Shih-Huang Tai

Melatonin inhibits postischemic matrix metalloproteinase-9 (MMP-9) activation via dual modulation of plasminogen/plasmin system and endogenous MMP inhibitor in mice subjected to transient focal cerebral ischemia

Abstract:  We have shown that melatonin attenuated matrix metalloproteinase‐9 (MMP‐9) activation and decreased the risk of hemorrhagic transformation following cerebral ischemia‐reperfusion. Herein, we investigate the possible involvement of the plasminogen/plasmin system and endogenous MMPs inhibitor underlying the melatonin‐mediated MMP‐9 inhibition. Mice were subjected to 1‐hr ischemia and 48‐hr reperfusion of the right middle cerebral artery. Melatonin (5 mg/kg) or vehicle was intravenously injected upon reperfusion. Brain infarction and hemorrhagic transformation were measured. Extracellular matrix damage was determined by Western immunoblot analysis for laminin protein. The activity and expression of MMP‐2 and MMP‐9 were determined by gelatin zymography, in situ zymography, and Western immunoblot analysis. In addition, the activities of tissue and urokinase plasminogen activators (tPA and uPA) were evaluated by plasminogen‐dependent casein zymography. Endogenous plasminogen activator inhibitor (PAI) and tissue inhibitors of MMP (TIMP‐1) were investigated using enzyme‐linked immunosorbent assay (ELISA) and Western immunoblot analysis, respectively. Cerebral ischemia‐reperfusion induced increased MMP‐9 activity and expression at 12–48 hr after reperfusion onset. Relative to controls, melatonin‐treated animals had significantly decreased MMP‐9 activity and expression (P < 0.05), in addition to reduced brain infarction and hemorrhagic transformation as well as improved laminin protein preservation. This melatonin‐mediated MMP‐9 inhibition was accompanied by reduced uPA activity (P < 0.05), as well as increased TIMP‐1 expression and PAI activity (P < 0.05, respectively). These results demonstrate the melatonin’s pluripotent mechanisms for attenuating postischemic MMP‐9 activation and neurovascular damage, and further support it as an add‐on to thrombolytic therapy for ischemic stroke patients.

Melatonin protects against transient focal cerebral ischemia in both reproductively active and estrogen-deficient female rats: the impact of circulating estrogen on its hormetic dose-response.

Abstract:  Melatonin (5–15 mg/kg) protects male animals against ischemic stroke. We explored the potential interactions and synergistic neuroprotection of melatonin and estrogen using a panel of lipid peroxidation and radical‐scavenging assays, primary neuronal cultures subjected to oxygen–glucose deprivation (OGD), and lipopolysaccharide (LPS)‐stimulated RAW 264.7 cells. Neuroprotective efficacy of melatonin was also evaluated in both reproductively active and ovariectomized female rats subjected to transient focal cerebral ischemia. Relative to melatonin or estradiol (E2) alone, a combination of the two agents exhibited robust, synergistic antioxidant and radical‐scavenging actions (P < 0.05, respectively). Additionally, the two agents, when combined at large doses, showed synergistic inhibition in the production of tumor necrosis factor alpha (TNF‐α) and interleukin‐6 (IL‐6) in the LPS‐stimulated RAW 264.7 cells (P < 0.05, respectively). Alternatively, co‐treatment with melatonin and E2 independently, but not combined, showed a U‐shaped dose‐responsive (hormetic) cytoprotection for neuronal cultures subjected to OGD. When combined at a dosage either positively or negatively skewed from each optimal dosage, however, co‐treatment caused synergistic neuroprotection. Relative to vehicle‐injected controls, melatonin given intravenously at 1–5 mg/kg, but not 0.1 or 15 mg/kg, significantly reduced brain infarction and improved neurobehavioral outcomes (P < 0.05, respectively) in reproductively active female rats. In ovariectomized stroke rats, melatonin was only effective at a large dosage (15–50 mg/kg). These results demonstrate complex interactions and synergistic antioxidant, radical‐scavenging, and anti‐inflammatory actions between estradiol and melatonin, and highlight the potential need to rectify the melatonin’s hormetic dose–response by the level of circulating estradiol in the treatment of female stroke patients.

