Encephalopathy associated with autoimmune thyroid disease in patients with Graves' disease: clinical manifestations, follow-up, and outcomes.

BACKGROUND: The encephalopathy associated with autoimmune thyroid disease (EAATD) is characterized by neurological/psychiatric symptoms, high levels of anti-thyroid antibodies, increased cerebrospinal fluid protein concentration, non-specific electroencephalogram abnormalities, and responsiveness to the corticosteroid treatment in patients with an autoimmune thyroid disease. Almost all EAATD patients are affected by Hashimoto's thyroiditis (HT), although fourteen EAATD patients with Graves' disease (GD) have been also reported. METHODS: We have recorded and analyzed the clinical, biological, radiological, and electrophysiological findings and the data on the therapeutic management of all GD patients with EAATD reported so far as well as the clinical outcomes in those followed-up in the long term. RESULTS: Twelve of the fourteen patients with EAATD and GD were women. The majority of GD patients with EAATD presented with mild hyperthyroidism at EAATD onset or shortly before it. Active anti-thyroid autoimmunity was detected in all cases. Most of the patients dramatically responded to corticosteroids. The long term clinical outcome was benign but EAATD can relapse, especially at the time of corticosteroid dose tapering or withdrawal. GD and HT patients with EAATD present with a similar clinical, biological, radiological, and electrophysiological picture and require an unaffected EAATD management. CONCLUSIONS: GD and HT equally represent the possible background condition for the development of EAATD, which should be considered in the differential diagnosis of all patients with encephalopathy of unknown origin and an autoimmune thyroid disease, regardless of the nature of the underlying autoimmune thyroid disease.

The role of MMP-9 in integrin-mediated hippocampal cell death after pilocarpine-induced status epilepticus.

Recent studies demonstrate that matrix metalloproteinase-9 (MMP-9) is closely involved in the pathogenesis of epilepsy. This study investigated the role of MMP-9 in hippocampal cell death after pilocarpine-induced status epilepticus (SE). We showed that MMP-9 expression and activity significantly increased and beta1-integrin levels decreased on day 3 after SE. beta1-integrin degradation was also observed in hippocampal ex vivo extracts incubated with recombinant active MMP-9. Treatment with a selective MMP-9 inhibitor attenuated MMP-9 up-regulation, beta1-integrin degradation, the reduction of ILK activity and Akt phosphorylation, and subsequent hippocampal damage after SE. However, co-treatment with anti-beta1-integrin antibody almost completely blocked the protective effects of the MMP-9 inhibitor on both integrin-mediated survival signaling and hippocampal cell death. Our study demonstrates that MMP-9 induces apoptotic hippocampal cell death by interrupting integrin-mediated survival signaling after SE and suggests that MMP-9 may be a promising target for a neuroprotective approach to preventing seizure-induced hippocampal damage.

Induction of apoptosis signal-regulating kinase 1 and oxidative stress mediate age-dependent vulnerability to 3-nitropropionic acid in the mouse striatum.

The mitochondrial toxin, 3-nitropropionic acid (3-NP), produces age-dependent oxidative stress and selective striatal damage, which may simulate Huntington's disease starting in middle age. Recent reports showed that apoptosis signal-regulating kinase 1 (Ask1) activated by oxidative stress triggers a cell death signaling pathway. 3-NP was injected to the striatum in C57BL/6J mice. We have confirmed that striatal lesion volume and DNA fragmentation were age-dependent after 3-NP treatment. In the non-injured striatum of the middle-aged group, the protein levels of Ask1 and its active form, phosphorylated Ask1 (pAsk1), were significantly higher than in the young group. Ask1 increased more in the 3-NP injured striatum of the middle-aged group than in the non-injured striatum, and subsequently the activity of pAsk1 was significantly higher than in the young group. However, middle-aged SOD1Tg mice showed significant reductions of Ask1 and pAsk1 in the injured and the non-injured striatum compared to the middle-aged group. In particular, apoptosis signal transduction and cell death were significantly inhibited by the reduction of Ask1 expression using siRNA. Present results suggest that age-related upregulation of Ask1 and oxidative stress may mediate age-dependent striatal vulnerability to 3-NP.

Metalloporphyrin-based superoxide dismutase mimic attenuates the nuclear translocation of apoptosis-inducing factor and the subsequent DNA fragmentation after permanent focal cerebral ischemia in mice.

