Titrimetric method for determination of O-desulfated heparin in physiological samples using protamine-sensitive membrane electrode as endpoint detector

Dose Escalation Trial of Desulfated Heparin (ODSH) in Septic Peritonitis

Objective

Septic peritonitis is associated with significant morbidity and mortality. As a potential therapeutic agent in the treatment of sepsis, 2-O, 3-O desulfated heparin (ODSH) reduces histones and platelet factor 4 (PF4) in mouse sepsis models. This pilot clinical trial evaluated the safety and effect of ODSH in client-owned dogs with septic peritonitis.

Interventions

In an IACUC-approved, open-label, prospective, dose-escalation clinical trial in 6 dogs with spontaneous septic peritonitis, ODSH administration was initiated following surgical explore to achieve source control. Acute patient physiology and laboratory evaluation (APPLE_fast and APPLE_full) scores on admission, source of septic peritonitis, requirement for vasopressors, the administration of blood products, and survival to discharge were recorded. Platelet count, cell free DNA (cfDNA) concentration, and platelet factor 4 (PF4) concentrations were measured at the time of each ODSH dosage. A dose of ODSH was administered every 8 hs for a total of 4 doses (maximum total dosage 75 mg/kg) based on a pre-determined escalation protocol. Patients were monitored in the ICU following administration for evidence of clinical hemorrhage.

Main Results

The mean APPLE_fast and APPLE_full scores on admission were 22 +/- 6 and 32 +/-10, respectively. Four dogs received 4 total dosages of ODSH and 2 dogs received 3 total dosages of ODSH intravenously. The mean total dosage of ODSH administered during the study period was 48.3 +/- 21.6 mg/kg. No dog required dose de-escalation or had any evidence of bleeding. Four dogs survived to discharge.

Conclusions

No adverse effects of ODSH administration were documented in dogs with septic peritonitis. A randomized controlled trial is necessary to evaluate ODSH as a novel therapeutic in the treatment of septic peritonitis.

Detecting Levels of Polyquaternium-10 (PQ-10) via Potentiometric Titration with Dextran Sulphate and Monitoring the Equivalence Point with a Polymeric Membrane-Based Polyion Sensor

Polymeric quaternary ammonium salts (polyquaterniums) have found increasing use in industrial and cosmetic applications in recent years. More specifically, polyquaternium-10 (PQ-10) is routinely used in cosmetic applications as a conditioner in personal care product formulations. Herein, we demonstrate the use of potentiometric polyion-sensitive polymeric membrane-based electrodes to quantify PQ-10 levels. Mixtures containing both PQ-10 and sodium lauryl sulfate (SLS) are used as model samples to illustrate this new method. SLS is often present in cosmetic samples that contain PQ-10 (e.g., shampoos, etc.) and this surfactant species interferes with the polyion sensor detection chemistry. However, it is shown here that SLS can be readily separated from the PQ-10/SLS mixture by use of an anion-exchange resin and that the PQ-10 can then be titrated with dextran sulphate (DS). This titration is monitored by potentiometric polyanion sensors to provide equivalence points that are directly proportional to PQ-10 concentrations.

Quantitative determination of fucoidan using polyion-sensitive membrane electrodes

The use of polyanion and polycation-sensitive membrane electrodes to detect five different preparations of fucoidan is described. Unlike linear polyanionic molecules previously measured with polymer membrane-based electrochemical sensors, fucoidans from marine brown algae are all highly branched, sulfated polysaccharides with varying charge densities and structures, depending on the species of seaweed, method of extraction used and extent of purification. When tridodecylmethylammonium (TDMA) was used as the ion-exchanger, a large, non-equilibrium EMF response was observed over a concentration range of 0.5-50 μg mL(-1) fucoidan. Fucoidan was also measured by titration with polycationic protamine, using a dinonylnaphthalene sulfonate (DNNS)-doped membrane electrode as the potentiometric endpoint detector. Potentiometric titration was used to determine the binding ratio between protamine and fucoidan at the neutralization endpoint for each fucoidan preparation. This binding ratio was then used to successfully determine the fucoidan content of commercially available nutritional supplements. Fucoidan was also measured in undiluted blood serum, demonstrating that this method may be applicable for measuring fucoidan for clinical applications.

Label-free detection of heparin, streptavidin, and other probes by pulsed streaming potentials in plastic microfluidic channels

In this paper, pulsed streaming potentials generated in plastic microfluidic channels are used for the label-free detection of some model analytes. The microchannels are fabricated with the commodity plastic cyclic olefin copolymer (COC), and the detection signal arises from a change in the surface charge upon analyte adsorption on the modified microchannel surface. The role of the surface modification is to confer the microchannel with a predetermined charge and a particular specificity toward the adsorption of the target analyte. In this work, several target probes displaying different levels of specificity were investigated. Heparin and streptavidin were detected by adsorption on microchannel surfaces modified with protamine and biotin, respectively, whereas bovine serum albumin (BSA) and methylene blue (MB) showed nonspecific adsorption on almost any modified or unmodified COC microchannel surface. The magnitude of the streaming potential was found to be proportional to the liquid pressure and the surface charge of the microchannel in accord with the Smoluchowski equation. Because the relative polarity of the streaming potential is determined by the surface charge, the most straightforward detection with this method occurs when the charge is reversed upon analyte adsorption. This strategy was used for the species described in this work, and the lowest concentrations detected were approximately 0.01 units/mL for heparin (below clinical relevance), approximately 10 (-9) M for BSA, and approximately 10 (-6) M for MB. Unlike the conventional method of steady flow, in this work, the streaming potentials were measured under pulsed conditions of flow and using nonreference electrodes. This approach removes the need of special electrolytes as it is usually required when using reference electrodes, and at the same time, it mitigates the interference of electrochemical drift from the electrodes. Relative standard deviations of approximately 1-2% and measuring times of approximately 10 s are readily attained with this experimental setup. The on-channel modification of the surface was carried out by UV-photografting methods given the significant UV transparency of COC.