Inhibition of neurite outgrowth in neuroblastoma cells by sphingosine

Mouse neuroblastoma NS-20Y cells were induced to grow neurites by removal of serum from the medium. The percentage of cells with neurites reached about 50-60% after 24 h, whereas in medium containing 10% serum only a few cells (1-3%) were bearing neurites. Sphingosine inhibited the neuritogenesis in serum-free medium in a dose-dependent manner; a maximal effect was observed at 1-2 microM. Sphingosine also caused retraction of neurites which had been induced to extend in serum-free medium. N,N-Dimethylsphingosine was 10 times more potent in preventing neurite outgrowth, and N-acetylsphingosine was 10 times less effective compared to sphingosine. However, 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7) did not inhibit the extension of neurites. Neurite outgrowth in serum-free medium and its inhibition by sphingosine were still observed in the cells made protein kinase C-deficient by prolonged treatment with phorbol ester. These results suggest that the effect of sphingosine is not mediated by inhibition of protein kinase C.

[Delayed vasospasm complicated with the postoperative stage of the meningioma: a case report]

Though it has been reported infrequently that delayed vasospasm may appear in head-injured patients, it is rather rarer to see it as a complication arising from tumor removal. Such a case was presented and gave rise to speculation of a possible underlying pathophysiology. A 46-year-old female patient was admitted to our neurosurgical service, complaining of aching pain in the forehead. No neurological deficits were elicited on admission. CT scans as well as MR imagings confirmed the existence of a left sphenoid wing meningioma whose gross total removal was accomplished. She was doing well till the 3rd postoperative day, when she developed transcortical motor aphasia. 123I-IMP SPECT revealed low perfusion over the left middle cerebral artery territory, and CT scans also showed low density areas in the same region, including the putamen, corona radiata and temporal lobe on the left side. Left carotid angiography disclosed diffuse arterial narrowings involving C1, C2, A1 and M1 portions. The authors suspect that indirect injury to those arteries and/or some kind of inflammatory process might have played a role.

Evaluation of critically perfused area in acute ischemic stroke for therapeutic reperfusion: a clinical PET study

To evaluate critically perfused areas in the acute ischemic brain, 9 patients were studied by positron emission tomography (PET) within 7-32 hours after the onset. The cerebral blood flow (CBF) and oxygen metabolic rate (CMRO2) were evaluated and compared with sequential change in CT findings. In all the regions developing subsequent necrosis on CT, CBF dropped below 17 ml/100 g/min. But in some of these lesions, CMRO2 remained above the minimum value for regions in which infarction did not develop, and the tissue density on CT obviously remained normal for several hours after PET scan. The mean CBF in these lesions (14.0 ml/100 g/min, range: 9.9-17.3 ml/100 g/min) was significantly higher than that in ischemic areas with low density on CT before or just after PET study (approximately 10 ml/100 g/min, range: 7.7-14.1 ml/100 g/min). These findings suggest that a part of the tissue with CBF between 10-17 ml/100 g/min is still viable at least 7 hours after the onset of ischemia, but becomes non-viable in a longer period of ischemia. These lesions should respond to effective treatment, including therapeutic reperfusion.

[A case of left atrial myxoma with acute myocardial infarction--emergency coronary artery bypass grafting and removal of left atrial myxoma]

A 68-year-old woman had clinical signs of an acute myocardial infarction. Echocardiography revealed a tumor in the left atrium. Coronary angiography demonstrated total occlusion at RCA#1. On emergency operation a left atrial myxoma was removed and aortocoronary saphenous vein graft to the right coronary artery was performed. The operative correction of coronary arterial obstruction due to cardiac myxoma or thrombus is rare.

Compression of the left brachiocephalic vein: cause of high signal intensity of the left sigmoid sinus and internal jugular vein on MR images

To study the asymmetry in signal intensity of the sigmoid sinuses, internal jugular veins (IJVs), or both sets of structures on magnetic resonance (MR) images, the authors reviewed 226 serial sets of routine MR imaging studies. Cerebral digital subtraction angiography was performed in 20 patients with a markedly higher intensity and/or enhancement on the left; 15 of them also underwent venography. With every sequence, the left sigmoid sinus, IJV, or both were higher in signal intensity significantly more often than the right (range, P = .0001 to .0129). Angiography revealed hemostasis in the left IJV in 16 patients that disappeared during full inspiration in 14. In 13, venography revealed that the left brachiocephalic vein was compressed to occlusion between the aortic arch and the sternum during tidal volume ventilation. The occlusion disappeared at full inspiration, when the distance between the aortic arch and the sternum increased. This hemostasis could be the major cause of the frequent increased signal intensity of the left sigmoid sinus and IJV on MR images.

