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Biomedical subjects

M Markowicz

Publications and source records attributed to M Markowicz.

9 recordsLinked to original sources
PubMed2006

Long-term nipple shrinkage following augmentation by an autologous rib cartilage transplant in free DIEP-flaps.

Aesthetically pleasing nipple-areola reconstruction is a satisfying part of a two-stage breast reconstruction. The up to 50% [Banducci DR, Le TK, Hughes KC. Long-term follow-up of a modified Anton-Hartrampf nipple reconstruction. Ann Plast Surg 1999;43(5):467-9; discussion 469-70] postoperative shrinkage following a conventional nipple reconstruction is a well-known problem. Augmentation of the nipple with autologous banked cartilage seems to be a promising solution. From 2000-2003, 17 patients underwent a nipple-areola-complex reconstruction following secondary breast reconstruction using free perforator flaps. The rib cartilage harvested during the preparation of the internal thoracic vessels was banked subcutaneously and six months later replanted under the 'arrow flap' after contouring it in a 'mushroom' shape. One year later the shrinkage of the nipple in comparison to the intraoperative status was measured. In addition, patients were asked about their personal palpation impression and the aesthetic outcome. The average height decreased one year postoperatively about 25%. Thirteen of 17 patients judged the aesthetic outcome as very good, 16 nipples healed without cartilage protrusion and no patient felt discomfortable stiffness of the nipple. Our concept of a nipple augmentation with rib cartilage improves the projection and allows a more correct judgement of the later nipple shrinkage. We consider this technique to be an aesthetically satisfying and safe method, which could be used with any kind of breast reconstruction.

Cartilage↗
PubMed2006

The impact of vacuum freeze-drying on collagen sponges after gas plasma sterilization.

The sterilization of porous collagen sponges remains a challenging procedure. Gamma irradiation denatures collagen, resulting in dramatic changes to its structure. Ethylene oxide leaves toxic residues requiring weeks to evaporate. This study investigated the impact on cell behavior of gas plasma treatment when combined with vacuum freeze-drying. The goal of this procedure is to eliminate the molecules of hydrogen peroxide remaining after the sterilization process, together with their decomposition products, from the scaffolds. These molecules hinder the immediate use of the porous designs. Collagen and EDC/NHS-heparinized collagen scaffolds were sterilized with gas plasma. H2O2 released by the collagen specimens was measured by peroxidase test both immediately and also 1 week after the plasma treatment. Further measurements were done 24, 36, 48 and 72 h after vacuum freeze-drying. The activity of these scaffolds was further evaluated in relation to the proliferation, migration and differentiation of human umbilical vein endothelial cells (HUVECs). Both immediately after exposure to gas plasma and also 1 week later, the collagen designs contained significantly higher concentrations of H2O2 than scaffolds having also undergone vacuum freeze-drying. This procedure achieved faster decontamination of the remaining H2O2. Following vacuum freeze-drying, sponges already allowed HUVEC proliferation after 48 h, but in non-lyophilized specimens after gas plasma treatment alone, cell death occurred as early as only 1 week later. These data highlight the advantages of carrying out vacuum freeze-drying following gas plasma sterilization. The results show the substantial impact of sterilization of porous materials made for tissue engineering.

Animals↗
PubMed2005

Effects of modified collagen matrices on human umbilical vein endothelial cells.

The most commonly used biomaterials fail to ensure sufficient angiogenesis for fast in vivo incorporation. This results in central necrosis and consequent infection. One way of obtaining a high angiogenic response is the application of vascular endothelial growth factor (VEGF). To obtain a sustained release of these cytokines, heparin was incorporated into collagen matrices using 1-ethyl-3(3-dimethyl-aminopropyl) carbodiimide (EDC) and N-hydroxysuccinmide (NHS). The functionality of the heparinized collagen matrices was then enhanced by immobilization of VEGF via its heparin-binding domain. This procedure changed in vitro degradation behavior and water-binding capacity. Accelerated endothelial cell proliferation was also achieved. A range of different heparin and EDC/NHS concentrations in combination with VEGF induced variation in endothelial cell growth and tubulogenic formation. Polymerized collagen scaffolds presented biointeractive systems with integrated angiogenic activity. This may become a useful tool in the clinical therapy of disorders connected with wound healing.

