Treatment of experimental osteomyelitis caused by methicillin-resistant Staphylococcus aureus with a synthetic carrier of calcium sulphate (Stimulan) releasing moxifloxacin

The objectives of this study were to assess the efficacy of a synthetic semihydrate form of calcium sulphate (Stimulan) in experimental bone infection caused by methicillin-resistant Staphylococcus aureus (MRSA). Osteomyelitis was induced after inoculation of the test pathogen in the left tibia of 72 New Zealand rabbits assigned to the following groups: 18 control rabbits (Group A); 18 rabbits with Stimulan implanted (Group B); and 36 rabbits with moxifloxacin-impregnated Stimulan implanted (Group C). Rabbits were sacrificed at weekly intervals and cancellous bone was harvested for histopathology and for estimation of bacterial growth and concentrations of moxifloxacin. Bacterial growth from cancellous bone of Group C was significantly lower than the respective growth of Groups A and B on all days of sacrifice. The main histological finding of animals in all three groups was a moderate to intense inflammatory reaction accompanied by fibrosis. The degree of fibrosis was higher in Group C compared with both other groups. Infiltration by giant cells was also observed, which was greater in Group C on Day 42. Antibiotic levels in bone were higher for bone samples closer to the site of implantation. In conclusion, Stimulan admixed with 10% moxifloxacin was very effective in achieving complete eradication of the causative pathogen in experimental osteomyelitis caused by MRSA.

In vivo models for heart failure research

The medical treatment of heart failure (HF) is associated with 50% survival at 5 years, thus being one of the major causes of mortality in Western countries. An understanding of the pathophysiology of HF is essential for the development of novel efficient therapies. Consequently, the use of animal models is indispensable. In addition, the development of new in vivo models of HF is critical for the evaluation of treatments such as gene therapy, mechanical devices and new surgical approaches. However, every animal model has advantages and limitations and none of them is suitable to study all aspects of HF. Besides the technical determinants of a model, species, strain and gender affect the pathophysiology of a given heart pathogenesis and, therefore, have to be considered in each animal model. The most common in vivo models used in cardiology research and in particular in HF remodeling are presented.

The effects of vasopressors on perfusion of gastric graft after esophagectomy. An experimental study

AIMS

To evaluate the impact of the perioperative administration of norepinephrine on the perfusion of the esophageal graft.

METHODS

This is an experimental study. Six swine underwent transhiatal esophagectomy; the stomach was used to replace the resected esophagus. We provoked hemorrhagic shock to the animals and then we administered noradrenaline to restore the blood pressure. We monitored the graft perfusion perioperatively using the technique of microdialysis.

RESULTS

In all animals, the graft experienced severe hypoperfusion after the administration of noradrenaline that was statistically significant.

CONCLUSIONS

Our data support the hypothesis that norepinephrine should be used with extreme caution in the perioperative setting after esophagectomy. Further studies, however, will be required to evaluate the clinical significance of this finding.

The Effect of Negative Pressure Therapy on the Femoral Vein Blood Flow and Wall Structure

Negative pressure therapy has been recently used for managing lymphatic or infective groin complications. The aim of this study was to investigate any possible association between application of negative pressure therapy in the groin area and deep-vein thrombosis. Acute surgical wounds were created at the inguinal areas in 7 pigs. Different negative pressures ranging from −50 to −200 mmHg were applied directly over the femoral vessels, and blood flow alterations were studied using a Doppler ultrasound. Femoral vein specimens were also removed for histological examination after 12 hours of therapy. It has been demonstrated that negative pressure therapy does not significantly alter the baseline lower limb venous return. Histology demonstrated several changes, which are associated with vein thrombogenesis. The hemodynamic and pathological findings still leave a potential for thrombogenic effects of negative pressure therapy and warrant care to protect the femoral veins, with the use of thrombosis prophylaxis measures.

