Magnetic-assisted laparoscopic liver transplantation in swine.

BACKGROUND: Although laparoscopic technology has achieved rapid development in the surgical field, it has not been applied to liver transplantation, primarily because of difficulties associated with laparoscopic vascular anastomosis. In this study, we introduced a new magnetic-assisted vascular anastomosis technique and explored its application in laparoscopic liver transplantation in pigs. METHODS: Two sets of magnetic vascular anastomosis rings (MVARs) with different diameters were developed. One set was used for anastomosis of the suprahepatic vena cava (SHVC) and the other set was used for anastomosis of the infrahepatic vena cava (IHVC) and portal vein (PV). Six laparoscopic orthotopic liver transplantations were performed in pigs. Donor liver was obtained via open surgery. Hepatectomy was performed in the recipients through laparoscopic surgery. Anastomosis of the SHVC was performed using hand-assisted magnetic anastomosis, and the anastomosis of the IHVC and PV was performed by magnetic anastomosis with or without hand assistance. RESULTS: Liver transplants were successfully performed in five of the six cases. Postoperative ultrasonographic examination showed that the portal inflow was smooth. However, PV bending and blood flow obstruction occurred in one case because the MVARs were attached to each other. The durations of loading of MVAR in the laparoscope group and manual assistance group for IHVC and PV were 13 ± 5 vs. 5 ± 1 min (P < 0.01) and 10 ± 2 vs. 4 ± 1 min (P < 0.05), respectively. The durations of MVAR anastomosis in the laparoscope group and manual assistance group for IHVC and PV were 5 ± 1 vs. 1 ± 1 min (P < 0.01), and 5 ± 1 vs. 1 ± 1 min (P < 0.01), respectively. The anhepatic phase was 43 ± 4 min in the laparoscope group and 23 ± 2 min in the manual assistance group (P < 0.01). CONCLUSIONS: Our study showed that magnetic-assisted laparoscopic liver transplantation can be successfully carried out in pigs.

A cone-beam computed tomographic study evaluating the efficacy of incisor movement with clear aligners: Assessment of incisor pure tipping, controlled tipping, translation, and torque.

INTRODUCTION: This retrospective clinical study aimed to evaluate the efficacy of different types of incisor movements with clear aligners in the sagittal plane. METHODS: Pretreatment and posttreatment cone-beam computed tomography (CBCT) scans were collected from 69 patients who underwent nonextraction treatment with clear aligners (Invisalign; Align Technology, San Jose, Calif). Integrated 3-dimensional models of the virtual incisor position (ClinCheck; Align Technology) and the posttreatment incisor position (from posttreatment CBCT scans) were superimposed over the pretreatment position (from pretreatment CBCT scans) using Mimics software (Materialise, Leuven, Belgium). On the basis of the location of the rotation center, incisors showing pure tipping (>10°), controlled tipping (>10°), translation (>1 mm), or torque (>10°) movements were selected. Efficacy was determined by comparing the predicted and achieved incisor movement, and differences with efficacy were analyzed using Kruskal-Wallis and Shapiro-Wilk tests (α = 0.05). RESULTS: In measurements for 231 incisors, the mean efficacy of incisor movements in the sagittal plane was 55.58%. The most and least predictable movements were pure tipping (72.48%) and torque (35.21%), respectively. Labial root movement was significantly more predictable than lingual root movement, and labial movement of the mandibular incisors was significantly easier than that of the maxillary incisors. The type of tooth movement achieved was different from the type designed. CONCLUSIONS: The efficacy of incisor movement in the sagittal plane using clear aligners varies with designed movement type, and labial root movement appears to be more accurate than the lingual root movement. The biomechanics of clear aligners remains to be further elucidated to achieve more predictable treatment results.

Tension-loaded bone marrow stromal cells potentiate the paracrine osteogenic signaling of co-cultured vascular endothelial cells.

Co-culture of bone marrow stromal cells (BMSCs) and vascular endothelial cells (VECs) is a promising strategy for better osteogenesis and pre-vascularization in bone tissue engineering. Recent reports have shown that mechanical stretching further promotes osteogenesis in BMSC/VEC co-culture systems, but the underlying mechanism of this process remains unclear. In this study, noncontact co-cultures of rat primary BMSCs and VECs were employed to interrogate paracrine cell-to-cell communications in response to tension. Exposure of VECs to 6% tension for 48 h elicited neither ALP activity nor mRNA expression of OCN and OPN in BMSCs incubated in a shared culture medium. Instead, BMSCs subjected to tension induced robust VEGF release, and its conditioned medium enhanced the proliferation and tubular formation of VECs with a concurrent increase in BMP-2 and IGF-1 production. Conditioned medium from activated VECs in turn promoted expression of osteogenic genes in BMSCs, followed by an increase in matrix mineralization. The addition of VEGF-R inhibitor Tivozanib to these systems abrogated the tension-induced paracrine effects on VECs and subsequently impaired BMSC osteogenesis. These results clearly demonstrate that the response of BMSCs to tension potentiates paracrine osteogenic signaling from VECs; this positive feedback loop is initiated by VEGF release.

[Clinical effect of premolar extraction with high torque self-locking appliances].

PURPOSE: To analyze the clinical effect of extraction correction of patients with maxillary protrusion by using Damon high torque appliances. METHODS: Forty patients with extraction of four first premolars due to orthodontic treatment were selected. They had protrusion of maxilla and were randomly divided into two groups. Both arches of Damon group were treated with Damon high torque appliances and MBT group were corrected with traditional MBT straight wire appliance; patients in two groups received sliding mechanics for adduction of upper anterior teeth. Cephalometric radiophotographs were analyzed before（T0）and after adduction of upper anterior teeth（T1）. The difference between the two groups was analyzed with SPSS15.0 software package. RESULTS: The upper incisors showed a more retruded position in the two groups at T1,although they showed a similar amount in both groups. The backward movement of upper lip was 2.31mm in Damon group, which was significantly less than that of 2.81mm in MBT group(P<0.05). No significant difference in the first molar mesialization was detected between Damon group(2.33 mm) and MBT group(2.36mm) (P>0.05). For anterior teeth retraction, nasolabial angle (NLA) in MBT and Damon group were 107.44°and 106.33°, increase of NLA in MBT group was 9.17°,which was significantly larger than that of 7.22°in Damon group (P<0.05). U1-MxP in MBT and Damon were 110.61°and 114.11°. U1-MxP decreased 12.06°in MBT group, while significant change was deteced in Damon group of 7.61°(P<0.05). CONCLUSIONS: Application of Damon high torque appliances in extraction treatment of maxillary protrusion patients yielded better control of the labial crown torque of anterior teeth, and avoided excessive lingual inclination of anterior teeth compared with MBT in adduction of upper anterior teeth.