Cell Proliferation↗
PubMed1993

Her-2/neu expression in node-negative breast cancer: direct tissue quantitation by computerized image analysis and association of overexpression with increased risk of recurrent disease.

The HER-2/neu proto-oncogene (also known as c-erb B-2) is homologous with, but distinct from, the epidermal growth factor receptor. Amplification of this gene in node-positive breast cancers has been shown to correlate with both earlier relapse and shorter overall survival. In node-negative breast cancer patients, the subgroup for which accurate prognostic data could make a significant contribution to treatment decisions, the prognostic utility of HER-2/neu amplification and/or overexpression has been controversial. The purpose of this report is to address the issues surrounding this controversy and to evaluate the prognostic utility of overexpression in a carefully followed group of patients using appropriately characterized reagents and methods. In this report we present data from a study of HER-2/neu expression designed specifically to test whether or not overexpression is associated with an increased risk of recurrence in node-negative breast cancers. From a cohort of 704 women with node-negative breast cancer who experienced recurrent disease (relapsed cases) 105 were matched with 105 women with no recurrence (disease-free controls) after the equivalent follow-up period. Immunohistochemistry was used to assess HER-2/neu expression in archival tissue blocks from both relapsed cases and their matched disease-free controls. Importantly, a series of molecularly characterized breast cancer specimens were used to confirm that the antibody used was of sufficient sensitivity and specificity to identify those cancers overexpressing the HER-2/neu protein in this formalin-fixed, paraffin-embedded tissue cohort. In addition, a quantitative approach was developed to more accurately assess the amount of HER-2/neu protein identified by immunostaining tumor tissue. This was done using a purified HER-2/neu protein synthesized in a bacterial expression vector and protein lysates derived from a series of cell lines, engineered to express a defined range of HER-2/neu oncoprotein levels. By using cells with defined expression levels as calibration material, computerized image analysis of immunohistochemical staining could be used to determine the amount of oncoprotein product in these cell lines as well as in human breast cancer specimens. Quantitation of the amount of HER-2/neu protein product determined by computerized image analysis of immunohistochemical assays correlated very closely with quantitative analysis of a series of molecularly characterized breast cancer cell lines and breast cancer tissue specimens.(ABSTRACT TRUNCATED AT 400 WORDS)

Biomarkers, Tumor↗
PubMedDate not supplied

Modulation of angiogenic potential of collagen matrices by covalent incorporation of heparin and loading with vascular endothelial growth factor.

One of the prominent shortcomings of matrices for tissue engineering is their poor ability to support angiogenesis. We report here on experiments to enhance the angiogenic properties of collagen matrices. Our aim is to achieve this goal by covalently incorporating heparin into collagen matrices and by physically immobilizing angiogenic vascular endothelial growth factor (VEGF) to the heparin. The immobilization of heparin was performed with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) and N-hydroxysuccinimide (NHS). Carboxyl groups on the heparin are activated to succinimidyl esters, which react with amino functions on the collagen to zero length cross-links. This modification leads--in addition to the incorporation of heparin--to gross changes in in vitro degradation behavior and water-binding capacity. As a first approach to testing angiogenic capabilities, endothelial cells were exposed to nonmodified and heparinized collagen matrices. This exposure leads to an increase in endothelial cell proliferation. The increase can be further enhanced by loading the (heparinized) collagen matrices with VEGF. Evaluation of the angiogenic potential of heparinized matrices was further investigated by exposing them to the chorioallantoic membrane of chicken embryos and to the subcutaneous tissue of rats. Both approaches show that heparinized matrices have substantially increased angiogenic potential. In particular, the loading of heparinized matrices with VEGF invokes a further increase in angiogenic potential. It is apparent that the physical binding of VEGF to heparin allows for a release that is beneficial to angiogenesis. By varying the heparin and EDC/NHS concentrations during the modification process and by varying the loading with VEGF, the angiogenic potential as well as the degradation behavior can be adapted to obtain matrices that fulfill specific angiogenic requirements in the field of tissue engineering.

Animals↗