Repair of periodontal tissues In vivo and in vitro

Repair of experimental cavities in dental roots and of periodontal wounds was studied in vivo and in vitro. Incisors from monkeys were extracted and experimental cavities were made in the roots. The teeth were either replanted immediately or cultured for 1-12 weeks in tissue culture medium. After 8 weeks the tissue reaction around the replanted teeth was evaluated on demineralized histological sections and undecalcified freeze-sections incubated for histochemical demonstration of certain enzymes. The cultured teeth were evaluated on decalcified histological sections. In the experimental cavities of the replanted teeth reparative cementum was found. It was frequently separated from the denuded dentin while a firm attachment was always established to the intermediate cementum and dental cementum at the periphery of the cavities. The reparative cementum was also firmly attached to some small areas on the exposed dentin surface where resorption had taken place. The activity of alkaline and acid phosphatase was lower in the connective tissue in the experimental cavities than in the surrounding PDM, suggesting an incomplete regeneration of the periodontal membrane in these areas. A loose connective tissue devoid of demonstrable collagen fibers was found in the cavities in vitro. The reparative cementum did not fill the experimental cavities in the replanted teeth. The alveolar bone extended into the experimental cavities and made the width of the PDM normal also in the experimental cavities. Epithelial and endothelial cells were numerous in the connective tissue separating the reparative cementum from the alveolar bone in the experimental cavities. It is possible that they contribute to the integrity of the PDM and prevent resorption of the dental root.     

Retardation of epithelial migration in new attachment attempts in intrabony defects in monkeys

Abstract New attachment procedures were performed in 80 three-wall intrabony defects produced adjacent to incisors and canines in monkeys. Following a reverse bevel incision, rnucoperiosteaS flaps were raised on the buccal and lingual aspect of 40 intrabony defects, AH soft tissue was removed from the defects and following transplantation of autogenous bone grafts, the tissue flaps were replaced and sutured. On the buccal and lingual aspect of another 40 intrabony defects a split flap procedure was performed. Granulation tissue was removed from the defects and following transplantation of autogenous bone grafts, the defects were covered with free palatal grafts. The animate were sacrificed (o yield observation periods from 0 to 42 days. After de-caicification of the specimens and embedding in paraffin, 8-μm serial sections were cut and stained. The epithelium on the full thickness flap seemed almost unaffected by the surgical procedure and had migrated between 0.2 mm and 2.0 mm along the root surface during the first week of healing. The epithelium on the transplants degenerated almost completely within the first week after surgery and epithelial migration along the root surface was not observed until after 10–12 days. These results indicate that the migration of epithelium during the postoperative phase of new attachment attempts can be retarded by covering the defects with free palatal grafts instead of full thickness flaps.     

New attachment following surgical treatment of human periodontal disease

Abstract The present experiment was undertaken to test the hypothesis that new connective tissue attachment may form on a previously periodontitis involved root surface provided cells originating from the periodontal ligament are enabled to repopulate the root surface during healing. A mandibular incisor with advanced periodontal disease of long standing (the distance between the cemento-enamel junction and the alveolar bone crest was 9 mm) was subjected to periodontal surgery using a technique which during healing prevented the dentogingival epithelium and the gingival connective tissue from reaching contact with the curetted root surface. Preference was hereby given to the periodontal ligament cells to repopulate the previously diseased root surface. After 3 months of healing a block biopsy containing the incisor and surrounding tissue was sampled. The histological analysis revealed that new cementum with inserting principal fibers had formed on the previously diseased root surface. This new attachment extended in coronal direction to a level 5 mm coronal to the alveolar bone crest. This finding suggests that new attachment can be achieved by cells originating from the periodontal ligament and demonstrates that the concept that the periodontitis affected root surface is a major preventive factor for new attachment is invalid.     

Radiographic study of periosteal new bone formation in osteomyelitis of the mandible

A total of 1008 cases with osteomyelitis of the mandible underwent radiological examinations at the department of Oral Radiology, Osaka Dental University Hospital from 1979 to 1988. Osteomyelitis with periosteal new bone formation was observed in 114 out of the 1008 cases (11.3%). The radiographic patterns of the periosteal new bone formation were grouped into 3 types: solid, laminated and one-layer. Sixty-seven of the 114 cases (58.8%) were of the solid type, 23 cases (20.2%) were the laminated type and 24 cases (21.0%) were the one-layer type. The average age in the solid type was 30.8 years, 23.8 years in the laminated type and 38.0 years in the one-layer type. Concerning the sites of periosteal new bone formation 94 out of 114 cases (82.5%) were in the mandibular body and 20 (17.5%) in the ascending ramus of the mandible. The extent of the periosteal new bone formation was far larger among the young. This was particularly remarkable in the ascending ramus of the mandible. These findings were proved to correlate with the age, the clinical symptoms, the route of infection and the condition of eruption in the lower molars.     

