline solutions reported by the symmetric carboxylate stretching and amide-II vibrations.

The "specific" interaction between metal cations (Na+, Ca2+, Mg2+, and Zn2+) and the charged COO- group, and the "non-specific" interaction between these cations and the peptide backbone of a zwitterionic trialanine (Ala3) in aqueous solutions were examined in detail, using linear infrared (IR) absorptions of the COO- symmetric stretching and the amide-II (mainly the C-N stretching) modes as IR probes. Different IR spectral changes in peak positions and intensities of the two IR probes clearly demonstrate their sensitivities to nearby cation distributions in distance and population. Quantum chemistry calculations and molecular dynamics simulations were used to describe the cation-peptide interaction picture. These combined results suggest that Na+ and Ca2+ tend to bind to the COO- group in the bidentate form, while Mg2+ and Zn2+ tend to bind to the COO- group in the pseudo-bridging form. The results also show that while all three divalent cations indirectly interact with the peptide backbone with large population, Ca2+ and Mg2+ can be sometimes distributed very close to the backbone. Such a non-specific cation interaction can be moderately sensed by the C-N stretching of the amide-II mode when cations approach the polar amide C[double bond, length as m-dash]O group, and is also influenced by the NH3+ charge group located at the N-terminus. The results suggest that the experimentally observed complication of the Hofmeister cation series shall be understood as a combined specific and non-specific cation-peptide interactions.

Evaluation of Physicochemical Properties Following Syringe-to-Syringe Mixing of Hyaluronic Acid Dermal Fillers.

BACKGROUND: Historically, soft-tissue hyaluronic acid (HA) fillers have been mixed with agents to reduce pain or alter physicochemical properties. OBJECTIVE: Evaluate the impact of dilution and mixing on HA filler physicochemical properties. MATERIALS AND METHODS: Crosslinked HA filler (VYC-20L, 20 mg/mL) was diluted to 15 mg/mL using saline through 5 or 10 passes between 2 syringes connected using a luer connector. Extrusion force, rheological properties, and microscopic appearance were assessed. Undiluted VYC-15L (15 mg/mL) served as the control. RESULTS: Average extrusion force was higher for diluted VYC-20L versus the control, with an increase in slope for gel diluted using 5 passes (0.65) and 10 passes (0.52) versus the control (<0.1). For diluted samples mixed with 5 or 10 passes, the rheological profile was different between the 2 halves of the syringe, with the second half more elastic than the first half, compared with the consistent profile of undiluted samples. Microscopically, diluted VYC-20L samples seemed more liquid near the luer and more particulate near the piston compared with the control, which was smooth throughout. CONCLUSION: In addition to potentially introducing contamination, diluting or mixing soft-tissue HA fillers yields a heterogeneous product with physicochemical characteristics that vary substantially throughout the syringe.

The effect of concentration, reconstitution solution and pH on the stability of a remifentanil hydrochloride and propofol admixture for simultaneous co-infusion.

BACKGROUND: There are scenarios where pre-mixing and infusing analgesic and anaesthetic agents as a single intravenous (IV) solution is highly desirable; however, it is important to ensure the agents are compatible when mixed. As such, the long-term stability of a remifentanil-propofol mixture, and means of improving this, were assessed across a range of remifentanil concentrations, diluents, and time points. METHODS: Remifentanil was reconstituted with ultrapure water, 0.9% saline, 20% saline, or 8.4% sodium bicarbonate solution (the latter two chosen for their pH characteristics, rather than their use in pharmaceutical reconstitution) and then mixed with propofol (1%) or further diluted with water to derive concentrations of 10-50 µg mL- 1. Remifentanil and propofol concentrations were determined initially and then periodically for up to 24 h using high performance liquid chromatography (HPLC). Mass spectrometry (MS) was used to detect degradation products in solutions containing 30 µg mL- 1 of remifentanil. Statistical analysis was performed using ANOVA and Student's t-test, with a significance value of 0.05. RESULTS: Isolated remifentanil (pH < 4) and propofol (pH 7.35) did not degrade significantly when reconstituted with water or saline solution over 24 h, while remifentanil reconstituted with sodium bicarbonate degraded significantly (P < 0.001, pH 8.65). Mixing with propofol substantially increased the pH of the mixture and resulted in significant remifentanil degradation for all reconstitution solutions used, while propofol remained stable (pH 6.50). The amount of degradation product detected in samples containing isolated remifentanil and a mixture of the drugs was proportional to the remifentanil degradation observed. CONCLUSIONS: Remifentanil stability is affected by both the reconstitution solution used and when mixed with propofol, with pH appearing to be a contributing factor to degradation. If the pH of the solution and concentration of remifentanil are correctly controlled, e.g. through the use of a more acidic diluent, an admixture of remifentanil and propofol may be useful clinically.

