Selective Pick-Up of Increased Iron by Deferoxamine-Coupled Cellulose Abrogates the Iron-Driven Induction of Matrix-Degrading Metalloproteinase 1 and Lipid Peroxidation in Human Dermal Fibroblasts In Vitro: A New Dressing Concept

Using atomic absorption spectrum analysis, we found iron levels in exudates from chronic wounds to be significantly increased (3.71 ± 1.56 µmol per g protein) compared to wound fluids from acute wounds derived from blister fluids (1.15 ± 0.62 µmol per g protein, p < 0.02), drainage fluids of acute wounds (0.87 ± 0.34 µmol per g protein, p < 0.002), and pooled human plasma of 50 volunteers (0.42 µmol per g protein). Increased free iron and an increase in reactive oxygen species released from neutrophils represent pathogenic key steps that – via the Fenton reaction – are thought to be responsible for the persistent inflammation, increased connective tissue degradation, and lipid peroxidation contributing to the prooxidant hostile microenvironment of chronic venous leg ulcers. We herein designed a selective pick-up dressing for iron ions by covalently binding deferoxamine to cellulose. No leakage occurred following gamma sterilization of the dressing and, more importantly, the deferoxamine-coupled cellulose dressing retained its iron complexing properties sufficient to reduce iron levels found in chronic venous ulcers to levels comparable to those found in acute wounds. In order to study the functionality of the dressing, human dermal fibroblasts were exposed to a Fenton reaction mimicking combination of 220 µM Fe(III) citrate and 1 mM ascorbate resulting in a 4-fold induction of matrix-degrading metalloproteinase 1 as determined by a matrix-degrading metalloproteinase 1 specific enzyme-linked immunosorbent assay. This induction was completely suppressed by dissolved deferoxamine at a concentration of 220 µM or by an equimolar amount of deferoxamine immobilized to cellulose. In addition, the Fe(III) citrate and ascorbate driven Fenton reaction resulted in an 8-fold increase in malondialdehyde, the major product of lipid peroxidation, as determined by high pressure liquid chromatography. This increase in malondialdehyde levels could be significantly reduced in the presence of the selective pick-up dressing coupled with deferoxamine suggesting that the deferoxamine dressing, in fact, prevents the development of a damaging prooxidant microenvironment and also protects from unfavorable consequences like matrix-degrading metalloproteinase 1 and lipid peroxide induction

Keratin 14 Cre Transgenic Mice Authenticate Keratin 14 as an Oocyte-Expressed Protein

Summary: Three mouse lines expressing Cre recombinase under the control of the human K14 promoter induced specific deletion of loxP flanked target sequences in the epidermis, in tongue, and thymic epithelium of the offspring where the Cre allele was inherited from the father. Where the mother carried the Cre allele, loxP flanked sequences were completely deleted in all tissues of the offspring, even in littermates that did not inherit the Cre allele. This maternally inherited phenotype indicates that the human K14 promoter is transcriptionally active in murine oocytes and that the enzyme remains active until after fertilization, even when the Cre allele becomes transmitted to the polar bodies during meiosis. Detection of K14 mRNA by RT-PCR in murine ovaries and immunohistochemical identification of the K14 protein in oocytes demonstrates that the human K14 promoter behaves like its murine homolog, thus identifying K14 as an authentic oocytic protein