Optimal Percoll concentration facilitates flow cytometric analysis for annexin V/propidium iodine‐stained ischemic brain tissues

We sought to determine the optimal Percoll concentration for ischemic rat brain prepared for flow cytometric (FC) measurements. Animals were subjected to the right middle cerebral artery (MCA) occlusion, and were euthanized at 3, 12, 24, and 72 h after reperfusion onset. The brains were processed by different concentrations (unisolated, 20, 25, 30, or 40%) of Percoll and stained with annexin V/propidium iodine (PI). Ischemic brain damage was evaluated by FC analysis and image analysis for histologic sections. The relative susceptibility of different phenotypes of cells to necrotic and apoptotic damage were evaluated by the FC analyses for the immunohistochemistry, PI, and the terminal deoxynucleotidyl transferase‐mediated deoxyuridine triphosphate nick‐end labeling (TUNEL)‐processed brain tissues. Our results showed that FC analysis effectively detected the extent and maturation of apoptotic/necrotic brain damage, and the results were consistent with those determined from histologic brain sections. Neuron was more vulnerable to apoptosis than glia, whereas both cellular phenotypes were compatible in susceptibility for necrotic cell death. Percoll at a low concentration (20%) could effectively remove tissue debris without affecting membranous integrity of the injured neurons. Conversely, high percentages of Percoll (30–40%) substantially increased membranous damage for the injured cells. These results supported the application of FC to determine the extent and progression in time, as well as relative phenotypes of apoptotic/necrotic cell deaths following ischemic damage. We highlighted the use of Percoll at low percentages to facilitate the removal of tissue debris and to improve membrane integrity preservation for the injured neurons.

Cinnamophilin offers prolonged neuroprotection against gray and white matter damage and improves functional and electrophysiological outcomes after transient focal cerebral ischemia

Objective:We have previously shown that cinnamophilin ([8R, 8′S]-4, 4′-dihydroxy-3, 3′-dimethoxy-7-oxo-8, 8′-neolignan) exhibited potent antioxidant, radical-scavenging, and anti-inflammatory actions and reduced acute ischemic brain damage, even when it was given up to 6 hrs postinsult. Here, we characterized the long-lasting neuroprotection of cinnamophilin against gray and white matter damage and its beneficial effects on electrophysiological and functional outcomes in a model of stroke. Design:Prospective laboratory animal study. Setting:Research laboratory in a university teaching hospital. Subjects:Adult male Sprague-Dawley rats (240–290 g). Interventions:Under controlled conditions of normoxia, normocarbia, and normothermia, spontaneously breathing, halothane-anesthetized (1.0–1.5%) rats were subjected to transient middle cerebral artery occlusion for 90 mins. Cinnamophilin (80 mg/kg) or vehicle was given intravenously at reperfusion onset. Measurements and Main Results:Physiological parameters, including arterial blood gases and cortical blood perfusion, somatosensory-evoked potentials, and neurobehavioral outcomes, were serially examined. Animals were euthanized at 7 days or 21 days postinsult. Gray matter and white matter (axonal and myelin) damage were then evaluated by quantitative histopathology and immunohistochemistry against phosphorylated component-H neurofilaments and myelin basic protein, respectively. After the follow-up period of 7 and 21 days, our results showed that cinnamophilin significantly decreased gray matter damage by 31.6% and 34.9% (p < .05, respectively) without notable adverse effects. Additionally, cinnamophilin effectively reduced axonal and myelin damage by 46.3–68.6% (p < .05) and 25.2–28.1% (p < .05), respectively. Furthermore, cinnamophilin not only improved the ipsilateral field potentials (p < .05, respectively), but also reduced the severity of contralateral electrophysiological diaschisis (p < .05). Consequently, cinnamophilin improved sensorimotor outcomes up to 21 days postinsult (p < .05, respectively). Conclusions:Administration with cinnamophilin provides long-lasting neuroprotection against gray and white matter damage and improves functional and electrophysiological outcomes after ischemic stroke. The results suggest a need for further studies to characterize the potential of cinnamophilin in the field of ischemic stroke.

Magnolol reduces glutamate-induced neuronal excitotoxicity and protects against permanent focal cerebral ischemia up to 4 hours.

Neuroprotective efficacy of magnolol, 5,5′-dially-2,2′-dihydroxydiphenyl, was investigated in a model of stroke and cultured neurons exposed to glutamate-induced excitotoxicity. Rats were subjected to permanent middle cerebral artery occlusion (pMCAO). Magnolol or vehicle was administered intraperitoneally, at 1 hr pre-insult or 1–6 hrs post-insult. Brain infarction was measured upon sacrifice. Relative to controls, animals pre-treated with magnolol (50–200 mg/kg) had significant infarct volume reductions by 30.9–37.8% and improved neurobehavioral outcomes (P<0.05, respectively). Delayed treatment with magnolol (100 mg/kg) also protected against ischemic brain damage and improved neurobehavioral scores, even when administered up to 4 hrs post-insult (P<0.05, respectively). Additionally, magnolol (0.1 µM) effectively attenuated the rises of intracellular Ca2+ levels, [Ca2+](i), in cultured neurons exposed to glutamate. Consequently, magnolol (0.1–1 µM) significantly attenuated glutamate-induced cytotoxicity and cell swelling (P<0.05). Thus, magnolol offers neuroprotection against permanent focal cerebral ischemia with a therapeutic window of 4 hrs. This neuroprotection may be, partly, mediated by its ability to limit the glutamate-induced excitotoxicity.

