Biomechanical effect of rapid mucoperiosteal palatal tissue expansion with the use of osmotic expanders

The comparative study was performed to investigate the biomechanical properties (maximum tangential stiffness, maximum tangential modulus and tensile strength) of expanded mucoperiosteal palatal tissue after rapid expansion regimen correlated with histological findings. Rabbit palatal model was used to correlate the non-operated control group, sham-operated control (subperiosteal tissue dissection) groups and 24- and 48-hour tissue expansion groups. There was no observed damage of tissue collagen network in both tissue expansion groups analyzed immediately after expansion, and biomechanical profile was not significantly different from the profile of control groups. However, rapid tissue expansion activates remodeling of mucoperiosteal tissue structure that revealed significant changes in mechanical properties during the 4-week follow-up. The 24-hour expansion induced transient increase of resilience observed 2 weeks after surgery in comparison to the control groups. As a result of maturation of newly created collagen fibers and mucoperiosteum rebuilding, there were no significant differences between any of the analyzed tensile parameters 4 weeks after the 24-hour expansion. Increased and elongated inflammatory response and connective matrix synthesis observed during healing of 48-hour expanded tissue led to a significant decrease of tensile strength value in comparison to the control groups. Even though 4 weeks after surgery, the resilience of 48-hour expanded tissue was similar to the control groups, tissue healing was not completed and limited scar formation might considerably change the final biomechanical tissue profile. These findings provide new information about tensile properties to rapid mucoperiosteal palatal tissue expansion with the use of osmotic expanders for cleft palate repair by tissue augmentation.     

Reconstruction of ablated rat rectus abdominis by muscle regeneration

Skeletal muscle regeneration is a powerful, naturally occurring process of tissue reconstruction that follows myofiber damage secondary to myotoxic injury that does not normally affect the tissue circulation and scaffold. The ablated tissue, in traumatology and free muscle grafts, is frequently replaced by scars. The final outcome is poor even after in situ myoblast seeding of the harvested muscle. The goal of this study was to identify protocols to reconstruct muscle tissue, even in such adverse environments. The authors applied a step-by-step approach to identify factors favoring the survival of autologous satellite cells and, thus, muscle regeneration. In a rat model of full-thickness rectus abdominis muscle ablation, autologous myoblasts were isolated from the explanted rectus abdominis and seeded in a homologous acellular matrix immediately after wall reconstruction (group 1, five animals). In group 2 (five animals), the ablated rectus abdominis was autografted in situ. In a third group of five rats, Marcaine was injected into both the autograft and the surrounding abdominal wall muscle. Three weeks after surgery, serial cross-sections of the reconstructed abdominal wall were stained with hematoxylin and eosin or embryonic myosin antibody, a well-characterized molecular marker of early myogenesis in development and regeneration. Percentages of the patch area covered by regenerated myofibers were determined by morphometry. When autologous myoblasts were seeded in a homologous acellular matrix, the only myofibers observed to regenerate were those along the border of the patch. Autografting of the middle third of the rectus abdominis muscle similarly resulted in scar formation. The few muscle cells in the graft core were scanty myoblasts that could be detected only by monoclonal embryonic myosin antibody. Although negative for myofiber regeneration, the results in both cases confirmed the mechanical patency of the patches with regard to abdominal organ support. Myofibers were successfully regenerated in the graft by injecting Marcaine into both the autograft and the surrounding muscles. Three weeks after surgery, the patch was paved with young, centrally nucleated myofibers intermixed with young myofibers and myotubes expressing embryonic myosin. The difference in percentage of patch area covered by regenerated myofibers in group 3 (Marcaine injection around the patch, 81.6 +/- 3.0 percent) (mean +/- SD) versus either group 1 (Myoblast-seeded acellular patch, 18.0 +/- 3.0 percent) or group 2 (Autograft, 25.8 +/- 7.0 percent) was statistically significant on independent t test analysis (p < 0.0001). Even an acellular matrix showed some myofiber regeneration after surrounding muscles had been injected with Marcaine. This is the first successful evidence of muscle reconstruction after full-thickness ablation of the middle third of the rectus abdominis. Muscle regeneration seems to be the result of successive waves of migration of angioblasts and then satellite cell-derived myoblasts from the muscles surrounding the patch. The results strongly suggest that vascularization of the scaffold and successive coordinate proliferation of the seeded cells are required for myoblasts to be able to migrate into the patch and differentiate up to myofiber stage.     