The effect of nifedipine on the patency of microvascular anastomosis in rats

Despite advances in microsurgical technique and experience in clinical microvascular surgery, there remains the possibility of vessel thrombosis. Factors that may contribute to vascular pedicle thrombosis include operative trauma, pedicle malposition, kinking, hypercoagulability and arterial vasoconstriction. The purpose of this study was to evaluate the effect of intravenous administration of nifedipine on the patency of the microvascular anastomosis of the femoral artery in rats. A total of 60 rats were used and divided into three groups. The first group (A) was used as a control group with no medical agent, the second group (B) was medicated with heparin, and the third group (C) was medicated with nifedipine. Patency was assessed with the distal empty refill test, one hour (1) and forty-eight hours (48) after completion of the anastomosis. The nifedipine and heparin treated groups (B & C) did not show higher patency rate compared to the control group (A). There was no statistically significant difference of patency percent after 1 hour and 48 hours among the three groups (p = 0.231/p = 0.480). Intravenous administration of nifedipine does not improve the patency of microvascular anastomosis. Surgical technique remains the most important factor for successful microvascular anastomosis.

Restenosis is not associated with stent length in a pig model of coronary stent implantation

BACKGROUND

The aim of this study was to determine if stent length is by itself a risk factor for intimal proliferation and restenosis. Long lesions represent an independent risk factor for restenosis after coronary stent implantation. A longer stented segment might result in a higher probability of restenosis.

METHODS

Twenty-two 7-month-old male farm pigs underwent implantation of two steel stents, one short (8 mm length) and one long (16 mm length), in the right coronary artery. The pigs were sacrificed 28 days after stent implantation and histomorphometric analysis of the coronary arteries was performed for neointimal area proliferation and area stenosis evaluation.

RESULTS

Seventeen short stents and 19 long stents were finally implanted. There were no differences in neointimal proliferation (1.84 +/- 0.64 mm2 vs. 1.81 +/- 0.94 mm2, p = 0.84), area stenosis (40 +/- 9% vs. 41 +/- 19%, p = 0.86) and lumen area (2.96 +/- 1.30 mm2 vs. 2.51 +/- +/- 1.18 mm2, p = 0.21) between the short stent group and the long stent group, respectively.

CONCLUSIONS

These data suggest that stent length by itself does not influence restenosis extent in the porcine model.

ACL reconstruction with semitendinosus tendon autograft without detachment of its tibial insertion: a histologic study in a rabbit model

The purpose of this study was to evaluate the histologic changes that occur between 3 and 12 weeks in an intra-articular, semitendinosus autograft, which was harvested without detachment of its tibial insertion and was placed through tibial and femoral drill holes, in a rabbit model. About 30 New Zealand white rabbits underwent ACL replacement using a semitendinosus tendon autograft. The normal ACL was transected at its femoral and tibial insertions. The tendon graft was harvested without detachment of its tibial insertion and its free end was secured with sutures. The graft was then passed through one tibial and one femoral tunnel and secured at the lateral femoral condyle. All animals were divided into three groups and were killed at 3, 6 and 12 weeks after surgery. Nine more animals underwent ACL reconstruction using a free semitendinosus tendon autograft. These animals were used as controls. The intra-articular portion of the graft and the interface between the bone tunnel and the graft was evaluated postoperatively for gross morphology and histological appearance. Results of this study showed that in a rabbit model the semitendinosus tendon autograft retained its viability when harvested without detachment of its peripheral insertion. On contrary, at the control group, necrosis of the graft was observed 3 weeks after surgery and progressively revascularization and maturation occurred 6 and 12 weeks after surgery. Retaining the tibial insertion of the semitendinosus autograft seems to preserves its viability and bypasses the stages of avascular necrosis and revascularization that occurs with the use of a free tendon autograft.