Cerebellar Hemorrhage After Multiple Manual Pumping Tests of a Ventriculoperitoneal Shunt: A Case Report

A manual pumping test is commonly used to verify the patency of a ventriculoperitoneal (V‐P) shunt. Complications occurring after manual pumping of the reservoir are rare. Here, we report a 73‐year‐old male hydrocephalic patient who had undergone uneventful V‐P shunt surgery 9 years ago. He developed a cerebellar hemorrhage after repetitive pressing of the shunt reservoir. The clinical manifestations, characteristic radiologic images, treatment outcome, and possible mechanisms of this late complication are presented. The risk of massive cerebrospinal fluid over‐drainage after repetitive manual pumping of the V‐P shunt reservoir, which can contribute to the formation of a cerebellar hemorrhage, warrants special attention and hydrocephalic patients and their caregivers should be informed and educated about this potential complication.

The application of flow cytometry for evaluating biological aggressiveness of intracranial meningiomas

Meningiomas have classically been considered to include benign and atypical/anaplastic tumors. Despite the availability of clinical and pathologic parameters for prognostic prediction prognosis, the behavior of each meningioma may be difficult to predict. Here, we used DNA flow‐cytometric studies to predict biological tumor behaviors of intracranial meningiomas.

Cinnamophilin Inhibits Neutrophilic Respiratory Burst and Protects Against Ischemia-Reperfusion Brain Damage

We have shown that administration of Cinnamophilin (CINN) effectively reduced oxidative damage, DNA lipid peroxidation, neutrophil infiltration, and ischemic brain damage by inhibiting oxidative stress and the resulting inflammation in experimental stroke. In this study the potential CINN to ameliorate neutrophilic respiratory burst and reduce neutrophil infiltration was investigated. Neutrophils pretreated or co-treated with CINN, were stimulated by phorbol 12-myristate 13-acetate (PMA) and the levels of superoxide radical (O2-.) and hydrogen peroxide (H2O2) produced were determined by dihydroethidium (DHE) and dihydrorhodamine-123 (DHR) fluorescence assays, respectively, while myeloperoxidase activity (MPO) was measured by the guaiacol method. Our results showed that both pretreatment and co-treatment with CINN significantly inhibited H2O2 production in PMA-stimulated neutrophils. Additionally, cotreatment, but not pretreatment, with CINN effectively inhibited O2-. production in the PMA-stimulated neutrophils. Both treatments did not effectively reduce the MPO activity in neutrophil. Finally, animals treated with CINN at reperfusion brain insults significantly reduced brain infarction and neutrophil infiltration, as well as improved neurobehavioral outcome following cerebral ischemic reperfusion. These results support pluripotent neuroprotection actions offered by CINN against cerebral ischemia-reperfusion.

A Patient With Two Episodes of Thoracic Spinal Cord Compression Caused by Primary Lymphoma and Metastatic Carcinoma of the Prostate, 11 Years Apart

We report a 75‐year‐old man with two spinal tumors, primary epidural lymphoma and metastatic carcinoma of the prostate, which caused thoracic spinal cord compression, with a long symptom free interval between episodes. The patient presented with back pain and progressive weakness and numbness in his lower limbs for 3 months. Eleven years earlier, he had a symptomatic T8‐10 primary spinal epidural lymphoma that was treated successfully with surgery and he made a full recovery. Magnetic resonance imaging of the thoracic and lumbar spines revealed multiple thoracic and lumbar vertebral osteolytic lesions. Extraosseous extension of a lesion at T1‐4 resulted in severe spinal cord compression. In consideration of recurrent lymphoma, emergent cord decompression was achieved via posterior T1‐4 decompressive laminectomy, and the patients neurological status improved rapidly after surgery. Pathological examination confirmed metastatic carcinoma of the prostate. After several courses of chemotherapy, the patient improved neurologically and could walk independently. Three years after surgery, magnetic resonance imaging showed complete resolution of cord edema at T1‐4 and T8‐9, and the high signal intensity at unoperated levels largely regressed. This report emphasizes that other newly developed lesions should be included in the differentiation of recurrent primary spinal epidural lymphoma, especially in patients who have long‐term, disease‐free intervals between episodes.

A Rare Occipital Condyle Fracture in a Patient With A Minor Head Injury

Occipital condyle fracture (OCF) is an uncommon but potentially fatal disease entity. It is most commonly identified in patients suffering from severe craniocerebral trauma. The advent of computed tomography has made early detection possible. Traditional treatment using a hard neck collar is sufficient to produce solid fusion in most OCF patients. Delayed diagnosis, however, may result in neurologic deterioration due to potential displacement of fractured condylar fragments. Here we report a case of isolated, stable OCF in a patient with a minor head injury. A high level of clinical awareness of this rare disease entity is imperative for the management of traumatized patients, especially for those who have minor head injuries but persistent neck pain.