Complications of postmastectomy breast reconstructions in smokers, ex-smokers, and nonsmokers

Smoking results in impaired wound healing and poor surgical results. In this retrospective study, we compared outcomes in 155 smokers, 76 ex-smokers, and 517 nonsmokers who received postmastectomy breast reconstructions during a 10-year period. Ex-smokers were defined as those who had quit smoking at least 3 weeks before surgery. Transverse rectus abdominis musculocutaneous (TRAM) flap surgery was performed significantly less often in smokers (24.5 percent) than in ex-smokers (30.3 percent) or nonsmokers (39.1 percent) (p < 0.001). Tissue expansion followed by implant was performed in 112 smokers (72.3 percent), 50 (65.8 percent) ex-smokers, and 304 nonsmokers (58.8 percent) (p = 0.002). The overall complication rate in smokers was 39.4 percent, compared with 25 percent in ex-smokers and 25.9 percent in nonsmokers, which is statistically significant (p = 0.002). Mastectomy flap necrosis developed in 12 smokers (7.7 percent), 2 ex-smokers (2.6 percent), and 8 nonsmokers (1.5 percent) (p < 0.001). Among patients receiving TR4AM flaps, fat necrosis developed in 10 smokers (26.3 percent), 2 ex-smokers (8.7 percent), and 17 nonsmokers (8.4 percent). Abdominal wall necrosis was more common in smokers (7.9 percent) than in ex-smokers (4.3 percent) or nonsmokers (1.0 percent). In this large series, tissue expansion was performed more often in smokers than was autogenous reconstruction. Complications were significantly more frequent in smokers. Mastectomy flap necrosis was significantly more frequent in smokers, regardless of the type of reconstruction. Breast reconstruction should be done with caution in smokers. Ex-smokers had complication rates similar to those of nonsmokers. Smokers undergoing reconstruction should be strongly urged to stop smoking at least 3 weeks before their surgery.     

Structural and functional healing of critical-size segmental bone defects by transduced muscle-derived cells expressing BMP4

BACKGROUND: Our previous studies have shown that muscle-derived cells, including a population of muscle stem cells, transduced with a retroviral vector expressing bone morphogenetic protein 4 (BMP4) can improve the healing of critical-size calvarial defects. However, we did not evaluate the functionality of the healed bone. The purpose of this study was to determine whether primary muscle-derived cells transduced with retroBMP4 can heal a long bone defect both structurally and functionally. METHODS: Primary muscle-derived cells were genetically engineered to express BMP4 and were implanted into 7-mm femoral defects created in syngeneic rats. Muscle-derived cells transduced with retroLacZ were used in the control group. Bone healing was monitored by radiography, histology, and biomechanical testing at designated time points. RESULTS: Most of the defects treated with muscle-derived cells expressing BMP4 formed bridging callous by 6 weeks after surgery, and exhibited radiographically evident union at 12 weeks after cell implantation. Histological analysis at 12 weeks revealed that the medullary canal of the femur was restored and the cortex was remodeled between the proximal and distal ends of each BMP4-treated defect. In contrast, the defects treated with muscle-derived cells expressing beta-galactosidase displayed nonunion at all tested time points. An evaluation of the maximum torque-to-failure in the treatment group indicated that the healed bones possessed 77 +/- 28% of the strength of the contralateral intact femora. Torsional stiffness and energy-to-failure were not significantly different between the treated and intact limbs. CONCLUSIONS: This study demonstrated that primary muscle-derived cells transduced with retroBMP4 can elicit both structural and functional healing of critical-size segmental long bone defects created in rats.     