EP2306 [2-(4-Biphenyl)-4-methyl-octahydro-1,4-benzoxazin-2-ol, hydrobromide], A Novel Squalene Synthase Inhibitor, Reduces Atherosclerosis in the Cholesterol-Fed Rabbit

EP2306 [2-(4-biphenyl)-4-methyl-octahydro-1,4-benzoxazin-2-ol, hydrobromide] inhibits squalene synthase and lipid biosynthesis and possesses antioxidant properties. We hypothesized that EP2306 can effectively modify circulating lipids and reduce atherosclerosis in the cholesterol-fed rabbit. Animals were fed a high-cholesterol diet for 4 weeks followed by 4 (phase 1 and 2) or 12 weeks (phase 3) of drug treatment while on high-cholesterol diet. In phase 1, the dose-effect relationship of EP2306 on lipids and atherosclerosis was established, and its most effective dose was determined (2 mg/kg). This dose reduced significantly total cholesterol (512 +/- 96 mg/dl before versus 320 +/- 124 mg/dl after treatment, p < 0.05) and atherosclerotic lesions compared with control animals. In phase 2, the effects of 2 mg/kg EP2306, 2.5 mg/kg simvastatin, and their combination were assessed. Although no significant effect on lipid parameters was observed, there was a significant reduction (35 +/- 5%, p < 0.05) of atherosclerotic lesions in animals treated with EP2306, a similar reduction with simvastatin, and a further reduction (48 +/- 7%, p < 0.05) when the two agents were combined. In animals treated for 12 weeks with the drugs (phase 3), only EP2306 significantly reduced atherosclerotic lesions by more than 50%, whereas simvastatin alone or in combination with EP2306 had no effect. Treatment with EP2306 did not adversely affect liver transaminases or cause any histopathological changes on various organs of the animals. In conclusion, we have shown that EP2306 inhibits atherosclerosis in vivo, indicating potential as a novel therapeutic agent for coronary artery disease and other atherosclerosis-related disorders.

Accumulation of dietary glycotoxins in the reproductive system of normal female rats

The aim of the present study was to investigate whether dietary advanced glycation end-products (AGEs) can be detected in the ovarian tissue of normal female rats and whether they can affect their metabolic or hormonal profile. Sixty normal rats (20 animals in each group) were randomly assigned to regular diet, either high (H-AGE) or low (L-AGE) in AGE content for 6 months. H-AGE rats demonstrated higher levels of fasting glucose (P < 0.001), insulin (P < 0.069), and serum AGEs (P < 0.001) than control and L-AGE rats. Additionally, the H-AGE group showed increased AGE localization in the theca interna cells of the ovarian tissue compared to control/L-AGE rats (P = 0.003). Furthermore, increased receptor for AGE (RAGE) staining was also observed in granulosa cells compared to control/L-AGE samples (P = 0.038). In the H-AGE group, plasma testosterone was higher than in control rats (P < 0.001) and in the L-AGE group (P < 0.001). However, H-AGE rats did not exhibit higher body weight compared with normal (P = 0.118) and L-AGE-fed rats (P = 0.35). These results demonstrate for the first time that administration of high AGE diet in female rats for a prolonged period is associated with increased deposition of AGEs in the theca cells and of RAGE in the granulosa and theca interna cells of the ovarian tissue compared with the corresponding ovarian compartments of the control and L-AGE-fed animals. The metabolic alterations in conjuction with the increased deposition in ovarian tissues of dietary glycotoxins and elevated levels of testosterone in H-AGE-fed animals compared to the controls suggest an impact of environmental factors on ovarian tissue and these findings need further exploration.

Coronary sinus stent implantation improves acute ischaemic mitral valve regurgitation; an experimental safety and efficacy study

AIMS

Percutaneous implantation of a large stent was performed in the coronary sinus of pigs, to assess safety and immediate efficacy for reduction of acute ischaemic mitral regurgitation.

