The vasodilating effect of a Hintonia latiflora extract with antidiabetic action.

In the present study, it is shown for the first time that an extract of Hintonia latiflora (HLE) which is used as an antidiabetic herbal medicine, is not only able to decrease blood glucose concentration but additionally exerts a vasodilating effect. Accordingly, this extract might have a positive influence on diabetes-associated dysfunction of blood vessels. The vasodilating effect was demonstrated in vitro in aortic rings of guinea pigs as well as in vivo in rabbits. Aortic rings pre-contracted with noradrenaline (NA) could completely be relaxed by HLE (EC50: 51.98 mg/l). In contrast, potassium-induced contractions were not diminished by HLE. Therefore, it can be suggested that the vasodilating effect of HLE is primarily the result of an inhibition of G protein-induced increase in intracellular calcium and not of a blockade of voltage-operated L-type calcium channels. The neoflavonoid coutareagenin (COU), a constituent of HLE which in part is responsible for the blood glucose-lowering effect of HLE, also relaxed NA-induced contractions of aortic rings (EC50: 32.55 mg/l) and only weakly inhibited potassium-induced contractions. Experiments in aortic rat cells revealed that calcium transients evoked by vasopressin were suppressed by 60 mg/l COU supporting the idea of an inhibition of G protein-induced intracellular calcium release by a constituent of HLE. To study the effect of HLE on vascular tone under in vivo conditions, ultrasound measurements were carried out in conscious rabbits which received a single oral dose of HLE. Under the influence of HLE, a vasodilation combined with a lowering of blood flow velocity could be observed in the abdominal aorta and the common carotid artery. Additionally, a decrease in blood glucose concentration in the HLE group occurred. The combination of a blood glucose-lowering with a vasodilating effect may be helpful for reducing angiopathies, typical long-term complications in patients with diabetes mellitus.

Effects of ketamine-xylazine intravenous bolus injection on cardiovascular function in rabbits.

The direct effects of ketamine-xylazine (KET-XYL) on vascular function have not been investigated in rabbits. The short-term cardiovascular effects of intravenous (IV) KET-XYL bolus injection, therefore, should be investigated using vascular ultrasonography.In this prospective experimental study, KET-XYL anesthesia was induced IV in 9 female New Zealand White rabbits before 3 defined test bolus injections of KET-XYL were given IV. Before and for 10 min after each KET-XYL injection vascular and hemodynamic variables were recorded at the left common carotid artery (ACC) after the 1st injection, and at the abdominal aorta (AA) after the 2nd injection. Echocardiography was performed after the 3rd injection to investigate changes in cardiac parameters.Ketamine-xylazine IV caused a significant increase in vessel diameter at the ACC and AA. Average volumetric flow significantly decreased at the ACC and pulsatility index significantly decreased at the AA. Fractional shortening (FS) and heart rate significantly decreased, while mean arterial blood pressure initially increased.Bolus injections of KET-XYL IV produced a transient vasodilatation at the ACC and AA. Despite central vasodilatation, bradycardia, and decrease of FS and average volumetric flow (VFave), mean arterial blood pressure did not significantly decrease indicating well-preserved cardiovascular compensatory mechanism after the ratio and doses of KET-XYL IV bolus injections used in this study.

Effects of medetomidine-midazolam-fentanyl IV bolus injections and its reversal by specific antagonists on cardiovascular function in rabbits.

The objective of this study was to investigate the short-term cardiovascular effects of intravenous (IV) medetomidine-midazolam-fentanyl (MMF) injections in the rabbit using vascular ultrasonography and echocardiography.Anesthesia with MMF was induced intramuscularly (IM) in 8 female New Zealand White rabbits before 3 defined bolus injections of MMF were given IV. Before and for 10 min after each MMF injection the following vascular variables [at the left common carotid artery (ACC) after the first injection and at the abdominal aorta (AA) after the second injection]: vessel diameter (D), peak systolic, minimum diastolic, end-diastolic and average blood flow velocities (psBFV, mdBFV, edBFV, Vave), average volumetric flow (VFave), resistance index (RI) and pulsatility index (PI) and other clinical variables: mean arterial pressure (MAP), heart rate (HR), peripheral arterial oxygen saturation and end-tidal CO2 were recorded. Echocardiography was used after the third injection to investigate changes in cardiac parameters. Additionally, hemodynamic effects were observed at the ACC after complete subcutaneous antagonism of anesthesia by atipamezole-flumazenil-naloxone (AFN) until recovery of the animals.Medetomidine-midazolam-fentanyl IV caused a significant decrease of blood flow velocity in both investigated vessels which was associated with a significant decrease of HR and cardiac performance indicated by the decrease of FS and average volumetric blood flow. Mean arterial pressure significantly increased after each MMF injection; whereas, it significantly decreased after AFN injection. Therefore, MMF and AFN should be carefully used in rabbits and may not be suitable in patients with ventricular dysfunction.

