[To have concern of prejudice to the authorized medical expert]. / Der Antrag der Besorgnis der Befangenheit aus praktischer Sicht.

In civil and criminal court cases, the medical expert must follow certain (legal) regulations which in general are not conveyed as part of his/hers medical education. The medical experts should observe, that they are themselves not the investigators, but rather only aids to the court. Above and beyond that, the medical experts must conduct themselves in such a manner as to avoid at all times any appearance of prejudice during the course of the judicial proceedings.

Influence of massage and occlusion on the ex vivo skin penetration of rigid liposomes and invasomes.

Liposomes are frequently described as drug delivery systems for dermal and transdermal applications. Recently, it has been shown that particulate substances penetrate effectively into hair follicles and that the follicular penetration depth can be increased by massaging the skin, which simulates the in vivo movement of hairs in the hair follicles. In the present study, massage was applied to skin mounted to Franz diffusion cells. By means of confocal laser scanning microscopy, the influence of massage and occlusion on the follicular penetration depths of rigid and flexible liposomes loaded with a hydrophilic and lipophilic dye was investigated. The application of massage increased follicular penetration significantly. Occlusion resulted in an increased follicular penetration depth only for rigid liposomes, whereas invasomes did not penetrate more effectively if occlusion was applied. The results confirm that massage is an important tool for increasing follicular penetration in ex vivo studies using Franz diffusion cells. Occlusion may reduce the efficacy of follicular penetration depending on the specific liposomal preparation. Rigidity in particular appears to be a relevant parameter.

Permeation of topically applied caffeine through human skin--a comparison of in vivo and in vitro data.

AIMS: Due to ethical reasons, in vivo penetration studies are not applicable at all stages of development of new substances. Therefore, the development of appropriate in vitro methods is essential, as well as the comparison of the obtained in vivo and in vitro data, in order to identify their transferability. The aim of the present study was to investigate the follicular penetration of caffeine in vitro and to compare the data with the in vivo results determined previously under similar conditions. METHODS: The Follicular Closing Technique (FCT) represents a method to investigate the follicular penetration selectively. In the present study, FCT was combined with the Franz diffusion cell in order to differentiate between follicular and intercellular penetration of caffeine into the receptor medium in vitro. Subsequently, the results were compared with the data obtained in an earlier study investigating follicular and intercellular penetration of caffeine in vivo. RESULTS: The comparison of the data revealed that the in vitro experiments were valuable for the investigation of the follicular penetration pathway, which contributed in vivo as well as in vitro to approximately 50% of the total penetration, whereas the kinetics of caffeine penetration were shown to be significantly different. CONCLUSIONS: The combination of FCT with the Franz diffusion cell represents a valuable method to investigate follicular penetration in vitro. Nevertheless, in vivo experiments should not be abandoned as in vitro, structural changes of skin occur and blood flow and metabolism are absent, probably accounting for reduced penetration rates in vitro.

Concentration decrease of nitric oxide in the postischemic muscle is not only caused by the generation of O2-.

Reperfusion of ischemic skeletal muscle is associated with an alteration of the concentrations of O(2) (-) and NO. In this study, the influence of epigallocatechin-3-gallate (EGCG), a known radical scavenger, on the balance of O(2) (-) and NO has been measured online in the skeletal muscle of Wistar rats. The hind limb of 14 male rats had been exposed to ischemic stress for 2 h. Seven rats received an infusion of 1.5 micromol EGCG/kg 5 min before reperfusion. O(2) (-), NO, and temperature were measured during reperfusion. The concentration of O(2) (-) declined under the influence of EGCG from 156.5 to 72.2 nmol/l (P = 0.01). The level of NO was found to decrease; this decrease was not significantly changed by EGCG (-175 nmol/l vs. - 227 nmol/l; P = 0.33). Thus the different superoxide concentrations did not correspond to different levels of NO, and the interaction of both radicals is not the only reason for the concentration decrease of NO in the reperfusion period. We conclude that EGCG protects skeletal muscle from I/R-injury without influencing the NO concentration profile to a large extent.

Re-endothelialization of punctured ePTFE graft: an in vitro study under pulsed perfusion conditions.

BACKGROUND: When used as arteriovenous (AV) shunts for haemodialysis, small diameter expanded polytetrafluoroethylene (ePTFE) grafts have a high failure rate in vivo. Attempts to improve graft patency are various, and focus on either improvement of implantation techniques or graft tissue engineering. The tissue engineering approach attempts to reproduce in grafts the properties of pristine vasculature. As shown in previous experiments, it is possible to grow on ePTFE grafts under shear stress in vitro an autologous endothelial cell layer, which will withstand physiological stress under in vivo conditions of blood flow. The aim of this study was to investigate in an in vitro model the regenerative potency of a tissue-engineered prosthetic vascular graft after repeated cannulation with a haemodialysis cannula. METHODS: Pig endothelial cells were harvested from an external jugular vein. Following processing of the endothelial cells, seven ePTFE grafts were coated with an inner cell layer and were kept under pulsed perfusion. Each graft was then cannulated three times with a standard shunt needle. The endothelium was then left to regenerate for a maximum of 48 h. The grafts were stained with haematoxylin/eosin before histological study. RESULTS: All grafts were endothelialized over the puncture sites within 48 h. Histological analysis revealed a confluent endothelial cell lining at each puncture site. Cell morphology and cell pattern over puncture sites were not different from randomly picked locations over the graft lumen. CONCLUSION: Our results underline the potential of endothelial tissue engineering in vascular shunt surgery. Vascular bio-hybrids that have the properties of pristine vascular endothelium may be a key step forward in maintaining angio-access in patients who require haemodialysis.

