Human group IIA secretory phospholipase A2 induces neuronal cell death via apoptosis.

Expression of group IIA secretory phospholipase A2 (sPLA2-IIA) is documented in the cerebral cortex (CTX) after ischemia, suggesting that sPLA2-IIA is associated with neurodegeneration. However, how sPLA2-IIA is involved in the neurodegeneration remains obscure. To clarify the pathologic role of sPLA2-IIA, we examined its neurotoxicity in rats that had the middle cerebral artery occluded and in primary cultures of cortical neurons. After occlusion, sPLA2 activity was increased in the CTX. An sPLA2 inhibitor, indoxam, significantly ameliorated not only the elevated activity of the sPLA2 but also the neurodegeneration in the CTX. The neuroprotective effect of indoxam was observed even when it was administered after occlusion. In primary cultures, sPLA2-IIA caused marked neuronal cell death. Morphologic and ultrastructural characteristics of neuronal cell death by sPLA2-IIA were apoptotic, as evidenced by condensed chromatin and fragmented DNA. Before apoptosis, sPLA2-IIA liberated arachidonic acid (AA) and generated prostaglandin D2 (PGD2), an AA metabolite, from neurons. Indoxam significantly suppressed not only AA release, but also PGD2 generation. Indoxam prevented neurons from sPLA2-IIA-induced neuronal cell death. The neuroprotective effect of indoxam was observed even when it was administered after sPLA2-IIA treatment. Furthermore, a cyclooxygenase-2 inhibitor significantly prevented neurons from sPLA2-IIA-induced PGD2 generation and neuronal cell death. In conclusion, sPLA2-IIA induces neuronal cell death via apoptosis, which might be associated with AA metabolites, especially PGD2. Furthermore, sPLA2 contributes to neurodegeneration in the ischemic brain, highlighting the therapeutic potential of sPLA2-IIA inhibitors for stroke.     

Systemic air embolism during preoperative pulmonary marking with a short hook wire and suture system under CT fluoroscopy guidance

We encountered a case of systemic air embolism during preoperative pulmonary marking with a short hook wire and suture system under CT fluoroscopy guidance. The pulmonary tumor was present in the right S3, and the procedural position was supine. The patient experienced cardiac symptoms, and systemic air embolism was confirmed on CT images. With the patient in the Trendelenburg position, 100% oxygen was immediately administered as therapy for the embolism. Subsequently, the symptoms and systemic air embolism were resolved. The patient underwent video-assisted thoracoscopic wedge resection after 5 days and was then discharged without any sequelae.     

Effect of nitroglycerin and nicardipine on ICG excretion during halothane anesthesia

We evaluated the effect of nitroglycerin and nicardipine on ICG excretion during halothane anesthesia in man. Induced hypotension with nitroglycerin during halothane anesthesia produced a significant prolongation in ICG excretion. No such significant prolongation occurred in the patients who received nicardipine. The results suggest that a reduction in hepatic blood flow during anesthesia may be much less in patients who receive halothane with nicardipine than in those who receive halothane with nitroglycerin.     

Sensitivity of immunoaffinity-purified porcine 5-lipoxygenase to inhibitors and activating lipid hydroperoxides

The requirement for hydroperoxide activation and the effect of inhibitors from different structural classes on 5-lipoxygenase activity were determined on the immunoaffinity-purified enzyme from porcine leukocytes. The 5-lipoxygenase activity was measured using a continuous spectrophotometric assay monitoring the increase in conjugated diene formation (A235) upon incubation of the enzyme with arachidonic acid. Under standard assay conditions, the reaction progress curves showed little or no lag phase, with a rapid first-order decay in enzyme activity (T1/2 = 0.7 to 1.1 min). Both the initial rate of the reaction and total product formation were stimulated by the addition of ATP, Ca2+ and phosphatidylcholine (PC). PC (24 micrograms/ml) was also found to increase the recovery of radiolabeled arachidonic acid from the assay mixture and thus part of the stimulation may be due to an increase in substrate availability and reduction of surface adsorption effects. The requirement of hydroperoxides for the initiation of the reaction was shown by the induction of 0.1 to 1-min lag phases using NaBH4 or glutathione peroxidase and by the reduction in lag times by 5-hydroperoxyeicosatetraenoic acid (5-HPETE) and 13-hydroperoxyoctadecadienoic acid (13-HPOD). The following compounds were evaluated as inhibitors of the 5-lipoxygenase reaction and caused a 50% decrease in product accumulation (IC50) at the indicated concentrations: quercetin, L-651,896, L-656,224, MTPPH and L-651,392 (0.3-0.5 microM); diphenyldisulfide (2-5 microM); phenidone (5-10 microM); AA861 (4-10 microM) and BW755C (4-15 microM). In addition, the presence of inhibitors extended the initial lag phase of the reaction and increased the dependence of the initiation of the reaction on exogenous lipid hydroperoxides. The inhibition by phenidone was accompanied by a 2-fold increase in the rate of enzyme inactivation, whereas other compounds such as AA861 and L-656,224 did not show this effect. The results indicate that the presence of inhibitors can modify the kinetics of 5-lipoxygenase at the levels of the initiation of the reaction and the rate of enzyme inactivation, with variations depending on the structural class of the inhibitor and the concentration of lipid hydroperoxides.     

A case of cerebellar neuroblastoma

A three-year-old boy with a progressive history of headache, vomiting and ataxia in the course of 2 months, was admitted on August 1983, when he was lethargic. Neurological examination revealed dysphagia, scanning speech and tremor in the bilateral hand. CT scan showed a very large enhanced mass in the center of posterior fossa with central necrosis in it and the dilatation of whole ventricular system. Suboccipital craniectomy was immediately performed and the tumor that occupied the vermis and invaded into both cerebellar hemisphere was subtotally removed. Postoperative irradiation was well performed: 4140 rads to the whole brain and 3162 rads to the spinal cord. However, 5 months later, facial palsy in the left side and progressive ataxia became prominent. CT scan showed multiple enhanced masses in the left trigonum and right anterior horn of the lateral ventricles and in the left cerebellopontine angle. In spite of chemotherapy, the patient had a down-hill course, especially after the ventricular hemorrhage, and died on June 9th, 1984. Histologically, the tumor had a lobulated appearance with an aggregation of tumor cells encircled by vascular septae. The cells within lobules generally had vesicular nuclei, which were arranged in parallel row. Occasionally smaller hyperchromatic cells with scant cytoplasm were present along the vascular septae. Reticulin was present within the septa, but was not observed within the lobules. Scattered astrocytic cells and processes were identified within the lobules by the immunoperoxidase technique for GFAP. The fibrillary cytoplasmic processes within the lobules were stained by immunoperoxidase technique for neurofilament (68K).(ABSTRACT TRUNCATED AT 250 WORDS)