Tension of knotted surgical sutures shows tissue specific rapid loss in a rodent model

<p>Abstract</p> <p>Background</p> <p>Every surgical suture compresses the enclosed tissue with a tension that depends from the knotting force and the resistance of the tissue. The aim of this study was to identify the dynamic change of applied suture tension with regard to the tissue specific cutting reaction.</p> <p>Methods</p> <p>In rabbits we placed single polypropylene sutures (3/0) in skin, muscle, liver, stomach and small intestine. Six measurements for each single organ were determined by tension sensors for 60 minutes. We collected tissue specimens to analyse the connective tissue stability by measuring the collagen/protein content.</p> <p>Results</p> <p>We identified three phases in the process of suture loosening. The initial rapid loss of the first phase lasts only one minute. It can be regarded as cutting through damage of the tissue. The percentage of lost tension is closely related to the collagen content of the tissue (r = -0.424; p = 0.016). The second phase is characterized by a slower decrease of suture tension, reflecting a tissue specific plastic deformation. Phase 3 is characterized by a plateau representing the remaining structural stability of the tissue. The ratio of remaining tension to initial tension of phase 1 is closely related to the collagen content of the tissue (r = 0.392; p = 0.026).</p> <p>Conclusions</p> <p>Knotted non-elastic monofilament sutures rapidly loose tension. The initial phase of high tension may be narrowed by reduction of the surgeons' initial force of the sutures' elasticity to those of the tissue. Further studies have to confirm, whether reduced tissue compression and less local damage permits improved wound healing.</p

Magnesium-induzierte Apoptose im Trophoblasten

OBJECTIVE: The application of magnesium during pregnancy is a controversial issue. Beyond evidenced-based indications for the use of magnesium as preeclampsia, numerous dubious indications exist. Anyhow the effect of magnesium on the placenta is little-known. First studies on the topic suggest an apoptosis-inducing effect of magnesium. METHODS: Placental explants from 22 placentas were incubated with extracellular magnesium concentrations from 0 - 2.0 mM. Placental apoptosis was evaluated by tissue morphology, cytokeratin-18 neoepitope formation in immunohistochemistry and Western blotting, TUNEL-Test and DNA-Laddering. RESULTS: Magnesium stimulated a concentration- and time-dependent placental apoptosis. In particular magnesium concentrations over 0.7 mM led to apoptotic changes. After removal of the explants the media with higher extracellular magnesium concentrations displayed apoptotic and aponecrotic fragments and cell-free DNA. CONCLUSION: Magnesium induces apoptosis in the trophoblast. It is known that an increased apoptosis rate is part of the pathogenesis of preeclampsia. Hence, the application of magnesium during pregnancy, especially for preeclampsia, should be considered well and strictly follow evidence-based criteria

Magnesium-induzierte Apoptose im Trophoblasten

OBJECTIVE: The application of magnesium during pregnancy is a controversial issue. Beyond evidenced-based indications for the use of magnesium as preeclampsia, numerous dubious indications exist. Anyhow the effect of magnesium on the placenta is little-known. First studies on the topic suggest an apoptosis-inducing effect of magnesium. METHODS: Placental explants from 22 placentas were incubated with extracellular magnesium concentrations from 0 - 2.0 mM. Placental apoptosis was evaluated by tissue morphology, cytokeratin-18 neoepitope formation in immunohistochemistry and Western blotting, TUNEL-Test and DNA-Laddering. RESULTS: Magnesium stimulated a concentration- and time-dependent placental apoptosis. In particular magnesium concentrations over 0.7 mM led to apoptotic changes. After removal of the explants the media with higher extracellular magnesium concentrations displayed apoptotic and aponecrotic fragments and cell-free DNA. CONCLUSION: Magnesium induces apoptosis in the trophoblast. It is known that an increased apoptosis rate is part of the pathogenesis of preeclampsia. Hence, the application of magnesium during pregnancy, especially for preeclampsia, should be considered well and strictly follow evidence-based criteria