AbstractpH-responsive polymers have been synthesised by grafting L-valine , L-leucine and L-phenylalanine onto the pendant carboxylic acid moieties of a pseudo-peptide, poly(Llysine iso-phthalamide), at a stoichiometric degree of substitution of 75 mol%. The effect of such modification on the pH-, concentration-and time-dependent cell membrane-disruptive activity of the grafted polymers has been investigated using a haemolysis model. At 0.025 mg mL −1 , the grafted polymers were almost non-haemolytic at pH 7.4, but mediated considerable membrane lysis after 60 min in the pH range characteristic of early endosomes, which ranked in the order: PP-75 > PL-75 > PV-75 > poly(L-lysine iso-phthalamide). PP-75 was 35-fold more lytic on a molar basis than the membrane-lytic peptide melittin. With increasing concentration, the grafted polymers showed an increased ability to lyse cell membranes and caused noticeable membrane disruption at physiological pH. The mechanism of the polymer-mediated membrane destabilisation has been investigated. The in-vitro cytotoxicity of the grafted polymers has been assessed using a propidium iodide fluorescence assay. It has been demonstrated by confocal microscopy that the grafted polymers can induce a significant release of endocytosed materials into the cytoplasm of HeLa cells, which is a feature critical for drug delivery applications.

Study Design. Retrospective database analysis. Objective. To identify preoperative risk factors for emergency department (ED) visit and unplanned hospital readmission after primary anterior cervical discectomy and fusion (ACDF) at 30 and 90 days. Summary of Background Data. Limited data exist to identify factors associated with ED visit or readmission after primary ACDF within the first 3 months following surgery. Methods. Patients undergoing ACDF from 2005 to 2012 were identified in the Statewide Planning and Research Cooperative System database. Multivariable regression models were created based on patient-level and surgical characteristics to identify independent risk factors for hospital revisit. Results. Of 41,813 patients identified, 2514 (6.0%) returned to the ED within 30 days of discharge. Risk factors included age < 35, black race (OR 1.19), Charlson Comorbidity index score > 1, length of stay (LOS) greater than 1 day (OR 1.23), and fusion of > 2 levels (OR 1.17). Four thousand six hundred nine (11.0%) patients returned to the ED within 90 days. Risk factors mirrored those at 30 days. Patients having private insurance or those discharged to rehab were less likely to present to the ED. One thousand three hundred ninety-four (3.3%) patients were readmitted by 30 days. Risk factors included male sex, Medicare, or Medicaid insurance (OR 1.71 and 1.79 respectively), Charlson comorbidity index > 1, discharge to a skilled nursing facility (OR 2.90), infectious/pathologic (OR 3.296), or traumatic (OR 1.409) surgical indication, LOS > 1 day (OR 1.66), or in-hospital complication. 2223 (5.3%) patients were readmitted by 90 days. Risk factors mirrored those at 30 days. No differences in readmission were seen based on race or number of levels fused. Patients aged 18 to 34 were less likely to be readmitted versus patients older than 35. Conclusion. Insurance status, comorbidities, and LOS consistently predicted an unplanned hospital visit at 30 and 90 days. Although nondegenerative surgical indications and in-hospital complications did not predict ED visits, these factors increased the risk for readmission. Level of Evidence: 3

Context:The rising popularity and intensity of youth sports has increased the incidence of patellar dislocation. These sports-related injuries may be associated with significant morbidity in the pediatric population. Treatment requires understanding and attention to the unique challenges in the skeletally immature patient.Evidence Acquisition:PubMed searches spanning 1970-2013.Study Design:Clinical review.Level of Evidence:Level 5.Results:Although nonoperative approaches are most often suitable for first-time patellar dislocations, surgical treatment is recommended for acute fixation of displaced osteochondral fractures sustained during primary instability and for patellar realignment in the setting of recurrent instability. While a variety of procedures can prevent recurrence, the risk of complications is not minimal.Conclusion:Patellar stabilization and realignment procedures in skeletally immature patients with recurrent patellar dislocation can effectively treat patellar instability without untoward effects on growth if careful surgical planning incorporates protection of growth parameters in the skeletally immature athlete.