Electron Beam-Modified Collagen Type I Fibers: Synthesis and Characterization of Mechanical Response

Ten MeV electron beam treatment facilitates a biomimetic introduction of cross-links in collagenous biopolymer systems, modifying their viscoelastic properties, mechanical stability, and swelling behavior. For reconstituted collagen type I fibers, electron-induced cross-linking opens up new perspectives regarding future biomedical applications in terms of tissue and ligament engineering. We demonstrate how electron irradiation affects stiffness both in low-strain regimes and in postyield regimes of biocompatible reconstituted rat tail collagen type I fibers. Stress-strain tests show a dose-dependent increase in modulus in the nonlinear elastic response, indicating a central role of induced cross-links in mechanical stability. Environmental scanning electron microscopy after fiber rupture reveals aligned distributed collagen fibril domains under the fiber surface for as-prepared fibers, accompanied by a ductile fracture behavior, whereas, in tensile tests imaged by light microscopy after 10 MeV electron treatment, isotropic network topologies are observed until the occurrence of a brittle type of rupture. Based on the biomimicry of the process, these findings might pave the way for a novel type of synthesis of tailored tendon or ligament substitutes.

Capsule colonoscopy increases uptake of colorectal cancer screening

BACKGROUND

Screening colonoscopy effectiveness is hampered by limited adherence by the general population. The present prospective study was performed to evaluate whether adding capsule colonoscopy to the endoscopic screening options increases uptake.

METHODS

Invitation letters were sent to 2150 persons above the age of 55 insured with a German medical insurance company in the area of Rinteln, Lower Saxony with a baseline spontaneous annual screening colonoscopy uptake of 1 %. Both capsule or conventional colonoscopy were offered. Interested persons were given information about the two screening options by four local gastroenterologists and examinations were then performed according to screenees' final choice.

RESULTS

154 persons sought further information, and 34 and 90 underwent conventional and capsule colonoscopy, respectively. Colonoscopy uptake was thus increased by the invitation process by 60 % (1.6 % vs. 1 %; p = 0.075), while the option of capsule endoscopy led to a fourfold increase of screening uptake (4.2 % vs. 1 %, p < 0.001). Despite similar age distribution in both sex groups, uptake in men was significantly higher (5.6 % vs. 2.8 %, p = 002). However, overall adenoma yield was not different in both groups.

CONCLUSIONS

The present study suggests that offering the option of capsule colonoscopy increases uptake of endoscopic colorectal cancer screening. However, capsule endoscopy sensitivity for adenoma detection needs to be improved.

[Optimized CRT programming: relevance and practical application]

Cardiac resynchronization therapy (CRT) can result in significant clinical improvement in patients with congestive heart failure. Non-response to CRT might be attributable to suboptimal programming. Follow-up has to ensure effective left ventricular (LV) stimulation at rest and also sufficient exercise-dependent atrial rates. Rate adaptive pacing is required in case of chronotropic incompetence. Specific algorithms may help to restore biventricular pacing or the enhance biventricular pacing rate when intrinsic AV conduction occurs, e.g., during intermittent atrial fibrillation. An individual adaptation of the AV interval is essential to achieve maximal benefit from resynchronization. Optimized AV interval programming synchronizes atrial and ventricular contraction, maximizing the atrial contribution to LV diastolic filling and preventing presystolic mitral regurgitation. Interventricular synchrony and LV contraction might be further harmonized by VV interval adaptation, although the impact of VV optimization on CRT outcome is still under debate. Non-invasive methods of AV and VV interval optimization by electro- and echocardiography are discussed.