A comparison principle for doubly nonlinear parabolic partial differential equations.

In this paper, we derive a comparison principle for non-negative weak sub- and super-solutions to doubly nonlinear parabolic partial differential equations whose prototype is ∂tuq-div(|∇u|p-2∇u)=0inΩT,with q>0 and p>1 and ΩT:=Ω×(0,T)⊂Rn+1. Instead of requiring a lower bound for the sub- or super-solutions in the whole domain ΩT, we only assume the lateral boundary data to be strictly positive. The main results yield some applications. Firstly, we obtain uniqueness of non-negative weak solutions to the associated Cauchy-Dirichlet problem. Secondly, we prove that any weak solution is also a viscosity solution.

Assessment of Multipotent Mesenchymal Stromal Cells in Bone Marrow Aspirate From Human Calcaneus.

Bone marrow aspirates (BMAs), owing to their innate osteogenic potential, are well-documented supplements to osteoconductive and/or osteoinductive materials. The calcaneal body provides foot and ankle surgeons a convenient harvest site with low morbidity and minimal cost. In the present study, we sought to identify and characterize multipotent mesenchymal stromal cells (MSCs) in BMAs harvested from the human calcaneal body. Ten healthy patients aged 18 to 65 years were enrolled in the present study. BMAs were harvested from the patients without any reported postoperative complications related to the harvest. Cells isolated from all the aspirates were adherent to culture plates and expressed positive MSC surface markers (CD105, CD90, and CD73) and a low level of negative MSC markers (CD34 and CD45). The cells maintained the ability to proliferate and differentiate into cells of mesenchymal lineages. The BMAs from the human calcaneal body offer a healthy source of multipotent MSCs.

Calcium phosphate combination biomaterials as human mesenchymal stem cell delivery vehicles for bone repair.

A new class of biomimetic, bioresorbable apatitic calcium phosphate cement (CPC) was recently developed. The handling characteristics, and the ability to harden at body temperature in the presence of physiological saline, make this material an attractive clinical bone substitute and delivery vehicle for therapeutic agents in orthopedic applications. The major challenge with the material is formulating an injectable paste with options for cell delivery, in order to regenerate new bone faster and with high quality. In this study, three different additives and/or viscosity modifiers (carboxymethylcellulose, silk, and alginate) were incorporated into a CPC matrix. Injectability, cell viability, cell proliferation, surface morphology, and gene expression for osteogenesis of hMSCs were all evaluated. Injectable CPC-gel composites with cell protection were achieved. The CPC modified with alginate provided the best results based on cell proliferation, ALP and collagen production, and osteogenic transcript increases (for ALP, type I collagen, BSP, and OP). Furthermore, osteogenic analysis indicated lineage-specific differentiation of hMSCs into osteogenic outcomes. The results suggest that CPC mixed with alginate can be used as a cell delivery vehicle for bone regeneration.

Association between achalasia and nitric oxide synthase gene polymorphisms.

BACKGROUND: Our group previously reported the absence of nitric oxide synthase (NOS) in the gastroesophageal junction of patients with achalasia. NOS exists in three distinct isoforms: neuronal NOS (nNOS), endothelial NOS (eNOS), and inducible isoform (iNOS). Some studies have shown that NO production is regulated by NOS polymorphisms. AIM: To assess whether some functional polymorphisms in the nNOS, iNOS, or eNOS genes are involved in susceptibility to suffer from achalasia. METHODS: Genomic DNA from 80 unrelated Spanish Caucasian patients with sporadic achalasia and 144 healthy subjects matched for age (+/-5 yr) and gender was typed by PCR and RFLP methods for the 27-bp variable number of tandem repeat (VNTR) polymorphism in intron 4 of the eNOS gene, a CA microsatellite repeat and a Nla III (C-->T) restriction fragment length polymorphism (RFLP) in exon 29 of the nNOS gene, and two nucleotide substitutions located in exon 16 (C-->T) and exon 22 (G-->A) of the iNOS gene. RESULTS: No significant differences in carriage, genotype, and allele frequencies of the nNOS, iNOS, or eNOS gene polymorphisms were found between patients with achalasia and controls. Individuals homozygous for genotype iNOS22*A/A tended to be more frequent in achalasia (20%vs 11%, odds ratio [OR] 1.79, 95% confidence interval [CI] 0.89-3.59, p= 0.09) as were those homozygous for the rare eNOS*4a allele (6.2%vs 1.4%, OR 4.5, 95% CI 0.89-22.67, p= 0.1) although the difference did not reach statistical significance. No differences in genotype and allele distribution were found with respect to epidemiological and clinical characteristics of patients with achalasia. CONCLUSION: Our data suggest that NOS gene polymorphisms are not involved in the susceptibility to and nature of the clinical course of sporadic achalasia. However, studies in a greater number of patients are required to analyze the tendency toward a higher prevalence of genotypes iNOS22*A/A and eNOS*4a4a.

Multivariate analysis of ATR-IR spectroscopic data: applications to the solid-liquid catalytic interface.

It is demonstrated that attenuated total reflection infrared (ATR-IR) spectroscopy coupled with multivariate data analysis can be effectively used for in situ investigation of supported catalyst-liquid interfaces. Both formaldehyde adsorption/dissociation in water and acetonitrile adsorption in hexane on thin (ca 10 mum) films of 5 wt % Pt/gamma-Al(2)O(3) deposited on a germanium waveguide have been investigated. The multivariate analysis applies classical least squares (CLS) and partial least squares (PLS) methods to the ATR-IR data in order to correlate spectral changes with known sources of experimental variation (i.e., time, concentration of solution species, etc.). The formaldehyde adsorption experiments revealed no spectroscopic evidence for adsorbed molecular formaldehyde under the conditions examined. However, the dissociation product carbon monoxide was observed to form in atop configuration on Pt, likely on edges and terrace sites. Isotope labeling experiments suggest that a pair of peaks observed at 1990 and 2060 cm(-)(1) during treatments of Pt in H(2)-saturated water arise at least in part from nu(Pt)(-)(H) stretching of adsorbed atomic hydrogen. Acetonitrile was found to adsorb on the Pt catalyst by sigma-bonding of the CN group with the platinum, yielding apparent surface peaks that are almost identical to that observed in the liquid phase. A peak at 1641 cm(-)(1) was observed which was assigned to the adsorption of the CN group in a tilted configuration involving a combination of end-on and pi interaction with the surface. This species was found to be reactive toward hydrogen, suggesting that it might play a role in nitrile hydrogenation. The prospects of using this approach to examine solid-catalyzed liquid-phase reactions are discussed in light of these findings.