OBJECTIVETo investigate the local changes of biomechanics after osteotomy of mandibular outer cortex in body and angle areas.

METHODSSix minitype pigs at the age of 8 to 12 months were selected. The mandibular outer cortex that involves angle and part of body was removed in one side. The animals were killed 24 weeks after operation. Bone strut was taken from mandibular angle region bilaterally and sent for biomechanical test

RESULTSThere was no biomechanical difference between the two angle areas of experimental and normal sides 24 weeks after mandibular outer cortex osteotomy (maximum load P > 0.05, rigidity P > 0.05).

CONCLUSIONSMandibular outer cortex osteotomy had no influence on local biomechanics.

Animals ; Biomechanical Phenomena ; Female ; Male ; Mandible ; physiology ; surgery ; Osteotomy ; Postoperative Period ; Swine ; Swine, Miniature

OBJECTIVETo explore the effect of burying testis in thigh pocket on spermatogenesis.

METHODSGuizhou miniature male pigs at child-bearing period were randomly divided to receive operation of scrotum incision and dissection with the testis burying in thigh pocket (experimental group) or without (control group). 3 months later, testis biopsy was performed on 2 pigs from each group for pathological examination. Then every male pig from both experimental (n = 6) and control group (n = 6) got a mating partner and lived together for 3 months. The fertility of the male pigs was observed. 6 months after operation, testis biopsy was performed again on all the animals from both the groups.

RESULTSBoth at 3 months and 6 months after operation, the pathological examination showed the spermatogenic cells of all stage in contorted seminiferous tubules markedly decreased with no mature sperm in experimental group, while normal spermatogenic cells with mature sperm in control group. After the male pigs lived with mating partners for 3 months, no female pigs staying with the experimental group became pregnant, but the male pigs in control group had a normal fertility.

CONCLUSIONSBurying testis in thigh pocket impedes spermatogenesis in the miniature male pig. So burying testis in thigh pocket is not recommended for patients with scrotum skin defect who wish to remain fertile.

Animals ; Female ; Fertility ; Male ; Pregnancy ; Pregnancy Rate ; Scrotum ; Skin ; injuries ; Spermatogenesis ; Swine ; Swine, Miniature ; Testis ; physiology ; Thigh ; surgery

In order to study the mechanical behavior of degeneration and nucleotomy of lumbar intervertebral disc, compression experiments with porcine lumbar intervertebral discs were carried out. The lumbar intervertebral discs with trypsin-treated and nucleus nucleotomy served as the experimental group and the normal discs as the control group. Considering the effects of load magnitude and loading rate, the relationship between stress and strain, instantaneous elastic modulus and creep property of intervertebral disc were obtained. The creep constitutive model was established. The results show that the strain and creep strain of the experimental group increase significantly with the increase of compression load and loading rate, whereas the instantaneous elastic modulus decreases obviously, compared with the control group. It indicates that the effect of load magnitude and loading rate on load-bearing capacity of intervertebral disc after nucleotomy is larger obviously than that of normal disc. The creep behavior of the experimental group can be still predicted by the Kelvin three-parameter solid model. The results will provide theoretical foundation for clinical treatment and postoperative rehabilitation of intervertebral disc disease.
Animals ; Biomechanical Phenomena ; Intervertebral Disc ; physiology ; surgery ; Lumbar Vertebrae ; Stress, Mechanical ; Swine ; Weight-Bearing

BACKGROUNDCyanotic congenital heart defects with decreased pulmonary blood flow due to lung ischemia, hypoxia, and others lead to infant morbidity and mortality more than acyanotic heart disease does. Despite the great effort of medical research, their genetic link and underlying microRNAs molecular mechanisms remain obscure. In this study, we aimed to investigate microRNAs regulation during cyanotic defects in lung of immature piglets.

METHODSCyanotic piglet model was induced by main pulmonary artery-left atrium shunt with distal pulmonary artery banding. Four weeks later, hemodynamic parameters confirmed the development of cyanotic defects and pulmonary lobe RNA was extracted from all animals. We studied the repertoire of porcine lung microRNAs by Solexa deep sequencing technology and quantified highly expressed microRNAs by microarray hybridization. Furthermore, we quantitated selected microRNAs from cyanotic and control piglets by quantitative RT-PCR.

RESULTSAfter surgical procedure 4 weeks later, the cyanotic model produced lower arterial oxygen tension, arterial oxygen saturation, and higher arterial carbon dioxide tension, hematocrit and hemoglobin concentration than controls (all P < 0.05). In 1273 miRNAs expressed in the immature piglets lungs, 2 most abundant microRNAs (miR-370 and miR-320) demonstrated significant difference between cyanotic and control group (all P < 0.05).

CONCLUSIONOur results extended lung microRNA profile in immature piglets and suggested that miR-370 and miR-320 are significantly up-regulated in cyanotic lung tissues.