METHODS AND RESULTS

Acute ischaemic mitral regurgitation (MR) was produced in seven pigs, continuously monitored with echocardiography, during repeated balloon inflations in the proximal left circumflex artery. The protocol was repeated following placement of a stent in the coronary sinus. Five pigs survived the period of acute ischaemia and developed severe mitral regurgitation (>/=3+/4+). Following successful stent implantation, the MR area decreased from 2.4+/-0.4 cm2 to 1.1+/-0.6 cm2 (p=0.016) and the proximal isovelocity surface area (PISA) MR flow from 63.9+/-37.3 ml/sec to 44.0+/-35.0 ml/sec (p=0.029). Coronary sinus stent prevented the ischaemia-induced increase in septal-lateral mitral annulus dimension (p=0.041) and left ventricular dilatation. Three animals were allowed to recover and underwent histological analysis of the coronary sinus stent at 30 days, showing endothelialisation and minimal hyperplasia, without thrombus formation.

CONCLUSIONS

A percutaneously deployed stent in the coronary sinus may help to decrease the severity of acute ischaemic mitral regurgitation.

Dexamethasone as adjuvant therapy to moxifloxacin attenuates valve destruction in experimental aortic valve endocarditis due to Staphylococcus aureus

Although the beneficial effects of dexamethasone have frequently been investigated in various serious-infection settings, insufficient data on valve histology and cardiac function for infective endocarditis are available. The efficacy of moxifloxacin for the treatment of experimental aortic valve endocarditis due to methicillin-susceptible Staphylococcus aureus and the long-term effects of dexamethasone were evaluated in the current study. Sixty-eight rabbits were randomly assigned to four groups: A, B, C, and D. Group A consisted of 18 animals and functioned as a control group. Groups B and C consisted of 11 and 23 subjects, respectively, which received moxifloxacin for 5 days in a human-like pharmacokinetic simulation. Group D consisted of 16 animals that were administered moxifloxacin plus dexamethasone (0.25 mg/kg of body weight twice a day intravenously). The group B animals were sacrificed a day after the completion of treatment, and group C and D animals were sacrificed after 12 days in order to monitor any possible relapse and allow microbiological, histopathological, and echocardiographic evaluation of the long-term effects of glucocorticoids. No differences in survival, sterilization rates, or inflammatory infiltration and calcification of valve tissue were observed among the treated groups. However, the degrees of valve damage and collagenization were significantly worse, the fibroblast content was higher, and fractional shortening of the left ventricle fluctuated significantly in group C compared to group D (all groups, P < 0.05). We concluded that dexamethasone treatment for experimental S. aureus endocarditis attenuates valve destruction and preserves overall cardiac function without impeding the efficacy of moxifloxacin.

Endoscopic transgastric procedures in anesthetized pigs: technical challenges, complications, and survival

BACKGROUND AND STUDY AIMS

An incisionless endoscopic peroral transgastric approach to the peritoneal cavity has shown promise in animals as a potentially less invasive form of surgery. We present our experience with various endoscopic peroral transgastric procedures, reporting on the technical aspects and challenges that arose.

MATERIALS AND METHODS

The following procedures were performed in 10 anesthetized pigs using a double-channel endoscope: peritoneoscopy (10 pigs), liver biopsy (one pig), cholecystectomy (six pigs), fallopian tube excision (one pig), and hysterectomy (one pig).

RESULTS

All the procedures were accomplished successfully. There were six minor intraoperative complications. Complete gastric cleansing and elimination of all bacteria was found to be impossible to achieve in the porcine model. Overinflation was a common problem. The lack of adequate endoscope support was a major limitation. Safe closure of the gastrotomy incision was difficult using the available clipping devices. Six pigs made an uncomplicated recovery after a follow-up period of 4-6 weeks. Subsequent pathological examination revealed deep gastric ulceration in one animal and a gastric wall abscess in another.

CONCLUSIONS

Peroral transgastric surgery is technically feasible and safe in a porcine model. Although all the procedures were performed successfully, the study highlights some technical difficulties and illustrates the need for major technical innovations and extensive animal studies in order to evaluate the merits of incisionless surgery.

