雌激素对大鼠肝再生过程中肝细胞超微结构的影响

本文采用形态测量技术,分析了雌激素对大鼠肝再生过程中肝细胞超微结构的影响。结果显示,使用雌激素的大鼠肝细胞核及核仁体积明显高于对照组,以术后1～3d最明显(P<0.001);同时,线粒体数密度也明显增加,术后1、3、7d与对照组比较差异有极显著性意义(P<0.01),表明雌激素具有促进肝再生过程中肝细胞线粒体增生的作用。作者认为,雌激素的上述作用是雌激索促进肝细胞再生的形态学表现。     

Role of progenitor endothelial cells in cardiovascular disease and upcoming therapies.

The field of cell-based transplantation has expanded considerably and is poised to become an established cardiovascular therapy in the near future. In this review, we will focus on endothelial progenitor cells (EPCs), which are immature cells capable of differentiating into mature endothelial cells. EPCs share many surface marker antigens such as CD34, AC133, Flk-1, etc. with hematopoietic stem cells (HSCs) and the major source of EPCs as well as HSCs is the bone marrow (BM). BM-derived EPCs are mobilized into peripheral blood and recruited to the foci of pathophysiological neovascularization and reendothelialization, thereby contributing to vascular regeneration. Severe EPC dysfunction is an indicator of poor prognosis and severe endothelial dysfunction. Indeed, number of circulating EPCs and their migratory activity are reduced in patients with diabetes, coronary artery disease (CAD), or subjects with multiple coronary risk factors. Effective neovascularization induced by EPC transplantation for hindlimb, myocardial, and cerebral ischemia has been demonstrated in many preclinical studies, and early clinical trials of EPC transplantation in chronic and acute CAD indicate safety and feasibility of myocardial cell-based therapies. For therapeutic reendothelialization in patients undergoing percutaneous coronary intervention, CD34 antibody-coated stents have been used clinically to capture circulating EPCs at the injury sites and enhance reendothelialization and safety of stents. Further development in cell processing technology for efficient isolation, expansion, mobilization, recruitment, and transplantation of EPCs into target tissues are underway and expected to be tested in clinical trials in the near future.     

Schwann cell invasion of the conus medullaris: case report

As Schwann cells possess regenerative capabilities there is intense interest concerning their role in central nervous system (CNS) regeneration. We report on a case of an intramedullary schwannoma involving the conus medullaris and spinal cord above it. We discuss the possible origin of these cells and the mechanisms by which these cells may invade the CNS. We offer imaging and discuss experimental studies to support our hypothesis. This case concerns a 48-year-old man, who presented with a 6-month history of bilateral lower extremity weakness. Magnetic resonance imaging (MRI) revealed an intramedullary tumour extending from the conus to T11. At operation, following laminectomy and durotomy, a schwannoma was dissected free from the conus. Total gross resection of tumour was achieved. The patient made an uneventful and full recovery. This case shows that Schwann cells can invade the CNS. Manipulation of the transitional zone astrocytic barrier may offer a potential avenue for Schwann cells to enter the CNS in pathological states.     

冷保存对大鼠部分移植肝再生的影响

目的探讨冷保存对大鼠部分肝移植术后肝再生的影响。方法健康SD大鼠分为Ⅰ组（肝切除组）、Ⅱ组（冷保存1h部分肝移植组）和Ⅲ组（冷保存8h部分肝移植组）。观察各实验组生存率，比较各组术后1、6、12、24、48、72、168h肝质量／体质量比率、肝再生率、有丝分裂指数及增殖细胞核抗原表达。结果Ⅰ、Ⅱ、Ⅲ组7d存活率分别为100％、90％、40％；Ⅲ组术后2～3d大鼠肝质量／体质量比率、肝再生率、有丝分裂指数较Ⅰ、Ⅱ组明显偏低（P〈0．05）；Ⅲ组术后12h内增殖细胞核抗原表达较其余两组明显偏低（P〈0．05），48h才达高峰，至第7天阳性表达仍处高水平。结论长时间冷保存降低了部分肝移植术后的肝再生能力和大鼠术后生存率。     

FK506缓释膜应用于同种异体神经移植的实验研究

目的研究普乐可复(prograf,FK506)缓释膜在同种异体神经移植中的作用。方法应用异体神经桥接大鼠坐骨神经缺损,术中局部应用FK506缓释膜,分别于术后4、8、12周对移植物行大体和光镜观察,及轴突图像分析、移植神经电镜检查、小腿三头肌肌湿重比较、患肢坐骨神经电生理检查。结果C组(应用FK506缓释膜)的神经生长最好,基本与D组(自体神经移植)相同,B组(经预处理异体神经移植)次之,A组(新鲜异体神经移植)最差。经过对肌电图、轴突计数、肌湿重的统计学分析,C、B、A组的差异有统计学意义(P<0.05),C、D组之间差异无统计学意义。结论应用FK506缓释膜有助于减轻同种异体神经的免疫排斥反应,为神经再生创造良好条件;在同种异体神经移植中应用FK506缓释膜有助于促进神经再生。     

重组肝细胞生长因子促进大鼠移植肝细胞的再生

目的探讨术后应用重组肝细胞生长因子(r HGF)对大鼠移植肝细胞再生的促进作用。方法采用改良“二袖套法”建立SD大鼠原位部分肝移植模型,受鼠分为实验组和对照组,术后经尾静脉分别给予r HGF和相同体积的生理盐水,2次/d。两个组分别在术后第1、2、4、7d时随机挑取5只大鼠处死,称取移植物湿重,采血检测血清丙氨酸转氨酶及白蛋白,流式细胞仪检测移植肝的增殖活性,免疫组织化学法检测移植肝Ki-67的表达情况。结果术后第1、2d,实验组移植物湿重较对照组同时间段明显增加;术后第4、7d,实验组血清丙氨酸转氨酶水平较对照组同时间段明显降低,而白蛋白水平较对照组同时间段明显增高;术后第2、4d,实验组的移植肝增殖指数和Ki-67表达较对照组高(P<0.05)。结论大鼠部分肝移植后使用r HGF能够明显促进移植肝细胞的再生。     

