Immunoreactivity of sinusoids in hepatoblastoma: an immunohistochemical study using lectin UEA-1 and antibodies against endothelium-associated antigens, including CD34

Sinusoids are found not only in the normal liver but also in certain liver tumours, including hepatoblastoma, the most common malignant liver tumour in childhood. In this study, sinusoids in 12 hepatoblastomas, of various subtypes, and in normal liver were investigated with UEA-1 and antibodies against von Willebrand's factor, CD31 and CD34 to detect differences of possible diagnostic significance. In the normal liver, staining of sinusoids was seen with all these markers, but it was focal and confined to a few sinusoids near the portal tracts. In hepatoblastoma, the endothelial markers reacted with the sinusoids to varying extents. UEA-1 and anti-CD34 usually stained the majority of these vessels, anti-CD34 staining greater numbers of sinusoids and with greater intensity. Immunostaining revealed that both number and spatial organization of sinusoids in hepatoblastoma are dependent on the subtype. In addition to staining of endothelium, one of the two small cell hepatoblastomas exhibited strong immunoreactivity of the tumour cells for CD34. These findings show that the marked difference in sinusoidal immunoreactivity for CD34 between normal liver and hepatoblastoma could be useful for discriminating between non-neoplastic liver tissue and highly differentiated fetal hepatoblastoma. Our findings also show that small cell hepatoblastoma, in addition to acute leukaemia, should be considered when immunoreactivity for CD34 is found in small round and blue cell tumours in childhood.     

Subregional topography of capillaries in the dorsal vagal complex of rats: I. Morphometric properties

Cytoarchitectonic and neurochemical studies of the dorsal vagal complex in the caudal medulla oblongata of rats indicate the existence of distinct anatomical and functional compartments within its components. We applied morphometric methods to discern whether capillary networks differed quantitatively between subregions and zones of area postrema, nucleus tractus solitarii (NTS), and dorsal motor nucleus of the vagus nerve (DMN) of rats. Analysis of 11 subdivisions of area postrema identified both "true" (range in luminal diameter of 3-7.5 microns) and sinusoidal (luminal diameter greater than 7.5 microns) capillaries that, together, made the capillary density for most of area postrema 75% greater than that found in NTS and DMN (526/mm2 vs about 300/mm2). The rank order of true capillary density in area postrema along its rostracaudal axis was caudal greater than central greater than rostral, whereas the reverse order was true for sinusoidal capillaries. Dorsal (periventricular) and medial zones of area postrema throughout its rostrocaudal axis tended to have higher values for capillary density, volume, surface area, luminal diameter, and pericapillary space volume than lateral or ventral zones bordering NTS. Within 200 microns of obex, the ventral zone of rostral area postrema was distinct, having a relatively sparse capillary density that may indicate morphological specializations limiting blood-tissue communication in this subregion. There were no quantitative differences in capillary dimensions between DMN and three subnuclei of NTS. These studies add to extant evidence that the dorsal vagal complex is differentiated for specific functions. Area postrema, especially, has topographical diversity in its capillary organization that likely corresponds to complex roles in neuroendocrine, autonomic, and chemosensory mechanisms.     

肝脏低温保存肝血窦变化的实验观察

目的：探讨低温保存肝血窦超微结构的变化及其在肝微循环障碍中的作用，方法：将63只大鼠肝脏分别在低温UW液中保存0（对照组）、2、8、16、24、32和48h，然后对肝血窦进行电镜观察，结果：肝血窦内皮细胞在保存2、8h后，筛板小孔扩大，融合成许多大洞隙，16、24h细胞胞明显回缩，呈树根状，32，48h似索网状，部分内皮细胞突起，脱落，肝细胞微绒毛在保存8h后出现肿胀并形成膜浆泡从扩大的内皮小孔突入血窦；随着保存时间延长，膜浆泡增多，变大并脱落或破裂，结论：肝血窦内皮细胞的低温保存损伤和膨入血窦内的膜浆泡可引起肝微循环紊乱，导致肝血流和肝功能障碍。     

Alcohol-associated capillarization of sinusoids: A critique since the discovery by Schaffner and Popper in 1963

This article reviews the literature on capillarization of hepatic sinusoids since its discovery in 1963. Liver sinusoidal endothelial cells are uniquely fenestrated and lack an underlying basement membrane. In chronic liver disease, the sinusoids capillarize and transform into systemic capillaries, a process termed capillarization of sinusoids. The histopathology is marked by defenestration, basement membrane formation, and space of Disse fibrogenesis. Capillarized sinusoids compromise the bidirectional exchange of materials between sinusoids and hepatocytes, leading to hepatocellular dysfunction. Sinusoidal capillarization was first described in active cirrhosis of alcoholics in 1963. Since then, it has been found in early and progressive stages of alcoholic hepatic fibrosis before the onset of cirrhosis. The sinusoidal structure is not altered in alcoholic steatosis without fibrosis. Defenestration impairs the ability of the endothelium to filter chylomicron remnants from sinusoids into the Disse's space, contributing to alcohol-induced postprandial hyperlipidemia and possibly atherosclerosis. Ethanol also modulates the fenestration dynamics in animals. In baboons, chronic alcohol consumption diminishes endothelial porosity in concomitance with hepatic fibrogenesis and in rats defenestrates the endothelium in the absence of fibrosis, and sometimes capillarizes the sinusoids. Acute ethanol ingestion enlarges fenestrations in rats and contracts fenestrations in rabbits. In sinusoidal endothelial cell culture, ethanol elicits fenestration dilation, which is likely related to its interaction with fenestration-associated cytoskeleton. Ethanol potentiates sinusoidal injury caused by cocaine, acetaminophen or lipopolysaccharide in mice and rats. Understanding ethanol's mechanisms on pathogenesis of sinusoidal capillarization and fenestration dynamics will lead to development of methods to prevent risks for atherosclerosis in alcoholism.     