Cardiovascular effects of dipyrone and propofol on hemodynamic function in rabbits.

OBJECTIVE: To evaluate the short-term cardiovascular effects of IV administration of dipyrone (metamizole) as an intraoperative analgesic during total IV anesthesia with propofol. ANIMALS: 6 healthy female New Zealand White rabbits. PROCEDURES: Anesthesia was induced with propofol (4.0 to 8.0 mg/kg, IV) and maintained with the same drug (1.2 to 1.3 mg/kg/min, IV). After induction, 3 doses of dipyrone (65 mg/kg each) were administered IV at 25-minute intervals. Before and for 10 minutes after each dipyrone injection, the following vascular and hemodynamic variables were recorded at the left common carotid artery every minute after the first injection: vessel diameter; peak systolic, minimum diastolic, end-diastolic, and mean blood flow velocities; mean volumetric flow; resistance and pulsatility indices; mean arterial blood pressure (MAP); heart rate; arterial oxygen saturation (SpO(2)); and end-tidal partial pressure of CO(2) (PETCO(2)). Echocardiography was performed after the second injection. The same variables were measured at the abdominal aorta (AA) after the third injection. RESULTS: Dipyrone injections caused a significant, transient decrease in the resistance index at the AA. Also detected were a minor decrease in pulsatility index at the left common carotid artery and a minor increase in end-diastolic blood flow velocity at the AA. The MAP, heart rate, SpO(2), and PETCO(2) did not significantly change after injections. A comparison of HR and MAP after the first and third bolus injections revealed only minor changes. CONCLUSIONS AND CLINICAL RELEVANCE: Dipyrone used with propofol anesthesia in rabbits appeared not to significantly impair cardiovascular and hemodynamic function.

Cardiovascular effects of fentanyl and propofol on hemodynamic function in rabbits.

OBJECTIVE: To evaluate short-term cardiovascular effects after IV administration of boluses of fentanyl in rabbits. ANIMALS: 6 healthy New Zealand White rabbits. PROCEDURES: Each rabbit was anesthetized with propofol (4.0 to 8.0 mg/kg, IV); anesthesia was maintained by administration of propofol (1.2 to 1.3 mg/kg/min, IV). Subsequently, 3 injections of fentanyl (0.0053 mg/kg) were administered. Before and for 10 minutes after injections, the following variables were measured: vessel diameter, peak systolic blood flow velocity, minimum diastolic blood flow velocity, end-diastolic blood flow velocity, time-average blood flow velocity, mean volumetric flow (VFmean), resistance index (RI), and pulsatility index for the left common carotid artery after the first injection and abdominal aorta after the third injection; mean arterial pressure (MAP); heart rate (HR); arterial oxygen saturation; end-tidal partial pressure of carbon dioxide; and body temperature. Echocardiography was performed after the second injection. RESULTS: Fentanyl injections caused a transient and significant decrease in diameter and VFmean of the abdominal aorta and end-diastolic blood flow velocity of the left common carotid artery and an increase in peak systolic blood flow velocity and RI of the left common carotid artery. Also, MAP, HR, and body temperature decreased significantly after injections. CONCLUSIONS AND CLINICAL RELEVANCE: Fentanyl injections induced a short-term decrease of vessel diameter in the abdominal aorta and increased resistance in the distal distribution area of the left common carotid artery. Results revealed decreases in MAP, HR, and body temperature, with an increasing effect after the third bolus injection, which indicated a cumulative drug effect.

Effects of propofol on ultrasonic indicators of haemodynamic function in rabbits.