Abnormal excretion of urinary phospholipids and sulfatide in patients with mitochondrial encephalomyopathies

We found that patients with mitochondrial encephalomyopathies excreted urinary phosphatidylethanolamine, cardiolipin, and phosphatidylserine most likely derived from mitochondria and sulfatide which is specific to myelin or the kidney. It is of interest that four patients with myoclonus epilepsy with ragged-red fibers and one patient with chronic progressive external ophthalmoplegia all showed qualitatively similar abnormal excretion of such urinary lipids. It is conceivable that the urinary acidic phospholipids reflect abnormalities in the mitochondrial phospholipids, which are very important for mitochondrial enzymatic activities.

Therapeutic effect of a new immunosuppressant, FK-506, on vasospasm after subarachnoid hemorrhage

We hypothesized that the immunological reaction against extravasated blood might play a role in the development of vasospasm after subarachnoid hemorrhage. Under the hypothesis, we had reported significant therapeutic efficacy of cyclosporin A on vasospasm in canine models. We here investigated the efficacy of a new, potent immunosuppressant, FK-506, on vasospasm in animal models. Dogs were randomly classified into sham operated, subarachnoid hemorrhage treated-1 group, (FK-506, 0.3 mg/kg-d, intramuscular injection), and treated-2 group (FK-506, 0.15 mg/kg-d, intramuscular injection). Levels of the third factor of complement (C3) and the activity of serum complement inducing 50% hemolysis of sheep erythrocytes (CH50) in serum were also determined. In the treated groups, the levels of FK-506 in serum were monitored. As for C3 and CH50, there were no statistically significant differences among the groups and there were no changes between Day 1 and Day 7 in any group. Angiographical diameters of a basilar artery on Days 1 and 7 were measured with a computed image analyzer, and the extent of vasospasm was compared among the groups. Statistically significant differences between the sham-operated group and the other three groups were noted. However, under sufficient levels of FK-506 in serum, the extent of vasospasm in either treated group was the same as that in the subarachnoid hemorrhage group. These results indicate a significant discrepancy in the therapeutic mechanism for vasospasm between cyclosporin A and FK-506. They have common aspects in the immunosuppressive mechanism. However, in T-cell suppression, the different mechanism in situ between the two drugs is also postulated.(ABSTRACT TRUNCATED AT 250 WORDS)

Embolic cerebral infarction: MR findings in the first 3 hours after onset

OBJECTIVE

MR imaging has a high sensitivity for detecting ischemic brain parenchyma. The aim of this study was to evaluate the changes in the signal intensity of infarcted brain parenchyma on MR images obtained within the first 3 hr after the onset of signs and symptoms in patients with embolic cerebral infarction.

MATERIALS AND METHODS

We studied MR images of 16 patients who had a diagnosis of embolic cerebral infarction (highly probable according to criteria of the National Institute of Neurological and Communicative Disorders and Stroke). T1-weighted, T2-weighted, and proton density-weighted MR images were obtained within 3 hr after the onset of symptoms. Two neuroradiologists who had no knowledge of the diagnoses reviewed the MR images of these 16 patients and 20 control subjects in random order and evaluated signal-intensity changes in the gray and white matter.

RESULTS

On proton density-weighted images, the central and cortical gray matter showed increased signal intensity in 63-69% and 88-94% of the patients, respectively. No abnormalities of the brain parenchyma were apparent on T1-weighted and T2-weighted images obtained within 3 hr after the onset of symptoms. The adjacent white matter appeared hyperintense on long TR images in only a few cases.

CONCLUSION

An increased signal intensity in the gray matter on proton density-weighted images was the most characteristic parenchymal change seen on MR images of the brain obtained within 3 hr after embolic cerebral infarction.

