Rosiglitazone ameliorates tissue plasminogen activator-induced brain hemorrhage after stroke.

OBJECTIVE: Delayed thrombolytic therapy with recombinant tissue plasminogen activator (tPA) may exacerbate blood-brain barrier (BBB) breakdown after ischemic stroke and lead to catastrophic hemorrhagic transformation (HT). Rosiglitazone(RSG), a widely used antidiabetic drug that activates peroxisome proliferator-activated receptor-γ (PPAR-γ), has been shown to protect against cerebral ischemia through promoting poststroke microglial polarization toward the beneficial anti-inflammatory phenotype. However, whether RSG can alleviate HT after delayed tPA treatment remains unknown. In this study, we sort to examine the role of RSG on tPA-induced HT after stroke. METHODS AND RESULTS: We used the murine suture middle cerebral artery occlusion (MCAO) models of stroke followed by delayed administration of tPA (10 mg/kg, 2 hours after suture occlusion) to investigate the therapeutic potential of RSG against tPA-induced HT. When RSG(6 mg/kg) was intraperitoneally administered 1 hour before MCAO in tPA-treated MCAO mice, HT in the ischemic territory was significantly attenuated 1 day after stroke. In the tPA-treated MCAO mice, we found RSG significantly mitigated BBB disruption and hemorrhage development compared to tPA-alone-treated stroke mice. Using flow cytometry and immunostaining, we confirmed that the expression of CD206 was significantly upregulated while the expression of iNOS was down-regulated in microglia of the RSG-treated mice. We further found that the expression of Arg-1 was also upregulated in those tPA and RSG-treated stroke mice and the protection against tPA-induced HT and BBB disruption in these mice were abolished in the presence of PPAR-γ antagonist GW9662 (4 mg/kg, 1 hour before dMCAO through intraperitoneal injection). CONCLUSIONS: RSG treatment protects against BBB damage and ameliorates HT in delayed tPA-treated stroke mice by activating PPAR-γ and favoring microglial polarization toward anti-inflammatory phenotype.

IL-2mAb reduces demyelination after focal cerebral ischemia by suppressing CD8+ T cells.

AIMS: Demyelination, one of the major pathological changes of white matter injury, is closely related to T-cell-mediated immune responses. Thus, we investigate the role of an IL-2 monoclonal antibody (IL-2mAb, JES6-1) in combatting demyelination during the late phase of stroke. METHODS: IL-2mAb or IgG isotype antibody (0.25 mg/kg) was injected intraperitoneally 2 and 48 hours after middle cerebral artery occlusion (MCAO) surgery. Infarct volume, peripheral immune cell infiltration, microglia activation, and myelin loss were measured by 2,3,5-triphenyte trazoliumchloride staining, immunofluorescence staining, flow cytometry, and Western blot. Intraperitoneal CD8 neutralizing antibody (15 mg/kg) was injected 1 day before MCAO surgery to determine the role of CD8+ T cells on demyelinating lesions. RESULTS: IL-2mAb treatment reduced brain infarct volume, attenuated demyelination, and improved long-term sensorimotor functions up to 28 days after dMCAO. Brain infiltration of CD8+ T cells and peripheral activation of CD8+ T cells were both attenuated in IL-2 mAb-treated mice. The protection of IL-2mAb on demyelination was abolished in mice depleted of CD8+ T cell 1 week after stroke. CONCLUSIONS: IL-2mAb preserved white matter integrity and improved long-term sensorimotor functions following cerebral ischemic injury. The activation and brain infiltration of CD8+ T cells are detrimental for demyelination after stroke and may be the major target of IL-2mAb posttreatment in the protection of white matter integrity after stroke.

Increased Renal Clearance of Rocuronium Compensates for Chronic Loss of Bile Excretion, via upregulation of Oatp2.

Requirement for rocuronium upon surgery changes only minimally in patients with end-stage liver diseases. Our study consisted of both human and rat studies to explore the reason. The reduction rate of rocuronium infusion required to maintain neuromuscular blockade during the anhepatic phase (relative to paleohepatic phase) was examined in 16 children with congenital biliary atresia receiving orthotopic liver transplantation. Pharmacodynamics and pharmacokinetics of rocuronium were studied based on BDL rats. The role of increased Oatp2 and decrease Oatp1 expressions in renal compensation were explored. The reduction of rocuronium requirements significantly decreased in obstructively jaundiced children (24 ± 9 vs. 39 ± 11%). TOF50 in BDL rats was increased by functional removal of the kidneys but not the liver, and the percentage of rocuronium excretion through urine increased (20.3 ± 6.9 vs. 8.6 ± 1.8%), while that decreased through bile in 28d-BDL compared with control group. However, this enhanced renal secretion for rocuronium was eliminated by Oatp2 knock-down, rather than Oatp1 overexpression (28-d BDL vs. Oatp1-ShRNA or Oatp2-ShRNA, 20.3 ± 6.9 vs. 17.0 ± 6.6 or 9.3 ± 3.2%). Upon chronic/sub-chronic loss of bile excretion, rocuronium clearance via the kidneys is enhanced, by Oatp2 up-regulation.

Overexcited MaxiK and KATP channels underlie obstructive jaundice-induced vasoconstrictor hyporeactivity of arterial smooth muscle.