OBJECTIVE: To evaluate the cardiovascular effects of intravenous propofol in rabbits. STUDY DESIGN: Randomized, prospective, experimental study. ANIMALS: Thirty-one female New Zealand White rabbits. METHODS: Rabbits were allocated to one of two groups [propofol (P) or conscious (C)]. In C (n = 16) vascular dimensions were measured using ultrasound of the left common carotid artery (ACC) and the abdominal aorta (AA). Group P (n = 15) received propofol 4.0-8.0 mg kg(-1) intravenously (IV). Anaesthesia was maintained with propofol at 1.2-1.3 mg kg(-1) minute(-1). Subsequently, three propofol injections (8 mg kg(-1)) were given. Before and for 10 minutes after each injection the following vascular and haemodynamic variables were recorded (a) at the ACC after the first injection; and (b) at the AA after the second injection: vessel diameter [D, (mm)], peak systolic, minimum diastolic, end-diastolic and average blood flow velocities [psBFV, mdBFV, edBFV, Vave (cm second(-1))], average volumetric flow [VFave (mL s(-1))], resistance index (RI) and pulsatility index (PI) mean arterial pressure (MAP), heart rate (HR), arterial oxygen saturation (SpO(2)) and end-tidal CO(2) (Pe'CO(2)). Echocardiography was performed after the third propofol bolus injection to investigate changes in cardiac parameters [fractional shortening, FS (%)]. RESULTS: Intravenous propofol injections caused a significant decrease in vessel diameter, volumetric flow and edBFV, and significant increases in psBFV, RI and PI. Baseline levels for vessel diameter and psBFV were restored 6-8 minutes after injection. Propofol injection decreased FS significantly by 7 minutes after injection while MAP and HR were significantly reduced for 4 minutes. CONCLUSION AND CLINICAL RELEVANCE: Injections of propofol (8 mg kg(-1)) produced an immediate, transient decrease in vascular diameters, a significant decrease in ventricular performance and an increase in peripheral vascular resistance (ACC and AA). Propofol should probably not be or only carefully used in rabbits with ventricular dysfunction.

[Evaluation of the toxicity of tirapazamine plus cisplatin in a mouse tumor model]. / Untersuchungen zur Toxizität von Tirapazamine plus Cisplatin in einem Maus-Tumormodell.

BACKGROUND AND PURPOSE: Tirapazamine (TPZ) is an anticancer drug that is selectively activated by the low oxygen environment in solid tumors. Furthermore, TPZ also enhances the tumor cell-killing effect of cisplatin. So far, detailed information on the toxicity of combined treatment is rare. The authors evaluated the toxicity of TPZ in combination with cisplatin in a mouse tumor model. For this purpose, general toxicity was monitored and all inner organs were examined histologically. MATERIAL AND METHODS: RIF-1 fibrosarcomas of murine origin growing in the right hindfoot dorsum of C3H mice were used. The animals were treated with 10 x 2 Gy irradiation plus six i.p. injections of 4 mg/kg cisplatin (total dose 24 mg/kg) together with varying doses of TPZ (0-28 mg/kg per injection; total dose 0, 43.2, 86.4, 129.6, 151.2, 172.8 mg/kg). Treatment was applied within 2 weeks (Figure 1). Total observation period was up to 35 days. RESULTS: Combined treatment with TPZ led to a dose-dependent, significant decrease in motor activity (Table 1) and body weight and an increase in mortality (Figures 2 and 3, Tables 2 and 3). Histological analyses showed areas of necrosis in the heart, liver and kidney and gastric ulcers (Table 4). Cisplatin alone produced no severe toxicity. Tumor doubling times were TPZ dose-dependent and comparable with data from the literature (Figures 4 and 5, Table 3). CONCLUSION: Unlike most data from the literature a dose-dependent increase in toxicity was seen when adding TPZ to a standard treatment of cisplatin plus irradiation. To the authors' knowledge this is the first study histologically examining in detail the organ toxicity of TPZ in a mouse model. Furthermore, they expand the rare data on long-term toxicity after TPZ plus cisplatin in a fractionated therapy regimen. The results question the usefulness of frequently performed therapeutic studies where only short-term treatment and observation endpoints are used, since essential toxicities are likely to be overlooked.

In vivo animal trials with a scanning CO2 laser osteotome.

BACKGROUND AND OBJECTIVES: We report first results of animal trials using an improved laser osteotomy technique. This technique allows effective bone cutting without the usual thermal tissue damage. STUDY DESIGN/MATERIALS AND METHODS: A comparative in vivo study on mandibles of seven canines was done with a mechanical saw and a CO(2) laser based osteotome with a pulse duration of 80 microseconds. The laser incisions were performed in a multipass mode using a PC-controlled galvanic beam scanner and an assisting water spray. RESULTS: A complete healing through a whole bony rearrangement of the osteotomy gap with newly build lamellar Haversian bone was observed 22 days after the laser operations under optimal irradiation conditions. CONCLUSIONS: An effective CO(2) laser osteotomy without aggravating thermal side effects and healing delay is possible using the described irradiation technique. It allows an arbitrary cut geometry and may result in new advantageous bone surgery procedures.

