The prospects for renal xenotransplantation

Summary: Xenotransplantation of non-human organs into human recipients has long been proposed as a possible strategy to overcome the acute shortage of donor organs. However, vascular organ transplants to humans from phylogenetically disparate species such as the pig are not currently possible due to a rapid rejection process termed hyperacute rejection. This process is initiated by the binding of host pre-formed 'natural antibodies' to the donor vascular endothelium, activation of the host complement system and activation or injury of the donor endothelial cells, leading to intravascular coagulation and loss of the graft due to ischaemic necrosis within minutes to hours of engraftment. Prevention of natural antibody binding and complement activation is viewed as paramount to preventing hyperacute rejection. Even if hyperacute rejection can be prevented, further barriers to successful discordant xenografts such as delayed xenograft rejection and a donor-directed cell-mediated rejection process will still represent major obstacles. This review examines recent advances being made in the various areas of xenograft research and the potential clinical application of pig-to-human xenografts that these strategies may bring.     

The inferior alveolar artery in its bony course

Based on the dissection of 30 hemi-mandibles, the authors report a study of the inferior alveolar artery in its intraosseous course. On morphologic considerations they propose a classification of the collaterals into two groups: the principal collaterals destined for the teeth and the bony alveolar tissue and the secondary collaterals destined for the sheath and the nerve as well as the bony tissue around the canal. Loss of the teeth and absorption of the alveolar bone modify the caliber of the inferior alveolar arterial axis, the distribution of its collaterals and possibly its mode of termination. These facts suggest a consideration of the vascularization of the mandible in terms of four sectors. They arrive at practical conclusions that may be drawn from this study in stomatology.     

Dural infolding during C1-2 myelography

Inward buckling of the dura at C1-2 may occasionally occur with hyperextension of the neck and can result in a difficult or unsuccessful puncture when the posterior lateral C1-2 approach is used for cervical myelography. In this circumstance, placement of the head in a neutral or slightly flexed position may widen the posterior subarachnoid space and facilitate the needle puncture.     

Expression and purification of functional recombinant epitopes for the platelet antigens, PlA1 and PlA2

The platelet antigens, PlA1 and PlA2, are responsible for most cases of posttransfusion purpura (PTP) and neonatal alloimmune thrombocytopenia (NAIT) in the caucasian population and are determined by two allelic forms of the platelet glycoprotein GPIIIa gene. To study the interaction between these antigens and their respective antibodies, we inserted the sequence that encodes the signal peptide and the N- terminal 66 amino acids of the PlA1 form of GPIIIa into the expression vector pGEX1. To express the PlA2 antigen, nucleotide 196 of the PlA1 coding sequence was mutated to the PlA2 allelic form. When transformed and induced in Escherichia coli, the two constructs produce glutathione S-transferase (GST)/N-terminal GPIIIa fusion proteins, one containing leucine at position 33 (PlA1), the other proline (PlA2). These proteins are easily purified in milligram quantities using glutathione-Sepharose and react specifically with their respective antibodies by immunoblot and enzyme-linked immunosorbent assay. Antigenicity of the PlA1 fusion protein in reduced glutathione increases with time; moreover, the addition of oxidized glutathione accelerates this process, presumably because of formation of the native disulfide bonds. Neutralization assays indicate that the PlA1 fusion protein competes for all of the anti-PlA1 antibody in the serum of patients with PTP and NAIT that is capable of interacting with the surface of intact platelets. This study shows that the GST/N-terminal GPIIIa fusion proteins contain conformational epitopes that mimic those involved in alloimmunization, and that regions other than the amino terminal 66 amino acids of GPIIIa are not likely to contain or be required for the development of functional PlA1 epitopes. Furthermore, these recombinant proteins can be used for the affinity-purification of clinical anti-PlA1 antibodies and specific antibody identification by western blotting, making them useful in the diagnosis of patients alloimmunized to PlA1 alloantigens.     

