Biomedical subjects

A Frentzel

Publications and source records attributed to A Frentzel.

5 recordsLinked to original sources

PubMed2003

[Topical treatment of blunt-impact soft tissue injuries].

Studies have shown that topical NSAIDs, e.g. diclofenac, easily penetrate the skin barrier to exert local therapeutic activity. In contrast to oral administration, plasma levels after application of topical formulations are by several magnitudes lower thus explaining the lack of systemic side effects. We discuss the clinical relevance of patches containing an NSAID by demonstrating the efficacy and safety of a newly developed diclofenac patch in the topical treatment of blunt impact soft tissue injuries in a randomised, placebo controlled, double blind, multicentre study. The results showed that the diclofenac patch was significantly more effective than placebo (p < 0.0001) with a significantly faster pain relief. The diclofenac patch was well tolerated. It might be used in indications with similar pathomechanisms.

Administration, Topical↗

PubMed2000

Phospholipid binding of synthetic talin peptides provides evidence for an intrinsic membrane anchor of talin.

Talin, an actin-binding protein, is assumed to anchor at the membrane via an intrinsic amino acid sequence. Three N-terminal talin fragments, 21-39 (S19), 287-304 (H18), and 385-406 (H17) have been proposed as potential membrane anchors. The interaction of the corresponding synthetic peptides with lipid model systems was investigated with CD spectroscopy, isothermal titration calorimetry, and monolayer expansion measurements. The membrane model systems were neutral or negatively charged small unilamellar vesicles or monolayers with a lateral packing density of bilayers (32 mN/m). S19 partitions into charged monolayers/bilayers with a penetration area A(p) = 140 +/- 30 A(2) and a free energy of binding of DeltaG(0) = -5.7 kcal/mol, thereby forming a partially alpha-helical structure. H18 does not interact with lipid monolayers or bilayers. H17 penetrates into neutral and charged monolayers/bilayers with A(p) = 148 +/- 23 A(2) and A(p) = 160 +/- 15 A(2), respectively, forming an alpha-helix in the membrane-bound state. Membrane partitioning is mainly entropy-driven. Under physiological conditions the free energy of binding to negatively charged membranes is DeltaG(0) = -9. 4 kcal/mol with a hydrophobic contribution of DeltaG(h) = -7.8 kcal/mol, comparable to that of post-translationally attached membrane anchors, and an electrostatic contribution of DeltaG(h) = -1.6 kcal/mol. The latter becomes more negative with decreasing pH. We show that H17 provides the binding energy required for a membrane anchor.

Amino Acid Sequence↗

PubMed1996

Ischemic preconditioning--a new concept in orthopedic and reconstructive surgery.

The duration of tourniquet-induced ischemia during orthopedic and reconstructive surgery is limited by the risk of ischemia and reperfusion injury to skeletal muscle. This study evaluated the potential of ischemic preconditioning (short periods of ischemia with intermittent reperfusion) to improve skeletal muscle function after ischemia and reperfusion in a rodent model. Preconditioning was found to improve force, contractility, and performance and to decrease fatigue of skeletal muscle. In contrast, energy-rich phosphates, measured concurrently, were not affected by preconditioning, suggesting mechanisms other than energy preservation to be involved. In summary, preconditioning may enable prolongation of orthopedic and reconstructive procedures.

Animals↗

PubMed1996

Ischemic preconditioning improves post-ischemic skeletal muscle function.

Ischemic preconditioning (IP), using one or more brief periods of ischemia before a sustained ischemia, represents a new approach to reduce tourniquet ischemia-induced skeletal muscle damage. The aim of this study was to investigate the effect of IP on skeletal muscle function and high-energy phosphate tissues levels in a rodent model. IP protocols using one, two, or three preconditioning cycles were compared. IP was found to significantly improve force, performance, endurance, and contractility of postischemic skeletal muscle. The efficacy of IP-induced protection was correlated with the number of preconditioning cycles. Preconditioning with three cycles resulted in a more effective protection as compared to one or two cycles. Three cycles of IP significantly improved force (409 +/- 63 versus 240 +/- 47 mN), performance (2546 +/- 481 versus 1081 +/- 242 mN*sec), endurance (46.7 +/- 5.0 versus 29.6 +/- 3.4 sec) and contractility (59.9 +/- 4.2 versus 38.7 +/- 5.1) in postischemic m.extensor dig. long. when compared to nonpreconditioned muscles. In contrast, high-energy phosphate tissue levels remained unchanged after three cycles of preconditioning. Altogether, this study describes, for the first time, the efficacy of IP to improve postischemic muscle function. The respective clinical potential warrants further exploration.

Animals↗

PubMed1995

[Ischemic preconditioning improves postischemic function, but not energy metabolism of skeletal muscles].

Ischemic preconditioning (IP) refers to a phenomenon whereby short periods of ischemia reduce tissue damage after a subsequent sustained ischemia. The effect of IP before tourniquet ischemia of the extremities has not yet been evaluated. We developed a rat model of skeletal muscle ischemia and measured the effect of IP on postischemic function and high-energy phosphate levels. IP consisted in three cycles of 10 min ischemia and 10 min reperfusion each. IP improved significantly skeletal muscle function after 3 hours of ischemia and 2 hours of reperfusion. High-energy phosphate levels, however, remained unchanged. This study is the first that shows a protective effect of IP in skeletal muscles. These results furthermore suggest that the protection of energy metabolism is not a mechanism of IP in this model. IP could be easily performed before surgery of the extremities under tourniquet ischemia. The protective effect on postischemic skeletal muscle has therefore to be further investigated.

Animals↗