Comparative study of three intramuscular anaesthetic combinations (medetomidine/ketamine, medetomidine/fentanyl/midazolam and xylazine/ketamine) in rabbits.

OBJECTIVE: To compare the quality of surgical anaesthesia and cardiorespiratory effects of three intramuscular (IM) anaesthetic combinations in rabbits. STUDY DESIGN: Prospective randomized cross-over experimental study. ANIMALS: Nineteen adult female chinchilla mixed-bred rabbits weighing 3.9 +/- 0.8 kg. METHODS: Rabbits were given one of three IM anaesthetic combinations: 0.25 mg kg(-1) medetomidine and 35.0 mg kg(-1) ketamine (M-K), 0.20 mg kg(-1) medetomidine and 0.02 mg kg(-1) fentanyl and 1.0 mg kg(-1) midazolam (M-F-Mz) and 4.0 mg kg(-1) xylazine and 50 mg kg(-1) ketamine (X-K). The effects of anaesthesia on nociceptive reflexes, circulatory and respiratory function were recorded. Statistical analyses involved repeated measures anova with paired Student's t-test applied post hoc. P-values <0.05 were considered as significant. RESULTS: Reflex loss was most rapid and complete in M-K recipients, whereas animals receiving M-F-Mz showed the longest tolerance of endotracheal intubation (78.1 +/- 36.5 minutes). Loss of righting reflex was significantly most rapid (p < 0.05) in the X-K group (114.7 +/- 24.0 minutes). Surgical anaesthesia was achieved in 16 of 19 animals receiving M-K, in 14 animals receiving M-F-Mz, and in seven animals with X-K, but only for a short period (7.1 +/- 11.6 minutes). This was significantly (p < 0.001) shorter than with M-K (38.7 +/- 30.0 minutes) and M-F-Mz (31.6 +/- 26.6 minutes). Heart rates were greatest in X-K recipients; lowest HR were seen in animals receiving M-F-Mz. Mean arterial blood pressure was significantly higher (about 88 mmHg) during the first hour in the M-K group. During recovery, the greatest hypotension was encountered in the X-K group; minimum values were 53 +/- 12 mmHg. Six of 19 animals in the M-F-Mz group showed a short period of apnoea (30 seconds) immediately after endotracheal intubation. Respiratory frequency was significantly lower in this group (p < 0.001). Highest values for arterial carbon dioxide partial pressures (PaCO(2)) (6.90 +/- 0.87 kPa; 52.5 +/- 6.5 mmHg) occurred after induction of anaesthesia in group M-F-Mz animals. There was a marked decrease in PaO(2) in all three groups (the minimum value 5.28 +/- 0.65 kPa [39.7 +/- 4.9 mmHg] was observed with M-K immediately after injection). Arterial PO(2) was between 26.0 and 43.0 kPa (196 and 324 mmHg) in all groups during O(2) delivery and decreased - but not <7.98 kPa - on its withdrawal. Immediately after drug injection, pH(a) values fell in all groups, with lowest values after 30 minutes (7.23 +/- 0.03 with M-K, 7.28 +/- 0.05 with M-F-Mz, and 7.36 +/- 0.04 with X-K). The X-K animals showed significantly (p < 0.001) higher pH values than medetomidine recipients. During 1 hour of anaesthesia pH values in the medetomidine groups remained below those of the X-K group. CONCLUSIONS: Surgical anaesthesia was induced in most animals receiving medetomidine-based combinations. Arterial blood pressure was maintained at baseline values for about 1 hour after M-K. Transient apnoea occurred with M-F-Mz and mandates respiratory function monitoring. Oxygen enrichment of inspired gases is necessary with all three combinations. Endotracheal intubation is essential in rabbits receiving M-F-Mz. CLINICAL RELEVANCE: The quality of surgical anaesthesia was greatest with M-K. All combinations allowed recoveries of similar duration. It is theoretically possible to antagonize each component of the M-F-Mz combination.

Simultaneous precise chemoradiation under inhalation anesthesia in an experimental mouse tumor model.

BACKGROUND: Performing radiobiological experiments under general anesthesia is, in many cases, superior to treatment in unanesthetized animals or with intraperitoneal (i.p.) anesthesia. This is especially true for experiments where highly fractionated treatment schedules are used. MATERIALS AND METHODS: An anesthesia system was employed to overcome several of the limitations associated with the use of pentobarbital and other i.p.-administered anesthetics in experimental radiotherapy. RESULTS: Several different experiments with a total of 152 mice were performed. The total of all anesthesia exposures amounted to approximately 1,520. The duration of anesthesia ranged from 3 to 5 min per session. No complications related to the anesthetic procedure were observed. CONCLUSION: The present anesthesia/irradiation setup is a simple, safe and perfectly reproducible system where even multiple fractionated treatments can be performed under anesthesia with excellent tolerance. Our system allows easy and fast handling and immobilization and thus reduces experimental times.

