Locoregional cancer treatment with magnetic drug targeting.

The specific delivery of chemotherapeutic agents to their desired targets with a minimum of systemic side effects is an important, ongoing challenge of chemotherapy. One approach, developed in the past to address this problem, is the i.v. injection of magnetic particles [ferrofluids (FFs)] bound to anticancer agents that are then concentrated in the desired area (e.g., the tumor) by an external magnetic field. In the present study, we treated squamous cell carcinoma in rabbits with FFs bound to mitoxantrone (FF-MTX) that was concentrated with a magnetic field. Experimental VX-2 squamous cell carcinoma was implanted in the median portion of the hind limb of New Zealand White rabbits (n = 26). When the tumor had reached a volume of approximately 3500 mm3, FF-MTX was injected intraarterially (i.a.; femoral artery) or i.v. (ear vein), whereas an external magnetic field was focused on the tumor. FF-MTX i.a. application with the external magnetic field resulted in a significant (P < 0.05), complete, and permanent remission of the squamous cell carcinoma compared with the control group (no treatment) and the i.v. FF-MTX group, with no signs of toxicity. The intratumoral accumulation of FFs was visualized both histologically and by magnetic resonance imaging. Thus, our data show that i.a. application of FF-MTX is successful in treating experimental squamous cell carcinoma. This "magnetic drug targeting" offers a unique opportunity to treat malignant tumors locoregionally without systemic toxicity. Furthermore, it may be possible to use these magnetic particles as a "carrier system" for a variety of anticancer agents, e.g., radionuclides, cancer-specific antibodies, and genes.

Inhibition of neointima formation after experimental coronary artery stenting: a new biodegradable stent coating releasing hirudin and the prostacyclin analogue iloprost.

BACKGROUND: To minimize acute stent thrombosis and development of restenosis, stents coated with biodegradable and nonbiodegradable polymers have been proposed to serve as sustained-release drug carriers. METHODS AND RESULTS: In both a sheep and a pig model, we examined the vascular response to standard and high-pressure implantation of coronary Palmaz-Schatz stents coated with a 10-microm layer of polylactic acid (MW 30 kDa) releasing recombinant polyethylene glycol (r-PEG)-hirudin and the prostacyclin analogue iloprost, both drugs with antithrombotic and potentially antiproliferative effects. Study observation time was 28 days. Between the corresponding stent groups, no differences were observed with regard to preplacement and postplacement implantation parameters. The morphometric analysis demonstrated that the coating was associated with a greater lumen diameter through a reduction in the mean restenosis area by 22.9% (P<0.02) in the standard-pressure model (sheep) and by 24.8% (P<0.02) in the overstretch pig model compared with uncoated control stents without inducing a local inflammatory response. CONCLUSIONS: The results from this study demonstrate beneficial effects of a polymeric stent coating with polylactic acid releasing r-PEG-hirudin and iloprost on the development of restenosis after coronary stent placement at 4 weeks, independent of the extent of vascular injury. Future studies are proposed to investigate the integration of other substances to further enhance the potential of the stent coating on reducing neointimal formation.

[Nerve repair strategies for restoration of erectile function after radical pelvic surgery]. / Nerveninterponate zur Wiederherstellung der erektilen Funktion bei radikalen Beckenoperationen.

Iatrogenic cavernous nerve lesions occurring during radical pelvic surgery often lead to irreversible erectile dysfunction. The nerve defects after excision of the neurovascular bundles must be reconstructed by interposition grafting to supply a permissive scaffold for oriented axonal regrowth. The use of autologous nerve grafts for the repair of human cavernous nerves during radical prostatectomy has been controversial regarding the limited success achieved with bilateral nerve grafting. Artificial nerve guides consisting of natural or synthetic materials have been successfully used for bridging peripheral nerve defects. The combination with Schwann cells, neurotrophic factors and extracellular matrix components has been shown to promote cavernous nerve regeneration.

Doppler energy: a new acquisition technique for the transthoracic detection of myocardial perfusion defects with the use of a venous contrast agent.