糖尿病对大鼠骨折愈合影响的实验研究

目的:观察糖尿病大鼠的骨折愈合过程,探讨糖尿病影响大鼠骨折愈合的可能的机制,为临床实践提供理论依据。方法:雄性Wister大鼠140只,随机分成二组,每组70只,A组为糖尿病骨折组;B组为非糖尿病骨折组。建立糖尿病动物模型后,无菌条件下在各组大鼠胫骨中点用手术方法制成骨折模型。术后1周、2周、4周、6周、8周各时间点进行X线检查,观察骨折愈合情况。术后1周、2周、3周、4周、6周、8周分别用ELISA法检测血清中IGF-1含量。分别在1、2、4、6、8周各时间点观察5只大鼠骨痂生长情况并取骨折断端组织行HE染色光镜观察。术后4周、6周、8周每组处死10只大鼠留取双侧胫骨标本,冷冻保存后集中进行生物力学检测。结果:1、大体标本观察结果:各时间点A组骨痂生长减缓延迟。2、X线结果:A组骨折愈合质量在各时间点均明显低于B组。3、生物力学测定结果:4周、6周、8周个时间点A组骨折处骨痂的机械强度均明显低于B组。4、组织学染色显示:术后各时间点1、2、4、6、8周A组与B组相比骨折处局部骨痂成熟延迟并且软骨细胞肥大。5、血清IGF-1含量测定:A组大鼠血清中IGF-1含量低于B组,且高峰延迟1周。结论:1.患有糖尿病后大鼠骨折愈合质量差,比较容易出现愈合延迟甚至不愈合;2.患有糖尿病的大鼠骨折后血清中的IGF-1表达明显低于对照组,且高峰推迟1周。     

The effect of thyroid hormones on the aerobic development of locomotor and cardiac muscles in the barnacle goose

The role of thyroid hormones in the development of the locomotor and cardiac muscles of the barnacle goose (Branta leucopsis) was investigated. From 2 weeks of age, goslings were treated with thyroxine, triiodothyronine, or methimazole (a thyroid inhibitor). Birds were killed at 6 weeks (n = 5) or 9 weeks (n = 4) and various locomotor and cardiac muscle masses recorded and tissue samples taken for analysis of citrate synthase activity. The effects of thyroxine and triiodothyronine were not significantly different from each other, except in the case of the iliofibularis at 9 weeks. The mass-specific citrate synthase activity of the iliofibularis, semimembranosus muscles and liver were significantly increased by thyroid hormone treatment. Cardiac muscle showed a significant hypertrophy at 9 weeks of age following treatment with thyroxine. Hypothyroidism induced by treatment with methimazole exhibited the greatest effect on the pectoralis muscle, reducing citrate synthase activity by 33%. Mass-specific citrate synthase activity of the pectoralis and pectoralis mass (% body wt.) were found to be highly correlated (r ² = 0.74) at 6 weeks of age. It is suggested that thyroid hormones may be involved in controlling the tissue-specific timing of the maturation of locomotor and cardiac muscles. Accepted: 16 September 1996     

Irradiation after immediate tissue expander/implant breast reconstruction: outcomes, complications, aesthetic results, and satisfaction among 156 patients

Chest wall irradiation is becoming increasingly common for mastectomy patients who have opted for immediate breast reconstruction with tissue expanders and implants. The optimal approach for such patients has not yet been defined. This study assesses the outcomes of a reconstruction protocol for patients who require irradiation after tissue expander/implant reconstruction. The charts of all patients who underwent immediate tissue expander/implant reconstruction at Memorial Sloan-Kettering Cancer Center between January of 1995 and June of 2001 and who had not previously undergone irradiation were retrospectively reviewed. A subgroup of patients who required chest wall irradiation after mastectomy and reconstruction was identified. Those patients were treated according to the following treatment algorithm: (1) reconstruction with tissue expander placement at the time of mastectomy , (2) tissue expansion during postoperative chemotherapy, (3) exchange of the tissue expander for a permanent implant approximately 4 weeks after the completion of chemotherapy, and (4) chest wall irradiation beginning 4 weeks after the exchange. All irradiated patients with at least 1 year of follow-up monitoring after the completion of radiotherapy were evaluated with respect to aesthetic outcomes, capsular contracture, and patient satisfaction. A control group of nonirradiated patients was randomly selected from the cohort of patients treated during the study period. During the 5-year study period, a total of 687 patients underwent immediate reconstruction with tissue expanders. Eighty-one patients underwent postoperative irradiation after placement of the final implant. A total of 68 patients who received postoperative chest wall irradiation underwent at least 1 year of follow-up monitoring after the completion of radiotherapy, with a mean follow-up period of 34 months. Seventy-five nonirradiated patients were evaluated as a control group. Overall, 68 percent of the irradiated patients developed capsular contracture, compared with 40 percent in the nonirradiated group (p = 0.025). Eighty percent of the irradiated patients demonstrated acceptable (good to excellent) aesthetic results, compared with 88 percent in the nonirradiated group (p = not significant). Sixty-seven percent of the irradiated patients were satisfied with their reconstructions, compared with 88 percent of the nonirradiated patients (p = 0.004). Seventy-two percent of the irradiated patients stated that they would choose the same form of reconstruction again, compared with 85 percent of the nonirradiated patients. The results of this study suggest that tissue expander/implant reconstruction is an acceptable surgical option even when followed by postoperative radiotherapy and should be considered in the reconstruction algorithm for all patients, particularly those who may not be candidates for autogenous reconstruction.     

