Receptor interacting protein kinases mediate retinal detachment-induced photoreceptor necrosis and compensate for inhibition of apoptosis

Apoptosis has been shown to be a significant form of cell loss in many diseases. Detachment of photoreceptors from the retinal pigment epithelium, as seen in various retinal disorders, causes photoreceptor loss and subsequent vision decline. Although caspase-dependent apoptotic pathways are activated after retinal detachment, caspase inhibition by the pan-caspase inhibitor Z-VAD fails to prevent photoreceptor death; thus, we investigated other pathways leading to cell loss. Here, we show that receptor interacting protein (RIP) kinase-mediated necrosis is a significant mode of photoreceptor cell loss in an experimental model of retinal detachment and when caspases are inhibited, RIP-mediated necrosis becomes the predominant form of death. RIP3 expression, a key activator of RIP1 kinase, increased more than 10-fold after retinal detachment. Morphological assessment of detached retinas treated with Z-VAD showed decreased apoptosis but significantly increased necrotic photoreceptor death. RIP1 kinase inhibitor necrostatin-1 or Rip3 deficiency substantially prevented those necrotic changes and reduced oxidative stress and mitochondrial release of apoptosis-inducing factor. Thus, RIP kinase-mediated programmed necrosis is a redundant mechanism of photoreceptor death in addition to apoptosis, and simultaneous inhibition of RIP kinases and caspases is essential for effective neuroprotection and may be a novel therapeutic strategy for treatment of retinal disorders.     

Transplants of encapsulated rat choroid plexus cells exert neuroprotection in a rodent model of Huntington's disease

Choroid plexus (CP) epithelial cells secrete several neurotrophic factors and have been used in transplantation studies designed to impart neuroprotection against central nervous system (CNS) trauma. In the present study, CP was isolated from adult rats, encapsulated within alginate microcapsules, and transplanted unilaterally into the rat striatum. Three days later, unilateral injections of quinolinic acid (QA; 225 nmol) were made into the ipsilateral striatum to mimic the pathology observed in Huntington's disease (HD). After surgery, animals were tested for motor function using the placement test. Rats receiving CP transplants were significantly less impaired on this test. Nissl-stained sections demonstrated that CP transplants significantly reduced the volume of the striatal lesion produced by QA. Quantitative analysis of striatal neurons further demonstrated that choline acetyltransferase-immunoreactive, but not diaphorase-positive, neurons were protected by CP transplants. These data demonstrate that transplanted CP cells can be used to protect striatal neurons from excitotoxic damage and that the pattern of neuroprotection varies across specific neuronal populations.     

Evidence-Based Choice of Esophageal Stent for the Palliative Management of Malignant Dysphagia

BACKGROUND: The type of stent used for the management of patients with malignant dysphagia is chosen according to subjective physician's preference. There is no recent study available to provide updated evidence on early outcomes related to the use of different types of stents. METHODS: A literature search was performed using Embase, MEDLINE, Cochrane Library, and Google Scholar databases for comparative studies assessing different types of stents. The primary end point was stent-related mortality; secondary end points included: stent-related morbidity, successful palliation of dysphagia, and 30-day mortality. A random-effects model was used and heterogeneity was assessed. RESULTS: Twelve studies that included 911 patients compared metallic (46.54%) and plastic stents (53.45%), and eight studies that included 564 patients compared covered (43.26%) and uncovered metal stents (56.73%). Meta-analysis of randomized, controlled trials showed that metallic stents were associated with significantly reduced stent-related mortality (1.7% vs. 11.1% for the plastic group, odds ratio (OR), 0.2; 95% confidence interval (CI), 0.06-0.74; P = 0.02), morbidity in the form of reduced esophageal perforation (1.4% vs. 9.4% for plastic stent, OR, 0.27; 95% CI, 0.08-0.89; P = 0.03), and stent migration, yet increased rate of tumor in-growth (13% vs. 1.6% for plastic stents, OR, 4.84; 95% CI, 0.99-23.76; P = 0.05). Covered metallic stents had significantly less tumor in-growth than the uncovered and an increased migration rate. There was no significant difference between metallic and plastic stents in terms of any other stent-related morbidity and 30-day mortality. CONCLUSION: Self-expanding metallic stents are superior to plastic stents in terms of stent insertion-related mortality, morbidity, and quality of palliation. The uncovered variety is disadvantaged by high rate of tumor in-growth; adequately designed randomized, controlled trials need to examine outcomes and cost-effectiveness of covered versus uncovered metallic stents.     