颈动脉血管重构特征在自发性高血压大鼠体内的表现

目的:血管重构是高血压的重要病理变化,是高血压导致器官损害的结构基础。实验观察自发性高血压大鼠颈动脉中层组织学的相关变化,以验证血管重构的特点。方法:实验于2006-06/2007-03在福建医科大学附属协和医院心血管内科实验室完成。①实验材料及分组:12周龄雄性自发性高血压大鼠10只,同性别周龄的WKY大鼠10只为对照,喂养18周后终止实验。②实验过程及评估:开始及每2周测鼠尾收缩压。实验结束后,麻醉后取颈动脉,行苏木精-伊红、苦味酸-天狼星红、弹力纤维和胶原纤维的双重染色(P/VB法),利用计算机辅助成像系统测算颈动脉中膜厚度、腔径、血管中膜厚/腔径、中膜横截面积、中膜细胞平均核面积及中膜的胶原面积百分比、弹性纤维面积百分比、弹性纤维面积与胶原面积的比值。SP免疫组织化学染色检测α-平滑肌肌动蛋白、增殖细胞核抗原、纤维粘连蛋白、层粘连蛋白等抗原在颈动脉壁的表达,并计算颈动脉中膜细胞增殖指数;以原位末端标记法标记血管壁的凋亡细胞,计算颈动脉中膜细胞凋亡指数。结果:20只大鼠全部进入结果分析。①自发性高血压大鼠实验开始和结束前的收缩压均>150mmHg,高于WKY大鼠(P<0.01)。②自发性高血压大鼠颈动脉中膜厚度、腔径、中膜厚度/腔径、中膜横截面积、中膜胶原面积百分比均高于WKY大鼠(P<0.01),而中膜弹性纤维面积百分比、弹性纤维面积与胶原面积比值均低于WKY大鼠(P<0.01)。③α-平滑肌肌动蛋白在两组大鼠颈动脉中膜均可表达,提示中膜细胞为血管平滑肌细胞。④自发性高血压大鼠中膜血管平滑肌细胞平均核面积大于WKY大鼠(P<0.01),中膜细胞增殖指数与WKY大鼠差异无显著性(P>0.05),中膜细胞凋亡指数显著低于WKY大鼠(P<0.01)。⑤自发性高血压大鼠颈动脉中膜纤维粘连蛋白、层粘连蛋白的光密度值(IA值)及染色阳性面积百分比高于WKY大鼠(P<0.01)。⑥颈动脉中膜血管平滑肌细胞凋亡指数与中膜横截面积呈显著负相关(r=-0.872,P<0.01);纤维连接蛋白表达的吸光度值与中膜横截面积呈显著正相关(r=0.954,P<0.01)。结论:自发性高血压大鼠颈动脉存在明显的重构,其特点为中膜肥厚、平滑肌细胞肥大、凋亡减少及胶原、纤维粘连蛋白、层粘连蛋白的过度沉积。     

Zebrin II: a polypeptide antigen expressed selectively by Purkinje cells reveals compartments in rat and fish cerebellum