Callus stimulation in distraction osteogenesis

Distraction osteogenesis has been described as in vivo tissue engineering. The ability to stimulate this process for the repair of bony defects or lengthening of congenitally shortened facial structures is likely to significantly impact the field of craniofacial surgery. The purpose of this study was to determine whether mechanical stimulation of the distracted rabbit mandible would accelerate the maturation of the bony callus when applied during the early consolidation period. Twenty adult New Zealand White rabbits underwent unilateral mandibular osteotomy. A uni-directional internal distractor device (Synthes, Paoli, Pa.) was positioned along a plane perpendicular to the line of osteotomy. After a 7-day latency period, distraction was commenced at a rate of 1.0 mm/day for 12 days in all animals. In a control group of 10 rabbits, a consolidation period of 8 weeks was observed before they were killed. In the experimental group of 10 rabbits, daily alternate compression and distraction of 1 mm (sequential compression and distraction) was performed for 3 weeks followed by a 5-week period of rigid fixation. Each animal received a dose of a fluorescent label at three different time points during the study: at the end of the distraction period, 3 weeks after the completion of the distraction phase, and 3 days before it was killed. All animals were killed 8 weeks after the completion of the distraction phase. Undecalcified histologic analysis and 3-point bending tests to failure were performed on the extracted mandibles. The results of the experimental and control groups were compared.Four animals in the control group and three animals in the experimental group were excluded from the study because of screw loosening resulting in distractor dislodgment or because of infection. On histologic analysis, cortical thickness at the center of the callus was found to be significantly greater in the experimental group compared with the control group when normalized to the contralateral hemimandible (83 percent versus 49 percent, respectively; p < 0.007). The ratio of cortical to cancellous bone in the distracted callus was uniformly found to be greater in the experimental specimens. The mineral apposition rate was calculated by using fluorescence microscopy and found to be significantly greater in the experimental group both during the period of sequential compression and distraction (3.2 microm/day versus 2.1 microm/day, p = 0.02) and after the period of sequential compression and distraction (1.4 microm/day versus 1.1 microm/day, p = 0.006). Mechanical testing revealed no significant differences in bending strength or stiffness between experimental or control groups (p = 0.54 and 0.47, respectively). This study has demonstrated that daily alternating compression and distraction of 1 mm amplitude during the early consolidation period has a stimulatory impact on callus formation with respect to osteoblastic activity, remodeling, and maturation of bone. Optimal timing and amplitude of sequential movement, long-term biomechanical differences, and molecular pathways have yet to be elucidated.     

