Role of ubiquitin carboxy terminal hydrolase-L1 in neural cell apoptosis induced by ischemic retinal injury in vivo

Ubiquitin is thought to be a stress protein that plays an important role in protecting cells under stress conditions; however, its precise role is unclear. Ubiquitin expression level is controlled by the balance of ubiquitinating and deubiquitinating enzymes. To investigate the function of deubiquitinating enzymes on ischemia-induced neural cell apoptosis in vivo, we analyzed gracile axonal dystrophy (gad) mice with an exon deletion for ubiquitin carboxy terminal hydrolase-L1 (UCH-L1), a neuron-specific deubiquitinating enzyme. In wild-type mouse retina, light stimuli and ischemic retinal injury induced strong ubiquitin expression in the inner retina, and its expression pattern was similar to that of UCH-L1. On the other hand, gad mice showed reduced ubiquitin induction after light stimuli and ischemia, whereas expression levels of antiapoptotic (Bcl-2 and XIAP) and prosurvival (brain-derived neurotrophic factor) proteins that are normally degraded by an ubiquitin-proteasome pathway were significantly higher. Consistently, ischemia-induced caspase activity and neural cell apoptosis were suppressed approximately 70% in gad mice. These results demonstrate that UCH-L1 is involved in ubiquitin expression after stress stimuli, but excessive ubiquitin induction following ischemic injury may rather lead to neural cell apoptosis in vivo.     

XIdax, an inhibitor of the canonical Wnt pathway, is required for anterior neural structure formation in Xenopus.

Wnt signaling pathways are involved during various stages in the development of many species. In Xenopus, the accumulation of beta-catenin on the dorsal side of embryo is required for induction of the organizer, while the head structure formation requires inhibition of Wnt signaling. Here, we report a role for xIdax, a negative regulator of Wnt signaling. XIdax is expressed in neural tissues at the neurula stage, and in the restricted region of the tadpole brain. Ectopic expression of xIdax inhibits the target gene expression, suggesting that xIdax can inhibit canonical Wnt signaling. To examine the function of xIdax, a morpholino oligo for xIdax (xIdaxMO) was designed. An injection into an animal pole cell caused a loss of forebrain. The anterior neural marker expression is decreased in xIdaxMO-injected embryo, suggesting that xIdax is required for anterior neural development. Moreover, a negative regulator that acts downstream of xIdax rescued this defect. We propose that Idax functions are dependent on the canonical Wnt pathway and are crucial for the anterior neural development.     

Neutrophil and endothelial cell activation in the vasa vasorum in vasculo-Behçet disease

AIM: The aim of this study was to analyse the immunopathological mechanisms of vasculo-Beh?et disease, which were also compared to cases of Takayasu's arteritis and inflammatory aneurysm to evaluate differences in inflammatory mechanisms. METHOD AND RESULTS: We reviewed six cases of vasculo-Beh?et disease, four of Takayasu's arteritis and seven inflammatory aneurysms which underwent surgical repair. Immunohistochemical studies were performed on paraffin-embedded tissue using a labelled streptavidin-biotin method, as was in-situ hybridization for Epstein-Barr virus. Microscopically, neutrophils and lymphocytes accumulated around the vasa vasorum. Neutrophils were prominent as compared to Takayasu's arteritis and inflammatory aneurysm. Elastic fibres were not severely destroyed. Endothelial cells (ECs) of most vasa vasorum expressed HLA-DR. The number of vasa vasorum around which inflammatory infiltrating cells were observed in vasculo-Beh?et disease was significantly greater than in inflammatory aneurysms and Takayasu's arteritis (P < 0.001). The cytokines IL-1alpha, TNF-beta and IFN-gamma were expressed in neutrophils and lymphocytes which were distributed around vasa vasorum, as well as neutrophils adherent to HLA-DR positive ECs. CONCLUSION: Our results suggest that vasculo-Beh?et disease should be classified as a neutrophilic vasculitis targeting the vasa vasorum. Aneurysm formation may be related to degeneration of arterial wall caused by inflammation of the vasa vasorum.     

A new approach to spike sorting for multi-neuronal activities recorded with a tetrode--how ICA can be practical

Multi-neuronal recording with a tetrode is a powerful technique to reveal neuronal interactions in local circuits. However, it is difficult to detect precise spike timings among closely neighboring neurons because the spike waveforms of individual neurons overlap on the electrode when more than two neurons fire simultaneously. In addition, the spike waveforms of single neurons, especially in the presence of complex spikes, are often non-stationary. These problems limit the ability of ordinary spike sorting to sort multi-neuronal activities recorded using tetrodes into their single-neuron components. Though sorting with independent component analysis (ICA) can solve these problems, it has one serious limitation that the number of separated neurons must be less than the number of electrodes. Using a combination of ICA and the efficiency of ordinary spike sorting technique (k-means clustering), we developed an automatic procedure to solve the spike-overlapping and the non-stationarity problems with no limitation on the number of separated neurons. The results for the procedure applied to real multi-neuronal data demonstrated that some outliers which may be assigned to distinct clusters if ordinary spike-sorting methods were used can be identified as overlapping spikes, and that there are functional connections between a putative pyramidal neuron and its putative dendrite. These findings suggest that the combination of ICA and k-means clustering can provide insights into the precise nature of functional circuits among neurons, i.e. cell assemblies.     

