Resuscitation of warm ischaemia predamaged porcine kidneys by fibrinolytic preflush with streptokinase: reduction of animal experiments

In order to reduce the number of animal experiments, the use of non-heart-beating donors (NHBDs) from a commercial abattoir has been proposed. Since the use of slaughterhouse organs is legally not defined as animal experiment, this would fulfil international standards as an alternative to animal experiments. The development of intravascular thrombosis after cardiac arrest negatively impacts organ preservation and thus viability during ischaemic storage and reperfusion. A fibrinolytic preflush with streptokinase might overcome these limitations. Therefore, the functional and histomorphological integrity of kidneys preserved immediately with intact circulation (control group A) and kidneys preserved after cardiac arrest with a 30 min period of warm ischaemia (WI) (group B) was compared with kidneys preflushed with 12.5 kU/L (group C) or 50 kU/L streptokinase (group D) after 30 min WI prior to preservation. We could demonstrate that kidneys preflushed with 12.5 kU/L streptokinase (group C) performed better than those without streptokinase pretreatment after WI (group B). Parameters like oxygen consumption, perfusion pressure, laboratory values, lactate dehydrogenase level and lipidperoxidation were closer to that of the control (group A) than in groups B and D. The higher streptokinase concentration of 50 kU/L (group D) resulted histologically in a more pronounced tissue damage and an attenuated renal function, indicating toxic effects. On the basis of our results we believe streptokinase preflushed slaughterhouse kidneys to be an adequate alternative to organs from laboratory animals with the potential to further reduce the number of animal experiments.

Investigation of the thermal tissue effects of the argon plasma coagulation modes "pulsed" and "precise" on the porcine esophagus, ex vivo and in vivo

BACKGROUND

Argon plasma coagulation (APC) is a monopolar, noncontact, thermal procedure that is widely used in therapeutic endoscopy. Systematic investigations of the tissue damage ex vivo and in vivo with the new, second-generation APC modes are lacking.

OBJECTIVE

The aim of this study is to compare the tissue effects of the pulsed effect 2 and precise APC modes.

DESIGN AND SETTING

Ex vivo and in vivo animal model.

SUBJECTS

This study involved 3 explanted porcine esophagi and 8 pigs under general anesthesia.

INTERVENTION

APC application on 3 explanted esophagi and during esophagoscopy.

MAIN OUTCOME MEASUREMENTS

The tissue effect was subjected to histological and statistical investigation.

RESULTS

In vivo, a well known type of superficial tissue damage (type A) of the tunica mucosa and a new injury pattern (type B) limited to the tunica muscularis, were found. Ex vivo, only type A injuries were seen. Thermal injury of the tunica muscularis was significantly lower with precise APC compared with pulsed APC in vivo. The pulsed effect 2 shows a positive correlation between the penetration depth and the power (r = 0.38, P < .0002) or application time for the highest power setting used (40 W, r = 0.77, P < .0001). This correlation could not be detected with precise APC because of its very superficial tissue effect.

LIMITATIONS

This was an animal study. The distance of the APC probe to the esophagus may have varied between applications in vivo.

CONCLUSION

Thermal damage by APC of the esophageal tunica muscularis seems to be underestimated ex vivo. The extent of tissue injury was significantly lower with precise APC than with pulsed APC, indicating that precise APC may be suitable for the treatment of particularly thermosensitive, thin-wall anatomy.

Evaluation of the hemostatic and coagulation effects of AUTO CUT and DRY CUT using a computer-controlled cutting system

OBJECTIVES

To evaluate a newly developed computer-controlled cutting system for the generation of standardized resections and to systematically compare the hemostatic properties and tissue effect of 2 cutting modes, namely, AUTO CUT and DRY CUT used in urologic procedures.

METHODS

An isolated perfused kidney model was used to assess blood loss and coagulation depth after resection of tissue specimens of standardized geometry, size, and cutting velocity with a resection loop. Three different effect settings (E1, E3, and E6; 200 W) of the electrosurgical modes AUTO CUT and DRY CUT were compared. Blood loss was determined semiquantitatively by weighing a swab before and after placing it onto the resection area. The coagulation depth was estimated microscopically on cross sections.

RESULTS

The computer-controlled cutting system creates resections of standardized geometry and size with a high reproducibility. An effect level-dependent increase in hemostasis and coagulation depth could be demonstrated with the cutting modes DRY CUT and AUTO CUT using this computer-controlled cutting system. The hemostatic effect with DRY CUT is significantly more pronounced than with AUTO CUT (E1, E3: P < .0001, E6: P = .004), and the coagulation is significantly deeper (E1, E3, E6: P < .0001).

CONCLUSIONS

The computer-controlled cutting system creating reproducible resections in combination with the isolated perfused kidney model offers the possibility to systematically investigate bleeding rate and coagulation depth. The stronger hemostatic properties of the DRY CUT mode are more favorable for urologic interventions requiring a higher hemostatic effect than the AUTO CUT mode.

Intracerebral and intrathecal infusion of the TGF-beta 2-specific antisense phosphorothioate oligonucleotide AP 12009 in rabbits and primates: toxicology and safety

Here, we provide first evidence that long-term continuous infusion of highly purified antisense phosphorothioate oligodeoxynucleotides (S-ODN) into brain parenchyma is well tolerated and thus highly suitable for in vivo application. AP 12009 is an S-ODN for the therapy of malignant glioma. It is directed against human transforming growth factor-beta (TGF-beta2) mRNA. In the clinical setting, AP 12009 is administered intratumorally by continuous infusion directly into the brain tumor. In view of this clinical application, the focus of our data is on local toxicology studies in rabbits and monkeys to evaluate the safety of AP 12009. AP 12009 was administered either by intrathecal bolus injection into the subarachnoidal space of the lumbar region of both cynomolgus monkeys and rabbits or by continuous intraparenchymatous infusion directly into the brain tissue of rabbits. Intrathecal bolus administration of 0.1 ml of 500 microM AP 12009 showed neither clinical signs of toxicity nor macroscopically visible or histomorphologic changes. After a 7-day intraparenchymatous continuous infusion of 500 microM AP 12009 at 1 microl/h in rabbits, there was no evidence of toxicity except for local mild to moderate lymphocytic leptomeningoencephalitis. Additionally, AP 12009 showed good tolerability in safety pharmacology as well as in acute toxicity studies and 4-week subchronic toxicity studies in mice, rats, and monkeys. This favorable safety profile proves the suitability of AP 12009 for local administration in brain tumor patients from the point of view of toxicology.