Metabolism and neurite promoting effect of exogenous sphingosylphosphocholine in cultured murine neuroblastoma cells

Exogenous sphingosylphosphocholine analogues and naturally occurring sphingomyelin stimulated the neurite outgrowth in cultured murine neuroblastoma cell lines, NS-20Y, Neuro2a, and N1E-115, whereas exogenous sphinganine at a non-cytotoxic concentration inhibited the neurite outgrowth in NS-20Y and Neuro2a cells. The effect of sphingosylphosphocholine on the neurite outgrowth was reversible, indicating that the extended neurites needed to be maintained by continuous stimulation. The uptake and metabolism of the exogenous [3-3H]sphingosylphosphocholine in pulse and chase experiments suggested that the radioactive ceramide and sphingomyelin, which were detected as major metabolic products, were in a precursor/product relationship. It is thus assumed that the exogenous sphingosylphosphocholine taken up by the cells is first degraded into phosphocholine and sphingosine, of which the latter is rapidly acylated to ceramide then converted to sphingomyelin by phosphocholine transfer. Metabolism of sphingosylphosphocholine through sphingomyelin synthesis in the cells may be associated with neurite outgrowth.

Study of neural activities of the primary auditory cortex and middle latency auditory evoked potentials

This study was undertaken to clarify the relationship between the neural activities of the auditory cortex and components of middle latency auditory evoked potentials (ML-AEPs) (NI and PI) in the cat. Extracellular single-unit activities in the auditory cortex AI (AC-AI) were recorded simultaneously with ML-AEPs. In addition, the effects of removal of the AC-AI and AII and the cerebral hemisphere on ML-AEPs were also studied. ML-AEPs of humans consist of Na, Pa, and Nb components with preceding VI and VII, and those of the cat consist of NI, PI and NII with preceding P6 and P7. Among the 21 unit activities obtained from the AC-AI, 14 showed time-locked responses to click stimuli. The positive and negative waves of these unit activities have a phase reversal relation to N7 and P7, respectively. They are not related in latencies to NI and PI. Recording of ML-AEPs from the surface of the AC-AI showed large negative potentials (No), which also had a phase reversal relation to P7. The amplitude of P7 and No decreased after the unilateral and the bilateral removal of the AC-AI and AII. NI and PI decreased in amplitude after the unilateral removal of the cerebral hemisphere and further decreased after the bilateral removal. The above mentioned findings indicate that the neural activities of the primary AC are the ones mostly related to P7 and that NI and PI reflect neural activities of the cerebral hemispheres.

(14C-methyl)-L-methionine uptake in rat brain tumors before and after treatment with the protein synthesis inhibitor cycloheximide

Autoradiographic study of (14C-methyl)-L-methionine with brain tumor bearing rats aimed at an elucidation of the mechanism of tracer accumulation in the protein synthesis of tumor. Twice as much tracer accumulated in the tumors compared as in the contralateral gray matter (nontumor region) at 90 min post intravenous injection. The protein-bound fraction of the tumors, expressed as acid-insoluble fraction (AIF), was 1.7 +/- 0.6 (mean +/- standard deviation, n = 6), significantly higher than that (0.8 +/- 0.2) of the nontumor region (p < 0.05 by the Mann-Whitney test). The tumor AIF comprised 82.3 +/- 9.2% of the total amount of the tracers accumulated in the tumors. The protein synthesis inhibitor cycloheximide reduced the tracer uptake and the AIF of the tumors to an almost same level as the nontumor region. These findings indicate that metabolic acceleration of protein synthesis may be a main reason for the high accumulation of (14C-methyl)-L-methionine in tumor.

Subarachnoid hemorrhage: evaluation with MR imaging

Thirty-seven magnetic resonance (MR) examinations were performed at 0.5 T in 33 patients with subarachnoid hemorrhage (SAH) caused by a ruptured aneurysm. Images were obtained 2 hours to 75 days after the ictus. Twenty-four proton-density-weighted (long repetition time [TR], short echo time [TE]) images were obtained in the acute stage (< 72 hours after the ictus) of SAH; SAH was hyperintense to brain parenchyma and cerebrospinal fluid in all cases. The detectability of acute SAH on T1- (short TR, short TE) and T2- (long TR, long TE) weighted images was 36% and 50%, respectively. In the subacute and chronic stages (> 3 days after the ictus), the detectability of SAH on T1-, T2-, and proton-density-weighted images was 73%, 31%, and 83%, respectively. Although computed tomography is still the modality of choice for evaluating acute SAH, the authors emphasize that even acute SAH can be reliably demonstrated with MR imaging with the appropriate parameters.