Three-dimensional fetal cephalometry: an evaluation of the reliability of cephalometric measurements based on three-dimensional CT reconstructions and on dry skulls of sheep fetuses.

AIM: To develop a 3D CT cephalometric analysis for maxillary growth evaluation of sheep fetuses operated in utero, and to evaluate the reliability of this analysis by comparing it with a direct cephalometric analysis on dry skulls. MATERIAL AND METHODS: Five skulls of operated sheep fetuses were used, which after preparation were CT scanned and a 3D reconstruction was performed. A cephalometric analysis was performed directly on the dry skulls as well as on the reconstructed 3D CT images. In total, 56 linear distances were measured. In order to access the error of the method, the procedure was repeated after a 2 week interval. RESULTS: The comparison between the direct cephalometric and the 3D CT analysis revealed that only 5 variables were significantly different. The evaluation of the error of method revealed that 7 variables of the direct cephalometric analysis and none of the 3D CT analysis differed significantly. CONCLUSIONS: According to the results of this study, it can be concluded that a cephalometric analysis on 3D CT reconstructed images of the skulls includes fewer identification errors and seems to be an accurate and reliable method that could be regarded at least as equivalent to conventional cephalometry.

Arterialisation of the portal vein as a model for the induction of hepatic fibrosis: description of microsurgical models in the rat.

Within the framework of liver transplantation, arterialisation of the portal vein in the case of non-recanalisable thrombosis has been reactivated. However, one of the consequences of this vascular reconstruction is the development of hepatic fibrosis. Clinical experience has shown that the development of fibrosis can be avoided by reducing portal inflow. We present, as a model for the induction of hepatic fibrosis, techniques of PVA, including transplantation. For PVA, several different techniques were used: the first with reduction of the portal inflow over a stent inserted in the right renal artery (PVA-B), the second with unrestricted flow using an aortic-portal segment (PVA-APS). The third technique was orthotopic liver transplantation with unrestricted portal arterialisation (OLTx-APS). Portal blood flow was measured with an ultrasonic flow probe. To determine the degree of hepatic fibrosis the amount of hydroxyproline was measured. Quantification of relative transcript levels of procollagen I was effected with real-time PCR using the TaqMan technology on a lightcycler instrument. The extracellular matrix was visualised with picro-sirius staining. Measurements with the ultrasonic probe showed a significant increase in flow rates, both with reduced (PVA-B) and unrestricted inflow (PVA-APS; OLTx-APS). The lowest survival rate (58%) was found in the group with unrestricted portal inflow. The reason for this was a high rate of thrombosis in the in the portal vascular tree (4 out of 12). In the OLTx-APS group four animals died within the first 3 postoperative days (69%), as a result of protracted postoperative shock. The overall survival rate was the highest (85%) in the group undergoing PVA with reduction of the portal inflow. PVA with unrestricted inflow was followed by a significant increase in extracellular collagen, which showed a clear correlation with the increase in the amount of hydroxyproline, the level of the mRNA for procollagen I and picro-sirius staining. With the operative PVA techniques presented herein, different arterial flow rates in the portal vein can be investigated. In our opinion these techniques represent an excellent animal model for studying the genesis of fibrosis and antifibrotic substances. By regulating the blood flow in the arterialised portal vein hepatic fibrosis can be reduced or even avoided. After a brief period of learning the microsurgical techniques, the surgeon can limit clamping times and achieve good results with these techniques.

PET of cardiac transgene expression: comparison of 2 approaches based on herpesviral thymidine kinase reporter gene.