Animals ; Chronic Disease ; Cyanosis ; genetics ; physiopathology ; Gene Expression Profiling ; Heart Atria ; surgery ; MicroRNAs ; analysis ; physiology ; Pulmonary Artery ; surgery ; Pulmonary Circulation ; Real-Time Polymerase Chain Reaction ; Swine ; Swine, Miniature

A set of system for in vitro testing and analyzing the 3D motion in the cervical spine specimen before and after the ACP's (anterior cervical plates) implantation is introduced in this paper. Six porcine specimens with C3 - C6 mounted by the custom clamp were used to mimic human physiological cervical motions. A non-contact real-time measurement system based on CCD was used to track segmental cervical motion signals during the motion. A Matlab program based on multibody dynamics was processed to give the angle changes between adjacent vertebras during the motion. The experimental results show that the methodology can appraise the clinical properties of the ACP effectively.
Animals ; Biomechanical Phenomena ; Cervical Vertebrae ; physiology ; surgery ; Range of Motion, Articular ; physiology ; Spinal Fusion ; methods ; Swine ; Treatment Outcome

BACKGROUNDMost of endovascular stent-graft modifications to preserve side branch must be customized according to extensive pre-operative assessment, which may not be possible in many hospitals and emergency settings. The study was to develop a novel stent-grafts system that would allow in situ "fenestration", with less reliance on preoperative imaging.

METHODSThe magnitude of pressure difference (PD) between left subclavian artery (LSA) and aortic arch were measured in 12 experimental pigs. Changes of PD before and after LSA was covered were analyzed respectively. The novel stent graft was made by multi-dimensional and multiple textiles forming technology. According to the PD measurement in pigs, we evaluated the feasibility of the stent-graft in a mock circulation system.

RESULTSIn pigs, the blood pressure of aortic arch was significantly higher than that of LSA after it was covered (P < 0.001) and PD was (42.78 ± 5.17) mmHg. After target vessel was covered and when PD between the LSA and aorta reached the magnitude measured in pigs, contrast media oozed from the cranny of graft to the LSA, which was generated by sliding and deformation of yarns of novel stent-graft.

CONCLUSIONSThe study proposes the design of pressure difference-induced perforation aortic stent-grafts system and verifies that the PD between LSA and aortic arch is high enough to allow in situ "fenestration" by stent graft made by multi-dimensional and multiple textiles forming technology.

Animals ; Aorta, Thoracic ; surgery ; Blood Pressure ; physiology ; Blood Vessel Prosthesis ; Blood Vessel Prosthesis Implantation ; Prosthesis Design ; Subclavian Artery ; Swine

OBJECTIVETo test the changes of the stiffness of the intact, released, and instrumented spines in an in vitro porcine model.

METHODSTwelve porcine spines (12 segments each) were harvested for the biomechanical tests with Material Test System. Stiffness during flexion, extension, lateral bending, and axial rotation were recorded; then the specimen was released with intervertebral discs and the facet joints removed, followed by repeating the biomechanical tests for stiffness; and finally, a double-rod titanium construct was applied for internal fixation to each released spine and stiffness tests were repeated again.

RESULTSCompared with the intact porcine spines [stiffness during flexion, extension, lateral bending, and axial rotation was 52.89 +/- 15.98, 105.43 +/- 56.38, 42.09 +/- 14.73, and (16.94 +/- 4.85) N x mm/degrees, respectively], the stiffness of the released porcine spines [stiffness during flexion, extension, lateral bending, and axial rotation was 44.04 +/- 13.73, 41.46 +/- 10.80, 31.75 +/- 7.23, and (9.10 +/- 2.07)N x mm/degrees, respectively] significantly decreased (P < 0.05), while significantly increased stiffness was found in the instrumented porcine spines [stiffness during flexion, extension, lateral bending, and axial rotation was 385.96 +/- 143.25, 138.96 +/- 59.41, 152.56 +/- 87.15, and (55.91 +/- 16.49) N x mm/degrees, respectively] (P < 0.05).

CONCLUSIONHigher instant stiffness was found in instrumented spine than the intact one during flexion, extension, lateral bending and axial rotation.

Animals ; Biomechanical Phenomena ; Diskectomy ; Fracture Fixation, Internal ; Internal Fixators ; Lumbar Vertebrae ; surgery ; Range of Motion, Articular ; physiology ; Spinal Fusion ; methods ; Spine ; surgery ; Stress, Mechanical ; Swine ; Thoracic Vertebrae ; surgery

To develop a better model of isolated perfused heart, a new apparatus of "coronary artery cannula- fixed-in-aortic tube" was developed for continuous normothermic perfusion and compared to the Casalis apparatus with cold ischemia. Eight mongrel pigs with the body weight of 18 to 24 kg were divided half into two groups.All the continuous perfusion experimental hearts resumed a spontaneous heart beat and stabilized earlier than the control hearts without the need of defibrillator or pacemaker, indicating no reperfusion injury on the heart. All the experimental hearts did not show fibrillation nor stopped beating during the entire experiment, whereas the control hearts fibrillated. Two control hearts stopped beating, and only one of the two survived with the help of pacemaker.The coronary systolic, diastolic, and mean pressures were more stable with low variation in the experimental hearts than the cold ischemic control hearts. The experimental hearts consumed more oxygen than the control hearts, indicating more cardiac output.According to these results, the continuous normothermic perfusion method by the new cannula, even though with a short-period of hypothermic perfusion, provided better myocardial protection than the cold ischemia.
Animals ; Blood Gas Analysis/veterinary ; Blood Pressure ; Cardioplegic Solutions/therapeutic use ; Catheterization/*methods/veterinary ; Heart/*physiology ; Heart Rate ; Perfusion/*methods/veterinary ; Swine/*physiology/surgery

