Chediak-Higashi syndrome: reversal of increased susceptibility to infection by bone marrow transplantation

Transplantation of normal bone marrow to mice with the Chediak-Higashi syndrome (CHS) resulted in normal granulopoiesis and a reversal of their increased susceptibility to challenge with intravenous Candida albicans. These findings suggest that (1) the leukocyte defect in CHS can be reversed by marrow transplantation and (2) the mechanism for increased susceptibility to infection in these animals is due to a bone- marrow-derived cellular defect. Because of similarities between murine and human CHS, bone marrow transplantation might be considered as a mode of therapy in selected cases of the human disease.     

Normal and degenerative posterior spinal structures: MR imaging

A retrospective study of the magnetic resonance (MR) images of the lumbar spines of 13 healthy subjects and 30 patients with degenerative changes was done. In the healthy subjects, the vertebral facets, thickness of the cartilage and ligamentum flavum, signal characteristics of the bone marrow, and size of the spinal canal were studied. In the patients with degenerative changes in one of these structures, MR images in the sagittal plane were useful in demonstrating hypertrophy of the ligamentum flavum or the vertebral facets, in grading the degree of foraminal stenosis, and in measuring the sagittal diameter of the spinal cord. MR images in the axial plane facilitated detailed analysis of the facet joint and more accurate measurements of the thickness of the ligamentum flavum and spinal canal diameter. MR images were compared with computed tomography scans in 12 patients.     

珍珠层／聚乳酸人工骨植入家犬颈椎椎间的融合效果

目的:观察珍珠层/聚乳酸人工骨植入家犬颈椎椎间的融合效果。方法:实验于2004-09/2005-06在南方医科大学附属南方医院实验动物中心及脊柱骨病科实验室完成。选择成年家犬14只,随机数字表法分为4组,实验组(n=4):在颈椎5/6或者6/7椎间植入珍珠层/聚乳酸人工骨;异体骨组(n=4):在相同部位植入体积分数为0.75的乙醇浸泡的新鲜同种异体髂骨;聚乳酸组(n=4):植入经环氧乙烷消毒的高分子聚乳酸材料;空白对照组(n=2):未植入任何材料,上述各组均用手外科微型钢板内固定。分别于术后4,8,12,16周行X射线片及组织病理检查。结果:纳入动物14只,均进入结果分析。①通过X射线及组织病理检查对椎间融合进行判断,在术后16周,实验组的融合程度差于异体骨组,优于聚乳酸组。②病理检查显示复合材料前方的软组织量极少,为非特异性的纤维结缔组织,在周围正常骨组织内可见珍珠层粉微粒,细小的颗粒被异物巨细胞吞噬,复合材料中可见大量类骨质,材料中的聚乳酸部分降解。③骨磨片显示新骨组织长入复合材料的小孔内,珍珠层粉微粒对骨组织无明显影响。结论:珍珠层/聚乳酸人工骨在体内有较好的植骨融合效果,并可以被缓慢降解吸收。     