UNLABELLED: PET of reporter gene expression holds promise for noninvasive monitoring of gene therapy. Previously, 2 approaches based on the herpes simplex virus type 1 thymidine kinase gene (HSV1-tk) have been successfully applied to the heart. Wild-type HSV1-tk was imaged with (124)I-labeled 2'-fluoro-2'-deoxy-5-iodo-1-beta-D-arabinofuranosyl-5-iodouracil (FIAU), and a mutant HSV1-tk (HSV1-sr39tk) was imaged with (18)F-labeled 9-[4-fluoro-3-(hydroxymethyl)butyl]guanine (FHBG). The aim of this study was to compare these 2 combinations with regard to specificity, imaging contrast, and reporter probe kinetics using dynamic PET in small and large animals. METHODS: Similar titers of adenovirus-expressing wild-type HSV1-tk (Ad(tk)), mutant HSV1-sr39tk (Ad(sr39tk)), or control genes were directly injected into the myocardium of 24 rats and 8 pigs. Two days later, dynamic PET was performed with a clinical scanner during the 120 min after injection of (124)I-FIAU (Ad(tk) animals and controls) or (18)F-FHBG (Ad(sr39tk) animals and controls). Imaging with (13)N-ammonia was performed to identify cardiac regions of interest. RESULTS: In rats, significant cardiac (124)I-FIAU accumulation occurred in images obtained early (10-30 min) after Ad(tk) injection. Because of tracer washout, however, no difference between Ad(tk)-injected animals and controls was seen in the images obtained later. For (18)F-FHBG, specific myocardial accumulation greater than background levels was detected in Ad(sr39tk)-injected animals at early imaging and, in contrast to (124)I-FIAU accumulation, increased over time until the latest imaging (105-120 min). At maximum, cardiac (18)F-FHBG concentration showed a 4.15 +/- 1.65-fold increase compared with controls (105-120 min), and cardiac (124)I-FIAU concentration reached a maximal increase of 1.34 +/- 0.38-fold compared with controls (10-30 min, P = 0.0014). Global cardiac reporter probe kinetics in rats were confirmed by regional myocardial analysis in pig hearts. Transgene expression was specifically visualized by both approaches. The highest target-to-background ratio of (124)I-FIAU in Ad(tk)-infected pig myocardium was 1.50 +/- 0.20, versus 2.64 +/- 0.49 for (18)F-FHBG in Ad(sr39tk)-infected areas (P = 0.01). In vivo results were confirmed by ex vivo counting and autoradiography. CONCLUSION: Both reporter gene/probe combinations were feasible for noninvasive imaging of cardiac transgene expression in different species. Specific probe kinetics suggest different myocardial handling of pyrimidine (FIAU) and acycloguanosine (FHBG) derivatives. The results favor (18)F-FHBG with mutant HSV1-sr39tk because of continuous accumulation over time and higher imaging contrast.

Effects of portal vein arterialization on regeneration and morphology in liver transplantation: investigations using the rat model.

BACKGROUND: Portal vein arterialization (PVA) has been proposed as a technical variant in liver transplantation in the case of non-recanalizable thrombosis. The present study investigates the effects of the arterialized portal vein on the function, morphology, and regenerative behavior of the liver. METHODS: Different PVA techniques, including orthotopic liver transplantation, were used in a rat model. Portal blood flow was measured using a ultrasonic flowmeter. The regeneration capacity was determined on the basis of the increase of liver weight and the proliferating cell nuclear antigen index. The amount of hydroxyproline and the transcript levels of procollagen I were measured to determine the degree of fibrosis. The extracellular matrix was visualized with Picro-Sirius staining. RESULTS: The measurements obtained with an ultrasonic probe revealed a significant increase in portal blood flow after PVA. The regeneration capacity in the groups after PVA with no flow reduction was comparable to that of the control. Liver transplantation and PVA with no flow reduction was followed by a significant increase (four- to sixfold) in the amount of hydroxyproline and the level of the mRNA for procollagen I. In the Picro-Sirius staining, periportal and perivascular fibrosis with incipient formation of septa was seen. After reduction of the portal blood flow, these effects were significantly less pronounced. CONCLUSIONS: These operative techniques represent an excellent small animal model for studying the mechanism of liver regeneration and the genesis of fibrosis in liver and vessel tissue. The presenting findings indicate that the negative effects of "overarterialization" may be largely avoided by reducing portal blood flow. This implies that permanent PVA in clinical liver transplantation should be performed only in conjunction with a down-regulation of portal flow.

Coexpression of herpesviral thymidine kinase reporter gene and VEGF gene for noninvasive monitoring of therapeutic gene transfer: an in vitro evaluation.

