Efficient factor VIII affinity purification using a small synthetic ligand

Summary.  Background:  Hemophilia A is currently treated by infusions of the coagulation factor (F) VIII, of which production and purification remain a challenging task. Current purification procedures using immunoaffinity chromatography are cumbersome, expensive, and suffer from the instability of the applied antibody ligands, which elute along with the product and contaminate it. Recently, FVIII was purified using octapeptide ligands, but their use is limited due to the low resistance to proteases. Objective:  Our goal was to develop and evaluate a novel ligand for FVIII purification, overcoming the drawbacks of current procedures. Methods:  Peptide ligands were screened for binding of ¹²⁵I-plasma-derived-FVIII (pdFVIII) in a microbead assay. A selected ligand-coated Toyopearl resin was then used for pdFVIII purification from cell-conditioned Delbucco's modified Eagle's medium (DMEM) containing fetal bovine serum. The proteolytic stability of ligand was measured by incubating with human serum and proteinase K, and its cytotoxicity towards human OV-MZ-6 cells was assayed. Results:  A high-affinity octapeptidic FVIII ligand was modified into the small, highly stable and non-toxic peptidomimetic ligand L4 by rational and combinatorial design without affecting its affinity for FVIII. Using ligand L4-coated Toyopearl resin, pdFVIII was isolated from cell-conditioned medium with high purity and 89% column retention after elution with a mild buffer containing 0.6  m NaCl at pH 6.8. Conclusions:  Ligand L4 offers a valuable alternative to antibody-based procedures for laboratory and industrial production. Its synthesis by established solid-phase procedures is straightforward and considerably cheaper than the biotechnological production of antibodies, and safety concerns associated with the use of biological material are overcome.     

An acute pain service improves postoperative pain management for children undergoing selective dorsal rhizotomy

Background: A continuous epidural infusion of morphine is the pain treatment modality for children undergoing selective dorsal rhizotomy (SDR) in our institution. The aim of the study was to evaluate the impact of having an organized acute pain service (APS) on postoperative pain management of these children. Methods: We conducted a retrospective cohort study using anesthetic records and the APS database to compare the postoperative pain management of children undergoing SDR before and after the introduction of the APS at the Montreal Children’s Hospital in April 2001. Ninety‐two consecutive children who had their surgery between January 1997 and July 2006 were included. We collected data regarding postoperative pain, opioid‐induced side effects, complications (sedation, desaturations < 92%), and hospital length of stay. Results: Pain scores were documented more frequently after the implementation of the APS (61% vs 48.5%). Sedation scores were documented only after the implementation of the APS. Postoperative desaturation was significantly more frequent in the pre‐APS group compared to the APS group (45.5% vs 6.8%, P < 0.001). Despite the fact that the epidural catheter was in place for the same duration for both groups [median of 3 days (3–3 25–75%ile)], the duration of hospitalization was 1 day shorter in the APS group compared to the pre‐APS group [median of 5 (5–5 25–75%ile) vs 6 (5–6 25–75%ile) days, P < 0.001]. Conclusions: Although we recognize that it is possible that there were changes in care not related specifically to the introduction of a dedicated APS that occurred in our institution that resulted in improvements in general postoperative care and in length of stay, our study did show that having an organized APS allowed to significantly decrease the incidence of postoperative oxygen desaturation and to decrease the hospital length of stay by 1 day.     

Performance of Implantable Cardiac Rhythm Management Devices

Our data represent use, follow-up, and management decisions from seven independently functioning centers and most importantly, actuarial survival of ICRMDs that have been implanted for sufficient time period to allow assessment of time versus failure. General patterns of possible target durations for adequate performance for present or future generations of similar clinical devices may be suggested by the data that we have presented. However, it would be inappropriate to conclude from these data that any presently implanted ICRMD would have a particular functional reliability. These data, furthermore, only summarized device hardware performance and cannot and must not be used to determine either short-term or long-term individual patient status, management, or outcome.     

Normal Electrophysiological Findings in a Patient with Symptomatic Intermittent Advanced Atrioventricular Block

This report describes an otherwise healthy young woman who presented with syncope during episodes of advanced atriovenlricular (A V) block. The His bundle recordings during normal sinus rhythm and atrial and ventricular pacing were normal. Carotid sinus massage produced no abnormality. Subsequently, (he patient received a permanent pacemaker and has been free of symptoms. In termittent advanced A V block has been observed on follow-up electrocardiograms. This unique case demonstrates a potential limitation of routine electrophysiologic investigation.