天然免疫与获得性免疫的进化关系

免疫有天然免疫和获得性免疫两种类型,它们有不同的机制和起源.天然免疫可识别某些"非己”细胞或分子并加以清除;获得性免疫则对分子抗原表位进行识别,按抗原提呈细胞等有无协同信号(发育阶段/类型)而有所区别.两者有不同的生物学起源与意义;天然免疫源于防御入侵者的需求,获得性免疫则源于系统及个体自身发育中调节细胞发育的需求.两者嫁接性混合进化形成了复杂的可识别"自己/非己”的免疫系统,并留下了神奇的机制.     

Different roles of arteriosclerosis in the rupture of intracranial dissecting aneurysms

AIMS: Although intracranial dissecting aneurysm (IDA) is a newly described variant of the brain aneurysms that affects mainly the vertebrobasilar arterial system, its pathogenesis remains obscure. We aimed to clarify the role of arteriosclerosis in the pathogenesis of IDA based on histopathological findings in seven autopsy cases of IDA. METHODS AND RESULTS: All cases exhibited systemic hypertension or left ventricular hypertrophy. Macroscopically, all cases exhibited subarachnoid haemorrhage. Two types of dissection were recognized in the vertebral artery. Six of seven IDA cases showed a widespread disruption of the entire thickness of the arterial wall with the formation of a dilated pseudoaneurysm, which consisted of thin adventitia (arterial wall disruption type). Medial disruption of the arterial wall and subadventitial dissecting haemorrhage were also found, resulting in the formation of a false lumen and stenosis of the 'true' lumen of the artery. However, these lesions were connected to the site of rupture of the entire arterial wall. Within 1 day after onset of IDA, the autopsy cases showed formation of fibrin thrombus, marked leucocyte infiltration and necrosis of the arterial wall at the site of the lesion. Cases that survived more than 1 week showed smooth muscle cell proliferation, macrophage accumulation and lymphocytic infiltration in the lesions. These cases showed no atherosclerotic plaque, but non-atherosclerotic fibrocellular intima. The thickness of intima and media was significantly less in the vertebral artery of IDA patients than that of non-IDA patients with systemic hypertension. On the other hand, the remaining case showed severe atherosclerosis with haemorrhage into the lipid core without connection to the arterial lumen (intra-atheromatous plaque haemorrhage type). However, unusual arterioles and neovascularization of the intra-and peri-arterial walls were observed. CONCLUSIONS: Our results suggest that disruption of the entire arterial wall may be a critical event in the development of IDA and result in the medial disruption and subadventitial haemorrhage. Non-atheromatous intima might function as a protective factor in arterial wall disruption. On the other hand, atherosclerosis may predispose to intra-atheromatous plaque haemorrhage type of IDA through intramural haemorrhage originating from the newly formed vessels.     

Trabecular Shear Stresses Predict <Emphasis Type="Italic">In Vivo</Emphasis> Linear Microcrack Density but not Diffuse Damage in Human Vertebral Cancellous Bone

Linear microcracks and diffuse damage (staining over a broad region) are two types of microscopic damage known to occur in vivo in human vertebral trabecular bone. These damage types might be associated with vertebral failure. Using microcomputed tomography and finite element analysis for specimens of cancellous bone, we estimated the stresses in the trabeculae of human vertebral tissue for inferosuperior loading. Microdamage was quantified histologically. The density of in vivo linear microcracks was, but the diffuse damage area was not, related to the estimates of von Mises stress distribution in the tissue. In vivo linear microcrack density increased with increasing coefficient of variation of the trabecular von Mises stress and with increasing average trabecular von Mises stress generated per superoinferior apparent axial stress. Nonlinear increase in linear crack density, similar to the increase of the coefficient of variation of trabecular shear stresses, with decreasing bone stiffness and bone volume fraction suggests that damage may accumulate rather rapidly in diseases associated with low bone density due to the dramatic increase of shear stresses in the tissue. © 2003 Biomedical Engineering Society. PAC2003: 8719Rr, 8719Xx, 8759Ls, 8759Fm, 8710+e     

Genomic imprinting and uniparental disomy in Angelman and Prader-Willi syndromes: A review

Although Angelman (AS) and Prader-Willi (PWS) syndromes are human genetic disorders with distinctly different developmental and neurobehavioural phenotypes, they both have abnormalities in inheritance of chromosome 15q11–q13. Whether AS or PWS arises depends on the parental origin of a deletion or uniparental disomy (the inheritance of 2 copies of a genetic locus from only one parent) for 15q11–q13. Normal development requires a genetic contribution for this genetic region from both a male and female parent. The dependence on parental origin implies that genes in human 15q11–q13 have distinct functions depending upon epigenetic, parent-of-origin differences, known as genomic imprinting. Here, I review the role of uniparental disomy and genomic imprinting in the pathogenesis of AS and PWS, and briefly discuss phenotype-genotype correlations using candidate genes and mouse models, in particular for hypopigmentation. © 1993 Wiley-Liss, Inc.     