功能矫形前伸青春期大鼠下颌后浅层嚼肌细胞凋亡的研究

目的：研究功能矫形前伸大鼠下颌后浅层嚼肌细胞凋亡的变化规律,探讨功能矫形的肌肉改建机理。方法：选用50只5周龄Sprague-Dawley（SD）雄性大白鼠,随机分为实验组和对照组各25只。实验组大鼠戴自制上颌功能矫治嚣,引导下颌前伸,并打开咬合。利用RT-PCR方法检测两组大鼠浅层嚼肌Bcl-2和Bax基因表达情况,利用TUNEL方法检测浅层嚼肌细胞凋亡情况。结果：①Bcl-2和Bax基因表达随大鼠戴用矫治器时间的延长而升高,至第3周开始下降但仍高于对照组,但Bax的表达高于Bcl-2。Bax/Bcl-2比值随大鼠戴用矫治器时间的延长而升高,至第4周开始下降。②TUNEL实验结果显示浅层嚼肌细胞在戴用矫治器1天后,开始出现凋亡,随着时间延长而增加,至第3周达到顶峰,第4周开始下降。结论：①Bax/Bcl-2比值升高促进浅层嚼肌细胞凋亡。②功能矫形可引起浅层嚼肌细胞凋亡,导致肌肉的结构和功能发生适应性改建。     

即时扩展型背阔肌肌皮瓣乳房再造在保留乳头乳晕复合体乳癌术后的运用分析

目的：探讨分析即时扩展型背阔肌肌皮瓣乳房再造在保留乳头乳晕复合体乳癌术后的运用。方法：回顾性分析我院2008年2月-2012年4月收治的乳腺癌术后患者106例,采用乳癌术即时扩展型背阔肌肌皮瓣乳房再造保留乳头乳晕复合体,观察手术效果以及满意度。结果：术后患者乳房美容优良率为88．68％明显大于对照组的47．17％,并且术后6个月治疗组生活质量评价总分明显大于对照组总分术后6个月患者生活质量评价总分明显大于术前评价总分,差异具有条件下意义（P〈0．05）,差异均具有统计学意义（P〈0．05）。结论：即时扩展型背阔肌肌皮瓣乳房再造在保留乳头乳晕复合体乳癌术后患者乳房美容效果较好,提高患者生活质量高,值得在临床上推广,但在手术后需积极处理可能存在的并发症情况。     

Easy tissue expansion of prelaminated mucosa-lined flaps for cheek reconstruction in a canine model

In head and neck reconstruction, there is sometimes the need for a skin flap lined with mucosa. The object of this study was to determine whether small pieces of mucosa grafted onto the undersurface of a skin flap can be expanded in a reasonable time to provide the material required to reconstruct a full-thickness cheek defect as a free flap. The study consisted of two phases: prelamination and expansion of the flap, and vascularized free-tissue transfer of the flap. Six adult mongrel dogs were used. First, a 5 x 10-cm flap based on the saphenous vessels was elevated on the lower leg, and then four 1 x 2-cm pieces of mucosa harvested from the tongue were grafted onto the undersurface of the flap. A tissue expander (5 x 10 cm) was then placed under the flap, and the incision was closed primarily. The expanders were initially filled with just enough normal saline to obliterate dead space immediately after surgery. The expansion was continued twice weekly for 3 weeks until sufficient expansion was obtained. Two of six flaps were followed for an additional 6 weeks after the 3-week expansion period to observe whether additional mucosa could be obtained. After measurement of the mucosal area, each flap was transferred as free flap to reconstruct an iatrogenic cheek defect. The increase of mucosal surface area was compared with the original graft, and differences were analyzed using the paired t test. All flaps were successfully expanded without any complications. Histologic evaluation revealed that grafted mucosa took well without evidence of graft necrosis, and the intergraft area was covered with histiocytes. Angiography revealed well-defined vascular structures covering the entire area of the flap. The new mucosal area (23.5 +/- 2.4 cm2) was significantly larger than the original mucosal graft (8.7 +/- 0.9 cm2) (p < 0.001). The net increase of the mucosal area was 172.9 +/- 32.4 percent. The increase of mucosal area in two flaps, following a 6-week consolidation period after 3 weeks of expansion, was only slightly greater (25.9 +/- 1.3 cm2) than those without the consolidation period (22.3 +/- 1.8 cm2). This increase of the mucosal area appears to be related to the amount of expansion, and not to the length of the consolidation period. The flaps were successfully transferred as free flaps to reconstruct the full-thickness cheek defects without major complications. Although a staged operation to allow flaps to mature is needed, the present procedure has the advantages of providing a mucosa-lined flap and allowing primary closure of the donor site. The authors conclude that expansion of this flap has great potential in reconstructive surgery.     