AIMS: This animal experiment was designed to study whether the new technique of Doppler energy imaging could display myocardial perfusion abnormalities with the use of a combination of transthoracic imaging and right atrial injection of a myocardial contrast agent. METHODS AND RESULTS: A series of 11 pigs were studied during (1) normal perfusion, (2) dipyridamole-induced coronary dilatation, and (3) during and after temporary occlusion of the left anterior descending or circumflex artery after a right atrial injection of 8 ml Levovist, 400 mg/ml. Short-axis views were obtained with the four following imaging modes: gray scale imaging (two-dimensional and M-mode), Doppler energy imaging (two-dimensional and M-mode). Visual inspection and off-line video densitometry (results expressed in arbitrary videointensity units 0 to 255) with digital background subtraction were performed. Doppler energy was significantly more sensitive in detecting the presence of contrast than gray scale imaging (background subtracted peak videointensity 32 +/- 17 versus 17 +/- 12, p < 0.001). Mean background-subtracted videointensity increased during dipyridamole-induced coronary hyperemia (40 +/- 14 versus 31 +/- 9, p < 0.003) using Doppler energy technique. Doppler energy imaging consistently detected absent perfusion (background subtracted videointensity -6 +/- 6) and immediate reperfusion (background subtracted peak videointensity 29 +/- 15, p < 0.001). CONCLUSIONS: With the use of a galactose-based contrast agent, Doppler energy data acquisition was superior to standard gray scale imaging in transthoracic evaluation of regional myocardial perfusion, absence of perfusion, and reperfusion.

Plasma epinephrine levels after epinephrine administration using different tracheal administration techniques in an adult CPR porcine model.

The aim of the study was to compare arterial plasma epinephrine levels after tracheal epinephrine application using three different tracheal instillation techniques at different tracheal levels in a porcine adult cardiopulmonary resuscitation model. In the prospective, randomized study, electrically-induced cardiopulmonary arrest was applied to 32 anaesthetized and paralyzed domestic pigs. After 3 min of cardiopulmonary arrest and 2 min of external chest compressions using a pneumatic compression device and mechanical ventilation, epinephrine was administered intravenously (20 microg/kg) or tracheally (50 microg/kg): using either direct injection into the upper end of the tracheal tube, via a catheter placed into the bronchial system and using a special tracheal application tube. In each group, there were eight pigs. Arterial blood samples were taken before and up to 10 min after epinephrine administration. Regression analysis was performed of the correlated data. The values of mean arterial blood pressure and end-tidal CO(2) during the time of observation did not differ between groups. Total plasma epinephrine concentrations showed a significant increase in all groups, but with no difference between the tracheal groups. However, peak epinephrine levels in the intravenous group were significantly higher than in tracheal groups. We conclude that administration using three different tracheal instillation levels result in similar onset and peak plasma epinephrine levels in this setting and therefore the preferred method of tracheal epinephrine application for cardiopulmonary resuscitation may be selected by other criteria.

Periarterial application of papaverine during laparoscopic donor nephrectomy improves early graft function after kidney transplantation in pigs.

BACKGROUND: Laparoscopic donor nephrectomy (LDN) increases incentives to donation by subjects who might refuse an open operation. However, the incidence of delayed graft function is higher after LDN than after open operation. This may be caused by the reduction of renal perfusion as a result of the raised intraabdominal pressure and mechanically induced renal angiospasm during the operation. We conducted experiments to find out whether the application of papaverine around the renal artery during LDN could improve early graft function after transplantation. METHODS: Renal function was studied in 10 male pigs (weight approximately 25 kg). The left kidney was harvested laparoscopically (intraabdominal pressure 8 mmHg). Five animals were randomly selected to have perivascular application of 50 mg papaverine (treatment group) before preparation of the vessels. In controls no papaverine was used. After LDN and open right nephrectomy the left kidney was autotransplanted. The main outcome measures were volume of urine produced and creatinine clearance during the first 20 h after the transplant. RESULTS: The groups were comparable in respect of body weight, hemodynamic values, amount of infusions, warm and cold ischemia time, and duration of anastomosis. Urine output and creatinine clearance were significantly higher in pigs treated with papaverine than in controls. CONCLUSIONS: Papaverine substantially improved early graft function in pigs when applied around the renal artery during LDN. Whether this is applicable to procurement of human kidneys remains to be evaluated.

The influence of periarterial papaverine application on intraoperative renal function and blood flow during laparoscopic donor nephrectomy in a pig model.