Correlation between serotonergic measures in cerebrospinal fluid and blood of subhuman primate

The relationship between the concentration of serotonin (5-hydroxytryptamine; 5-HT), its precursor; tryptophan (Trp) and the main metabolite 5-hydroxyindoleacetic acid (5-HIAA) in cerebrospinal fluid (CSF) and blood of monkey have been studied. 5-HT, Trp and 5-HIAA underwent circadian changes in both CSF and blood. Significant correlations were found between 5-HT, 5-HIAA and Trp in CSF and blood. The significance of these findings and their relationship to the use of peripheral serotonergic system as a functional model of the central nervous system are discussed.

Relation between protein kinase C and calmodulin systems in cerebrovascular contraction: investigation of the pathogenesis of vasospasm after subarachnoid hemorrhage

The protein kinase C (PKC) and calmodulin systems each play a role in vascular contraction. However, the correlation of these two systems in producing contraction has been unclear. To clarify the pathophysiology of vasospasm after subarachnoid hemorrhage, the authors demonstrated tonic contraction of the cerebral artery in a study of isometric tension, and investigated the correlation of the PKC and calmodulin systems in producing the contraction. To develop better management for vasospasm, they also examined the effect of calmodulin antagonists on tonic contraction. The development of isometric tension in canine basilar arteries was measured, with the following results: 1) tonic contraction was dependent on the PKC system, but initiation of the contraction by the calmodulin system was necessary for the subsequent PKC-dependent tonic contraction; 2) specific calmodulin antagonists like chlorpromazine and pimozide partially inhibited the tonic contraction associated with PKC activation; 3) another calmodulin antagonist, trifluoperazine, inhibited the PKC system as well. On the basis of these results, the authors conclude that the PKC system plays a role in the development of vasospasm. In the early phase of contraction, the calmodulin system contributes to the subsequent fully-activated, PKC-induced tonic contraction. To manage vasospasm, a specific calmodulin antagonist would therefore not be sufficient. Suppression of both the calmodulin and PKC systems with trifluoperazine in the earliest stage of vasospasm is recommended.

Cerebral blood flow and glucose metabolism measurements in a patient surviving one year after carbon monoxide intoxication

A 29-yr-old woman was studied for 1 yr after acute carbon monoxide intoxication following an attempted suicide by inhalation of automobile exhaust fumes. The patient demonstrated impaired responsiveness to stimuli without any specific neurological deficits for 1 yr after carbon monoxide intoxication. Repeated brain magnetic resonance imaging consistently displayed only bilateral globus pallidus lesions, but no lesions in either deep white matter or cerebral cortex. Position emission tomography measurements of regional cerebral blood flow, and glucose utilization rate were made in this patient at 6 mo and 1 yr following carbon monoxide intoxication. Impairment of both blood flow and glucose metabolism were found not only in the basal ganglia but also in morphologically normal frontal cortex. The decrease in glucose utilization in the frontal cortex was greater than that in the basal ganglia. During the period of 6 mo to 1 yr, blood flow and glucose metabolism in the basal ganglia recovered to the normal range. In the frontal cortex, however, blood flow and glucose metabolism remained approximately 20% lower than the normal mean values. This prolonged dysfunction in the frontal cortex may therefore be responsible for the impaired responsiveness of the subject.

[Long-term prognosis of nonoperative acute epidural hematoma in children]

Computed tomography(CT) scan has revealed that certain acute epidural hematomas(AEH) don't need operative therapies. But, it is difficult to determine especially in childhood, whether AEH compressing the brain for a short-term would or would not effect the function of the central nervous system in the future. For this reason, the authors report the long-term prognosis of nonoperative AEH in children. Twelve children suffering from AEH were transported to our clinic. On admission, they had no neurological deficits and CT scan revealed hematomas that had maximum thickness of 5-19 mm without midline shift. With nonoperative therapy they were discharged and the hematomas disappeared within 3-12 weeks. After long-term follow-up (3-10 years), it was shown that they had no epileptic episodes, and no changes in their school study records. Also, the Yatabe-Guilford personality test revealed no abnormal data. These data suggest that children can be cured who suffer from AEH with no neural deficits, and in whom the maximum thickness of the AEH is less than 20 mm, and in whom there is no midline shift in CT scan, can be cured without undergoing an operation, and will have a good long-term prognosis.