Skeletal muscle hypertrophy in rats having growth hormone-secreting tumor

Plantaris muscle hypertrophy resulting from surgical ablation of the synergistic gastrocnemius muscle was compared between nontumor- and GH3 tumor-bearing rat groups (n = 8-10). GH3 cells (10(6)) were subcutaneously injected into 150-g female Wistar-Furth rats to initiate the tumor. After 17 days, the tumor-bearing rats gained 5.7 g body wt/day compared with 2.0 for the nontumor-bearing rats. The left gastrocnemius muscle was surgically removed from both nontumor and tumor groups. The gastrocnemius was removed from the tumor group after an increased growth rate was achieved. Seven days after surgery, the animals were killed and plantaris muscles were removed. The wet weight of the left plantaris muscle increased 45.6 and 44.0% over the unoperated contralateral control (right side) in the nontumor and tumor groups, respectively. The right control plantaris muscle in the tumor group was 63% heavier than the right control plantaris from the nontumor group; however, the proportion of body weight for plantaris was similar between the two groups. The effect of gastrocnemius ablation and tumor treatment on plantaris weight was additive, and the percent increase over the unoperated contralateral control side was similar between the two groups. These data demonstrate that skeletal muscle hypertrophy occurs in adult animals in which growth has been stimulated by a growth hormone-secreting tumor and could suggest that the muscle growth response caused by the tumor is operating by a mechanism different than work-induced hypertrophy.     

First-line treatment of deep sternal infection by a plastic surgical approach: superior results compared with conventional cardiac surgical orthodoxy

A majority of cardiac surgeons manage deep sternal infection with sternal wound debridement, rewiring, and closed drainage, with or without antibiotic saline tube irrigation (the traditional approach). The authors' experience with the traditional approach was unsatisfactory; therefore, they undertook a radical change in management: an immediate plastic surgical approach. Hence, deep sternal infection was managed by immediate debridement followed by a bilateral pectoralis major myocutaneous advancement flap with greater omental transposition (PMOFR). This is the first such study reporting the effect of this strategy on the rate of eradication of deep sternal infection, intensive care unit stay, total hospital length of stay, major complications, mortality, intermediate survival, and patient satisfaction, as compared with the traditional approach used by cardiac surgeons at the authors' institution.All patients who developed a deep sternal infection from 1993 through 1998 at a tertiary teaching hospital were included. In the PMOFR group (nine patients), after a diagnosis of clinical sternal wound infection, debridement was performed immediately, either if sternal dehiscence occurred or in the absence of clinical dehiscence, if the patient or the sternotomy wound did not clinically improve with medical therapy within 48 hours from suspected diagnosis. Open irrigation and packing for 2 to 4 days was followed by treatment with a PMOFR. In the group treated using the traditional approach (12 patients), no predetermined plan was present. Thus, at the cardiac surgeon's discretion, wound debridement was undertaken, followed by closed drainage (three patients), closed tube irrigation (six patients), and open granulation with delayed plastic surgery (three patients).The incidence of major complications (PMOFR, 22 percent; traditional approach, 92 percent; p = 0.001), intensive care unit readmission (PMOFR, 0 percent; traditional approach, 58 percent; p = 0.005), total hospital length of stay (PMOFR, 32 days; traditional approach, 79 days; p = 0.001), reoperation rates (PMOFR, 0 percent; traditional approach, 100 percent; p = 0.001) and in-hospital 30-day mortality rate (PMOFR, 0 percent; traditional approach, 33 percent; p = 0.05) were superior in the PMOFR group. At a mean follow-up of 2 years, freedom from recurrence of the infection (PMOFR, 100 percent; traditional approach, 11.5 percent; p = 0.005) and overall survival rate (PMOFR, 100 percent; traditional approach, 50 percent; p = 0.005) were also superior with PMOFR. A majority of patients in the PMOFR group (90 percent) had no functional or cosmetic complaints secondary to the procedure.A predetermined plan of immediate debridement followed by treatment with PMOFR rapidly, reliably, and effectively eradicated deep sternal infection. This translated to reduced length of stay and need for additional surgery, improved survival, and excellent intermediate freedom from deep sternal infection, with minimal patient dissatisfaction. The traditional approach to managing deep sternal infection was thus abandoned.     