BACKGROUND AND PURPOSE: Recently, apoptosis- inducing factor (AIF), a mitochondrial proapoptotic protein, and its nuclear translocation have been reported in caspase-independent neuronal apoptosis. In this study, we investigated the contribution of reactive oxygen species (ROS) to the nuclear translocation of AIF and the subsequent DNA fragmentation after permanent focal cerebral ischemia (pFCI) using manganese tetrakis (4-benzoic acid) porphyrin (MnTBAP), which mimics mitochondrial superoxide dismutase. METHOD: Adult male ICR mice were subjected to pFCI by intraluminal suture blockade of the middle cerebral artery. Immunohistochemistry and Western blot analysis were performed. Large-scale DNA fragmentation was evaluated by pulse field gel electrophoresis, and apoptotic cell death was quantified. MnTBAP was injected into the ventricle to determine whether the removal of ROS contributes to AIF translocation and the subsequent DNA fragmentation. RESULTS: Western blot analysis showed that the nuclear translocation of AIF occurred as early as 2 hours after pFCI. AIF translocation was not blocked by a pan-caspase inhibitor. MnTBAP-treated mice had attenuated AIF translocation and blocked large-scale DNA fragmentation. Caspase-3 activity was similarly inhibited between the pan-caspase inhibitor- and MnTBAP-treated mice, but the amount of apoptosis-associated DNA fragmentation in the MnTBAP-treated mice was less than in the pan-caspase inhibitor-treated mice (P<0.001). CONCLUSIONS: These results suggest that the MnTBAP, a mitochondrial O2- scavenger, may attenuate the caspase-independent nuclear translocation of AIF after pFCI and subsequent apoptosis-associated DNA fragmentation.

Early nuclear translocation of endonuclease G and subsequent DNA fragmentation after transient focal cerebral ischemia in mice.

We investigated whether the endonuclease G (endoG) translocated from mitochondria to nucleus after transient focal cerebral ischemia (tFCI), thereby contributed to subsequent DNA fragmentation. Adult male mice were subjected to 60min of focal cerebral ischemia by intraluminal suture blockade of the middle cerebral artery. Western blot analysis for endoG was performed at various time points of tFCI. Nuclear endoG was detected as early as 4h after tFCI in the ischemic brain, and correspondingly mitochondrial endoG showed a significant reduction at 4h after reperfusion (p<0.01). Immunohistochemistry of endoG confirmed that the nuclear translocation of endoG was detected as early as 4h after tFCI in the middle cerebral artery (MCA) territory of the ischemic brain. Double immunofluorescent staining with endoG and AIF showed that endoG was predominantly colocalized with AIF at 24h after tFCI. Double staining with endoG immunohistochemistry and TdT-mediated dUTP-biotin nick end labeling showed a spatial relationship between endoG expression and DNA fragmentation at 24h after tFCI. These data suggest that the early nuclear translocation of endoG occurs and could induce DNA fragmentation in the ischemic brain after tFCI.

Post-ischemic administration of peptide with apurinic/apyrimidinic endonuclease activity inhibits induction of cell death after focal cerebral ischemia/reperfusion in mice.

Previous scientific research has elucidated the correlation between changes in levels of the DNA base excision repair protein, apurinic/apyrimidinic endonuclease/redox factor-1 (APE/Ref-1), and ischemic neuronal DNA damage. However, to date, no studies have addressed the question of whether treatment involving this protein's repair function may prevent ischemic neuron death in vivo. Therefore, we aimed to investigate whether treatment with APE peptide is sufficient to prevent neuron death after ischemia/reperfusion (I/R) in mice. Mice were subjected to intraluminal suture occlusion of the middle cerebral artery for 1h followed by reperfusion. Post-ischemic treatment with the peptide containing only the APE repair functional domain was introduced intracerebroventricularly. Endonuclease activity assay and immunohistochemistry were performed. Assays of apurinic/apyrimidinic (AP) sites, single-strand DNA breaks, caspase-3 activity, and cell death were examined and quantified. We found that post-ischemic administration of the APE peptide up to 4h after reperfusion significantly inhibited the induction of cell death and subsequent infarct volume, measured 24h after I/R.

Electrical conductivity imaging by magnetic resonance electrical impedance tomography (MREIT).

Magnetic resonance electrical impedance tomography (MREIT) is a recently developed imaging technique that combines MRI and electrical impedance tomography (EIT). In MREIT, cross-sectional electrical conductivity images are reconstructed from the internal magnetic field density data produced inside an electrically conducting subject when an electrical current is injected into the subject. In this work the results of an electrical conductivity imaging experiment are presented, along with some practical considerations regarding MREIT. The MREIT experiment was performed with a 0.3 Tesla MRI system on a phantom made of two compartments with different electrical conductivities. The current density inside the phantom was measured by the MR current density imaging (MRCDI) technique. The measured current density was then used for conductivity image reconstruction by the J-substitution algorithm. The conductivity phantom images obtained with an injection current of 28mA showed conductivity errors of about 25.5%.

Magnetic resonance electrical impedance tomography at 3 Tesla field strength.

Magnetic resonance electrical impedance tomography (MREIT) is a recently developed imaging technique that combines MRI and electrical impedance tomography (EIT). In MREIT, cross-sectional electrical conductivity images are reconstructed from the internal magnetic field density data produced inside an electrically conducting object when an electrical current is injected into the object. In this work we present the results of electrical conductivity imaging experiments, and performance evaluations of MREIT in terms of noise characteristics and spatial resolution. The MREIT experiment was performed with a 3.0 Tesla MRI system on a phantom with an inhomogeneous conductivity distribution. We reconstructed the conductivity images in a 128 x 128 matrix format by applying the harmonic B(z) algorithm to the z-component of the internal magnetic field density data. Since the harmonic B(z) algorithm uses only a single component of the internal magnetic field data, it was not necessary to rotate the object in the MRI scan. The root mean squared (RMS) errors of the reconstructed images were between 11% and 35% when the injection current was 24 mA.