大鼠壁胸膜通透性的电镜观察

目的观察大鼠壁胸膜的通透性，胸膜腔内物质的吸收途径。方法向大鼠胸膜腔内注射示踪剂，应用光镜、透射电镜方法观察壁胸膜的物质吸收途径以及壁胸膜间皮的形态变化。结果壁胸膜表面覆盖一层连续的间皮细胞，间皮细胞按形态可分为立方形和扁平形问皮细胞，立方形间皮细胞下的结缔组织内存在大量的毛细淋巴管。由毛细淋巴管内皮细胞突起穿过间皮下结缔组织与问皮细胞相连接而形成的间皮孔，是物质吸收的主要途径。结论壁胸膜通过三种途径吸收物质：①间皮孔的吸收作用；②问皮细胞的吞噬作用；③通过问皮细胞间裂隙吸收。     

Testosterone and androstanediol production by regenerating Leydig cells in the ethylene dimethane sulphonate-treated mature rat

Mature (60-65 day old) male Sprague-Dawley rats received a single intraperitoneal injection of ethylene dimethane sulphonate (EDS; 100 mg/kg) and were subsequently killed at various times from day 2 to day 40 post-treatment. Testes were removed from these animals and age-matched controls and utilized either for light and electron microscopical analyses or for in-vitro assessment of Leydig cell function. Interstitial cells were prepared by collagenase digestion and used to measure 125I-labelled human chorionic gonadotrophin (hCG) binding capacity and androgen production in the presence or absence of hCG or dibutyryl cyclic AMP (dbcAMP). At day 2 after EDS treatment, 125I-labelled hCG binding capacity was reduced to 10% of control values, while the production of testosterone and 5 alpha-androstane-3 alpha, 17 beta-diol (adiol) were non-detectable. Histological observations confirmed the lack of identifiable Leydig cells at day 2-16 after EDS treatment. Between days 24 and 40 post-treatment, Leydig cell regeneration occurred, as indicated by a rise in 125I-labelled hCG binding capacity, increased androgen production and the presence of histologically identifiable Leydig cells. A pattern of adiol production similar to that seen in the immature rat during Leydig cell development was observed with peak synthesis occurring at day 30 post-treatment. Adiol production fell to barely detectable levels by day 36 and remained low at day 40. It is concluded that the steroidogenic pattern of regenerating Leydig cells in the EDS-treated animal is similar to that of developing Leydig cells in the immature animal.     

Evaluation of filling materials in membrane‐protected bone defects. A comparative histomorphometric study in the mandible of miniature pigs.

In recent years, bone grafts and bone substitutes have been increasingly utilized underneath barrier membranes to optimize the treatment outcome of bone reconstructive therapy for defects in the alveolar process. In the present study, 4 different filling materials were evaluated in bone defects of similar dimensions in the mandible of miniature pigs. Blood clots and autografts were used as controls. The defects were covered with barrier membranes and allowed to heal for 4, 12 or 24 weeks. Histologic examination demonstrated that bone repair progressed through a programmed sequence of maturation steps closely resembling the pattern of bone development and growth regardless of whether bone grafts or substitutes were present or not. Histomorphometric analysis showed that autologous bone grafts (autografts) had the best osteoconductive properties during the initial healing period, with 39% of newly formed bone inside the membrane-covered defects at 4 weeks of healing. In addition, 87% of the graft surfaces were already covered by bone at this time. Both values were significantly higher for autografts than for the 4 alternative bone fillers (P < or = 0.05). At 12 weeks, these differences were no longer apparent, with all 5 filling materials showing similar values. Among the tested bone substitutes, tricalcium phosphate (TCP) showed a significantly higher percentage of bone fill at 24 weeks of healing. It can be concluded that sites filled with autografts clearly demonstrated the best results underneath barrier membranes in the early phase of healing. As far as degradation and substitution are concerned, TCP showed the most promising results. This filler, however, needs to be tested further in a more demanding animal model. Less favorable results were obtained for coral-derived hydroxyapatite granules and for demineralized freeze-dried bone allografts.     

Effect of Tisseel on healing after periodontal flap surgery.

The purpose of this investigation was to evaluate the effect on healing of fast and slow absorbable Tisseel in combination with periodontal flap surgery. Mucoperiosteal flaps were raised on the buccal aspect of maxillary premolars and mandibular premolars and first molars in 4 beagle dogs. The underlying buccal, interproximal and inter-radicular bone was then removed to a level of approximately 5 mm apically to the original bone crest and half way into the interdental spaces and bifurcations. The exposed root surfaces were curetted in order to remove the periodontal ligament tissue, and a notch was made in the root surface at the base of the defects. On the control teeth, the flaps were sutured immediately after creation of the defects, while on the test teeth, a layer of fast (group I) or slow (group II) absorbable Tisseel was applied between the curetted roots and the subsurface of the flaps prior to suturing. Postoperatively, the teeth were brushed 2 x weekly. The dogs were sacrificed after 4 months. Histological analysis revealed that the amounts of new attachment and bone regrowth were similar in the test and control groups, although the results tended to be most favorable for the group of teeth treated with fast absorbable Tisseel (Group I).