BACKGROUND: The transplantation of live donor kidneys harvested laparoscopically is associated with a higher incidence of delayed graft function than the transplantation of grafts harvested via the open technique. The delay is believed to be due to a decrease in renal blood flow during laparoscopic donor nephrectomy (LDN). The aim of this study was to evaluate whether renal function and blood perfusion can be enhanced by the periarterial application of papaverine during LDN. METHODS: Renal function and blood flow were studied in a porcine model that included a total of 24 pigs (20-30 kg). In 12 of the pigs, urine output and creatinine clearance were determined as measures of renal function. In the other 12 pigs, renal blood flow was determined using fluorescent-labeled microspheres. In each group, the pigs were randomized into two subgroups, one with and one without a perivascular injection of 50 mg papaverine. RESULTS: As compared to the controls, the animals receiving papaverine had a significantly higher urine output (3.1 +/- 1.6 vs 0.9 +/- 0.45 ml/h/kg; p = 0.02), superior creatinine clearance (2.22 +/- 0.5 vs 0.95 +/- 0.1 ml/min/kg; p = 0.038), and enhanced renal blood flow (4.9 +/- 2.2 vs 2.1 +/- 0.8 ml/min/g; p = 0.008). CONCLUSIONS: When applied to the tissue surrounding the renal artery, papaverine substantially improves renal function and blood flow during laparoscopic live kidney donation. Whether graft optimization during kidney procurement also translates into improved posttransplantation function remains to be established.

Medial meniscus replacement by a tendon autograft. Experiments in sheep.

In 20 skeletally mature female merino sheep, divided into four groups, we performed total medial meniscectomy, removal of the middle third of the patellar tendon, and tenotomy of the calcaneal tendon of the right hind leg. Group I (control) had no additional procedures. In the other three groups the medial meniscus was replaced by the middle third of the patellar tendon from the ipsilateral knee. The animals were killed at three (group II), six (group III), or 12 months (group IV) and the tendon-meniscus examined macroscopically, by light and scanning electron microscopy, and biomechanically. Remodelling of the tissue had taken place by 12 months but the failure stress and tensile modulus for the tendon-meniscus were lower than for the normal meniscus. Our evidence suggests that, in sheep, replacement of a meniscus by a tendon autograft may decrease the severity of the degenerative changes that occur after meniscectomy.

Recording of unexpectedly high frequency vibrations of blood vessel walls in experimental arteriovenous fistulae of rabbits using a laser vibrometer.

Because arteriovenous fistulae are associated with a palpable thrill and an audible murmur, the vibrational activity of the blood vessel walls about experimental arteriovenous fistulae in rabbits was investigated using, for the first time, a high-resolution laser vibrometer. Frequencies of mural vibrations up to 2200 Hz were recorded at different sites about the fistulae. The relationship of this vibratory activity of blood vessel walls to physiological and pathological conditions warrants further investigation.

[Tissue engineering of erectile nerves]. / Tissue Engineering erektiler Nerven.

Dissection of the cavernous nerves eliminates spontaneous erections and may lead to irreversible erectile dysfunction due to degeneration of cavernous tissue. Novel procedures to reconstruct penile innervation include cavernous nerve interposition grafting and neurotrophic treatments to revitalize penile neural input, evaluated thus far in various preclinical models of cavernous nerve injury. Schwann cells crucially contribute to successful axonal regeneration by mechanical and paracrine mechanisms in the injured nerve, and Schwann cells seeded into guidance channels have been successfully employed to support regeneration in animal models of cavernous nerve injury. Gene therapy, tissue engineering, and reconstructive techniques have been combined to deliver neurotrophic factors and recover erectile function.

[Recent aspects of the treatment of local hydrofluoric acid erosion]. / Neue Aspekte in der Behandlung lokaler Flusssäureverätzunger.

In experimental studies we compared the intraarterial injection of calcium to local infiltration of calcium as treatment of local hydrofluoric acid burns. We showed that intraarterial injection of calcium is the superior therapy in terms of earlier and more effective arrest of destruction. The results are better the earlier the injection is given. There were no local or systemic disturbances due to the intraarterial injection of calcium.

[Meniscus transplantation--animal experiment study]. / Die Meniskustransplantation--Tierexperimentelle Untersuchung.

