Standardized procedure prevents perioperative and early complications in totally implantable venous-access ports-a complication analysis of more than 1000 TIVAP implantations.

PURPOSE: Since their invention 40 years ago, totally implantable venous-access ports (TIVAPs) have become indispensable in cancer treatment. The aim of our study was to analyze complications under standardized operative and perioperative procedures and to identify risk factors for premature port catheter explantation. METHODS: A total of 1008 consecutive TIVAP implantations were studied for success rate, perioperative, early, and late complications. Surgical, clinical, and demographic factors were analyzed as potential risk factors for emergency port catheter explantation. RESULTS: Successful surgical TIVAP implantation was achieved in 1005/1008 (99.7%) cases. No intraoperative or perioperative complications occurred. A total of 32 early complications and 88 late complications were observed leading to explantation in 11/32 (34.4%) and 34/88 (38.6%) cases, respectively. The most common complications were infections in 4.7% followed by thrombosis in 3.6%. Parameters that correlated with unplanned TIVAP explantation were gender (port in situ: female 95% vs. male 91%, p = 0.01), underlying disease (breast cancer 97% vs. gastrointestinal 89%, p = 0.004), indication (chemotherapy 95% vs. combination of chemotherapy and parenteral nutrition 64%, p < 0.0001), and type of complication (infection 13.4% vs. TIVAP-related complication 54% and thrombosis 95%, p < 0.0001). CONCLUSION: Standardized operative and perioperative TIVAP implantation procedures provide excellent results and low explantation rate.

Preserving duodenal passage for bone mineralization: Billroth I versus Billroth II reconstruction after partial gastrectomy in growing minipigs.

INTRODUCTION: Recent data in morbid obesity surgery have shown that the Roux-en-Y gastric bypass results in a decrease in bone mass. Therefore, we investigated the impact of duodenal exclusion on bone mineralization in respect to newer duodenal preserving operations in morbid obesity surgery. METHODS: Twelve female minipigs underwent Billroth I (n = 6) or Billroth II (n = 6) reconstruction. Serum parameters were investigated and bone mineral density of the fourth lumbar vertebra was evaluated by quantitative CT scan at monthly intervals over a 1-y period. Calcium absorption was measured as (47)calcium-carbonate at 3-mo intervals. RESULTS: At the end of the study, the cancellous volumetric bone mineral density (cancvBMD) and the cortical volumetric bone mineral density (cortvBMD) were significantly more decreased in Billroth II (BII) than in Billroth I (BI) reconstructed minipigs (371.86 +/- 1.61 versus 386.96 +/- 5.01 mg/cm(3); 402.22 +/- 1.64 versus 410.7 +/- 2.08 mg/cm(3); both P < 0.05). Similar distribution was measured for cancellous and cortical bone mineral content (670.0 +/- 7.5 versus 712.8 +/- 11.3 mg; 682.2 +/- 40.5 versus 717.8 +/- 43.4 mg; both P < 0.05). Medullary and cortical areas were significantly decreased in BII pigs compared with BI pigs. (47)Ca absorption was significantly decreased in BII 3 and 6 mo following the operation, then reached values similar to those in BI animals. CONCLUSION: Exclusion of the duodenum from the passage resulted in impaired mineralization of the axial skeleton due to decreased calcium absorption and impaired vertebral bone volume.

Long-term stable fibrin gels for cartilage engineering.

It is essential that hydrogel scaffold systems maintain long-term shape stability and mechanical integrity for applications in cartilage tissue engineering. Within this study, we aimed at the improvement of a commercially available fibrin gel in order to develop a long-term stable fibrin gel and, subsequently, investigated the suitability of the optimized gel for in vitro cartilage engineering. Only fibrin gels with a final fibrinogen concentration of 25mg/ml or higher, a Ca(2+) concentration of 20mm and a pH between 6.8 and 9 were transparent and stable for three weeks, the duration of the experiment. In contrast, when preparing fibrin gels with concentrations out of these ranges, turbid gels were obtained that shrank and completely dissolved within a few weeks. In rheological characterization experiments, the optimized gels showed a broad linear viscoelastic region and withstood mechanical loadings of up to 10,000 Pa. Bovine chondrocytes suspended in the optimized fibrin gels proliferated well and produced the extracellular matrix (ECM) components glycosaminoglycans and collagen type II. When initially seeding 3 million cells or more per construct (5mm diameter, 2mm thick), after 5 weeks of culture, a coherent cartilaginous ECM was obtained that was homogenously distributed throughout the whole construct. The developed fibrin gels are suggested also for other tissue engineering applications in which long-term stable hydrogels appear desirable.

In vitro and in vivo cartilage engineering using a combination of chondrocyte-seeded long-term stable fibrin gels and polycaprolactone-based polyurethane scaffolds.