[Allogenic islet transplantation on the rat liver after allogenic nonparenchymal cells injection in the thymus]

BACKGROUND

[corrected] The major indication for pancreas or islet transplantation is diabetes mellitus type I. This process has to supply the insulin necessity keeping glucose under control

AIM

We studied allogenic islet transplantation on the rat liver, Wistar (RT1u) to Lewis (RT1(1)) as a recipient. Control group (n = 8) and nonparenchymal cell group (n = 8) respectively with injection of Hanks solution and nonparenchymal cells in the thymus before islet transplantation.

MATERIAL AND METHODS

With the method of isolation and purification of the islets we obtained both in the control group 3.637 +/-783,3 islets with purity of 85 +/- 3,52% and nonparenchymal cell group 3.270 +/- 770 islets with purity of 84,25 +/- 2,76%. The nonparenchymal cells were retrieved from the liver and we obtained 2 x 106 cells. Diabetes was induced by i.v. streptozotocin

RESULTS

Control group the transplantation of 3.637 +/- 783,3 islets in the rat liver normalized glucose test, 7,21 +/- 0,57 mmol/L in the 2nd postoperative day. Acute rejection came in the 6th postoperative day with significantly increase of glucose test in nonparenchymal cell group, the transplantation of 3.270 +/- 770 islets in the rat liver, almost normalized the glucose test was 17,95 +/- 5,33 mmol/L in the 2nd postoperative day. From the 4th postoperative day to 10th postoperative day. The glucose test increase significantly showing an early acute rejection

CONCLUSION

The injection of nonparenchymal cells in the thymus before allogenic islet transplantation in the rat liver lead to an early acute rejection.

Simultaneous deregulation of p16 and cyclin D1 genes in pancreatic ductal adenocarcinoma: a combined immunohistochemistry and image analysis study based on tissue microarrays

PURPOSE

Deregulation of cell cycle control molecules, such as cyclins and their inhibitors, is a crucial event in the carcinogenetic process. Our aim was to identify potential correlations between p16 and cyclin D1 expression in pancreatic ductal adenocarcinoma (PDAC) that affect the biological behavior of this neoplasm.

MATERIALS AND METHODS

Using tissue microarray (TMA) technology, 50 paraffin-embedded tissue samples of histologically confirmed primary PDACs were cored twice and re-embedded to the final recipient block. Immunohistochemistry (IHC) was performed using monoclonal anti-p16 and anti-cyclin D1 antibodies. Protein expression levels were determined by performing computerized image analysis (CIA; estimation of Nuclear Labeling Index-NLI). SPSS (chi square test and interrater Cohen's kappa) was used for statistical analysis.

RESULTS

Cyclin D1 overexpression was observed in 24/50 (48%) of the examined carcinomas, whereas p16 loss or reduced expression was detected in 40/50 (80%) cases. Statistical significance was noted when correlating grade to cyclin D1 (p=0.038), stage to p16 (p=0.012) and also to cyclin D1 (p=0.011). Interestingly, combined protein alterations (p16 loss and cyclin D1 overexpression) were observed in 23/50 (46%) cases associated with advanced stage (p=0.019). Overall combined expression of the two molecules demonstrated a significantly low value (kappa=0.012; 95% confidence interval-CI: 0.010-0.014).

CONCLUSION

A significant proportion of PDACs is characterized by simultaneous protein alterations regarding p16 and cyclin D1 genes. This mechanism of genetic deregulation in cell cycle potentially explains in part the aggressive phenotype of this neoplasm.

Beneficial effect of an antibody against interleukin-2 receptor (daclizumab) in an experimental model of hepatocyte xenotransplantation

AIM: To investigate the use of Daclizumab (Dmab) as an immunosuppressive agent in an experimental model of hepatocyte xenotransplantation (XenoTx) in rats with fulminant hepatic failure (FHF).

