脊髓损伤后真皮多能干细胞移植时机的选择

目的:观察脊髓损伤后不同时间移植真皮多能干细胞对大鼠运动功能修复的影响。方法:实验于2006-06/2007-03在第三军医大学生理学教研室完成。①实验材料:实验动物2～4月龄SPF级SD大鼠,体质量(210±40)g,雌雄不限,由第三军医大学实验动物中心提供。真皮多能干细胞为第三军医大学防原医学系从SD大鼠真皮中提取和分离。②实验方法:将42只SD大鼠在L4水平制成脊髓全横断损伤模型。将动物随机分为对照组(n=6)、真皮多能干细胞移植组(n=36)。真皮多能干细胞移植组又分为6个时间点:损伤后1,4,7,10,14,21d移植组,每组6只。各移植组于伤处移植大鼠真皮多能干细胞,而对照组于损伤后7d注射等量磷酸盐缓冲液。③实验评估:分别于移植后1d、1周、4周、8周、12周对各组大鼠进行动物行为学和脊髓诱发电位检测。结果:42只实验大鼠均进入结果分析,无脱落。①动物行为学评分:4周以后各组动物行为学评分比较差异有显著性意义(P<0.05),移植组明显高于对照组(P<0.05),各移植组间比较,以损伤后7,10d移植组动物行为学评分改善最显著。②各组大鼠脊髓诱发电位检查:体感诱发电位和运动诱发电位潜伏期和波幅值于移植后8,12周后明显高于对照组(P<0.05),各移植组间比较,以损伤后7,10d移植组体感诱发电位和运动诱发电位潜伏期和波幅值改善最显著。结论:脊髓损伤后7～14d进行真皮多能干细胞移植可明显改善大鼠后肢的运动功能。     

应用28通道近红外光谱分析恢复过程中老年期抑郁症患者前额叶的激活特征

目的：认知功能障碍是老年期抑郁症的可逆性症状，试验以认知功能研究为突破口，采用28通道的近红外光谱技术分析处于恢复过程中的老年期抑郁症患者在执行词语流畅性测验时前额叶的激活特点，探讨老年期抑郁症的发病机制。 方法：①分组：患者组为2006～03／12首都医科大学附属北京安定医院收治的12例处于恢复过程中的老年期抑郁症患者，入组时符合DSM-4有关重度和中度抑郁发作或复发的标准诊断，首次发病年龄≥60岁，均服用SSRIs类抗抑郁药物治疗。对照组为12例性别、年龄和教育程度与患者组相匹配的健康志愿者。所有受试者排除脑器质性病变：②试验方法：所有受试者接受近红外光谱测查，在28通道的CW5（TechEnInc．American）NIRS系统上完成。通过近红外光谱系统监测被试者在执行词语流畅性测验任务过程中，前额叶氧合血红蛋白和脱氧血红蛋白浓度的变化，从而反映前额叶认知任务相关的激活效应。采用组块设计的词语流畅性测验作为认知激活任务，任务范式包括词语重复任务和词语流畅性任务两种试验。 结果：24例受试者均进入结果分析。①在健康老年人和处于恢复过程中的老年期抑郁症患者，词语流畅性测验能够激活双侧前额叶．未发现半球单侧化激活效应。②处于恢复过程中的老年期抑郁症患者在词语流畅性测验任务过程中，左侧前额叶激活效应较对照组减弱。③尽管在健康老年人和处于恢复过程中的老年期抑郁症患者，近红外光谱显示了不同的激活模式，但词语流畅性测验的成绩不存在显著性的组间差异（P〉0．05）。 结论：处于恢复过程中的老年期抑郁症患者存在词语流畅性测验相关的功能性左侧前额叶功能减退，微血管功能失调和多巴胺系统异常也许在老年期抑郁症的病理生理学机制中起重要作用。     

Dynamics of major histocompatibility complex class II compartments during B cell receptor-mediated cell activation

Antigen recognition by clonotypic B cell receptor (BcR) is the first step of B lymphocytes differentiation into plasmocytes. This B cell function is dependent on efficient major histocompatibility complex (MHC) class II-restricted presentation of BcR-bound antigens. In this work, we analyzed the subcellular mechanisms underlying antigen presentation after BcR engagement on B cells. In quiescent B cells, we found that MHC class II molecules mostly accumulated at the cell surface and in an intracellular pool of tubulovesicular structures, whereas H2-M molecules were mostly detected in distinct lysosomal compartments devoid of MHC class II. BcR stimulation induced the transient intracellular accumulation of MHC class II molecules in newly formed multivesicular bodies (MVBs), to which H2-M was recruited. The reversible downregulation of cathepsin S activity led to the transient accumulation of invariant chain-MHC class II complexes in MVBs. A few hours after BcR engagement, cathepsin S activity increased, the p10 invariant chain disappeared, and MHC class II-peptide complexes arrived at the plasma membrane. Thus, BcR engagement induced the transient formation of antigen-processing compartments, enabling antigen-specific B cells to become effective antigen-presenting cells.     

Mycophenolate mofetil in children with steroid/cyclophosphamide-resistant nephrotic syndrome

The purpose of this study was to assess the results of therapy with mycophenolate mofetil (MMF) in children with idiopathic nephrotic syndrome (INS) who were both steroid- and cyclophosphamide-resistant. Treatment lasted a minimum of 6 months, and follow-up data were collected over a 2-year period. The children were divided into two groups: Group 1 (n?=?34) comprised patients who had received cyclosporine A (CsA) before the initiation of MMF therapy; Group 2 (n?=?18) comprised patients who received only MMF. Among the 34 patients of Group 1, complete and partial remission were achieved in seven (20.6%) and 13 patients (38.6%), respectively; there was no response in 14 patients (41.2%). Among the 18 patients in Group 2, complete and partial remission occurred in five (27.8%) and six (33.3%) patients, respectively; there was no response in seven patients (38.9%). Eight patients developed chronic kidney disease. The main side-effects were gastrointestinal complaints (n?=?11, 21%), recurring severe infections (n?=?1, 1.9%), and mild thrombocytopenia/leucopenia (n?=?1, 1.9%). MMF proved to be therapeutically effective in 59.5% of the cases. These beneficial effects need to be confirmed in studies with a long-term follow-up after discontinuation of the treatment. Our statistical analysis of the results of therapy with MMF did not reveal any significant difference between its use alone or following CsA administration.     