Deregulated overexpression of hCdt1 and hCdc6 promotes malignant behavior

The accurate execution of DNA replication requires a strict control of the replication licensing factors hCdt1 and hCdc6. The role of these key replication molecules in carcinogenesis has not been clarified. To examine how early during cancer development deregulation of these factors occurs, we investigated their status in epithelial lesions covering progressive stages of hyperplasia, dysplasia, and full malignancy, mostly from the same patients. Abnormal accumulation of both proteins occurred early from the stage of dysplasia. A frequent cause of unregulated hCdc6 and hCdt1 expression was gene amplification, suggesting that these components can play a role per se in cancer development. Overexpression of hCdt1 and hCdc6 promoted rereplication and generated a DNA damage response, which activated the antitumor barriers of senescence and apoptosis. Generating an inducible hCdt1 cellular system, we observed that continuous stimulus by deregulated hCdt1 led to abrogation of the antitumor barriers and resulted in the selection of clones with more aggressive properties. In addition, stable expression of hCdc6 and hCdt1 in premalignant papilloma cells led to transformation of the cells that produced tumors upon injection into nude mice depicting the oncogenic potential of their deregulation.     

Recertification: What do specialists think about skill assessment?

BackgroundContinuing medical education and objective performance assessment remain the key components of recertification. Objective skills assessment in routine practice remains challenging due to extensive variations in case selection and treatments. This study explores expert opinions regarding objective skills assessment for specialists within the framework of recertification.MethodsWe used a qualitative, semi-structured interview-based approach to obtain information and suggestions about key issues and recommendations relating to specialists' skills assessment. Twenty-two face-to-face interviews were conducted. Interviews were transcribed and analysed by two reviewers.ResultsThe information from the interviews was categorized under the headings of: (1) the components of specialist-level skills, (2) the methods for assessing specialist skills, (3) the types of tools and procedures used during observational assessment, (4) the unsuccessful specialists, and (5) the selection and training of assessors for specialist assessment.ConclusionsOutcome-based assessment of performance followed by observation of practice, were recommended as effective modes of evaluation of performance.     

Monoclonal antibody HMB-45 in diagnosis of intra-ocular melanoma]

69 eyes, which had to be enucleated because of an uveal melanoma, were investigated immunohistologically. HMB-45-antigen, which is supposed to be highly specific for melanocytic tumours, was found in 68 cases (sensitivity 99%) with a monoclonal antibody. S 100-antigen was positive in 63 cases (sensitivity 91%) using a polyclonal antibody. The addition of HMB-45-immunohistochemistry to routine histological diagnostic procedures is valuable, when a non-melanocytic uveal tumour cannot be ruled out or when the degree of melanoma-invasion has to be determined with greater accuracy. At the site of melanoma-invasion changes of cellular reactivity seem to occur, as 11 of the 69 studied tumours (16%) showed an increased HMB-45-expression in this area. HMB-45-antigen was detectable even in paraffin embedded material obtained from eyes enucleated 30 years ago.     

Effect of bilateral tectum lesions on retinal ganglion cell morphology in rats.

We have examined morphological changes of retinal ganglion cells (RGCs) during postnatal development in albino rats. Somatic diameter, dendritic field diameter, and branching frequencies of RGCs of normal rats were compared with those of animals that had received bilateral lesions of the tectum immediately after birth. Bilateral lesions of the tectum at P1 (first postnatal day) induced a dramatic increase in RGC death during the time of naturally occurring cell death in the first postnatal week. RGC densities in adult experimental animals were found to be reduced to about 55% of normal. RGCs of normal and operated animals were retrogradely stained with crystals of the fluorescent dye DiI, which was applied to the optic disc of flat mounted and fixed retinae. In normal rats, the somatic and the dendritic field diameters of the RGCs increased and the branching frequency of type I and III RGCs decreased from P1 to P14. By P14, neither the somatic diameter nor the dendritic field size had yet reached adult values and the branching frequencies were still higher than those of adult rat RGCs. In animals with bilateral lesions of the tectum, all cell types showed an increase in somatic sizes, and in type I and II RGCs an expansion of dendritic territories could be observed. The branching frequencies, however, were significantly lower than those of normal rats of the same age. The dendritic morphology in type III RGCs in operated animals was not significantly different from controls. These findings demonstrate a potential plasticity of type I and II RGCs, which respond to a loss of neighbouring cells by expansion of their dendritic field during postnatal development.