Effect of low intensity laser irradiation on surgically created bony defects in rats

Low intensity lasers have been used by clinicians to improve healing and reduce pain in humans. Lasing also results in new bone formation around hydroxyapatite implants and a significant increase in the total bone area. However, the exact mechanism of cell biostimulation by laser is still unclear. This study biochemically assessed the effects of low intensity laser (Gallium-Arsenide) using 4 and 22.4 mW cm(-2) power density on the bone healing process after surgically creating bony cavities in rat mandibles. Rats (n = 24) were divided into two groups each treated with specific energy, 4 or 22.4 mW cm(-2), for 3 min each day post-surgery. Surgical cavities were created on both sides of the mandible: the left served as an untreated control, the right was treated with laser. All rats were sacrificed after 1, 2 and 4 weeks of treatment. In the newly formed callus, accumulation of radiocalcium and alkaline phosphatase activity was measured to indicate osteogenic activity. One-way anova with repeated measures showed that the low intensity laser using 4 mW cm(-2) power density significantly increased radiocalcium accumulation from 2 weeks post-surgery, whereas 22.4 mW cm(-2) had no effect. No changes were noted in the activity of alkaline phosphatase with the laser treatment. These results suggest that laser therapy of low power density is effective on the bone healing process in artificially created osseous cavities by affecting calcium transport during new bone formation.     

Evidence that cyclosporin A administration induces the formation of new cementum-like islets inside the gingival connective tissue

Two groups of 3 male Sprague-Dawley rats were given orally 30 mg/kg/d of vehicle (control group) or cyclosporin-A (experimental group) solution for 14 wk. The rats were anesthetized, tissues fixed by intracardiac perfusion of fixative solution and jaws dissected, demineralized, processed for Epon inclusion and cut by semi-thin serial sections. Histological examination revealed the presence of several islets located paravascularly inside the gingival connective tissue in the proximity of the root surfaces. The structure of these new cementum-like islets (NCLIs) was either compact and homogeneous or heterogeneous, but identical to that of the adjacent new cementum (NC) deposits. Histomorphometric evaluation indicated that the volume and the external surface of the NCLIs varied from 2354 to 679,497 μm³ and from 465 to 47,517 μm², respectively. These observations (a) suggest that CsA stimulates possibly paravascular progenitor cells which secrete in situ a NC-like material and (b) provides further evidence about the high potential of CsA to induce NC formation.     

针对性护理干预对根治性膀胱全切回肠原位膀胱术后新膀胱功能的影响

目的 分析针对性护理干预对根治性膀胱全切回肠原位膀胱术后新膀胱功能的影响.方法 选择2018年7月至2020年7月收治的80例行根治性膀胱全切回肠原位膀胱术治疗患者为研究对象,按照护理方法将其分为对照组与观察组,各40例.对照组给予常规护理干预,观察组在此基础上给予针对性护理干预.比较两组的护理效果.结果 观察组的排尿困难、尿失禁、泌尿系统感染发生率低于对照组,膀胱功能分级优于对照组(P<0.05).术后3个月,观察组的膀胱容量、膀胱逼尿肌压力大于对照组,残余尿量少于对照组,SF-36各维度评分高于对照组(P<0.05).观察组的护理满意度显著高于对照组(P<0.05).结论 针对性护理干预应用于根治性膀胱全切回肠原位膀胱术后患者中,有助于促进新膀胱排尿功能恢复,改善患者预后.     

三氧化二砷新剂型的研究进展

三氧化二砷是急性早幼粒细胞白血病的一线用药,对多种实体瘤也具有抑制作用。然而,三氧化二砷肾脏清除速率快,无组织特异性分布,靶向性较差,易产生心、肝和肾等毒性作用,限制了其在实体瘤的临床应用。近年来,科学家开发大量三氧化二砷新剂型以提高其疗效,降低其不良反应,包括脂质体、微球、纳米粒、乳剂和悬浮剂等。本文对三氧化二砷的新剂型研究进展进行梳理,以期为三氧化二砷新剂型的合理开发和应用提供新思路。     

人工智能在抗肿瘤药物研发中的应用与进展

随着人工智能的飞速发展以及人们对肿瘤疾病机制的认识逐渐加深,人工智能在抗肿瘤药物的研发中起到了重要作用。本文简要介绍了人工智能的主要模型及在药物研发方面的优势,并基于结构、配体、肿瘤细胞表型及电子健康记录四大方面综述了近年来人工智能在抗肿瘤药物研发中的应用与进展,并总结了人工智能应用于抗肿瘤药物研发中的机遇与挑战,以期为从事相关领域的科研技术人员提供思路与参考。     

植物外泌体样纳米囊泡的研究进展

植物外泌体样纳米囊泡(plantexocrine-likenano-vesicles,PELNs)是一种新兴的纳米治疗剂及传递平台,不但具有疾病治疗潜力,而且可以作为药物的载体靶向疾病位点,起到治疗递送双重作用,更重要的是PELNs具有绿色天然和低免疫原性等特点。本综述系统介绍了PELNs的外囊阳性细胞器、多囊泡体、液泡和自噬小体几种分泌机制;脂质、蛋白质和核酸3种组成成分;离心法、超滤法、尺寸排阻色谱法、流场-流分馏法、免疫磁珠法、聚合物沉淀法等分离方法及其抗炎、抗肿瘤、保护再生、抗病毒、保肝等生物学功能,整理了PELNs作为治疗剂及分子传递平台目前已发现的潜在机制,提出了PELNs研究过程中存在的产量化、机制研究及临床试验少等问题,并展望了其未来的发展潜力。