血管内皮生长因子对佐剂性关节炎滑膜细胞基质金属蛋白酶3及基质金属蛋白酶9表达的影响

目的:观察血管内皮生长因子对佐剂性关节炎滑膜细胞质金属蛋白酶3及质金属蛋白酶9表达的影响,并探讨其意义。方法:实验于2006-02/12在桂林医学院实验中心完成。①实验材料:清洁级8周龄雄性Wistar大鼠6只,血管内皮生长因子为Peprotech EC LTD公司产品,基质金属蛋白酶3(扩增369bp)上游引物、下游引物,基质金属蛋白酶9(扩增405bp)上游引物、下游引物均购自晶美公司。②实验干预:先用弗氏完全佐剂造Wistar大鼠模型;造模20d后取Wistar大鼠右后足滑膜细胞进行原代培养。③实验分组:实验分为血管内皮生长因子组:取P2代细胞接种于6孔培养板,分别加入终浓度为5,25,50μg/L血管内皮生长因子;对照组:不加血管内皮生长因子。④实验评估:取病理切片观察滑膜细胞形态学改变;采用半定量反转录聚合酶链反应检测Wistar大鼠佐剂性关节炎滑膜细胞基质金属蛋白酶3及基质金属蛋白酶9的m-RNA表达。结果:①培养细胞的形态学观察:原代培养14d滑膜细胞从组织块边缘逸出,21d密集生长开始传代;传代细胞48h可明显分辨出树突样细胞、巨噬细胞样细胞和成纤维细胞样细胞;传至21代,细胞生长及特性稳定。②病理切片:滑膜组织有中性粒细胞、单核细胞、淋巴细胞浸润,滑膜细胞增生、排列紊乱,纤维素渗出,胶原纤维沉着,纤维素样坏死,呈滑膜炎表现。③基质金属蛋白酶3、基质金属蛋白酶9的mRNA表达:对照组基质金属蛋白酶3mRNA表达相对灰度值与血管内皮生长因子终浓度5,25,50μg/L组比较,差异有显著性意义(0.32±0.03,0.77±0.06,1.12±0.12,1.59±0.02,P<0.05);对照组基质金属蛋白酶9mRNA表达相对灰度值与血管内皮生长因子终浓度5,25,50μg/L组比较,差异有显著性意义(0.47±0.07,0.50±0.10,0.91±0.10,1.31±0.06,P<0.05);基质金属蛋白酶3和基质金属蛋白酶9mRNA表达随血管内皮生长因子浓度的加大表达增加。结论:血管内皮生长因子以剂量递增的方式对体外培养的佐剂性关节炎滑膜细胞基质金属蛋白酶3及基质金属蛋白酶9的表达有促进作用。     

食欲素和食欲素受体与运动

目的:食欲素是一种重要的神经肽,通过了解食欲素的相关作用及其表达的调节因素等,可以为肥胖的发生机制及其防治工作,以及在运动中的研究开辟新的途径。资料来源:应用计算机检索1998/2006Medline的相关文章,检索词"orexin""hypocretin",并限定文章语言种类为英文。同时计算机检索1998/2006中国期刊全文数据库(http://www.cnki.net)的相关文章,检索项"关键词",检索词"食欲素""食欲肽""增食因子""胖素""阿立新素",限定文章语言种类为中文。共检索到200余篇文献。资料选择:对资料进行初审,纳入标准:①食欲素及其受体研究。②影响食欲素表达因素的研究。③食欲素与肥胖关系的研究。④食欲素与运动行为关系的研究。排除标准:重复性研究。资料提炼:共收集到56篇相关文献,中文文献均为全文,大部分外文文献为全文,其他为摘要。在这些文献中18篇为重复或类似的同一研究,38篇文献纳入分析。资料综合:食欲素是orphanG蛋白质共轭受体的配体,是下丘脑重要的神经肽。可分为食欲素A和食欲素B两种,它们来源于同一前体,其神经纤维贯穿脑和脊髓。食欲素受体分为OX1R和OX2R两型,OX1RmRNA和OX2RmRNA在脑内的分布不同。食欲素有调节摄食和能量平衡、调节睡眠觉醒状态、调节饮水等功能;其表达量受睡眠、营养状况、环境、性别等因素的影响。国内对食欲素的研究不多,主要是肥胖、低氧以及低糖状态对食欲素影响的研究;国外可见通过行为干预对食欲素的研究,以及其他因子对食欲素的影响。结论:食欲素作为一种重要的神经肽,除具有调节食欲和平衡能量的作用外,还具有保持觉醒,参与免疫应答等功能;食欲素抗体或受体拮抗剂还可能治疗肥胖、糖尿病等能量代谢失衡性疾病。但国内外对食欲素在运动训练及减肥中的相关研究还较少。     