Saline vs. dextrose for local anesthetic dilution in brachial plexus block: A randomized study.

Higher sodium ions in saline diluted local anesthetic may reduce the anesthetic action of the drug as injected around the nerves. However, the impact of local anesthetic dilution agents on the quality of peripheral nerve blockades has not yet been widely investigated. This study was aimed at evaluating the impact of lidocaine dilution with normal saline vs dextrose 5% on onset time of supraclavicular approach to brachial plexus block. Sixty American Society of Anesthesiologists class 1or2 patients, scheduled for elective upper extremity surgeries under sono-guided supraclavicular block were randomly assigned to receive lidocaine 2% diluted with either dextrose 5% or normal saline. At the end of lidocaine injection, sensory and motor blocks were evaluated at 5 min intervals for 30 min in the areas innervated by median, radial, ulnar and musculocutaneous nerves. Block onset time and number of patients with complete sensory or motor blockade were similar in both groups. Lidocaine diluted with either normal saline or dextrose 5% produces comparable sensory and motor block onset time and success rate in ultrasound guided supraclavicular block.

Polycarboxylated Dextran as a Multivalent Linker: Synthesis and Target Recognition of the Antibody-Nanoparticle Bioconjugates in PBS and Serum.

Nanoparticles (NPs) functionalized with antibodies on their surface are used in a wide range of research applications. However, the bioconjugation chemistry between the antibodies and the surface of nanoparticles can be very challenging, often accompanied by several undesired effects such as nanoparticle aggregation, antibody denaturation, or poor target recognition of the surface-bound antibodies. Here, we report on a synthesis of fluorescent silica nanoparticle-antibody (NP-Ab) conjugates, in which polycarboxylated dextran is used as the multivalent linker. First, we present a synthetic methodology to prepare polycarboxylated dextrans with molecular weights of 6, 40, and 70 kDa. Second, we used water-soluble, polycarboxylated dextrans as a multivalent spacers/linkers to immobilize antibodies onto fluorescent silica nanoparticles. The prepared NP-Ab conjugates were tested in a direct binding assay format in both phosphate-buffered saline buffer and whole serum to investigate the role of the spacer/linker in the capacity of the NP-Ab to specifically recognize their target in "clean" and also in complex media. We have compared the dextran conjugates with two standards: (a) NP-Ab with antibodies attached on the surface of nanoparticles through the classical physical adsorption method and (b) NP-Ab where an established poly(amidoamine) (PAMAM) dendrimer was used as the linker. Our results showed that the polycarboxylated 6 kDa dextran facilitates antibody immobilization efficiency of nearly 92%. This was directly translated into the improved molecular recognition of the NP-Ab, which was measured by a direct binding assay. The signal-to-noise ratio in buffered solution for the 6 kDa dextran NP-Ab conjugates was 81, nearly 3 times higher than that of PAMAM G4.5 conjugates and 9 times higher than the physically adsorbed NP-Ab sample. In whole serum, the effect of 6 kDa dextran was more hindered due to the formation of protein corona but the signal-to-noise ratio was at least double that of the physically adsorbed NP-Ab conjugates.

Sickle red blood cells are more susceptible to in vitro haemolysis when exposed to normal saline versus Plasma-Lyte A.