The possibility of repairing meniscus lesions by transplantation was studied in 30 sheep. Grafting of the meniscus was performed in 15 animals each either with lyophilised homologous menisci that had been sterilised by gamma rays, or with deep frozen homologous menisci. 27 menisci could be evaluated over a period of 48 weeks. Besides the clinical, microscopical and scanning electron microscopical evaluation, the grafts were also examined microangiographically and biomechanically. Both lyophilised and deep-freeze menisci are suitable for transplantation, but the processes of transformation of the grafts are significantly different: Whereas complete transformation takes place in the lyophilised transplant during the study period of 48 weeks, the deep-frozen transplant is accepted and heals without any remarkable transformation process to full function. Although the biomechanical stress tests yielded good stress tolerance for both types of transplants, the deep frozen homologous menisci appear to be more favourable with regard to possible clinical aspects since they do not undergo any transformation.

[Ban of the use of metomidate (Hypnodil) in swine. Background, consequences and alternatives]. / Anwendungsverbot für Metomidat (Hypnodil) bei Schweinen. Hintergründe, Konsequenzen und Alternativen.

Since the beginning of 1997 the use of the hypnotic drug metomidate (Hypnodil) in swine is not longer allowed. This ban caused a substantial therapeutic deficit for anesthesia in swine. The ban is based on provisions of the European Council Directive 2377/90 for fixing maximum residue limits (MRL) of veterinary drugs in animal-derived food and due to the fact that the pharmaceutical industry has not submitted any application for determining an MRL for metomidate. According to the regulations of the German drug law only those substances can be used as alternatives which are authorized for use in swine or another food-producing animal species. Registrations for use in swine exist for the barbiturates thiamylal and narcobarbital, for ketamine and for the neuroleptics azaperone, acepromazine and propionylpromazine. In the exceptional case of therapeutic emergency levomethadone or xylazine can be used. The administration of propofol, thiopentone, opioids (except levomethadone) or benzodiazepines (except brotizolam) to swine is not allowed since these drugs are authorized only for use in humans or companion animals. At present the most appropriate alternative for anesthesia in swine is thiamylal after premedication of azaperone and ketamine inducing general anesthesia with sufficient tolerance at low risks. In current studies general anesthesia with tolerance could further be produced by combinations of levomethadone, ketamine and azaperone or xylazine. Combined use of levomethadone with benzodiazepines appeared to be not suitable in swine.

[Salivary cortisol as a stress parameter in piglets]. / Speichelkortisol als Stressparameter bei Saugferkeln.

The relationship between salivary and plasma levels of total and free cortisol was monitored in 97 male piglets, aged two to four weeks, subjected to castration. Samples were taken 10 minutes before (basal value) as well as one, two, three, four and 24 hours post castration and at the same time intervals from a control group of 17 animals which did not undergo surgery. Simultaneously to blood (indwelling catheter) withdrawing saliva was collected by two cotton swabs. Cortisol levels were measured by radioimmunoassay (RIA). A highly significant increase in total, free and salivary cortisol was found within the first four hours after castration compared to the control group. The percentage increase one hour after castration above basal values was highest in free plasma cortisol (21.08 +/- 2.03 nmol/l vs. 61.26 +/- 4.16 nmol/l; 290.6%), and lowest in total plasma cortisol (177.33 +/- 9.69 nmol/l vs. 374.09 +/- 18.21 nmol/l; 211.0%), whereas salivary cortisol showed an 255.7% increase (10.46 +/- 1.03 nmol/l vs. 26.75 +/- 1.93 nmol/l). Total cortisol included 11.9-16.4% free cortisol. Salivary cortisol concentration was between 5.9% and 7.5% of the total plasma cortisol concentration. The highest correlation between total plasma cortisol and salivary cortisol occurred one hour after castration (r = 0.57; p < 0.01). The correlation between free and salivary cortisol was lowest for basal values (r = 0.27; p < 0.05), whereas correlations for the remaining time points were highly significant (0.41 < or = r < or = 0.61; p < 0.01). For the control group significant correlations were found between salivary and total plasma cortisol (0.58 < or = r < or = 0.89; p < 0.05) and between free and salivary cortisol (0.63 < or = r < or = 0.92; p < 0.05). The present work indicates that the measurement of salivary levels of cortisol reflects the concentration of this hormone in plasma samples of piglets.

