A tetraspecific VHH-based neutralizing antibody modifies disease outcome in three animal models of Clostridium difficile infection

Clostridium difficile infection (CDI), a leading cause of nosocomial infection, is a serious disease in North America, Europe, and Asia. CDI varies greatly from asymptomatic carriage to life-threatening diarrhea, toxic megacolon, and toxemia. The incidence of community-acquired infection has increased due to the emergence of hypervirulent antibiotic-resistant strains. These new strains contribute to the frequent occurrence of disease relapse, complicating treatment, increasing hospital stays, and increasing morbidity and mortality among patients. Therefore, it is critical to develop new therapeutic approaches that bypass the development of antimicrobial resistance and avoid disruption of gut microflora. Here, we describe the construction of a single heteromultimeric VHH-based neutralizing agent (VNA) that targets the two primary virulence factors of Clostridium difficile, toxins A (TcdA) and B (TcdB). Designated VNA2-Tcd, this agent has subnanomolar toxin neutralization potencies for both C. difficile toxins in cell assays. When given systemically by parenteral administration, VNA2-Tcd protected against CDI in gnotobiotic piglets and mice and to a lesser extent in hamsters. Protection from CDI was also observed in gnotobiotic piglets treated by gene therapy with an adenovirus that promoted the expression of VNA2-Tcd

Hysteresis and the dynamic phase transition in thin ferromagnetic films

Hysteresis and the non-equilibrium dynamic phase transition in thin magnetic films subject to an oscillatory external field have been studied by Monte Carlo simulation. The model under investigation is a classical Heisenberg spin system with a bilinear exchange anisotropy in a planar thin film geometry with competing surface fields. The film exhibits a non-equilibrium phase transition between dynamically ordered and dynamically disordered phases characterized by a critical temperature Tcd, whose location of is determined by the amplitude H0 and frequency w of the applied oscillatory field. In the presence of competing surface fields the critical temperature of the ferromagnetic-paramagnetic transition for the film is suppressed from the bulk system value, Tc, to the interface localization-delocalization temperature Tci. The simulations show that in general Tcd < Tci for the model film. The profile of the time-dependent layer magnetization across the film shows that the dynamically ordered and dynamically disordered phases coexist within the film for T < Tcd. In the presence of competing surface fields, the dynamically ordered phase is localized at one surface of the film.Comment: PDF file, 21 pages including 8 figure pages; added references,typos added; to be published in PR

Dose-adapted post-transplant cyclophosphamide for HLA-haploidentical transplantation in Fanconi anemia.

We developed a haploidentical transplantation protocol with post-transplant cyclophosphamide (CY) for in vivo T-cell depletion (TCD) using a novel adapted-dosing schedule (25 mg/kg on days +3 and +4) for Fanconi anemia (FA). With median follow-up of 3 years (range, 37 days to 6.2 years), all six patients engrafted. Two patients with multiple pre-transplant comorbidities died, one from sepsis and one from sepsis with associated chronic GVHD. Four patients without preexisting comorbidities and early transplant referrals are alive with 100% donor chimerism and excellent performance status. We conclude that adjusted-dosing post-transplant CY is effective in in vivo TCD to promote full donor engraftment in patients with FA

HLA-DPB1 matching status has significant implications for recipients of unrelated donor stem cell transplants.

Studies in unrelated donor (UD) hematopoietic stem cell transplantations (HSCT) show an effect of the matching status of HLA-DPB1 on complications. We analyzed 423 UD-HSCT pairs. Most protocols included T-cell depletion (TCD). All pairs had high-resolution tissue typing performed for 6 HLA loci. Two hundred eighty-two pairs were matched at 10 of 10 alleles (29% were DPB1 matched). In 141 HILA-mismatched pairs, 28% were matched for DPB1. In the 10 of 10 matched pairs (n = 282), the 3-year probability of relapse was 61%. This was significantly higher in DPB1-matched pairs (74%) as compared with DPB1-mismatched pairs (56%) (log rank, P = .001). This finding persisted in multivariate analysis. In the group overall (n = 423), relapse was also significantly increased if DPB1 was matched (log rank; P < .001). These results were similar in chronic myeloid leukemia (CML; P < .001) and acute lymphoblastic leukemia (ALL; P = .013). In ALL, DPB1-matched pairs had a significantly worse overall survival (log rank; P = .025). Thus, in recipients of TCD UD-HSCT, a match for DPB1 is associated with a significantly increased risk of disease relapse, irrespective of the matching status for the other HILA molecules. It is possible that this effect is especially apparent following TCD transplantations and invites speculation about the function of DPB1 within the immune system

Barriers to Pediatric Sickle Cell Disease Guideline Recommendations.