BACKGROUND: Normal saline has been the fluid of choice for resuscitation, rehydration and fluid replacement during plasma or red cell exchange/cytapheresis. There are increased concerns about its clinical effects and data showing it causes more haemolysis in vitro than buffered solutions such as Plasma-Lyte A. METHODS: We investigated whether normal saline or Plasma-Lyte A was associated with greater haemolysis during hours of in vitro incubation with both normal red cells and samples from patients with sickle cell anaemia. RESULTS: Sickle red cells haemolysed more than normal red cells did in both crystalloid solutions. The results of 24-hour exposure to saline were particularly striking (median of 163 mg/dl (IQ range 105-247) for sickle red cells vs. 53 (48-92) for normal red cells (P < 0·0001). In patient samples containing variable quantities of haemoglobin S red cells, increased haemoglobin S was associated with increased haemolysis. This effect was greater for normal saline than Plasma-Lyte A (P = 0·12). CONCLUSIONS: These in vitro models demonstrate that short-term ex vivo exposure of sickle red cells to normal saline leads to greater haemolysis than short-term exposure of normal red cells, and this effect is exacerbated by normal saline. Whether use of normal saline causes increased haemolysis in vivo is unknown. Given recent evidence that normal saline increases renal failure and mortality in critically ill patients, further studies are urgently needed.

Characterization of Phosphate Buffered Saline (PBS) in Frozen State and after Freeze-Drying.

PURPOSE: To study the effect of mannitol or trehalose on the crystallization behavior of solutes in phosphate buffered saline (PBS) when the solutions were frozen and freeze-dried. METHODS: PBS (pH 7.5 at RT) either alone, or with trehalose (5% w/v) or mannitol (1% w/v), were frozen and characterized using low temperature differential scanning calorimetry (DSC), X-ray diffractometry (XRD), and pH measurement. Freeze dried lyophiles were characterized by XRD. RESULTS: In the absence of cosolutes, upon freezing PBS, a pH shift of ~ 4 units was observed due to crystallization of Na2HPO4•12H2O. XRD indicated sequential crystallization of Na2HPO4•12H2O, NaCl•2H2O and KCl during cooling. When the frozen solutions were heated, two eutectics were observed - the first at ~ -24°C (ternary, NaCl•2H2O-KCl-ice) and the second at ~ -22°C (binary, NaCl•2H2O-ice). Trehalose completely inhibited buffer salt crystallization, whereas mannitol suppressed it partially thereby attenuating the magnitude of pH shift. The two eutectic meltings were also suppressed by the cosolutes. XRD of final lyophiles from PBS alone revealed peaks of anhydrous Na2HPO4, NaCl, and KCl. Trehalose rendered the lyophiles completely XRD amorphous, whereas in presence of mannitol, all the solutes except KH2PO4 crystallized. CONCLUSIONS: Freezing of PBS solution caused a pronounced pH shift due to selective crystallization of Na2HPO4•12H2O. The addition of trehalose or mannitol suppressed the buffer salt crystallization and attenuated the magnitude of pH shift. The potential instability of biologics due to pH shift in PBS, can be potentially mitigated with the cosolutes.

Normal Saline and Dextrose 5% in Water Do Not Support Bacterial Growth 24 Hours After Being Spiked in the Perioperative Environment.

BACKGROUND: The Joint Commission requirement is that the US Pharmacopeia Chapter <797> is followed, which recommends that administration of compounded sterile preparations should begin no later than 1 hour after their preparation. We hypothesized that simply spiking the IV fluid in a nonsterile environment does not pose an increased risk of infection to the patient. METHODS: Two 1000-mL bags of IV fluid (normal saline and dextrose 5% in water) were spiked and hung in 5 busy perioperative locations, once a week for a 13-week period. A 10-mL sample was drawn from each bag of IV fluid at time zero and 24 hours resulting in 260 samples in total. All samples were inoculated in 2 separate growth media (sheep's blood agar and thioglycollate broth). The primary outcome was growth versus no growth in any of the specimens. If any growth was noted, the sample was marked as positive and further testing to identify the organism was undertaken. RESULTS: A total of 257 samples (normal saline = 127, dextrose 5% in water = 129) were collected over a period of 13 weeks, yielding 514 specimens. Three samples were excluded from the study secondary to the IV bags being discarded accidentally. No growth was identified in any of the specimens. The 97.5% CIs were as follows: normal saline = 127 (0-0.034) and dextrose 5% in water = 129 (0-0.033), correcting for multiple tests. CONCLUSIONS: No bacterial growth was noted in any of the 257 samples collected. Normal saline and dextrose 5% in water do not support bacterial growth 24 hours after their preparation using standard sterile techniques in the perioperative space.