Epigallocatechin gallate can significantly decrease free oxygen radicals in the reperfusion injury in vivo.

OBJECTIVE: There is experimental evidence that oxygen-derived free radicals (Superoxide (O(2)(-))) play a key role in tissue damage in ischemia-reperfusion injury. Among various antioxidants tested in vitro, natural polyphenols like Epigallocatechine gallate (EGCG) show a 164-fold higher scavenging activity for O(2)(-) than ascorbic acid We therefore conducted an animal study in order to investigate the impact of EGCG on O(2)(-) production during reperfusion after defined periods of ischemia in the muscle tissue of the rat, using a recently developed cytochrome c-based biosensor for on-line in vivo monitoring of O(2)(-). MATERIALS AND METHODS: Femoral artery and vein were dissected below the inguinal ligament in male Wistar rats. The cytochrome c-based biosensor was placed in the gastrocnemius muscle. Ischemia was induced by clamping the femoral vessels. Ischemia times were either 60 (n = 14) or 120 (n = 14) minutes. Six animals in each group received 4 mg/kg body weight EGCG intravenously at the time of reperfusion, another six animals in each group served as controls (no treatment). Additionally, two animals in each group received the same volume of saline instead of EGCG. The current response of the biosensor corresponding to the O(2)(-) concentrations in vivo was recorded on a PC. The gastrocnemius muscles were harvested for histological evaluation. RESULTS: The average maximum O(2)(-) concentration after 60 minutes of ischemia was 188, 18 nmol/L (23 pA) compared to 90 nmol/L (11 pA) (P <.01) with EGCG application. The mean O(2)(-) value after 120 minutes was 220 nmol/L (27 pA) versus 135 nmol/L (16.5 pA) (P <.01) with EGCG, respectively. Histological analysis showed advanced muscle cell injury and neutrophil infiltration in the group without EGCG. No O(2)(-) reduction could be verified administering saline instead of EGCG. CONCLUSION: For the first time the scavenging activity of an antioxidant was verified in vivo on-line. EGCG significantly diminished O(2)(-) tissue concentrations after 60 or 120 minutes of ischemia by an average of nearly 50%, suggesting its therapeutic potential.

Intraperitoneal administration of the angiogenesis inhibitor thalidomide does not impair anastomotic healing following large bowel resection in a rabbit model.

The effects of thalidomide after intraperitoneal instillation on the healing of colonic anastomoses are not known. A series of 40 New Zealand White rabbits underwent an end-to-end colonic anastomosis. The animals were randomized into four groups. Groups 1 (n = 10) and 2 (n = 10) were treated with dissolved thalidomide 200 mg/kg intraperitoneally, whereas groups 3 (n = 10) and 4 (n = 10) were treated only with the dissolver. Animals were sacrificed at day 3 (groups 1, 3) and day 7 (groups 2, 4). Anastomotic healing was tested by measuring the bursting pressure in vitro. Immunohistochemical staining of the anastomotic site was performed with polyclonal antibodies against CD31 and Mib-1, to determine a possible antiangiogenic or antiproliferative effect. Statistical analysis was performed using Spearman's log rank correlation and paired t-test. On postoperative day 3 (p > 0.19) and postoperative day 7 (p > 0.73), there was no difference in bursting pressure in the treatment and the control groups. Angiogenesis scores were reduced at day 3 in the thalidomide group (p < 0.05), but did not differ between the groups at day 7. White blood cell counts were decreased in the treatment groups at day 3 (p < 0.01) and day 7, compared to control groups (p < 0.01). There was no difference in the expression of Mib-1 in either group at day 3 or day 7. The intraperitoneal administration of thalidomide does not interfere with the healing of colonic anastomosis. Although the angiogenesis score is diminished at day 3, this did not lead to a reduced bursting pressure at day 3 or day 7.

In vivo measurement of oxygen-derived free radicals during reperfusion injury.

By use of an optimized cytochrome c-based biosensor, superoxide radical production was measured continuously in vivo. The aim of this study was the online detection of superoxide concentration during reperfusion after a variable time of ischemia. Measurements were performed by placing the detecting sensor into gastrocnemius muscle tissue. Ischemia was induced by clamping the vena and arteria femoralis. Current response of the sensor was recorded continuously as an equivalent for superoxide concentration. Ischemia times varied from 5 to 120 minutes. The minimum ischemia time to record superoxide production was 10 minutes. By inducing longer periods of ischemia, an increase in superoxide concentration reached its highest levels at 2 hours. Furthermore, the total time of superoxide production after reperfusion depended on the total time of ischemia.