Canine mammary tumours as a model to study human breast cancer: most recent findings

Clinical and molecular similarities between canine mammary tumours and human breast cancer have been described in recent decades. Clinically, the similarities are very strong: spontaneous tumours, hormonal aetiology, age of onset and an identical course of the disease. The clinical characteristics that have an impact on the clinical outcome are also identical: tumour size, lymph node invasiveness and clinical stage. Nowadays, as far as human medicine is concerned, the goal is to identify prognostic factors, mainly at the molecular level, such as those involved in metastasis, which could be used as therapeutic targets to support a better outcome. Moreover, in this area, canine mammary tumours seem to mimic human breast cancer, as a range of similarities are found at the molecular level concerning the overexpression of steroid receptors, proliferation markers, epidermal growth factor, p53 supressor gene mutations, metalloproteinases, cyclooxygenases, among many others. Clinical and molecular data that support canine mammary tumours as a model to study human breast cancer are analysed in this review. Additionally, it is shown that some recent molecular targets in canine mammary tumours may be seen as indicators for similar research to be performed in the corresponding human disease.     

A novel SRY missense mutation affecting nuclear import in a 46,XY female patient with bilateral gonadoblastoma

Patients with disorders of sex development (DSD), especially those with gonadal dysgenesis and hypovirilization, are at risk of developing the so-called type II germ cell tumors (GCTs). Both carcinoma in situ and gonadoblastoma (GB) can be the precursor lesion, resulting in a seminomatous or non-seminomatous invasive cancer. SRY mutations residing in the HMG domain are found in 10–15% of 46,XY gonadal dysgenesis cases. This domain contains two nuclear localization signals (NLSs). In this study, we report a unique case of a phenotypical normal woman, diagnosed as a patient with 46,XY gonadal dysgenesis, with an NLS missense mutation, on the basis of the histological diagnosis of a unilateral GB. The normal role of SRY in gonadal development is the upregulation of SOX9 expression. The premalignant lesion of the initially removed gonad was positive for OCT3/4, TSPY and stem cell factor in germ cells, and for FOXL2 in the stromal component (ie, granulosa cells), but not for SOX9. On the basis of these findings, prophylactical gonadectomy of the other gonad was performed, also showing a GB lesion positive for both FOXL2 (ovary) and SOX9 (testis). The identified W70L mutation in the SRY gene resulted in a 50% reduction in the nuclear accumulation of the mutant protein compared with wild type. This likely explains the diminished SOX9 expression, and therefore the lack of proper Sertoli cell differentiation during development. This case shows the value of the proper diagnosis of human GCTs in identification of patients with DSD, which allows subsequent early diagnosis and prevention of the development of an invasive cancer, likely to be treated by chemotherapy at young age.     

T84-intestinal epithelial exosomes bear MHC class II/peptide complexes potentiating antigen presentation by dendritic cells

BACKGROUND & AIMS: Intestinal epithelial cells release antigen-presenting vesicles (exosomes) bearing major histocompatibility complex class II/peptide complexes stimulating specific immune responses in vivo. To characterize further the role of human epithelial exosomes in antigen presentation, their capacity to load antigenic peptides, bind immune target cells, and induce T-cell activation was analyzed in vitro. METHODS: The capacity of exosomes derived from the HLA-DR4-expressing, intestinal epithelial cell line T84 to load the HLA-DR4-specific peptide (3)H-HSA 64-76 and to activate a HLA-DR4-restricted T-cell hybridoma was tested in the presence or absence of human monocyte-derived dendritic cells (DCs). Interaction of fluorescein isothiocyanate-labeled exosomes with T cells and DCs was analyzed by flow cytometry and confocal microscopy. RESULTS: T84-derived exosomes, enriched in CD9, CD81, CD82, and A33 antigen, were capable of binding specifically human serum albumin (HSA) 64-76 peptide on HLA-DR4 molecules and of interacting preferentially with DCs. HSA-loaded exosomes were unable to activate the T-cell hybridoma directly but induced a productive T-cell activation through DCs. When HSA peptide was bound to exosomal HLA-DR4 molecules instead of in a soluble form, the threshold of peptide presentation by DCs was markedly decreased (x10(-3)). CONCLUSIONS: Exosomes released by intestinal epithelial cells bear exogenous peptides complexed to major histocompatibility complex class II molecules and interact preferentially with DCs, strongly potentiating peptide presentation to T cells. Epithelial exosomes constitute a powerful link between luminal antigens and local immune cells by mediating the transfer of tiny amounts of luminal antigenic information and facilitating immune surveillance at mucosal surfaces.     

Postoperative imaging in cyanotic congenital heart diseases: part 2, Complications

OBJECTIVE: The purpose of this article is to illustrate the MRI appearance of postoperative complications in the surgical procedures most commonly performed to correct cyanotic congenital heart disease. CONCLUSION: The radiologist must be familiar with the morphologic and functional MRI appearances of surgical complications in patients with palliated or repaired cyanotic congenital heart disease to deliver an accurate diagnosis on which to base management decisions.