The rate of polymerization of rabbit skeletal muscle actin is enhanced by polyethylene glycol

Summary The effect of polyethylene glycol on the kinetics of actin polymerization was determined by monitoring the enhancement in the fluorescence of pyrenyl-labelled actin. The polymerization of actin at 15 mM KCl was in addition followed by viscometry and light scattering. All three methods showed that the overall rate of polymerization of actin increased 3-4-fold when the concentration of polyethylene glycol was increased from 0 to 6% (w w^–1). A further increase in polyethylene glycol concentration to 10% (w w^–1) caused a relatively small contribution to the increase in the rate of polymerization. The enhancement of the overall rate of polymerization by polyethylene glycol was also reflected in a significant decrease in the lag time observed when the time course of polymerization was followed by viscometry and light scattering. The steady-state value of fluorescence enhancement and critical concentration of actin were also influenced by polyethylene glycol and the results showed that the extent of polymerization was increased by an increase in the concentration of polyethylene glycol in solution. The effect of polyethylene glycol on both rate and extent of polymerization persisted at physiological salt concentration (150mm KCl, 2mm MgCl₂). Since the rate of elongation was affected only to a small extent by polyethylene glycol, we propose that its main effect is on nucleation.     

Penile Gangrene and Urethrocutaneous Fistula Following Transurethral Resection of Prostatic Carcinoma. A Case Report

Channel transurethral resection of prostate (TURP) is an accepted treatment for advanced carcinoma of prostate (CaP) to improve quality of life. We are presenting a case of penile gangrene and urethrocutaneous fistula following TURP in a CaP. This is the first case in literature to our knowledge.     

Bone tissue engineering in oral peri‐implant defects in preclinical in vivo research: A systematic review and meta‐analysis

The regeneration and establishment of osseointegration within oral peri‐implant bone defects remains a clinical challenge. Bone tissue engineering (BTE) is emerging as a promising alternative to autogenous and/or biomaterial‐based bone grafting. The objective of this systematic review was to answer the focused question: in animal models, do cell‐based BTE strategies enhance bone regeneration and/or implant osseointegration in experimental peri‐implant defects, compared with grafting with autogenous bone or only biomaterial scaffolds? Electronic databases were searched for controlled animal studies reporting on peri‐implant defects and implantation of mesenchymal stem cells (MSC) or other cells seeded on biomaterial scaffolds, following Preferred Reporting Items for Systematic reviews and Meta‐Analyses (PRISMA) guidelines. Random effects meta‐analyses were performed for the outcomes histomorphometric bone area fraction (BA) and bone‐to‐implant contact (BIC). Nineteen studies reporting on large animal models (dogs and sheep) were included. Experimental defects were created surgically (16 studies) or via ligature‐induced peri‐implantitis (LIPI, three studies). In general, studies presented with an unclear to high risk of bias. In most studies, MSC were used in combination with alloplastic mineral phase or polymer scaffolds; no study directly compared cell‐loaded scaffolds vs. autogenous bone. In three studies, cells were also modified by ex vivo gene transfer of osteoinductive factors. The meta‐analyses indicated statistically significant benefits in favour of: (a) cell‐loaded vs. cell‐free scaffolds [weighted mean differences (WMD) of 10.73–12.30% BA and 11.77–15.15% BIC] in canine surgical defect and LIPI models; and (b) gene‐modified vs. unmodified cells (WMD of 29.44% BA and 16.50% BIC) in canine LIPI models. Overall, heterogeneity in the meta‐analyses was high (I² 70–88%); considerable variation was observed among studies regarding the nature of cells and scaffolds used. In summary, bone regeneration and osseointegration in peri‐implant defects are enhanced by the addition of osteogenic cells to biomaterial scaffolds. Although the direction of treatment outcome is clearly in favour of BTE strategies, due to the limited magnitude of treatment effect observed, no conclusive statements regarding the clinical benefit of such procedures for oral indications can yet be made. Copyright © 2017 John Wiley & Sons, Ltd.     

Adherence to evidence-based guidelines for heart failure in physicians and their patients: lessons from the Heart Failure Adherence Retention Trial (HART)

The Heart Failure Adherence and Retention Trial (HART) provided an opportunity to determine adherence to evidence-based guidelines (EBG) in patients with heart failure (HF). Ten hospitals were the source of 692 patients with HF (EF < 40%). Physicians of patients with HF were classified as adherent to EBG if the patient chart audit showed they were on a beta-blocker, ACE-inhibitor (ACE-I), or angiotensin receptor blocker (ARB). Patients were classified as adherent to EBG if MEMS pill caps were used appropriately more than 80% of the time. Sixty-three percent of physicians prescribed evidence-based medications that were adherent to clinical practice guidelines. New York Heart Association (NYHA) III patients were less likely to be adherent (P < 0.001), as were those with renal disease (P < 0.001) and asthmatics (P < 0.001). Nonadherent physicians were less likely to treat patients with beta-blockers (39% vs 98%, P < 0.001) and ACE-I or ARBs (71% vs 98% P < 0.001). Thirty-seven percent of patients prescribed evidence-based therapy failed to use the MEMS pill cap bottles appropriately and were more likely a minority or higher NYHA class. Adherence to evidence-based therapy is less than optimal in HF patients based on a combination of both physician and patient nonadherence.     

Neurovascular protection by targeting early blood–brain barrier disruption with neurotrophic factors after ischemia–reperfusion in rats

The ‘new penumbra'' concept imbues the transition between injury and repair at the neurovascular unit with profound implications for selecting the appropriate type and timing of neuroprotective interventions. In this conceptual study, we investigated the protective effects of pigment epithelium-derived factor (PEDF) and compared them with the properties of epidermal growth factor (EGF) in a rat model of ischemia–reperfusion injury. We initiated a delayed intervention 3 hours after reperfusion using equimolar amounts of PEDF and EGF. These agents were then administered intravenously for 4 hours following reperfusion after 1 hour of focal ischemia. Magnetic resonance imaging indices were characterized, and imaging was performed at multiple time points post reperfusion. PEDF and EGF reduced lesion volumes at all time points as observed on T₂-weighted images (T₂-LVs). In addition PEDF selectively attenuated lesion volume expansion at 48 hours after reperfusion and persistently modulated blood–brain barrier (BBB) permeability at all time points. Intervention with peptides is suspected to cause edema formation at distant regions. The observed T₂-LV reduction and BBB modulation by these trophic factors is probably mediated through a number of diverse mechanisms. A thorough evaluation of neurotrophins is still necessary to determine their time-dependent contributions against injury and their modulatory effects on repair after stroke.     

Laboratory aspects of zirconia restorations

Zirconia restorations are now accepted and commonly prescribed in dentistry. However, these materials undergo hydrothermal ageing which can reduce their clinical performance. Appropriate handling is essential to limit the restorations' susceptibility to low temperature degradation/ageing. Through appropriate clinical prescribing and laboratory manufacture, an aesthetic, strong and long-lasting restoration can be fabricated. Clinical Relevance: This article will inform the reader about zirconia as a dental material as well as how best to handle a zirconia restoration.