Substantial evidence has shown that obstructive jaundice can induce vascular hyporesponsiveness. The present study was designed to investigate mechanisms of MaxiK channel and KATP underlying cholestasis-induced vascular dysfunction. The isolated thoracic aorta was used to explore norepinephrine (NE)-induced contraction. The function of MaxiK and KATP channels were investigated using whole-cell patch clamp recording. Compared with Sham group, NE-induced vascular contraction was blunted after bile duct ligation (BDL), which could not be ameliorated significantly after endothelial denudation. Charybdotoxin and glibenclamide induced a more pronounced recovery from vascular hyporesponsiveness to NE in BDL group compared with Sham group. BDL significantly promoted the charybdotoxin sensitive MaxiK current and KATP current in isolated aortic smooth muscle cells. In addition, the expression of auxiliary subunits (MaxiK-ß1 and SUR2B) rather pore-forming subunits (MaxiK-α and Kir6.1) was significantly up-regulated after BDL. These findings suggest that MaxiK and KATP channels play an important role in regulating vascular hyporesponsiveness in BDL rats.

Increase of beta-amyloid and C-reactive protein in liver transplant recipients with postoperative cognitive dysfunction.

BACKGROUND: Postoperative cognitive dysfunction (POCD) is an adverse condition characterized by declined cognitive functions following surgeries and anesthesia. POCD has been associated with increased hospital stay and mortality. There are histological similarities to Alzheimer's disease. Most early studies were conducted in patients receiving cardiac surgery. Since there is no information about POCD in liver transplant recipients, we measured the incidence of POCD in patients after liver transplantation and examined the correlation between neurological dysfunction and biological markers of dementia-based diseases. METHODS: We studied 25 patients who had a liver transplan-tation between July 2008 and February 2009. Patients with prior encephalopathy or risk factors associated with the development of POCD were excluded from the study. Five validated neuropsychiatric tests were used for diagnosis. The diagnosis was based on one standard deviation decline in two of the five neuropsychiatric tests. The correlation between patient variables and the development of POCD was examined. Serum levels of beta-amyloid and C-reactive protein were measured by standard ELISA and compared between patients with and without POCD. RESULTS: POCD was present in 11 (44%) of the 25 patients. Patients with POCD had significantly higher MELD scores, were more often Child-Pugh class C and received more blood transfusion during surgery. The serum beta-amyloid protein and C-reactive protein concentrations were significantly increased at 24 hours after surgery in the POCD group. CONCLUSIONS: The incidence of POCD in our group of liver transplant patients was greater than that reported in other surgical patients. The increase in the serum biomarkers of dementia in the POCD patients supports the hypothesis that chronic cognitive defects are due to a process similar to that seen in Alzheimer's disease.

Hippocampus bcl-2 and bax expression and neuronal apoptosis after moderate hypothermic cardiopulmonary bypass in rats.

Using a rat model of moderate hypothermic (26 degrees C-28 degrees C) cardiopulmonary bypass (CPB) with hemodilution, we investigated hippocampal apoptotic gene expression and neuronal apoptosis up to 6 h after CPB. The CPB was performed on male rats (380-400 g) under general anesthesia with isoflurane and fentanyl. The right atrium and tail artery were cannulated, and a peristaltic pump and membrane oxygenator were used for CPB. Two groups were studied: Group 1 consisted of fasted rats (n = 15) subjected to 60 min of moderate hypothermic nonpulsatile CPB; Group 2 consisted of sham-operated rats (n = 15). At 1 h after CPB, in 6 rats per group, hippocampus was processed for the apoptotic gene (bcl-2 and bax) messenger RNAs detection by reverse transcriptase polymerase chain reaction, and messenger RNA expression was determined by the ratio of the polymerase chain reaction product of bcl-2 or bax to the beta-actin gene. At 6 h after CPB, in 6 rats per group, hippocampus expression of Bcl-2 and bax protein was determined by immunohistochemistry, and neuronal apoptosis was detected by TUNEL. At 6 h after CPB, in three rats per group, changes in hippocampal CA1 neuronal ultra structure were determined with electron microscopy. Group 1 had increased ratios of bcl-2/beta-actin, bax/beta-actin, and bax/bcl-2 mRNA at 1 h after CPB (bcl-2/beta-actin, 0.82 +/- 0.14 versus 0.63 +/- 0.07; P = 0.03; bax/beta-actin, 1.04 +/- 0.14 versus 0.56 +/- 0.03; P = 0.00; bax/bcl-2, 1.31 +/- 0.12 versus 0.84 +/- 0.09; P = 0.02; Group 1 versus Group 2, respectively). Group 1 had increased bcl-2 and bax protein expression in hippocampal CA1 region at 6 h after CPB (bcl-2, 0.18 +/- 0.05 versus 0.09 +/- 0.01; P = 0.02; bax, 0.20 +/- 0.06 versus 0.04 +/- 0.02; P = 0.01; Group 1 versus Group 2, respectively). Group 1 had increased TUNEL staining in hippocampus CA1 at 6 h after CPB (0.14 +/- 0.02 versus 0.03 +/- 0.01; P = 0.00; Group 1 versus Group 2, respectively). In Group 1 CA1 hippocampus neurons, ultra-structural changes consistent with apoptosis occurred. In rats, moderate hypothermic CPB with hemodilution is associated with CA1 hippocampus bax and bcl-2 gene expression and neuronal apoptosis during the early post-CPB recovery period.