Biomedical subjects

Andreas Greiner

Publications and source records attributed to Andreas Greiner.

22 records · Page 2Linked to original sources

PubMedDate not supplied

The course of the suprascapular nerve in the supraspinatus fossa and its vulnerability in muscle advancement.

Twenty-four cadaveric shoulders were evaluated to assess damage to the suprascapular nerve in relation to Debeyre's advancement of the supraspinatus muscle for rotator cuff repair. In all cases the neurovascular pedicle was tethered at the suprascapular notch and at the periosteum of the supraspinatus fossa. The medial motor branches were directed to the trigonum spinae or the superior angle of the scapula (group 1). The dorsal branches crossed the muscle at the bottom of the supraspinatus fossa (group 2) or directly entered the muscle (group 3). The lateral group remained in the supraspinatus fossa (group 4) or entered the infraspinatus fossa (group 5). The mean distance between the scapular notch and the point of entry of the medial branches into the muscle was 2.9 cm. Branches of group 1 and the main nerve are at risk of injury when detaching muscle from bone. This risk is minimized by subperiosteal detachment. Branches of group 1 are tensioned when advancing the muscle 1 cm laterally.

Cadaver↗

PubMedDate not supplied

Design, synthesis, and properties of new biodegradable aromatic/aliphatic liquid crystalline copolyesters.

Liquid crystalline copolyesters of high molecular weight were obtained by polycondensation of aromatic diols, diacyl dichlorides, oligolactides, and poly(ethylene glycol)s. Hydrophilicity of the copolyesters was controlled by the content of ethyleneoxy moieties as verified by contact angle measurements. Copolyesters with ethyleneoxy moieties showed significant enhancement of degradability under physiological conditions in comparison to copolyester without ethyleneoxy moieties, which makes these copolyesters promising materials for bone tissue engineering as also verified by hardness testing and mechanical testing.

Absorbable Implants↗

PubMedDate not supplied

Hydrolytic and enzymatic degradation of liquid-crystalline aromatic/aliphatic copolyesters.

Aromatic/aliphatic copolyesters containing hydrophilic moieties in the main chain or side chain were synthesized by bulk polycondensation of aromatic monomers without or with solubilizing substituents and aliphatic monomers. Hydrolytic and enzymatic degradation studies were carried out in vitro at 37 degrees C in pH 7.4 phosphate buffer and in Tris-HCl buffer containing proteinase K. The results indicate that liquid-crystalline aromatic/aliphatic copolyesters are degradable hydrolytically as well as enzymatically. The change in composition and morphology of the polyester films were monitored by nuclear magnetic resonance and scanning electron microscopy. The results suggested that aromatic species and aliphatic moieties could be released into aqueous solution during hydrolytic degradation of aromatic/aliphatic copolyesters with ethyleneoxy groups on the side chain. Modifying aromatic species with hydrophilic groups in aromatic/aliphatic copolyesters was an efficient method to improve degradability and biocompatibility due to improved solubility of degradation products in aqueous solution. Mechanical tests indicated that the copolyesters exhibited good mechanical properties prior to degradation, which can be of relevance for bone tissue engineering.

Alkanes↗

PubMedDate not supplied

Poly(vinyl alcohol) nanofibers by electrospinning as a protein delivery system and the retardation of enzyme release by additional polymer coatings.

Protein-loaded (bovine serum albumin (BSA) or luciferase) poly(vinyl alcohol) (PVA) nanofibers were obtained by electrospinning. Poly(p-xylylene) (PPX, also coined as parylene) coated PVA/BSA nanofibers were prepared by chemical vapor deposition (CVD). The release of BSA from PVA nanofibers under physiological conditions was monitored by absorption spectroscopy. Burst release of BSA was noted with uncoated PVA nanofibers. In contrast, PPX-coated nanofibers exhibited a significantly retarded release of BSA depending on the coating thickness of PPX (ranging from 40 to 300 nm). Luciferase was used here as model enzyme, which after electrospinning retained its enzyme activity. This preservation of enzyme activity and the continuous release of the intact enzyme from the immersed fibers meets a fundamental prerequisite for the application of enzymes or other sensitive agents released from electrospun nanofibers under physiological conditions.

Animals↗