The use of either a hydrogel or a solid polymeric scaffold alone is often associated with distinct drawbacks in many tissue engineering applications. Therefore, in this study, we investigated the potential of a combination of long-term stable fibrin gels and polyurethane scaffolds for cartilage engineering. Primary bovine chondrocytes were suspended in fibrin gel and subsequently injected into a polycaprolactone-based polyurethane scaffold. Cells were homogeneously distributed within this composite system and produced high amounts of cartilage-specific extracellular matrix (ECM) components, namely glycosaminoglycans (GAGs) and collagen type II, within 4 weeks of in vitro culture. In contrast, cells seeded directly onto the scaffold without fibrin resulted in a lower seeding efficiency and distinctly less homogeneous matrix distribution. Cell-fibrin-scaffold constructs implanted into the back of nude mice promoted the formation of adequate engineered cartilaginous tissue within the scaffold after 1, 3, and 6 months in vivo, containing evenly distributed ECM components, such as GAGs and collagen. Again, in constructs seeded without fibrin, histology showed an inhomogeneous and, thus, not adequate ECM distribution compared to seeding with fibrin, even after 6 months in vivo. Strikingly, a precultivation for 1 week in vitro elicited similar results in vivo compared to precultivation for 4 weeks; that is, a precultivation for longer than 1 week did not enhance tissue development. The presented composite system is suggested as a promising alternative toward clinical application of engineered cartilaginous tissue for plastic and reconstructive surgery.

Development of volume-stable adipose tissue constructs using polycaprolactone-based polyurethane scaffolds and fibrin hydrogels.

Adipose tissue engineering aims at the restoration of soft tissue defects and the correction of contour deformities. It is therefore crucial to provide functional adipose tissue implants with appropriate volume stability. Here, we investigate two different fibrin formulations, alone or in combination with biodegradable polyurethane (PU) scaffolds as additional support structures, with regard to their suitability to generate volume-stable adipose tissue constructs. Human adipose-derived stem cells (ASCs) were incorporated in a commercially available fibrin sealant as well as a stable fibrin hydrogel previously developed by our group. The composite constructs made from the commercially available fibrin and porous poly(ε-caprolactone)-based polyurethane scaffolds exhibited increased volume stability as compared to fibrin gels alone; however, only constructs using the stable fibrin gels completely maintained their size and weight for 21 days. Adipogenesis of ASCs was not impaired by the additional PU scaffold. After induction with a common hormonal cocktail, for constructs with either fibrin formulation, strong adipogenic differentiation of ASCs was observed after 21 days in vitro. Furthermore, upregulation of adipogenic marker genes was demonstrated at mRNA (PPARγ, C/EBPα, GLUT4 and aP2; qRT-PCR) and protein (leptin; ELISA) levels. Stable fibrin/PU constructs were further evaluated in a pilot in vivo study, resulting in areas of well-vascularized adipose tissue within the implants after only 5 weeks. Copyright © 2013 John Wiley & Sons, Ltd.

Limited nutritional energy supply differentially impairs growth and bone mineralization of the developing lumbar vertebrae in minipigs.

Bone development during puberty and adolescence may influence the later risk of osteoporosis. The aim of this study was to investigate whether the three-dimensional development of the lumbar vertebrae is impaired in terms of bone mineral density and temporal control during the pubertal growth spurt when caloric intake is limited. Two groups of prepubertal female Gottingen minipigs (each n = 6) were fed either ad libitum (free fed) or with reduced food intake (controlled fed) for 12 months using a standard diet. Apparent volumetric bone mineral densities (vBMD) and size of the 4th vertebra were measured by quantitative CT in monthly intervals. The weight of free-fed animals was 29.5 +/- 0.9 kg compared to 25.9 +/- 3.5 kg in the controlled-fed group at the end of the observation period (mean +/- SD; p < 0.05). The maximal cross-sectional area of the 4th vertebra was 148.2 +/- 3.4 mm(2) in free-fed animals compared to 143.1 +/- 6.3 mm(2) in controlled-fed animals (P < 0.05) as both, the cortical and the medullary area were greater in the free-fed group. In contrast, cancellous and cortical bone mineral densities were not different between the two groups; however, maximal densities were reached earlier in the free-fed group. As regards the height of the vertebra, no difference was observed between the groups after 12 months (25.46 +/- 0.54 mm in controlled fed vs. 25.56 +/- 0.45 mm in free fed), although the peak height was reached earlier in the free-fed group. In both groups, the maximal growth rate in the cross-sectional direction was reached earlier compared to the longitudinal direction (both P < 0.05). Growth in the longitudinal direction that occurs in the primary and secondary epiphysis does not appear to depend on caloric intake contrary to the periosteal and endocortical bone generation in the cross-sectional direction. When limited energy is available, the organism seems to preserve the development of normal body height, while accepting reduced strength of the vertebra.

Mating frequency and interspecific matings in some freshwater cyclopoid copepods.