METHODS: Two white male New Zealand rabbits were used as donors and 68 Wistar rats as recipients. FHF was induced by intravenous application of dimethylnitrosamine (DMNA). The isolated hepatocytes of the rabbits were xenotransplanted into the spleen of the rats 24 h after FHF induction. Group A (n = 13): no treatment; Group B (n = 14): FHF and XenoTx; Group C (n = 14): FHF and XenoTx and cyclosporin (CsA); Group D (n = 14): FHF and XenoTx and Dmab; Group E (n = 13): FHF and XenoTx and CsA and Dmab. The rats were followed for 15 d.

RESULTS: Statistical analysis showed better survival among groups D (92.86%) and E (76.92%) compared to group A (all rats died after 72 h), group B (28.57%) or group C (71.43%), although the differences were not statistically significant. Biochemical evaluation of the liver enzymes and histology confirmed satisfactory function and engraftment, respectively.

CONCLUSION: This experimental model has shown the safe, effective and beneficial use of Dmab in a xenotransplantation model of rabbit hepatocytes in rats.

The prophylactic effect of L-arginine in acute ischaemic colitis in a rat model of ischaemia/reperfusion injury

BACKGROUND/AIMS

The decreased synthesis of nitric oxide (NO) during ischaemia/reperfusion (I/R) has been implicated as the major underlying mechanism for the pathogenesis of acute ischaemic colitis (A.I.C.). The aim of this study was to investigate the prophylactic effect of L-arginine, a NO donor, on tissue injury during intestinal I/R, and compare its efficacy with that of exogenous vasodilators (molsidomine) and inert nitrogen-containing molecules (casein).

MATERIAL AND METHODS

One hundred forty four Wistar rats underwent occlusion of the superior mesentery artery for 30, 60 and 90 min for induction of intestinal ischaemia, followed by 90 min of reperfusion. The rats were randomly assigned to receive L-arginine, molsidomine, or casein hydrolysate. In all groups, apart of the histological study, we determined the levels of serum malondialdehyde (MDA), a reliable marker indicating the degree of the tissue damage after intestinal I/R.

RESULTS

Serum MDA levels were significantly lower in the L-arginine group compared to the untreated animals or those that had received molsidomine or casein, after a period of ischaemia of 90 minutes (p < 0.0005), as well as after a period of ischaemia of 60 or 90 minutes followed by a 90 minutes reperfusion (p = 0.011, and p < 0.0005, respectively). In addition, lesser histopathological damage was noted after the use of L-arginine compared to that caused by the administration of molsidomine and casein.

CONCLUSION

These findings support a prophylactic effect of L-arginine in experimentally induced intestinal ischaemia. In short, L-arginine attenuates the degree of tissue damage in intestinal ischaemia and promotes healing of intestinal mucosa.

Repeated Balloon Inflations Do Not Diminish ST Segment Elevation even though Coronary Collateral Recruitment Is Promoted in Pigs

OBJECTIVE

Attempts to demonstrate preconditioning during repeated angioplasty balloon inflations (BIs) have not been universally successful. The main obstacle is that the first BI is unreliable, due to the variable degrees of occlusion by the deflated balloon. In the present study, we examined whether ST segment elevation decreases and evaluated its relation to collateral recruitment during repeated angioplasty BIs in the pig.

METHODS AND RESULTS

Twenty male pigs, 7 months old, under general anesthesia, underwent 3 repeated BIs of 120 s, with a 5-min interval between them, in the left anterior descending artery or the right coronary artery. A pressure wave wire was used for the measurement of coronary wedge pressure and to obtain the intracoronary ST segment elevation. Intracoronary ST segment elevation was 1.97 +/- 0.76 mV during the 1st BI, 2.09 +/- 0.82 mV during the 2nd BI and 1.84 +/- 0.82 mV during the 3rd BI (p = n.s.). Coronary wedge pressure was 12 +/- 6, 18 +/- 18 and 20 +/- 20 mm Hg (p < 0.05 vs. 1st BI) during the 3 BIs, respectively.