A novel permanent maglev rotary LVAD with passive magnetic bearings

It has been widely acknowledged that permanent maglev cannot achieve stability; however, the authors have discovered that stable permanent maglev is possible under the effect of a combination of passive magnetic and nonmagnetic forces. In addition, a rotary left ventricular assist device (LVAD) with passive magnetic bearings has been developed. It is a radially driven impeller pump, having a rotor and a stator. The rotor consists of driven magnets and impeller; the motor coil and pump housing form the stator. Two passive magnetic bearings counteract the attractive force between motor coil iron core and rotor magnets; the rotor thereafter can be disaffiliated from the stator and become levitated under the action of passive magnetic and haemodynamic forces. Because of the pressure difference between the outlet and the inlet of the pump, there is a small flow passing through the gap of rotor and stator, and then entering the lower pressure area along the central hole of the rotor. This small flow comes to a full washout of all blood contacting surfaces in the motor. Moreover, a decreased Bernoulli force in the larger gap with faster flow produces a centring force that leads to stable levitation of the rotor. Resultantly, neither mechanical wear nor thrombosis will occur in the pump. The rotor position detection reveals that the precondition of levitation is a high rotating speed (over 3250 rpm) and a high flow rate (over 1?l min^?1). Haemodynamic tests with porcine blood indicate that the device as a LVAD requires a rotating speed between 3500 and 4000 rpm for producing a blood flow of 4?–?6?l min^?1 against 100?mmHg mean pressure head. The egg-sized device has a weight of 200?g and an O.D. of 40?mm at its largest point.     

Supervisory needs of research doctoral students in a university teaching hospital setting

Background/Hypothesis: Teaching hospitals affiliated with universities are now common sites for research higher degree supervision. We hypothesised that the hospital environment poses unique challenges to supervision compared with the traditional university research institute setting. Aims: This study aimed to identify and rank important supervision issues in a clinical setting from the students' perspective. Methods: Using the Delphi method to explore issues and facilitate consensus, small group discussions were conducted with 10 research doctoral students from a tertiary teaching hospital. Results: We identified supervision issues that are unique to the hospital‐based context. These include the demands placed on supervisors combining clinical and supervisory roles, the challenges of academic medical/scientific writing and career issues for students who are already established in their professions. Other issues identified, common to all doctoral students, include differing expectations between students and supervisors (with students wanting support for their career plans, training in research skills and increasing autonomy and responsibility), supervisor access, quality and frequency of meetings, lack of training in writing and dealing with conflicts. Conclusion: Our research identified that postgraduate students of supervisors who combine clinical and supervisory roles report significant issues with supervision, some of which are unique to the clinical setting. Clinician researchers who supervise postgraduate students need to balance clinical and supervisory responsibilities, identify and negotiate student expectations early in candidature and provide career counselling to students who are already highly experienced. Furthermore, clinician supervisors should undertake postgraduate supervisor training programme tailored to the hospital setting to better support their students.     

ROLE OF CYCLIC NUCLEOTIDES IN THE CONTROL OF CYTOSOLIC Ca2+ LEVELS IN VASCULAR ENDOTHELIAL CELLS

• 1 Endothelial cells have a key role in the cardiovascular system. Most endothelial cell functions depend on changes in cytosolic Ca²⁺ concentrations ([Ca²⁺]_i) to some extent and Ca²⁺ signalling acts to link external stimuli with the synthesis and release of regulatory factors in endothelial cells. The [Ca²⁺]_i is maintained by a well‐balanced Ca²⁺ flux across the endoplasmic reticulum and plasma membrane.
• 2 Cyclic nucleotides, such as cAMP and cGMP, are very important second messengers. The cyclic nucleotides can affect [Ca²⁺]_i directly or indirectly (via the actions of protein kinase (PK) A or PKG‐mediated phosphorylation) by regulating Ca²⁺ mobilization and Ca²⁺ influx. Fine‐tuning of [Ca²⁺]_i is also fundamental to protect endothelial cells against damaged caused by the excessive accumulation of Ca²⁺.
• 3 Therapeutic agents that control cAMP and cGMP levels have been used to treat various cardiovascular diseases.
• 4 The aim of the present review is to discuss: (i) the functions of endothelial cells; (ii) the importance of [Ca²⁺]_i in endothelial cells; (iii) the impact of excessive [Ca²⁺]_i in endothelial cells; and (iv) the balanced control of [Ca²⁺]_i in endothelial cells via involvement of cyclic nucleotides (cAMP and cGMP) and their general effectors.