NECROSIS OF PORTAL TUMOR EMBOLUS OF HEPATOCELLULAR CARCINOMA BY LIPIODOL TRANSCATHETER CHEMO-EMBOLIZATION. A Case Report

We describe a case of hepatocellular carcinoma in which a tumor embolus in the portal vein and 3 of 4 intrahepatic metastases were necrosed completely by Lipiodol transcatheter chemo-embolization (Lipiodol-TCE). Tumor emboli in the portal vein and intrahepatic metastases usually cannot be necrosed by conventional transcatheter chemo-embolization alone, because small nodules such as intrahepatic metastases and tumor emboli in the portal vein are supplied blood from the portal vein. However, in this case, Lipiodol-TCE was effective against tumor emboli in the portal vein and intrahepatic metastases. ACTA PATHOL JPN 38: 1363-1367, 1988.     

CARCINOID TUMOR OF THE MIDDLE EAR: An Immunohistochemical and Electron Microscopic Study Report of a Case

A primary tumor of the middle ear was examined histologically, histochemi-cally, immunohistochemically and ultrastructurally. Neuroendocrine cell differentiation, a carcinoid feature, was demonstrated by the presence of numerous argyrophil granules, as well as positive serotonin, glicentin, glucagon, and human pancreatic polypeptide (hPP) granules in some of the Grimelium-positive cells. Chromogranin A was also detected in the cells, but much less frequently than Grimelius-positive staining. Neither neuron-specific enolase (NSE) nor epithelial membrane antigen (EMA) was demonstrated in the tumor. Mucin was demonstrated only intraluminally. Electron microscopy revealed many typical neurosecretory granules in tumor cells, but no apical mucin granules. The tumor appeared to be benign, and there has been no sign of recurrence during a postoperative period of one year. ACTA PATHOL JPN38: 1453–1460, 1988.     

Hepatocellular carcinoma and myocardial sarcoidosis.--An autopsy case.

An autopsy case of a 65-year-old male who died of hepatocellular carcinoma superimposed on liver cirrhosis complicated with systemic sarcoidosis is presented. No organ metastasis of hepatocellular carcinoma was found except for a minute tumor embolus in the left upper lobe of the lung. Involved organs by sarcoidosis were the lymph nodes, lungs, heart, liver and spleen, but its presence was not noticed before death. Its cardiac involvement coincide with his clinical symptom of exertional dyspnea and the ECG finding of A-V block.     

Vascular endothelial growth factor acts as a pericyte mitogen under hypoxic conditions

Angiogenesis is the process by which new vascular networks are formed from preexisting capillaries. The small vessels are composed of two types of cells, namely endothelial cells (EC) and pericytes, with the former being encircled by the latter. We previously showed that hypoxia, the principal cause of angiogenesis, can induce the proliferation of pericytes as well as EC. In this report we present evidence that the hypoxic induction of pericyte growth can be ascribed at least in part to vascular endothelial growth factor (VEGF) produced by this very cell type. First, the finding that hypoxia can stimulate the proliferation of pericytes was confirmed by cultivating bovine retinal pericytes in a controlled-atmosphere culture chamber containing various concentrations of oxygen and then assaying pericyte synthesis of DNA. Second, Northern blot analysis revealed that pericyte levels of mRNA encoding VEGF increased as the atmospheric oxygen tension was decreased; this was accompanied by an increase in de novo synthesis of VEGF proteins. Third, pericytes were able to respond to exogenously added VEGF, resulting in a dose-dependent increase in viable cell numbers. Fourth, polyclonal antibodies against VEGF efficiently blocked the hypoxic induction of pericyte growth. Fifth, pericytes expressed the gene for fms-like tyrosine kinase 1 (flt1) as the predominant form of VEGF receptor, and tyrosine phosphorylation of this receptor protein was enhanced when pericytes were exposed to hypoxia, as it was when cells were exposed to VEGF. Sixth, the antisense DNA complement of flt1 mRNA abolished the hypoxia-induced stimulation of pericyte growth. Finally, exogenous VEGF stimulated the migration of pericytes in a dose-dependent manner. The results thus suggest that VEGF, which has been thought to be a specific mitogen for EC, also acts on neighboring pericytes, probably in both autocrine and paracrine manners, and that the hypoxia-induced overproduction of VEGF could promote not only EC sprouting but also the recruitment of pericytes, thereby contributing to the maturation of newly formed microvessels.