Comparative effectiveness of a bioengineered living cellular construct vs. a dehydrated human amniotic membrane allograft for the treatment of diabetic foot ulcers in a real world setting

We evaluated the comparative effectiveness of a bioengineered living cellular construct (BLCC) and a dehydrated human amnion/chorion membrane allograft (dHACM) for the treatment of diabetic foot ulcers (DFUs). Using a wound care–specific electronic medical record database, we assessed real‐world outcomes in 218 patients with 226 DFUs receiving treatment in 2014 at 99 wound care centers. The analysis included DFUs ≥1 and <25 cm² with duration <=1 year and area reduction ≤20% in 14 days prior to treatment (N=163, BLCC; N=63, dHACM). The average baseline areas and durations were 6.0 cm² and 4.4 months for BLCC and 5.2 cm² and 4.6 months for dHACM, respectively. Patients treated with dHACM had more applications compared to those treated with BLCC (median 3.0 vs. 2.0) (p=0.003). A Cox model adjusted for key covariates including area and duration found the median time to closure for BLCC was 13.3 weeks compared to 26 weeks for dHACM, and the proportion of wounds healed were significantly higher for BLCC by 12 weeks (48% vs. 28%) and 24 weeks (72% vs. 47%) (p=0.01). Treatment with a bioengineered living cellular technology increased the probability of healing by 97% compared with a dehydrated amniotic membrane (hazard ratio = 1.97 [95% confidence interval 1.17, 3.33], p=0.01).     

Functionally deficient mesenchymal stem cells reside in the bone marrow niche with M2‐macrophages and amyloid‐β protein adjacent to loose total joint implants

We sought to demonstrate whether there is a difference in the local mesenchymal stem cells (MSC) niche obtained from patients undergoing their first total joint replacement surgery versus those patients undergoing a revision surgery for an failing total joint implant. Bone marrow aspirates collected from patients undergoing revision total joint arthroplasty were observed to be less clonal and the expression of PDGFRα, CD51, ALCAM, endoglin, CXCL12, nestin, and nucleostemin were decreased. Revision MSC were also less able to commit to an osteoblast‐lineage or an adipocyte‐lineage. Further, in revision MSC, OPG, and IL6 expression were increased. Monocytes, derived from revision whole marrow aspirates, were less capable of differentiating into osteoclasts, the cells implicated in the pathologic degradation of bone. Osteoclasts were also not observed in tissue samples collected adjacent to the implants of revision patients; however, the alternatatively activated M2‐macrophage phenotype was observed in parallel with pathologic accumulations of amyloid‐β, τ‐protien and 3‐nitrotyrosine. Despite the limited numbers of patients examined, our data suggest that nucleostemin may be a useful functional marker for MSC while the observation of M2‐macrophage infiltration around the implant lays the foundation for future investigation into a novel mechanism that we propose is associated with loose total joint implants. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:615–624, 2014.     

The effect of race and gender on invasive treatment for cardiovascular disease

The purpose of this study was to investigate racial and gender differences in the utilization of invasive procedures for cardiovascular treatment. Medical records data of 3015 patients were abstracted from a Medical System Database from 1999 to 2001. Logit models were used to estimate the adjusted odds in the utilization, referral, and acceptance of invasive procedures, while controllingfor confounders (age, race, sex, comorbidity, disease severity, payer type, marital status and family history) simultaneously. When considering utilization of invasive procedures, the adjusted odds were lower for African-Americans compared to Caucasians. There was a statistically significant difference (p < .05) in Coronary Artery Bypass Graft (CABG) utilization between African Americans and Caucasians. African Americans were less likely than Caucasians to receive a CABG. Although not statistically significant, African-Americans were less likely than Caucasians to receive a cardiac catheterization and Percutaneous Transluminal Coronary Angioplasty (PTCA). Findings failed to yield a statistical significance for gender disparities regarding invasive procedure utilizations.     

Crystal structures of Escherichia coli topoisomerase IV ParE subunit (24 and 43 kilodaltons): a single residue dictates differences in novobiocin potency against topoisomerase IV and DNA gyrase

Topoisomerase IV and DNA gyrase are related bacterial type II topoisomerases that utilize the free energy from ATP hydrolysis to catalyze topological changes in the bacterial genome. The essential function of DNA gyrase is the introduction of negative DNA supercoils into the genome, whereas the essential function of topoisomerase IV is to decatenate daughter chromosomes following replication. Here, we report the crystal structures of a 43-kDa N-terminal fragment of Escherichia coli topoisomerase IV ParE subunit complexed with adenylyl-imidodiphosphate at 2.0-A resolution and a 24-kDa N-terminal fragment of the ParE subunit complexed with novobiocin at 2.1-A resolution. The solved ParE structures are strikingly similar to the known gyrase B (GyrB) subunit structures. We also identified single-position equivalent amino acid residues in ParE (M74) and in GyrB (I78) that, when exchanged, increased the potency of novobiocin against topoisomerase IV by nearly 20-fold (to 12 nM). The corresponding exchange in gyrase (I78 M) yielded a 20-fold decrease in the potency of novobiocin (to 1.0 micro M). These data offer an explanation for the observation that novobiocin is significantly less potent against topoisomerase IV than against DNA gyrase. Additionally, the enzyme kinetic parameters were affected. In gyrase, the ATP K(m) increased approximately 5-fold and the V(max) decreased approximately 30%. In contrast, the topoisomerase IV ATP K(m) decreased by a factor of 6, and the V(max) increased approximately 2-fold from the wild-type values. These data demonstrate that the ParE M74 and GyrB I78 side chains impart opposite effects on the enzyme's substrate affinity and catalytic efficiency.