Up-regulation of TNF-α convertase (TACE/ADAM17) after oxygen–glucose deprivation in rat forebrain slices

Tumour necrosis factor-α (TNF-α) is a major immunomodulatory and proinflammatory cytokine which is shed in its soluble form by a membrane-anchored zinc protease, identified as a disintegrin and metalloproteinase (ADAM) called TNF-α convertase (TACE; ADAM17). The role of this protease in the adult nervous system remains poorly understood. During cerebral ischemia and subsequent reperfusion, expression and release of TNF-α have been shown. We have investigated the expression and activity of TACE in an in vitro model of brain ischemia consisting of rat forebrain slices exposed to oxygen–glucose deprivation (OGD). OGD caused the release of TNF-α, an effect which was inhibited by a hydroxamate-based metalloprotease inhibitor, BB-3103, with an IC₅₀ of 0.1 μM, suggesting that TNF-α release results selectively from TACE activity. Assay of TACE enzymatic activity on a fluorescein-labelled peptide spanning the cleavage site in pro-TNF-α, as well as Western blot and RT–PCR analyses showed that TACE is present in control forebrain and, more interestingly, that TACE expression is increased in OGD-exposed tissue. TACE enzymatic activity from OGD-exposed slices was significantly inhibited by cycloheximide, suggesting that de novo synthesis of TACE contributes to TNF-α release after ischaemia. Moreover, it was also inhibited by bisindolylmaleimide I, indicating that TACE activity is regulated by PKC. These findings posed the question of what was its function therein. Among other actions, TNF-α has been described to be involved in the expression of inducible nitric oxide synthase (iNOS), a high-output NOS isoform associated to cellular damage, but the link between TNF-α release after brain ischaemia and iNOS expression in this condition has not been shown. We have now found that iNOS expression in OGD-subjected brain slices is inhibited by BB-3103 at concentrations below 1 μM, indicating that shedding of TNF-α by TACE plays a necessary part in the induction of this NOS isoenzyme after OGD. Taken together, these data demonstrate that (1) TACE/ADAM17 activity accounts for the majority of TNF-α shedding after OGD in rat forebrain slices, (2) an increase in TACE expression contributes, at least in part, to the rise in TNF-α after OGD and (3) iNOS expression in OGD-subjected brain slices results from TACE activity and subsequent increase in TNF-α levels.     

COX-2 in liver,from regeneration to hepatocarcinogenesis: What we have learned from animal models?

The use of animals lacking genes or expressing genes under the control of cell-specific promoters has signifi cantly increased our knowledge of the genetic and molecular basis of physiopathology,allowing testing of functional hypotheses and validation of biochemical and pharmacologic approaches in order to understand cell function.However,with unexpected frequency,gene knockout animals and,more commonly,animal models of transgenesis give experimental support to even opposite conclusions on gene function.Her...     

H-Ras-specific activation of NF-kappaB protects NIH 3T3 cells against stimulus-dependent apoptosis

Ras signaling involves the activation of several downstream pathways that exhibit isoform specificity. In this study, the basal and tumor necrosis factor alpha (TNFalpha)-induced activation of NF-kappaB has been examined in cells overexpressing H-Ras, K-Ras or N-Ras. Cells expressing H-Ras exhibited a basal kappaB activity that correlated with sustained IkappaB kinase activation and lower steady-state levels of IkappaBalpha in the cytosol. Upon activation with TNFalpha, the cells expressing the distinct Ras isoforms behaved similarly in terms of binding of nuclear proteins to a kappaB sequence and induction of a kappaB-dependent reporter gene. The basal activation of NF-kappaB in cells expressing H-Ras impaired staurosporine-induced apoptosis in these cells, through a mechanism that was NF-kappaB-dependent and inhibitable in the presence of z-VAD. Moreover, titration of caspase activation in response to staurosporine showed a significant resistance in cells expressing H-Ras when compared with the void vector or the N-Ras counterparts. These results indicate that the distinct Ras proteins have specific effects on the NF-kappaB pathway and that this action contributes to protect cells against apoptosis.     

Invasive aspergillosis treated with adjunctive hyperbaric oxygenation: a retrospective clinical series at a single institution

BACKGROUND: Invasive aspergillosis is the leading cause of early death in many transplant centers and has a major impact on the management of hematologic malignancies. The mortality rate with current therapy (amphotericin B and surgery) has remained unacceptably high. In vitro data along with a few case reports have suggested a potential benefit of hyperbaric oxygen (HBO). METHODS: We retrospectively studied all patients referred to our service when histologic specimens suggested invasive aspergillosis. Our main assessment of outcome was survival 3 months after initiation of HBO. RESULTS: Ten patients were included. All received adjunctive HBO along with the standard of care. Rhinosinusinal infection was the primary presentation. The most common underlying conditions were hematologic malignancies. Six patients were free of signs of infection 3 months after the first HBO treatment. CONCLUSIONS: Adjunctive HBO appears to be a valuable tool in this devastating condition. Further studies are warranted to clarify its role.     

SWCNT–porphyrin nano-hybrids selectively activated by ultrasound: an interesting model for sonodynamic applications

Sonodynamic therapy (SDT) is an innovative anticancer approach, based on the excitation of a given molecule (usually a porphyrin) by inertial acoustic cavitation that leads to cell death via the production of reactive oxygen species (ROS). This study aims to prepare and characterize nanosystems based on porphyrin grafted carbon nanotubes (SWCNTs), to understand some aspects of the mechanisms behind the SDT phenomenon. Three different porphyrins have been covalently linked to SWCNTs using either Diels–Alder or 1,3-dipolar cycloadditions. ROS production and cell viability have been evaluated upon ultrasound irradiation. Despite the low porphyrin content linked on the SWCNT, these systems have shown high ROS production and high tumour-cell-killing ability. The existence of a PET (photoinduced electron transfer)-like process would appear to be able to explain these observations. Moreover, the demonstrated ability to absorb light limits the impact of side effects due to light-excitation.

Sonodynamic therapy (SDT) is an innovative anticancer approach, based on the excitation of a given molecule (usually a porphyrin) by inertial acoustic cavitation that leads to cell death via the production of reactive oxygen species (ROS).     

Simultaneous complete supraaortic debranching and thoracic aortic endografting in an angiography suite setting

This case series reports an initial experience in three patients treated with simultaneous complete supraaortic debranching and thoracic aortic endografting in an angiography suite setting. The article focuses on logistics and structural considerations of the setting. This includes size and equipment of the angiography suite, extent and supply of conventional surgical instruments, and safety considerations. The clinical outcome of the patients is reported. This limited experience shows that simultaneous aortic arch hybrid procedures can be performed in an angiography suite setting, given the structural and logistic requirements described.