A prospective pilot study of a novel alemtuzumab target concentration intervention strategy.

Alemtuzumab is used as part of reduced-intensity and reduced-toxicity transplant conditioning regimens for nonmalignant diseases. Prior studies identified an ideal target concentration range of 0.15-0.6 mcg/mL at day 0. However, only 24% of patients fall within this window using standard intermediate dosing. We performed a pilot study of a novel target concentration intervention strategy to target day 0 alemtuzumab concentrations to 0.15-0.6 mcg/mL. Twelve patients received model-informed alemtuzumab dosing of 0.5-0.6 mcg/kg divided over days -14 to -12. Alemtuzumab concentrations were measured, and pharmacokinetic (PK) modeling was performed on day -5 to predict day 0 concentrations. If the day 0 alemtuzumab concentration was predicted to fall below 0.15 mcg/mL, simulations were performed to identify the individual "top-up" dose needed to achieve the target day 0 concentration window. Six (50%) patients achieved day 0 alemtuzumab concentrations between 0.15 and 0.6 mcg/mL (4 received a top-up dose). Five patients had day 0 concentrations above the target window (no top-up doses). One patient had a day 0 concentration below the target range in the presence of anti-alemtuzumab antibodies. A concentration intervention strategy approach to alemtuzumab treatment can successfully target a greater proportion of patients into the ideal therapeutic window. Additional dose-reduction studies are needed to further optimize the initial dosing and achieve target attainment in all patients.

Peroxynitrite and hydrogen peroxide elicit similar cellular stress responses mediated by the Ccp1 sensor protein.

Peroxynitrite [ONOO(H)] is an oxidant associated with deleterious effects in cells. Because it is an inorganic peroxide that reacts rapidly with peroxidases, we speculated that cells may respond to ONOO(H) and H2O2 challenge in a similar manner. We exposed yeast cells to SIN-1, a well-characterized ONOO(H) generator, and observed stimulation of catalase and peroxiredoxin (Prx) activities. Previously, we reported that H2O2 challenge increases these activities in wild-type cells and in cells producing the hyperactive mutant H2O2 sensor Ccp1(W191F) but not in Ccp1-knockout cells (ccp1Δ). We find here that the response of ccp1Δ and ccp1(W191F) cells to SIN-1 mirrors that to H2O2, identifying Ccp1 as a sensor of both peroxides. SIN-1 simultaneously releases (•)NO and O2(•-), which react to form ONOO(H), but exposure of the three strains separately to an (•)NO donor (spermine-NONOate) or an O2(•-) generator (paraquat) mainly depresses catalase or Prx activity, whereas co-challenge with the NONOate and paraquat stimulates these activities. Because Ccp1 appears to sense ONOO(H) in cells, we examined its reaction with ONOO(H) in vitro and found that peroxynitrous acid (ONOOH) rapidly (k2>10(6)M(-1)s(-1)) oxidizes purified Ccp1 to an intermediate with spectral and ferrocytochrome-oxidizing properties indistinguishable from those of its well-characterized compound I formed with H2O2. Importantly, the nitrite released from ONOOH is not oxidized to (•)NO2 by Ccp1(׳)s compound I, unlike peroxidases involved in immune defense. Overall, our results reveal that yeast cells mount a common antioxidant response to ONOO(H) and H2O2, with Ccp1 playing a pivotal role as an inorganic peroxide sensor.

Complications of intrathecal baclofen pump: prevention and cure.

Increasingly, spasticity is managed with surgically implanted Intrathecal Baclofen pumps. Intrathecal Baclofen pump revision surgery unrelated to programmable pump end-of-life is not uncommon, requiring special attention during pre-, intra-, and postoperative management. We aimed to identify and describe complications of Intrathecal Baclofen pump as well as to report avoidance and management of complications. Methods and Materials. Through 2002-2006, at the department of neurosurgery, Henry Ford and Oakwood Health Systems, Intrathecal Baclofen pumps were implanted in 44 patients: 24 children versus 20 adults; 30 "primary-implant-patients"; 14 "revision-only patients". We evaluated reasons for revision surgeries and diagnostic workup requirements. Results. Eight primary-implant-patients required 14 revisions and 7 of revision-only patients needed 13 procedures. Seven patients with slowly increasing baclofen-resistant spasticity had either (i) unsuspected pump-catheter connector defects, (ii) an X-ray-documented pump-catheter connector defect, (iii) X-ray-demonstrated fractured catheter with intrathecal fragment. Implant infections occurred in 4 cases. Scintigraphy revealed occult CSF leakage N=1 and intrinsic pump failure N=1. Conclusion. Intrathecal Baclofen pumps, although very gratifying, have a high, technique-related complication incidence during implant life. Meticulous technique, high clinical suspicion, appropriate workup, and timely surgical management can reduce surgical complications of Intrathecal Baclofen pump implantation.