乙醇对大鼠肝窦内皮细胞窗孔的影响

目的 研究慢性乙醇摄取对大鼠肝窦内皮细胞(LSEC)窗孔的影响。方法 用乙醇直接灌胃的方法建立大鼠酒精性肝病动物模型，并于开始灌胃4周末、8周末、12周末，以及停止灌酒后(用平衡饲料继续喂养)12周末，分别处死实验组及对照组动物，经心脏灌流后取肝脏组织行HE染色和透射电镜观察LSEC窗孔的动态变化。结果 正常的LSEC扁平，胞核及细胞器排列规则，远侧胞质呈薄片状，有许多窗孔，内皮下缺乏基底膜(BM)；乙醇喂养4周末，可见部分LSEC远侧胞窗孔数减少，但BM未形成；8周末，窗孔数明显减少或消失，内皮下开始有不完全的BM形成，同时有功能活跃的纤维母细胞形成；12周末进一步加重，甚至可见完整的BM形成，但这种改变也多限于单个或邻近的窦状隙内，极少有广泛的纤维化形成；停药12周末，失窗孔及内皮下BM形成明显减轻。结论 随着乙醇的慢性刺激LSEC的去窗孔化和BM的形成也逐渐发生，严重时可形成肝窦毛细血管化和肝纤维化；这种早期即有局限性的去窗孔化改变和毛细血管化的生成可能是形成酒精性周围型纤维化的基础；去除病因后这种肝纤维化是可逆的。     

Effect of Semen Persicae Extract Combined with Cultured Cordyceps on Reversing Capillarization of Sinusidsin patients with Hepato-Cirrhosis

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Hepatic microvascular effects of terbutaline in experimental cardiogenic shock in rats

1. Experimental myocardial infarction was produced in rats by direct electrical cauterization of the myocardium of left ventricle. This produced cardiogenic shock with the accompanying haemodynamic changes of low cardiac output, low mean arterial pressure, raised central venous pressure and an absence of cardiac arrhythmias. 2. The liver microcirculation was observed using in vivo television microscope method. The diameter and erythrocyte flow velocity in the liver sinusoids were measured quantitatively. 3. During experimental cardiogenic shock 80% of the liver sinusoids were constricted; the remaining 20% showed dilatation. In all these liver sinusoids the erythrocyte flow velocity was only 50% of the pre-shock level. 4. Intravenous injection of the selective beta 2-adrenoceptor agonist terbutaline (0.15 mg/kg) restored the systemic arterial pressure to pre-shcok levels and partially raised the cardiac output. In the liver microcirculation terbutaline restored both constricted and dilated liver sinusoids to pre-shock calibres, but only partially raised erythrocyte flow velocity. 5. It is proposed that during experimental cardiogenic shock, terbutaline produces dilatation in the terminal liver microcirculation by opening sphincters of liver sinusoids and restores sinusoid diameters to pre-shock calibres. Therefore, terbutaline has the capacity to decrease peripheral resistance and unload the circulation during cardiogenic shock.     

Immunomagnetic exclusion of E-cadherin-positive hepatoblasts in fetal mouse liver cell cultures impairs morphogenesis and gene expression of sinusoidal endothelial cells

Previous studies have shown that various cell-cell interactions between hepatoblasts and nonparenchymal cells, including sinusoidal endothelial cells and stellate cells, are indispensable for the development of fetal murine hepatic architecture. The present study was undertaken to determine the effects of hepatoblasts on the sinusoidal structural formation using a culture system of fetal mouse livers. Primitive sinusoidal structures extensively developed in fetal livers, and were composed of LYVE-1- and PECAM-1-positive endothelial cells, desmin-positive stellate cells and F4/80-positive macrophages. When fetal liver cells at 12.5 days of gestation were cultured in vitro, hepatoblasts spread on glass slides and gave rise to hepatocytes on day 5. Desmin-positive stellate cells also spread on the glass slides. PECAM-1-positive endothelial cells became slender and developed into anastomosing capillary networks. When fetal liver cells were cultured without hepatoblasts, which were excluded by an immunomagnetic method using anti-E-cadherin antibodies, endothelial cells had impaired growth and capillary formation. These results demonstrated that capillary formation of endothelial cells was induced by the presence of hepatoblasts. VEGF and the conditioned medium containing humoral factors produced by hepatoblasts/hepatocytes did not induce capillary formation of endothelial cells in cultures of nonparenchymal cells, although they significantly increased the number of endothelial cells on the glass slides. The presence of hepatoblasts also significantly stimulated expression of CD32b mRNA, which is a sinusoidal endothelial marker. Hepatoblasts may work as a positive stimulator of sinusoid morphogenesis and maturation in liver development, in which a signal other than VEGF may play a decisive role, together with VEGF.