[Carbon dioxide stunning for the slaughter of turkeys]. / CO2-Betäubung zur Schlachtung von Puten.

In an experimental study on stunning of 460 turkeys in a CO2 enriched atmosphere (60-70% CO2 in air), as a more animal protecting and more economic alternative to conventional electrical stunning, the following results are obtained: all animals show respiratory arrest within 100 seconds. After being dipped in a CO2 enriched atmosphere for a few seconds the turkeys show head shaking and forced respiration which has to be considered as a strain the animals are conscious of. The meat hygienic results after CO2 stunning are much better than after electrical stunning.

[CO2-stunning of swine for slaughter from the anesthesiological viewpoint]. / Die CO2-Betäubung von Schlachtschweinen aus anästhesiologischer Sicht.

For investigations of CO2-stunning of feeder- and slaughter-pigs parameters of behaviour, blood-gas-analyses and electroencephalograms were chosen. The following results were obtained: 1. Blood-gas-analyses proved that the CO2-stunning does not produce unconsciousness due to a lack of oxygen. 2. The criterias of general anaesthesia: unconsciousness, muscle-relaxation and analgesia with total reversibility could be confirmed. 3. The violent convulsive symptoms were evaluated as reactions identical with the stage II of GUEDEL's scheme of anaesthesia. 4. Muscular agitation, which sometimes appeared a few seconds before the stage of excitation, was judged to belong either to the start of the excitation phase or to the end of Guedel's stage of analgesia, during which the sensitivity is decreased. Neither study of behavior nor objective measurements showed, during the first 10 to 20 seconds of exposure to the CO2, any sign of pain or suffering related to the Act for Prevention of Cruelty to Animals, and accordingly such suffering should not be ascribed to the CO2 stunning method.

[Fulminating malignant hyperthermia in swine--an alternative therapy concept]. / Die fulminante maligne Hyperthermie beim Schwein--Ein alternatives Therapiekonzept.

An inexpensive therapeutic concept compared to the dantrolene-therapy to counter the malignant hyperthermia (MH) is to be discussed, using a case-study from swine-anaesthesia. Hyperventilating the animals (with O2), administering metamizol, beta-blocker, bicarbonate and sufficiently cooling the patient can, if the symptoms are recognized early enough, arrest the hypermetabolic cascade in its track. All the animals that were treated according to this scheme survived the (MH) crisis without any lasting post operative damage.

Comparison of dipyrone/propofol versus fentanyl/propofol anaesthesia during surgery in rabbits.

In this study, the investigation of the intraoperative effects of dipyrone (metamizol) on heart rate (HR), mean arterial pressure (MAP) and analgesic efficacy in rabbits is described for the first time. This was carried out to evaluate the cardiovascular stability achieved using dipyrone compared with fentanyl. In this prospective study, 17 female New Zealand White rabbits were randomly allocated to either one of two groups: dipyrone/propofol (DP) or fentanyl/propofol (FP). Anaesthesia was induced in both groups using propofol to effect (4.0-8.0 mg/kg intravenously) until the swallowing reflex was lost for intubation. After induction, anaesthesia was maintained with continuous infusion of propofol 1.5-1.7 mg/kg/min intravenously. Analgesics were then injected in defined boluses of either dipyrone 65 mg/kg or fentanyl 0.0053 mg/kg. After surgical tolerance, defined as loss of the ear pinch reflex and loss of the anterior and posterior pedal withdrawal reflex, was achieved, two surgical procedures were performed. The surgical procedures (implantation of either a pacemaker or an electrocardiogram transmitter), both require a comparable level of analgesic depth. During and after surgery, clinical variables, such as MAP, HR, peripheral arterial oxygen saturation (SpO2) and end-tidal CO2 (P(E')CO2) were recorded simultaneously every 2 min. Eight time points were chosen for comparison: baseline, surgical tolerance (ST), values at 10, 20 and 30 min after reaching ST, values at the end of propofol infusion (EI) and data at 10 and 20 min after EI. Both FP and DP combinations provided effective anaesthesia and analgesia in rabbits. In both groups a significant decrease of HR and MAP was measured. The results of this study indicate that the non-opioid drug dipyrone produces similar analgesic and even better cardiovascular effects by trend in rabbits. Therefore we conclude that dipyrone in combination with propofol can be used as an alternative to FP for intraoperative analgesia.