OBJECTIVE: We wanted to compare the efficiency of multipolar radiofrequency ablation (RFA) using three perfused-cooled electrodes with multiple overlapping- and simultaneous monopolar techniques for creating an ablation zone in ex vivo bovine livers and in in vivo porcine livers. MATERIALS AND METHODS: In the ex vivo experiments, we used a 200 W generator (Valleylab, CC-3 model) and three perfused-cooled electrodes or internally cooled electrodes to create 30 coagulation zones by performing consecutive monopolar RFA (group A, n = 10), simultaneous monopolar RFA (group B, n = 10) or multipolar RFA (group C, n = 10) in explanted bovine livers. In the consecutive mode, three ablation spheres were created by sequentially applying 150 watts radiofrequency (RF) energy to the internally cooled electrodes for 12 minutes each for a total of 36 minutes. In the simultaneous monopolar and multipolar modes, RF energy was concurrently applied to the three perfused-cooled electrodes for 20 minutes at 150 watt with instillation of 6% hypertonic saline at 2 mL/min. During RFA, we measured the temperatures of the treated area at its center. The changes in impedance, the current and liver temperature during RFA, as well as the dimensions of the thermal ablation zones, were compared among the three groups. In the in vivo experiments, three coagulations were created by performing multipolar RFA in a pig via laparotomy with using same parameter as the ex vivo study. RESULTS: In the ex vivo experiments, the impedance was gradually decreased during the RFA in groups B and C, but in group A, the impedance was increased during RFA and this induced activation by the pulsed RF technique. In groups A, B and C, the mean final-temperature values were 80 +/- 10 degrees C, 69+/-18 degrees C and 79 +/- 12 degrees C, respectively (p < 0.05). The multipolar mode created a larger volume of ablation than did the other modes: 37.6 +/-4.0 cm3 (group A); 44.9 +/- 12.7 cm3 (group B); and 78.9 +/- 6.9 cm3 (group C) (p < 0.05). In the in vivo experiment, the pig well tolerated the RFA procedure and no major complications occurred during the 4 days of the follow-up period. The mean volume of coagulations produced by multipolar RFA in the pig liver was 60.5+/-17.9 cm3. CONCLUSION: For the multiple probe RFA, the multipolar mode with hypertonic saline instillation was more efficient in generating larger areas of thermal ablation than either the consecutive or simultaneous monopolar modes.
Tomography, X-Ray Computed ; Swine ; Necrosis ; Liver Neoplasms/pathology/surgery ; Liver/pathology/physiology/radiography/*surgery ; Equipment Design ; *Electrodes ; Cattle ; Catheter Ablation/*instrumentation/methods ; Body Temperature ; Animals

BACKGROUNDHilar cholangiocarcinoma is a malignant tumor that is difficult to cure. The aim of this study was to observe the effects of flow-controlled partial portal vein arterializations (PPVA) on liver regeneration after hepatectomy in minipigs with chronic obstructive jaundice.

METHODSEight minipigs were made into chronic obstructive jaundice models. United semi-hepatectomy, which imitates extended radical surgery for treatment of hilar cholangiocarcinoma, was then performed. The eight minipigs were randomly divided into groups A and B (n = 4 minipigs each). PPVA was performed in Group A but not in Group B. The effects of flow-controlled PPVA on live regeneration after hepatectomy were observed for 30 days after hepatectomy.

RESULTSThe portal vein PO(2) at the immediate time point and on postoperative day 30 was higher in Group A ((47.33 ± 2.43) and (48.50 ± 4.44) mmHg) than in Group B ((35.38 ± 4.06) and (35.55 ± 2.55) mmHg respectively, all P < 0.01). The mitotic index of liver cells on postoperative days 14 and 21 was higher in Group A (12.55% ± 2.85% and 15.25% ± 1.99% respectively) than in Group B (6.85% ± 2.10% and 11.88% ± 1.15% respectively, all P < 0.05). The regeneration rate of residual liver on postoperative days 14 and 21 was higher in Group A (24.56% ± 6.15% and 70.63% ± 9.83% respectively) than in Group B (11.96% ± 5.43% and 44.92% ± 7.42% respectively, P < 0.05 and P < 0.01 respectively).

CONCLUSIONFlow-controlled PPVA can promote liver regeneration after hepatectomy and prevent liver failure in minipigs with chronic obstructive jaundice.

Acepromazine ; therapeutic use ; Animals ; Arteriovenous Shunt, Surgical ; methods ; Atropine ; therapeutic use ; Female ; Hepatectomy ; methods ; Jaundice, Obstructive ; surgery ; Ketamine ; therapeutic use ; Liver Regeneration ; physiology ; Portal Vein ; surgery ; Swine ; Swine, Miniature