UNLABELLED: Coexpression of a reporter gene and a therapeutic gene may allow for noninvasive monitoring of cardiac gene therapy. We sought to evaluate the usefulness of an adenoviral vector expressing mutant herpesviral thymidine kinase reporter gene (HSV1-sr39tk) and vascular endothelial growth factor (VEGF) 121 in independent expression cassettes (Ad4tk). METHODS: Accumulation of 14C-2'-fluoro-5-methyl-1-beta-D-arabinofuranosyluracil (FIAU) and 9-(4-18F-fluoro-3-hydroxymethylbutyl)guanine (FHBG) as reporter probes, and secretion of VEGF into medium, were determined for Ad4tk-infected H9c2 rat cardiac cells in vitro. RESULTS: In vitro tracer uptake increased with increasing vector concentration and over time. It was comparable to cells infected with adenovirus expressing only wild-type HSV1-tk (reporter probe: 14C-FIAU) or mutant HSV1-sr39tk (reporter probe: 18F-FHBG). No significant uptake was observed in cells infected with adenovirus expressing VEGF alone. With increasing vector concentration, Ad4tk-infected cells increasingly released VEGF into medium. VEGF production correlated significantly with cellular reporter probe uptake (r = 0.93; P = 0.0003). CONCLUSION: The usefulness of a vector coexpressing HSV1-tk and VEGF for noninvasive imaging of expression of a therapeutic transgene has been demonstrated in vitro. This approach may allow for future in vivo monitoring of cardiac angiogenesis gene therapy.

[Clinical comparison of isoflurane and sevoflurane anaesthesia in the gerbil (Meriones unguiculatus)]. / Klinischer Vergleich einer Iso- und Sevofluranmononarkose beim Gerbil (Meriones unguiculatus).

The objective of this study was a comparison of the volatile anaesthetics isoflurane and sevoflurane in terms of their clinical effects in gerbils (Meriones unguiculatus) (n=12 each). Induction of anaesthesia was performed in a body chamber with an anaesthetic concentration of 4.0 Vol.% at an oxygen flow of 500 ml/min for isoflurane and 8.0 Vol.% at an oxygen flow of 1000 ml/min for sevoflurane, respectively. Anaesthesia was maintained via nose cone with an anaesthetic concentration of 2.8 to 3.2 Vol.% at an oxygen flow of 200 ml/min for isoflurane and 5.0 to 5.2 Vol.% at an oxygen flow of 400 ml/min for sevoflurane. Those anaesthetic concentrations ensured reflex status conform with surgical tolerance. In spite of its higher blood-gas coefficient induction time was slightly faster for isoflurane. Recovery time was significantly longer in the isoflurane group than it was in the sevoflurane group. Both inhalants caused respiratory depression. Respiratory rate was lower in sevoflurane animals compared to isoflurane. The animals were positioned on a heating pad immediately after induction, thus a decrease of the body temperature could be prevented. Both inhalants can be recommended for usage in gerbils. Sevoflurane showed no clinical benefit compared to isoflurane.

Intrauterine autogenous foetal bone transplantation for the repair of cleft-like defects in the mid-gestational sheep model.

AIM: The success of intrauterine surgery in treating non-life-threatening malformations such as myelomeningocoele, has also renewed strong interest in using this technique for treating craniofacial malformations. Nevertheless, the only experimental cleft-like defect models known, are those concerning wound healing of soft tissues. MATERIAL AND METHODS: Attempts were made to repair artificial cleft-like defects including transplantation of 11 autogenous foetal bone grafts from the iliac crest or ulna, and were randomly assigned to three study groups, using the mid-gestational sheep model. In a 4th study group, lyophilized collagen, a bone-regenerating bioresorbable implant material, was used to fill the alveolar defect. RESULTS: In all groups, there was a slight degree of asymmetry and thinning of the lip. Radiological studies demonstrated a variable degree of abnormality of the maxilla, ranging from none to a mild deviation. Three-dimensional computer tomography, two-dimensional maximal intensity projection findings, and histological analysis confirmed bony healing of the alveolar cleft-like defect. DISCUSSION/CONCLUSION: Intrauterine autogenous foetal bone transplantation for the repair of cleft-like defects in the sheep is feasible. This is a reliable and valuable model toward a possible clinical application for intrauterine treatment of clefts.

Noninvasive imaging of transgene expression by use of positron emission tomography in a pig model of myocardial gene transfer.