Effects of Remifemin Treatment on Bone Integrity and Remodeling in Rats with Ovariectomy-Induced Osteoporosis

This study aims to evaluate the effects of Remifemin (isopropanolic extract of Cimicifuga Racemosa) on postmenopausal osteoporosis. 120 female Sprague-Dawley rats were randomly assigned to four groups: sham surgery with vehicle, ovariectomy with vehicle, ovariectomy with estradiol valerate, or ovariectomy with Remifemin. Daily oral administrations of the vehicle, estradiol valerate, or Remifemin began 2 weeks after surgery and lasted to 4, 8, or 12 weeks. Ten rats in each group were sacrificed at each timestep with assessment of bone mineral density, trabecular bone structure, and biomechanical parameters of the femur and lumbar vertebra. Bone turnover markers were evaluated 12 weeks after surgery. Both drugs prevented bone density loss in the distal end of the femur and preserved the trabecular bone structure in both the lumbar vertebra and distal end of the femur following ovariectomy. Both drugs protected bone stiffness at the tested regions and reduced bone reabsorption in ovariectomized rats. The preventive effects of Remifemin against bone-loss can rival those of estradiol valerate if treatment duration is adequately extended. In conclusion, Remifemin may demonstrate equivalent effects to estradiol valerate in terms of preventing postmenopausal osteoporosis.     

Engineering of pre‐vascularized urethral patch with muscle flaps and hypoxia‐activated hUCMSCs improves its therapeutic outcome

Tissue engineering has brought new hopes for urethral reconstruction. However, the absence of pre‐vascularization and the subsequent degradation of materials often lead to the failure of in vivo application. In this study, with the assistance of hypoxia‐activated human umbilical cord mesenchymal stem cells (hUCMSCs), pedicled muscle flaps were used as materials and pre‐incubated in ventral penile subcutaneous cavity of rabbit for 3 weeks to prepare a pre‐vascularized urethral construct. We found that small vessels and muscle fibres were scattered in the construct after 3 weeks' pre‐incubation. The construct presented a fibrous reticular structure, which was similar to that of the corpus spongiosum under microscope examination. The produced constructs were then used as a patch graft for reconstruction of the defective rabbit urethra (experimental group), natural muscular patch was used as control (control group). Twelve weeks after the reconstructive surgery, urethrography and urethroscope inspections showed wide calibres of the reconstructed urethra in the experimental group. Histopathological studies revealed that fibrous connective tissues and abundant muscle fibres constituted the main body of the patch‐grafted urethra. In contrast, in the control group, only adipose tissue was found in the stenosis‐reconstructed urethra, replacing the originally grafted muscular tissue. To our knowledge, this is the first report that successfully constructed a pre‐vascularized urethral construct by using hypoxia‐activated hUCMSC and pedicled muscle flaps. More importantly, the pre‐vascularized construct showed a good performance in urethral reconstruction when applied in vivo. The study provided a novel strategy for tissue engineering of pre‐vascularized urethral construct for the defective urethra, representing a further advancement in urethral reconstruction.     

Immediate breast reconstruction: reducing the risks

One-hundred and sixty-five consecutive immediate breast reconstructions in 157 patients were reviewed. Reconstructions were performed with tissue expanders (53 percent) or immediate gel prostheses (47 percent). Immediate reconstruction was associated with an 18 percent rate of implant loss. Certain risk factors were identified at the p less than 0.05 level using immediate gel implants: failure to achieve complete muscle coverage of the implant, smoking at the time of surgery, initial gel implants of 400 ml or more volume, and age. Expander loss was increased by detaching the pectoralis major (p less than 0.05) and probably by lack of complete muscle coverage in general. Chemotherapy, history of previous smoking, and clinical stage of the carcinoma did not seem to affect reconstructive success. Smoking and patient age should be considered during patient selection for immediate reconstruction. Muscle coverage of the prosthesis should always be attempted. Muscle coverage is mandatory in the smoker. Gel implants of 400 ml or more volume are to be avoided at the initial operation. This approach should enable all surgeons to achieve lower rates of implant loss.     