CONCLUSION

Repeated BIs do not diminish ST segment elevation in the pig model, even though coronary collateral recruitment is promoted.

The effect of pulsed electromagnetic fields on secondary skin wound healing: An experimental study

A variety of pulsed electromagnetic fields (PEMFs) have already been experimentally used, in an effort to promote wound healing. The aim of the present study was to investigate the effects of short duration PEMF on secondary healing of full thickness skin wounds in a rat model. Full thickness skin wounds, 2 by 2 cm, were surgically inflicted in two groups of male Wistar rats, 24 animals each. In the first group (experimental group - EG), the animals were placed and immobilized in a special constructed cage. Then the animals were exposed to a short duration PEMF for 20 min daily. In the second group (control group - CG), the animals were also placed and immobilized in the same cage for the same time, but not exposed to PEMF. On days 3, 6, 9, 12, 18, and 22, following the infliction of skin wounds, the size and healing progress of each wound were recorded and evaluated by means of planimetry and histological examination. According to our findings with the planimetry, there was a statistically significant acceleration of the healing rate for the first 9 days in EG, whereas a qualitative improvement of healing progress was identified by histological examination at all time points, compared to the control group.

Implants of type I collagen gel containing MG-63 osteoblast-like cells can act as stable scaffolds stimulating the bone healing process at the sites of the surgically-produced segmental diaphyseal defects in male rabbits

BACKGROUND

Three-dimensional (3-D) type I collagen gel culture systems allow long-term growth of osteoblast-like cells, in vitro. Whether the implantation of 3-D collagen systems can stimulate new bone formation was assessed in male rabbits.

MATERIALS AND METHODS

A 10-mm segmental diaphyseal defect was surgically produced at the left and right limbs of 50 adult male rabbits. The 3-D systems containing MG-63 osteoblast-like cells were implanted at the right-limb defects of all 50 animals. Twenty-five left-limb defects were implanted with 3-D collagen gels containing no MG-63 cells, while the rest were left empty. The bone repair process was serially assessed by radiography for up to 8 weeks and by histological analysis for up to the week 32 post-surgery.

RESULTS

Ninety-four per cent (94%) of the right-limb defects, presented radiographic evidence of complete bone-end bridging within 8 weeks. None of the 50 left-limb defects presented radiographic post-implantation evidence of bone-end bridging. The radiographic evidence of the bone-end bridging was corroborated with histological evidence of new bone formation, while the medullar canals were filled with bone marrow elements.

CONCLUSION

Implants of the 3-D collagen gels containing osteoblast-like cells can be used as stable scaffolds allowing the migration/proliferation of the bone regenerating cells in male rabbits.

Comparison of monopolar electrocoagulation, bipolar electrocoagulation, Ultracision, and Ligasure

PURPOSE

Hemostasis is a fundamental principle of surgery. We compared the safety and efficacy of monopolar electrocoagulation (ME), bipolar electrocoagulation (BE), Ligasure (LS), a modern bipolar vessel sealing system, and Ultracision (UC), a system of ultrasound energy based shears. We also studied the healing process after their use.

METHODS

We used each of the above methods to coagulate and divide the short gastric vessels of 16 white male New Zealand rabbits. The animals were killed after 3, 7, 14, or 21 days, and the coagulation sites and the adjacent gastric wall were examined histologically.

RESULTS

LS and UC achieved complete hemostasis without any complications. Conversely, ME and BE often resulted in failed coagulation and perforation of the neighboring gastric wall from a side thermal injury. Histologically, LS demonstrated the mildest side thermal injury and the fastest healing process. We noted greater thermal injury and inflammatory response after UC than after LS on days 7 and 14; however, ME and BE caused the most severe lesions.

CONCLUSIONS

LS and UC are clearly the safest and most efficient methods of coagulation, whereas ME and BE could cause serious clinical and histological complications. We found histological evidence that UC causes a slightly greater inflammatory response than LS, and the clinical implications of this warrant further investigation.