National guidelines recommend that providers counsel all patients with sickle cell anemia about hydroxyurea (HU) therapy and screen children with sickle cell anemia annually for the risk of stroke with transcranial Doppler (TCD). We surveyed a national convenience sample of sickle cell disease clinicians to assess factors associated with low adherence. Adherence was 46% for TCD screening. Low adherence was associated with a lack of outcome expectancy (eg, a belief that there would be poor patient follow-up to TCD testing; P &lt; .05). Adherence was 72% for HU counseling. Practice barriers (eg, lack of support staff or time) and a lack of agreement with HU recommendations were associated with low adherence (P &lt; .05). This study demonstrates that different types of strategies are needed to improve TCD screening (to address follow-up and access to testing) versus HU counseling (to address physician agreement and practice barriers)

Supramolecular Composite Materials from Cellulose, Chitosan, and Cyclodextrin: Facile Preparation and Their Selective Inclusion Complex Formation with Endocrine Disruptors

We have successfully developed a simple one-step method of preparing high-performance supramolecular polysaccharide composites from cellulose (CEL), chitosan (CS), and (2,3,6-tri-O-acetyl)-α-, β-, and γ-cyclodextrin (α-, β-, and γ-TCD). In this method, [BMIm+Cl–], an ionic liquid (IL), was used as a solvent to dissolve and prepare the composites. Because a majority (\u3e88%) of the IL used was recovered for reuse, the method is recyclable. XRD, FT-IR, NIR, and SEM were used to monitor the dissolution process and to confirm that the polysaccharides were regenerated without any chemical modifications. It was found that unique properties of each component including superior mechanical properties (from CEL), excellent adsorption for pollutants and toxins (from CS), and size/structure selectivity through inclusion complex formation (from TCDs) remain intact in the composites. Specifically, the results from kinetics and adsorption isotherms show that whereas CS-based composites can effectively adsorb the endocrine disruptors (polychlrophenols, bisphenol A), their adsorption is independent of the size and structure of the analytes. Conversely, the adsorption by γ-TCD-based composites exhibits a strong dependence on the size and structure of the analytes. For example, whereas all three TCD-based composites (i.e., α-, β-, and γ-TCD) can effectively adsorb 2-, 3-, and 4-chlorophenol, only the γ-TCD-based composite can adsorb analytes with bulky groups including 3,4-dichloro- and 2,4,5-trichlorophenol. Furthermore, the equilibrium sorption capacities for the analytes with bulky groups by the γ-TCD-based composite are much higher than those by CS-based composites. Together, these results indicate that the γ-TCD-based composite with its relatively larger cavity size can readily form inclusion complexes with analytes with bulky groups, and through inclusion complex formation, it can strongly adsorb many more analytes and has a size/structure selectivity compared to that of CS-based composites that can adsorb the analyte only by surface adsorption

Ischemic Stroke in Children and Young Adults with Sickle Cell Disease (SCD) in the Post-STOP Era