Anterior Cruciate Ligament Reconstruction in a Rabbit Model Using Silk-Collagen Scaffold and Comparison with Autograft

The objective of the present study was to perform an in vivo assessment of a novel silk-collagen scaffold for anterior cruciate ligament (ACL) reconstruction. First, a silk-collagen scaffold was fabricated by combining sericin-extracted knitted silk fibroin mesh and type I collagen to mimic the components of the ligament. Scaffolds were electron-beam sterilized and rolled up to replace the ACL in 20 rabbits in the scaffold group, and autologous semitendinosus tendons were used to reconstruct the ACL in the autograft control group. At 4 and 16 weeks after surgery, grafts were retrieved and analyzed for neoligament regeneration and tendon-bone healing. To evaluate neoligament regeneration, H&E and immunohistochemical staining was performed, and to assess tendon-bone healing, micro-CT, biomechanical test, H&E and Russell-Movat pentachrome staining were performed. Cell infiltration increased over time in the scaffold group, and abundant fibroblast-like cells were found in the core of the scaffold graft at 16 weeks postoperatively. Tenascin-C was strongly positive in newly regenerated tissue at 4 and 16 weeks postoperatively in the scaffold group, similar to observations in the autograft group. Compared with the autograft group, tendon-bone healing was better in the scaffold group with trabecular bone growth into the scaffold. The results indicate that the silk-collagen scaffold has considerable potential for clinical application.     

普罗布考对动脉粥样硬化大鼠平滑肌细胞凋亡及p53和Fas蛋白表达的影响

目的探讨普罗布考防治动脉粥样硬化（AS）的机制。方法选用雄性大鼠,复制大鼠AS模型,随机分为动脉粥样硬化模型组、普罗布考组和正常对照组。大鼠造模成功后给予普罗布考治疗,6周后处死大鼠,采用流式细胞术检测平滑肌细胞凋亡率及凋亡相关基因p53和Fas蛋白的表达。结果模型组大鼠血管平滑肌细胞凋亡率明显高于对照组（P〈0．05）,p53和Fas蛋白的表达增强（P％0．05）,主动脉壁可肉眼观测典型斑块。普罗布考组大鼠平滑肌细胞的凋亡率明显低于模型组（P〈0．05）,p53和Fas蛋白表达下调（P〈0．05）,主动脉斑块面积较模型组减小明显。结论普罗布考通过调节p53和Fas蛋白表达来调节AS大鼠平滑肌细胞的凋亡。     

Immediate reconstruction of a composite mandibular defect with a regional osteomusculocutaneous flap

This is a report of an immediate reconstruction of a composite mandibular defect, using a pectoralis major osteomusculocutaneous flap incorporating a segment of the fifth rib. Viability of the transferred rib segment was established by tetracycline labeling at 2 weeks and technetium scanning at 3 months postoperatively. This clinical example supports the experimental observations of a vascular network interconnecting muscle, periosteum, and compact bone.     

A retrospective analysis of 48 infected sternal wound closures: delayed closure decreases wound complications

Forty-eight patients who suffered sternal wound infections following coronary artery bypass grafting were retrospectively reviewed over a 5-year period. All patients in this study had clinical signs of major infection including redness, pain, and purulence at the time of mediastinal drainage and debridement. One patient died 11 days postoperatively because of heart failure, leaving 47 patients available for long-term follow-up. All muscle flaps (pectoralis and rectus abdominis) survived completely. All wound complications were related to chest wall skin flap dehiscence or continued infection. Seventeen of 22 patients (77 percent) undergoing flap closure 4 days or less after sternal debridement and irrigation suffered wound complications. Five of these 22 patients (23 percent) had major wound complications, meaning that the wound required more than 2 months of care before healing was complete. No major wound complications and only three minor complications (12 percent) occurred in 25 patients undergoing sternal flap closure 5 days or more after mediastinal debridement and irrigation. The frequency and severity of wound complications were significantly decreased in the group of patients undergoing sternal flap closure 5 or more days after sternal drainage and debridement (p < 0.00005). In the majority of cases [29 of 47 (62 percent)], secure sternal wound closure was obtained with a single, split, medially based, right pectoralis major muscle flap.