Laboratory investigations with Cyclops vicinus and Metacyclops minutus documented that mating frequency decreased significantly after the initial mating, i.e. re-mating is relatively rare in cyclopoid copepods. Re-mating is unnecessary because females are able to fertilize multiple clutches of viable eggs from one insemination. Similar sized Cyclops vicinus and Cyclops furcifer interbreed frequently. Interbreeding does not occur when size differences and taxonomic differences are as great as between C. vicinus and M. leuckarti. In C. vicinus and M. leuckarti, the duration of the last mating phase (spermatophore transfer until release of the female) and consequently the duration of the entire mating process, is different. I conclude that the low re-mating frequency in cyclopoid copepods probably evolved to accelerate clutch production in unpredictable environments and to reduce predation risk. The occurrence of interspecific mating discourages the co-existence of similarly sized, related species. Mating behaviour may have a considerable influence on zooplankton community structure.

Gas Separation with Polymer Membranes.

Gas-selective polymer membranes have long been used in industrial applications. Studies of polymers with well-defined flexible phenyl ether segments such as 1 should contribute to the understanding of the selection mechanism and thus ultimately lead to the synthesis of optimized membrane materials. Various different bridging groups X were used in the studies.

Nanorings and rods interconnected by self-assembly mimicking an artificial network of neurons.

Molecular electronics based on structures ordered as neural networks emerges as the next evolutionary milestone in the construction of nanodevices with unprecedented applications. However, the straightforward formation of geometrically defined and interconnected nanostructures is crucial for the production of electronic circuitry nanoequivalents. Here we report on the molecularly fine-tuned self-assembly of tetrakis-Schiff base compounds into nanosized rings interconnected by unusually large nanorods providing a set of connections that mimic a biological network of neurons. The networks are produced through self-assembly resulting from the molecular conformation and noncovalent intermolecular interactions. These features can be easily generated on flat surfaces and in a polymeric matrix by casting from solution under ambient conditions. The structures can be used to guide the position of electron-transporting agents such as carbon nanotubes on a surface or in a polymer matrix to create electrically conducting networks that can find direct use in constructing nanoelectronic circuits.

Ontogeny of the Marmorkrebs (marbled crayfish): a parthenogenetic crayfish with unknown origin and phylogenetic position.

Development, growth, and egg production of the Marmorkrebs (marbled crayfish), a crayfish with parthenogenetic reproduction, uncertain geographic origin, and taxonomic position, was studied under laboratory conditions. Length and weight increments strongly depended on temperature being highest at 30 degrees C, and lowest at 15 degrees C. At 25 degrees C, cephalothorax length and weight increased by 17.5 mm and 1700 mg, respectively, in the course of 150 d, whereas at 15 degrees C these parameters increased by only 7 mm and 100 mg during the same period of time. Photoperiod slightly affected growth at 25 degrees C. During growth experiments, mortality was lower at 20 degrees C compared to higher (25 degrees , 30 degrees C) or lower temperatures (15 degrees C), and lower under short-day than under long-day conditions. Females matured early (at an age of 141-255 d, a cephalothorax length of 14-21.5 mm, and a weight of 0.63-2 g) compared to other crayfish species. Reproductive females with a cephalothorax length of between 25-35 mm produced large clutches (up to 416 eggs) and brooding periods varied between 22 and 42 d. In order to establish a staging scheme for Marmorkrebs embryos, embryos were photographed, externally visible ontogenetic events charted, and dissected embryos stained with a nuclear dye. These experiments indicate that their development is virtually identical to that of other crayfish. In conclusion, these results and others show that the Marmorkrebs may be taken as a representative valid model organism for future developmental studies on Crustacea.

Absence of tumor growth stimulation in a panel of 16 human tumor cell lines by mistletoe extracts in vitro.

Extracts of Viscum album (mistletoe) are widely used as complementary cancer therapies in Europe. The mistletoe lectins have been identified as the main active principle of mistletoe extracts. They have been shown to exhibit cytotoxic effects as well as immunomodulatory activities. The latter is exemplified by induction of cytokine secretion and increased activity of natural killer cells. Recent reports, however, indicated possible tumor growth stimulation by mistletoe extracts. Therefore, the three aqueous mistletoe extracts (Iscador M special, Iscador Qu special and Iscador P) were evaluated for antiproliferative and/or stimulatory effects in a panel of 16 human tumor cell lines in vitro using a cellular proliferation assay. The results show no evidence of stimulation of tumor growth by any of the three Iscador preparations, comprising central nervous system, gastric, non-small cell lung, mammary, prostate, renal and uterine cancer cell lines, as well as cell lines from hematological malignancies and melanomas. On the contrary, Iscador preparations containing a high lectin concentration (Iscador M special and Iscador Qu special) showed antitumor activity in the mammary cancer cell line MAXF 401NL at the 15 microg/ml dose level with a more than 70% growth inhibition compared to untreated control cells. In addition, a slight antitumor activity (growth inhibition 30-70%) was found in three tumor cell lines for Iscador M special and in seven tumor cell lines for Iscador Qu special, respectively. Iscador P, which contains no mistletoe lectin I, showed no antiproliferative activity.