Prevalence of Infections After In-Office Hysteroscopy in Premenopausal and Postmenopausal Women.

STUDY OBJECTIVE: To estimate the incidence of infection after diagnostic and operative hysteroscopic procedures performed in an in-office setting with different distension media (saline solution or CO2). DESIGN: Prospective, multicenter, observational study (Canadian Task Force classification II-2). SETTING: Tertiary women's health centers. PATIENTS: A total of 42,934 women who underwent hysteroscopy between 2015 and 2017. INTERVENTIONS: Of the 42,934 patients evaluated, 34,248 underwent a diagnostic intervention and 8686 underwent an operative intervention; 17,973 procedures used CO2 and 24,961 used saline solution as a distension medium. Patients were contacted after the procedure to record postprocedure symptoms suggestive of infection, including 2 or more of the following signs occurring within the 3 weeks after hysteroscopy: fever; lower abdominal pain; uterine, adnexal, or cervical motion tenderness; purulent leukorrhea; vaginal discharge or itchiness; and dysuria. Vaginal culture, clinical evaluation, transvaginal ultrasound, and histological evaluation were completed to evaluate symptoms. MEASUREMENTS AND MAIN RESULTS: Operative hysteroscopies comprised polypectomies (n = 7125; 82.0%), metroplasty (n = 731; 15.0%), myomectomy (n = 378; 7.8%), and tubal sterilization (n = 194; 4.0%). Twenty-five of the 42,934 patients (0.06%) exhibited symptoms of infection, including 24 patients (96%) with fever, 11 (45.8%) with fever as a single symptom, 7 (29.2%) with fever with pelvic pain, and 10 (41.7%) with fever with dysuria. In 5 patients with fever and pelvic pain, clinical examination and transvaginal ultrasound revealed monolateral or bilateral tubo-ovarian abscess. In these patients, histological examination from surgical specimens revealed the presence of endometriotic lesions. CONCLUSION: The present study suggests that routine antibiotic prophylaxis is not necessary before hysteroscopy because the prevalence of infections following in-office hysteroscopy is low (0.06%).

Magnetic Induction Spectroscopy for Biomass Measurement: A Feasibility Study.

BACKGROUND: Biomass measurement and monitoring is a challenge in a number of biotechnology processes where fast, inexpensive, and non-contact measurement techniques would be of great benefit. Magnetic induction spectroscopy (MIS) is a novel non-destructive and contactless impedance measurement technique with many potential industrial and biomedical applications. The aim of this paper is to use computer modeling and experimental measurements to prove the suitability of the MIS system developed at the University of South Wales for controlled biomass measurements. METHODS: The paper reports experimental measurements conducted on saline solutions and yeast suspensions at different concentrations to test the detection performance of the MIS system. The commercial electromagnetic simulation software CST was used to simulate the measurement outcomes with saline solutions and compare them with those of the actual measurements. We adopted two different ways for yeast suspension preparation to assess the system's sensitivity and accuracy. RESULTS: For saline solutions, the simulation results agree well with the measurement results, and the MIS system was able to distinguish saline solutions at different concentrations even in the small range of 0-1.6 g/L. For yeast suspensions, regardless of the preparation method, the MIS system can reliably distinguish yeast suspensions with lower concentrations 0-20 g/L. The conductivity spectrum of yeast suspensions present excellent separability between different concentrations and dielectric dispersion property at concentrations higher than 100 g/L. CONCLUSIONS: The South Wales MIS system can achieve controlled yeast measurements with high sensitivity and stability, and it shows promising potential applications, with further development, for cell biology research where contactless monitoring of cellular density is of relevance.

Microfluidic Microwave Sensor for Detecting Saline in Biological Range.