Abstract Background: The Stroke Prevention Trial in Sickle Cell Anemia (STOP) and Optimizing Primary Stroke Prevention in Sickle Cell Anemia (STOP 2) established routine transcranial Doppler ultrasound (TCD) screening with indefinite chronic red cell transfusions (CRCT) for children with abnormal TCD as standard of care. To identify children at high-risk of stroke, annual TCD screening is recommended from ages 2 to 16 years, with more frequent monitoring if the result is not normal. A reduction in stroke incidence in children with SCD has been reported in several clinical series and analyses utilizing large hospital databases when comparing rates before and after the publication of the STOP study in 1998. We sought to determine the rate of first ischemic stroke in a multicenter cohort of children who had previously participated in the STOP and/or STOP 2 trials and to determine whether these strokes were screening or treatment failures. Subjects and Methods: Between 1995 and 2005, STOP and STOP 2 (STOP/2) were conducted at 26 sites in the US and Canada. These studies included 3,835 children, ages 2 to 16 y with SCD type SS or S-beta-0-thalassemia. Participation in STOP/2 ranged from a single screening TCD to randomization. STOP 2 also had an observational arm for children on CRCT for abnormal TCD whose TCD had not reverted to normal. The Post-STOP study was designed to follow-up the outcomes of children who participated in one or both trials. 19 of the 26 original study sites participated in Post-STOP, contributing a total of 3,539 (92%) of the STOP/2 subjects. After exit from STOP/2, these children received TCD screening and treatment according to local practices. Data abstractors visited each clinical site and obtained retrospective data from STOP/2 study exit to 2012-2014 (depending on site) including follow-up TCD and brain imaging results, clinical information, and laboratory results. Two vascular neurologists, blinded to STOP/2 status and prior TCD and neuroimaging results, reviewed source records to confirm all ischemic strokes, defined as a symptomatic cerebral infarction; discordant opinions were resolved through discussion. For the first Post-STOP ischemic stroke, prior TCD result and treatment history subsequently were analyzed. Results: Of the 3,539 subjects, follow-up data were available for 2,850 (81%). Twelve children who had a stroke during STOP or STOP2 were excluded from these analyses resulting in data on 2,838 subjects. The mean age at the start of Post-STOP was 10.5 y and mean duration of follow-up after exiting STOP/2 was 9.1 y. A total of 69 first ischemic strokes occurred in the Post-STOP observation period (incidence 0.27 per 100 pt years). The mean age at time of stroke was 14.4±6.2 (median 13.8, range 3.5-28.9) y. Twenty-five of the 69 patients (36%) had documented abnormal TCD (STOP/2 or Post-STOP) prior to the stroke; 15 (60%) were receiving CRCT and 9 (36%) were not (treatment data not available for 1 subject). Among the 44 subjects without documented abnormal TCD, 29 (66%) had not had TCD re-screen in the Post-STOP period prior to the event; 7 of these 29 (24%) were 16 y or older at the start of Post-STOP, which is beyond the recommended screening age. Four of the 44 (9%) patients had inadequate TCD in Post-STOP (1 to 10.7 y prior to event). Six (14%) had normal TCD more than a year before the event (1.2 - 4 y); all but one of these children were younger than 16 y at the time of that TCD. Only 5 (11%) had a documented normal TCD less than 1 year prior to the event. Conclusions: In the Post-STOP era, the rate of first ischemic stroke was substantially lower than that reported in the Cooperative Study of Sickle Cell Disease, prior to implementation of TCD screening. Many (39%) of the Post-STOP ischemic strokes were associated with a failure to re-screen according to current guidelines, while only 11% occurred in children who had had recent low-risk TCD. Among those known to be at high risk prior to stroke, treatment refusal or inadequate treatment may have contributed. While TCD screening and treatment are effective at reducing ischemic stroke in clinical practice, significant gaps in screening and treatment, even at sites experienced in the STOP protocol, remain to be addressed. Closing these gaps should provide yet further reduction of ischemic stroke in SCD. Disclosures No relevant conflicts of interest to declare

Physician attitude, awareness, and knowledge regarding guidelines for transcranial Doppler screening in sickle cell disease.

ObjectiveWe explored factors that may influence physician adherence to transcranial Doppler (TCD) screening guidelines among children with sickle cell disease.MethodsPediatric hematologists, neurologists, and primary care physicians (n = 706) responded to a mailed survey in May 2012 exploring factors hypothesized to influence physician adherence to TCD screening guidelines: physician (internal) barriers and physician-perceived external barriers. Responses were compared by specialty using chi-square tests.ResultsAmong 276 physicians (44%), 141 currently treated children with sickle cell disease; 72% recommend screening. Most primary care physicians (66%) did not feel well informed regarding TCD guidelines, in contrast to neurologists (25%) and hematologists (6%, P &lt; .0001). Proportion of correct answers on knowledge questions was low (13%-35%). Distance to a vascular laboratory and low patient adherence were external barriers to receipt of TCD screening.ConclusionsAdditional research regarding physicians' lack of self-efficacy and knowledge of recommendations could help clarify their role in recommendation of TCD screening