Identification of nociceptive neurons in the medial thalamus: morphological studies of nociceptive neurons with intracellular injection of horseradish peroxidase

Somatosensory neurons including nociceptive ones in the medial thalamus have been studied extracellularly, and are classified into three types: nociceptive-specific, wide dynamic range, and tap neurons. However, the morphological characteristics of these three neurons have not yet been clarified. We studied the morphological characteristics of the neurons by iontophoretic injection of HRP into single neurons in 32 cats. Nine wide dynamic range neurons and two tap neurons were electrophysiologically identified and successfully stained with HRP in and around the parafascicular and subparafascicular nuclei, and in the mediodorsal nucleus. All nine wide dynamic range neurons had fewer dendrites which formed scanter tufts, whereas the two tap neurons had many more dendrites which formed denser tufts: i.e. wide dynamic range neurons were of the isodendritic type, and the tap neurons were of the allodendritic type, according to Ramón-Moliner's classification. The axons of the two tap neurons ran antero-laterally whereas those of wide dynamic range neurons ran in many directions. These morphological differences suggest that tap neurons may have more specialized and fixed functions than wide dynamic range neurons.

MRI of intracranial neurovascular compression

Twelve patients with clinical indications of intracranial neurovascular compression (6, hemifacial spasm; 4, trigeminal neuralgia; 2, vertigo and tinnitus) were studied by MRI. Axial 1 mm thick slices were obtained in a 1.5 T unit using a three-dimensional (3D) fast low angle shot data set of 32 contiguous slices. The data were post-processed with multiplanar reconstruction algorithms to obtain oblique sagittal (along the long axis of a nerve) images or coronal images with a slice thickness of 0.8 mm. The MR angiographic images were also obtained from the same 3D data set with maximum intensity projection algorithms. The MR studies showed that 9 of 12 patients had neurovascular compression caused by one or two arteries. These findings were verified at surgery. In two of the remaining three patients, MRI failed to delineate the affected nerves compressed by a vein in one, and a previously applied prosthesis in the other. In the last patient no neurovascular compression was found by MRI or at surgery.

[Phenylalanine transport in the living human brain by a dynamic PET of L-[2-18F]-fluorophenylalanine]

The transport kinetics of L-[2-18F]-Fluorophenylalanine in the human brain were studied in one normal subject and 6 patients with brain tumor using a dynamic positron emission tomography. The tracer kinetics from blood to brain were described by two compartment model with K1 (influx) and k2 (efflux). The rate constants in normal brain tissue and tumor tissue were K1 = 0.045 ml/g/min, k2 = 0.078 ml/g/min and K1 = 0.122 ml/g/min, k2 = 0.102 ml/g/min, respectively. The Michaelis-Menten constants (Kt and Tmax) for phenylalanine transport in the normal cortex were graphically estimated. The estimated Kt was 35 nmol/ml, whereas the Tmax varied with cerebral blood flow.

Antibody to hepatitis C virus in patients with chronic schistosomiasis

To clarify the effect of hepatitis C virus (HCV) infection in patients with chronic schistosomiasis, 96 patients with schistosomiasis and 137 patients with chronic liver disease without schistosomal infection were analysed by domination of antibody to HCV (anti-HCV). In 45 of 96 schistosomiasis patients, the serum alanine aminotransferase (ALT) level was continuously elevated, and the positive rate of anti-HCV was 52.9%, which is almost the same prevalence rate as in patients with chronic liver disease (48.9%). In contrast, in the remaining 51 schistosomiasis patients, serum ALT level was continuously within the normal range and the positive rate of anti-HCV was 0%. Histological investigation showed that the positive rate of anti-HCV in HBsAg-negative schistosomiasis patients was 14% for hepatic fibrosis, 71% for chronic hepatitis, 80% for liver cirrhosis and 56% for hepatocellular carcinoma. In all anti-HCV-positive patients, serum ALT level was continuously elevated. The serum transaminase levels in anti-HCV-positive patients were higher than those in anti-HCV-negative patients. These data suggest that in patients with chronic schistosomiasis, HCV infection accelerates the derangement of liver function, and may be a major aetiological factor in the development of chronic hepatitis and liver cirrhosis, supporting a causative association between HCV infection and hepatocellular carcinoma.