A device for measuring biological small volume liquid samples in real time is appealing. One way to achieve this is by using a microwave sensor based on reflection measurement. A prototype sensor was manufactured from low cost printed circuit board (PCB) combined with a microfluidic channel made of polymethylsiloxane (PDMS). Such a sensor was simulated, manufactured, and tested including a vacuum powered sample delivery system with robust fluidic ports. The sensor had a broad frequency band from 150 kHz to 6 GHz with three resonance frequencies applied in sensing. As a proof of concept, the sensor was able to detect a NaCl content of 125 to 155 mmol in water, which is the typical concentration in healthy human blood plasma.

Exosome Isolation: Cyclical Electrical Field Flow Fractionation in Low-Ionic-Strength Fluids.

The influence of buffer substitution and dilution effects on exosome size and electrophoretic mobility were shown for the first time. Cyclical electrical field flow fractionation (Cy-El-FFF) in various substituted fluids was applied to exosomes and other particles. Tested carrier fluids of deionized (DI) water, 1× phosphate buffered saline (PBS), 0.308 M trehalose, and 2% isopropyl alcohol (IPA) influenced Cy-El-FFF-mediated isolation of A375 melanoma exosomes. All fractograms revealed a crescent-shaped trend in retention times with increasing voltage with the maximum retention time at ∼1.3 V AC. A375 melanoma exosome recovery was approximately 70-80% after each buffer substitution, and recovery was independent of whether the sample was substituted into 1× PBS or DI water. Exosome dilution in deionized water produced a U-shaped dependence on electrophoretic mobility. The effect of dilution using 1× PBS buffer revealed a very gradual change in electrophoretic mobility of exosomes from ∼-1.6 to -0.1 µm cm/s V, as exosome concentration was decreased. This differed from the use of DI water, where a large change from ∼-5.5 to -0.1 µm cm/s V over the same dilution range was observed. Fractograms of separated A375 melanoma exosomes in two substituted low-ionic-strength buffers were compared with synthetic particle fractograms. Overall, the ability of Cy-El-FFF to separate exosomes based on their size and charge is a highly promising, label-free approach to initially catalogue and purify exosome subtypes for biobanking as well as to enable further exosome subtype interrogations.

Insidious Harm of Medication Diluents as a Contributor to Cumulative Volume and Hyperchloremia: A Prospective, Open-Label, Sequential Period Pilot Study.

OBJECTIVES: Although the potential dangers of hyperchloremia from resuscitation fluids continue to emerge, no study to date has considered the contribution of medication diluents to cumulative volume and hyperchloremia. This study compares saline versus dextrose 5% in water as the primary medication diluent and the occurrence of hyperchloremia in critically ill patients. DESIGN: Prospective, open-label, sequential period pilot study. SETTING: Medical ICU of a large academic medical center. PATIENTS: Adult patients admitted to the medical ICU were eligible for inclusion. Patients who were admitted for less than 48 hours, less than 18 years old, pregnant, incarcerated, or who had brain injury were excluded. INTERVENTIONS: Saline as the primary medication diluent for 2 months followed by dextrose 5% in water as the primary medication diluent for 2 months. MEASUREMENTS AND MAIN RESULTS: A total of 426 patients were included, 216 in the saline group and 210 in the dextrose 5% in water group. Medication diluents accounted for 63% of the total IV volume over the observation period. In the saline group, 17.9% developed hyperchloremia compared with 10.5% in the dextrose 5% in water group (p = 0.037), which was statistically significant in multivariable analysis (odds ratio, 0.50; 95% CI, 0.26-0.94; p = 0.031). In the saline group, 34.2% developed acute kidney injury versus 24.5% in the dextrose 5% in water group (p = 0.035); however, this was not statistically significant when adjusting for baseline covariates. No other significant differences in dysnatremias, insulin requirements, glucose control, ICU length of stay, or ICU mortality were observed. CONCLUSIONS: This study identified that medication diluents contribute substantially to the total IV volume received by critically ill patients. Saline as the primary medication diluent compared with dextrose 5% in water is associated with hyperchloremia, a possible risk factor for acute kidney injury.