Monoclonal antibody mab-zebrin II was generated against a crude homogenate of cerebellum and electrosensory lateral line lobe from the weakly electric fish Apteronotus leptorhynchus. On Western blots of fish cerebellar proteins, mab-zebrin II recognizes a single polypeptide antigen of apparent molecular weight 36 kD. Immunocytochemistry of apteronotid brains reveals that zebrin II immunoreactivity is confined exclusively to Purkinje cells in the corpus cerebelli, lateral valvula cerebelli, and the eminentia granularis anterior. Other Purkinje cells, in the medial valvula cerebelli and eminentia granularis posterior, are not zebrin II immunoreactive. Immunoreactive Purkinje cells are stained completely, including dendrites, axons, and somata. The antigen seems to be absent only from the nucleus. A similar distribution is seen in catfish, goldfish, and a mormyrid fish. Zebrin II immunoreactivity is also found in the rat cerebellum. Western blotting of rat cerebellar proteins reveals a single immunoreactive polypeptide, with apparent molecular weight 36 kD, as in the fish. Also as in the fish, staining in the adult rat cerebellum is confined to a subset of Purkinje cells. Peroxidase reaction product is deposited throughout the immunoreactive Purkinje cells with the exception of the nucleus. No other cells in the cerebellum express zebrin II. At higher antibody concentrations, a weak glial cross reactivity is seen in most other brain regions: we believe that this is probably nonspecific. Zebrin II+ Purkinje cells are clustered together to form roughly parasagittal bands interposed by similar nonimmunoreactive clusters. In all there are 7 zebrin II+ and 7 zebrin II- compartments in each hemicerebellum. One immunoreactive band is adjacent to the midline; two others are disposed laterally to each side in the vermis; there is a paravermal band; and finally three more bands are identified in each hemisphere. Both in number and position, these compartments correspond precisely to the bands revealed by using another antibody, mabQ113 (anti-zebrin I). In both fish and rat the compartmentation revealed by zebrin II immunocytochemistry is related to the organization of cerebellar afferent and efferent projections and may provide clues as to the fundamental architecture of the vertebrate cerebellum.     

The double puncture: an effective percutaneous technique for removing complex, multiple renal calculi

Percutaneous nephrostolithotomy, which can require a double puncture, is presently the method of choice in our institution for the removal of renal stones. Patients that underwent this procedure were evaluated to identify the possible reasons for the double puncture. Of 200 patients evaluated, 14 needed a second tract. The three variables that determined whether a second puncture was needed, in order of importance, were number and size of the stones, with second tracts needed in patients with multiple stones and staghorn calculi; anatomical variations of the renal collecting system itself, with bifid systems the most significant anatomic variation; and the dexterity of the radiologist in performing the puncture and the ability of the urologist to extract the stone. Second tracts were needed more frequently in patients who presented with stones in both the lower and middle poles of the collecting systems.     

Experience with the Amplatz retrievable vena caval filter. Work in progress

The Amplatz retrievable vena caval filter was designed in an attempt to decrease complications associated with the placement of Mobin-Uddin or Kimray-Greenfield filters. The design allows percutaneous retrieval, thus expanding application of the filter to situations requiring temporary prophylaxis against pulmonary embolism. Filters have been placed in 16 patients, nine (56%) for prophylactic purposes. All filters were easily inserted percutaneously. Complications occurred in three patients; these included complete thrombosis of the inferior vena cava below the filter, misplacement of one filter into the pericaval retroperitoneal tissue, and development of thrombus cranial to the filter. With the current introduction system, the possibility of filter misplacement has been essentially eliminated. No patient experienced symptoms suggestive of pulmonary embolism after filter insertion. One filter retrieval has been performed, with no complications.     

Occupational asthma caused by exposure to neurospora in a plywood factory worker

A 24 year old man developed severe asthma two years after starting to work in a plywood plant. Four years later the patient had to stop working because of the increasing severity of his asthma. Three months after leaving his job, the patient's asthma was greatly improved. His job consisted of placing plywood sheets into a drying machine. The plywood sheets had stayed outside in wet conditions for at least four to six weeks and were usually covered with moulds. Drying the plywood sheets changed the mould into a fine orange powder. Exposure to this in the laboratory induced an isolated immediate asthmatic reaction. The same reaction was seen when the patient was challenged with an extract of the mould powder at a 0.1% w/v concentration. Skin prick test with the mould extract induced a weal and flare reaction and IgE antibodies against the dry mould powder were identified. A control patient with the same degree of bronchial hyperreactivity did not have any asthmatic reaction when challenged with the same mould extract. Culture of the dry mould powder on Sabouraud agar plates grew pure Neurospora sp. This mould has not been previously reported as a cause of occupational asthma. The immunological mechanism is probably related to an IgE mediated mast cell allergy.