谷氨酸脱羧酶67-绿色荧光蛋白基因敲入小鼠三叉神经尾侧亚核内GFP阳性神经元的分布及与小白蛋白的共存

目的观察谷氨酸脱羧酶67-绿色荧光蛋白（GAD67-GFP）基因敲入小鼠三叉神经尾侧亚核（Vc）浅层内，表达GFP的GABA能神经元的分布及其与小白蛋白（PV）的共存。方法分别运用原位分子杂交与免疫组织化学相结合；GFP与神经元标记物——神经元核蛋白（NeuN）或PV免疫荧光染色相结合的双重标记方法，在光学显微镜和激光共聚焦显微镜下进行观察。结果1．Vc浅层内90％以上的GFP阳性神经元同时表达GAD67 mRNA，而几乎所有表达GAD67 mRNA的阳性神经元都呈GFP阳性；2．GFP阳性神经元主要分布于Ｖc的Ⅰ－Ⅱ层内，细胞较小，尤其在Ⅱ层内可见大量密集分布的GFP阳性细胞和突起。GFP阳性神经元分别占Ⅰ、Ⅱ层内NeuN阳性神经元总数的19．4％和24．3％；3．GFP／PV双标神经元主要分布于Ｖc的Ⅰ－Ⅱ层，这些双标神经元大约占PV阳性神经元的62．4％，占GFP阳性神经元的12．8％。结论在Ｖc表达GFP的GABA能神经元主要密集分布于与外周伤害性信息传递关系密切的板层内，且大部分PV样阳性神经元属于GABA能神经元。     

Epidural mass due to aspergillus flavus causing spinal cord compression--a case report and brief update

Aspergillus infection of the central nervous system (CNS) is an uncommon disease. Most of the reported cases are of sinocranial spread and cases with contiguous spread to spinal cord from lung and other organs are uncommon. A case of pulmonary aspergillosis with extension to thoracic vertebrae forming a paraspinal mass resulting in neurological deficit due to Aspergillus flavus, is reported. The 43 year old patient did not have any obvious predisposing condition. He presented with loss of motor function and succumbed to the infection despite operative intervention and antifungal therapy. A brief update on CNS aspergillosis is presented along with detailed clinical, radiological and laboratory work up of the patient.     

Pseudo dicentric chromosome (5;21): a rare example of maternal germline mosaicism

Karyotyping of a malformed male newborn revealed the unbalanced karyotype of 46,XY, psudic(5;21)(q12;p13), +5 resulting in trisomy for the short arm of chromosome 5 and partial trisomy for 5q. Both parents had normal karyotypes in their peripheral blood lymphocytes. A second pregnancy ended in a miscarriage at 16 weeks gestation, sonographically 12 weeks. Karyotyping of chorionic villi from the abortus revealed the same unbalanced karyotype that had been identified in the first child. Fluorescence in-situ hybridization analysis confirmed a trisomy 5p. Microsatellite marker analysis ruled out illegitimacy and proved the maternal origin of the trisomic section of chromosome 5. Extended chromosome analysis of 60 metaphase cells from maternal skin fibroblasts and 40 metaphase cells from lymphocytes did not reveal mosaicism for psudic(5;21). These findings suggest the presence of a maternal germline mosaicism.     

DNA content and expression of tumour markers in germ cells adjacent to germ cell tumours in childhood: Probably A different origin for infantile and adolescent germ cell tumours

The origin of testicular germ cell tumours occurring during childhood is poorly understood. In adults, the classical seminomas and non-seminomas originate from carcinoma in situ of the testis, which can usually also be detected in seminiferous tubules adjacent to the tumours. In order to contribute with information regarding a possible association between carcinoma in situ and the childhood group of germ cell tumours, we investigated seminiferous tubules adjacent to 13 infantile yolk sac tumours, five infantile teratomas, and six adolescent germ cell tumours of various types, using morphological evaluation, immunohistochemical staining with markers for carcinoma in situ cells, and densitometric DNA measurement of the germ cells. We detected clear differences between the germ cell populations adjacent to adolescent and infantile germ cell tumours. The former were associated with both normal germ cells and carcinoma in situ cells. The presence of carcinoma in situ cells strongly suggested that the adolescent tumours arose from carcinoma in situ cells, like germ cell tumours occurring in adult men. Although we were in doubt in two cases, the infantile germ cell tumours were in general not associated with carcinoma in situ cells. The aetiology of infantile yolk sac tumours and teratomas may therefore be fundamentally different from that of adolescent and adult germ cell tumours. The origin of yolk sac tumours and teratomas remains to be elucidated.     

选择腰椎椎弓根螺钉长度的放射解剖学研究

目的 :探讨在腰椎侧位片及CT片上推算椎弓根螺钉长度的方法 ,为临床提供参考。方法 :随机在 3 0个腰椎骨标本上用 1mm软钢丝在椎弓根最狭窄处缠绕 ,按人字嵴进钉方法打入椎弓根直钢丝 ,拍正侧位片、横断面片及椎弓根CT扫描 ,分别在标本、CT及侧位片上测量椎弓根螺钉长度 ,三组数据比较。结果 :腰椎侧位片上测量的自关节突关节间隙下缘至椎体前缘距离乘以 0 .83即是螺钉长度 ,椎弓根CT扫描测量其长度更为准确。结论 :正常拍照条件下 ,用腰椎侧位片和椎弓根CT片可准确地推算螺钉长度 ,具有临床实用意义。