BACKGROUND: Radionuclide imaging of reporter gene expression may be useful for noninvasive monitoring of clinical cardiac gene therapy. Experience until now, however, has been limited to small animals. METHODS AND RESULTS: To evaluate feasibility in a clinically applicable setting, pigs were studied by conventional positron emission tomography (PET) 2 days after regional intramyocardial injection of control adenovirus or adenovirus carrying herpesviral thymidine kinase reporter gene (HSV1-tk). Myocardial blood flow was quantified by use of [13N]ammonia. Subsequently, kinetics of the reporter substrate [124I]-2'-fluoro-2'-deoxy-5-iodo-1-beta-d-arabino-furanosyluracil (FIAU) were assessed over a period of 2 hours. Areas infected with adenovirus expressing HSV1-tk showed significantly elevated FIAU retention during the first 30 minutes after injection. At later times, washout was observed, and retention was not different from that in areas infected with control virus or remote myocardium. Early in vivo FIAU uptake correlated with ex vivo images, autoradiography, and immunohistochemistry for reporter gene product after euthanasia. After intramyocardial injection of both adenoviruses, myocardial blood flow was mildly elevated compared with that in remote areas, consistent with histological signs of regional inflammation. CONCLUSIONS: In vivo quantification of regional myocardial transgene expression is feasible with clinical PET methodology, the radioiodinated reporter probe FIAU, and the HSV1-tk reporter gene. Radioactivity efflux after specific initial uptake was not observed previously in tumor studies, suggesting that tissue-specific differences in nucleoside metabolism influence reporter probe kinetics. By coregistering reporter gene expression with additional biological parameters such as myocardial blood flow, PET allows for noninvasive characterization of the success of cardiac gene transfer along with its functional correlates.

Magnetic drug targeting--biodistribution of the magnetic carrier and the chemotherapeutic agent mitoxantrone after locoregional cancer treatment.

Magnetic Drug Targeting means the specific delivery of chemotherapeutic agents to their desired targets, e.g. tumors, by using magnetic nanoparticles (ferrofluids) bound to these agents and an external magnetic field which is focused on the tumor. This type of target directed drug injection attempts to concentrate a pharmacologic agent by enhancing its efficacy while simultaneously minimizing deleterious side effects. In previous studies, we have been able to demonstrate the efficacy of this type of localized intraarterial chemotherapy in VX2 squamous cell carcinoma among rabbits [Alexiou, C., Arnold, W., Klein, R.J., Parak, F.G., Hulin, P., Bergemann, C., Erhardt, W., Wagenpfeil, S. and Lübbe, A.S. "Locoregional cancer treatment with Magnetic Drug Targeting", Cancer Res. 60 (2000) 6641-6648]. In the present investigation, we have studied the biodistribution of ferrofluids and chemotherapeutic agent by measuring the amount in the tumor, peritumoral area, various organs and body fluids (e.g. blood and urine), with and without Magnetic Drug Targeting. We compared results to that of administering a chemotherapeutic agent soley. An external magnetic field was directed toward the tumor for 60 min. Biodistribution of ferrofluids in the tumor was investigated using histological cross sections and measured semi-quantitatively using 123I-labeled nanoparticles and quantitatively by the use of radioactive 59Fe-ferrofluids. Mitoxantrone was quantitatively measured using HPLC-analysis. The strength of the external magnetic field was 0.6 Tesla (permanent magnet) in the 123iodine study and 1.7 Tesla (electromagnet) in the 59Fe-study and HPLC-analysis. The concentration of the ferrofluids (FFs) in the tumor region i.e. the tumor tissue and the surrounding area, which was under the influence of an external magnetic field, was found to be much higher than in the absence of one. In contrast to systemic chemotherapy, a much higher concentration of mitoxantrone in the tumor and the peritumoral area (region surrounding the tumor < or = 1 cm), by using only 50% and 20% of the normal dose was seen. Thus, the higher concentration of mitoxantrone could explain the therapeutic efficacy of Magnetic Drug Targeting in treatment of VX2 squamous cell carcinoma in rabbits in our previous studies with the advantage of no adverse clinical side effects.

Prostate lymphoscintigraphy for sentinel lymph node identification in canines: reproducibility, uptake, and biokinetics depending on different injection strategies.

At present there are neither clinical nor experimental data available on the influence of technical details on the quality and reproducibility of prostate lymphoscintigraphy. Six adult fox hounds received repeated transrectal ultrasound guided intraprostatic injections of a technetium 99m labeled nanocolloid to prove the influence of different techniques of injection (one central injection in both prostate lobes vs two peripheral injections in both lobes) on tracer accumulation in sentinel lymph nodes (SLN) and other organs. The reproducibility of the favored technique was examined and in a last step it was subject to scrutiny following a reduction of the injected volume to 1% of the prostate volume. The number of scintigraphically visualized SLN varied between four and seven. They were located in the region of the internal and external iliac vessels, presacrally, paravesically, and directly paraprostatically. In five of six cases, the localization was reproducible both with the central application of an identical volume as well as with the volume reduced central injection. Tracer accumulation of SLNs and other organs varied enormously. We expect that with the combination of both injection techniques, even with the reduced injection volume, an optimized prostate lymphoscintigraphy will be the outcome.