Investigations into the polymorphism of rat tail tendon fibrils using atomic force microscopy

Collagen type I displays a typical banding periodicity of 67 nm when visualized by atomic force or transmission electron microscopy imaging. We have investigated collagen fibers extracted from rat tail tendons using atomic force microscopy, under different ionic and pH conditions. The majority of the fibers reproduce the typical wavy structure with 67 nm spacing and a height difference between the peak and the grooves of at least 5 nm. However, we were also able to individuate two other banding patterns with 23 +/- 2 nm and 210 +/- 15 nm periodicities. The small pattern showed height differences of about 2 nm, whereas the large pattern seems to be a superposition of the 67 nm periodicity showing height differences of about 20 nm. Furthermore, we could show that at pH values of 3 and below the fibril structure gets dissolved whereas high concentrations of NaCl and CaCl2 could prevent this effect. (C) 2003 Elsevier Science (USA). All rights reserved

Force spectroscopy of collagen fibers to investigate their mechanical properties and structural organization

Tendons are composed of collagen and other molecules in a highly organized hierarchical assembly, leading to extraordinary mechanical properties. To probe the cross-links on the lower level of organization, we used a cantilever to pull substructures out of the assembly. Advanced force probe technology, using small cantilevers (length <20 μm), improved the force resolution into the sub-10 pN range. In the force versus extension curves, we found an exponential increase in force and two different periodic rupture events, one with strong bonds (jumps in force of several hundred pN) with a periodicity of 78 nm and one with weak bonds (jumps in force of <7 pN) with a periodicity of 22 nm. We demonstrate a good correlation between the measured mechanical behavior of collagen fibers and their appearance in the micrographs taken with the atomic force microscope

[Locally recurrent rectal cancer. Our experience].

The aim of this study was to describe the personal experience in the treatment of 31 patients (19 males, 12 females) with local recurrence following surgery for rectal adenocarcinoma. The exeresis of recurrence was possible in 17 patients (6 Miles, 9 Hartmann, 1 re-resection, 1 transanal resection); of these, only 6 patients reported an improvement of the quality of life. Patients surgically treated and patients with recurrence inoperable and submitted to palliative treatment (colostomy, pain control, radio- and/or chemotherapy) showed similar survival rates

Avicholic Acid: A Lead Compound from Birds on the Route to Potent TGR5 Modulators

Grounding on our former 3D QSAR studies, a knowledge-based screen of natural bile acids from diverse animal species has led to the identification of avicholic acid as a selective but weak TGRS agonist. Chemical modifications of this compound resulted in the disclosure of 6 alpha-ethyl-16-epi-avicholic acid that shows enhanced potency at TGRS and FXR receptors. The synthesis, biological appraisals, and structure-activity relationships of this series of compounds are herein described. Moreover, a thorough physicochemical characterization of 6 alpha-ethyl-16-epi-avicholic acid as compared to naturally occurring bile acids is reported and discussed

Toolbox study for application of hydrogen peroxide as a versatile, safe and industrially-relevant green oxidant in continuous flow mode

Hydrogen peroxide embodies an ideal oxidant in terms of atom-economy, availability and green metrics. However, its use has been limited because of risks associated with disproportionation and the exothermic potential of oxidizing reaction mixtures. This study aims to showcase the versatility of hydrogen peroxide in a range of oxidations, while ensuring that such processes operate practically and with a defined and minimized risk. To offset the hazards of using peroxides, continuous-flow equipment was utilized to limit the volume of unquenched peroxides and to maintain process control. A methodological approach was established relying on kinetic and calorimetric understanding. Finally, scalability was highlighted in an organocatalysed heterocyclic N-oxidation using a cascade of stirred tank reactors with nitrogen flushing

Toolbox study for application of hydrogen peroxide as a versatile, safe and industrially-relevant green oxidant in continuous flow mode

Hydrogen peroxide embodies an ideal oxidant in terms of atom-economy, availability and green metrics. However, its use has been limited because of risks associated with disproportionation and the exothermic potential of oxidizing reaction mixtures. This study aims to showcase the versatility of hydrogen peroxide in a range of oxidations, while ensuring that such processes operate practically and with a defined and minimized risk. To offset the hazards of using peroxides, continuous-flow equipment was utilized to limit the volume of unquenched peroxides and to maintain process control. A methodological approach was established relying on kinetic and calorimetric understanding. Finally, scalability was highlighted in an organocatalysed heterocyclic N-oxidation using a cascade of stirred tank reactors with nitrogen flushing

Toolbox study for application of hydrogen peroxide as a versatile, safe and industrially-relevant green oxidant in continuous flow mode

Hydrogen peroxide embodies an ideal oxidant in terms of atom-economy, availability and green metrics. However, its use has been limited because of risks associated with disproportionation and the exothermic potential of oxidizing reaction mixtures. This study aims to showcase the versatility of hydrogen peroxide in a range of oxidations, while ensuring that such processes operate practically and with a defined and minimized risk. To offset the hazards of using peroxides, continuous-flow equipment was utilized to limit the volume of unquenched peroxides and to maintain process control. A methodological approach was established relying on kinetic and calorimetric understanding. Finally, scalability was highlighted in an organocatalysed heterocyclic N-oxidation using a cascade of stirred tank reactors with nitrogen flushing