Transient ischemic attack without self-awareness of symptoms witnessed by bystanders: analysis of the PROMISE-TIA registry.

BACKGROUND AND PURPOSE: A transient ischemic attack (TIA) can occur without self-awareness of symptoms. We aimed to investigate characteristics of patients with a tissue-based diagnosis of TIA but having no self-awareness of their symptoms and whose symptoms were witnessed by bystanders. METHODS: We used data from the multicenter registry of 1414 patients with a clinical diagnosis of TIA. For patients without evidence of ischemic lesions on imaging, clinical characteristics were compared between patients with and without self-awareness of their TIA symptoms. RESULTS: Among 896 patients (559 men, median age of 70 years), 59 (6.6%) were unaware of their TIA symptoms, but had those symptoms witnessed by bystanders. Patients without self-awareness of symptoms were older and more frequently female, and more likely to have previous history of stroke, premorbid disability, and atrial fibrillation, but less likely to have dyslipidemia than those with self-awareness. Patients without self-awareness of symptoms arrive at hospitals earlier than those with self-awareness (P < 0.001). ABCD2 score was higher in patients without self-awareness of symptoms than those with self-awareness (median 5 vs. 4, P = 0.002). Having no self-awareness of symptoms was a significant predictor of ischemic stroke within 1 year after adjustment for sex, ABCD2 score, and onset to arrival time (hazard ratio = 2.44, 95% confidential interval: 1.10-4.83), but was not significant after further adjustment for arterial stenosis or occlusion. CONCLUSIONS: Patients with a TIA but having no self-awareness of their symptoms might have higher risk of subsequent ischemic stroke rather than those with self-awareness, suggesting urgent management is needed even if patients have no self-awareness of symptoms.

Is the Susceptibility Vessel Sign on 3-Tesla Magnetic Resonance T2*-Weighted Imaging a Useful Tool to Predict Recanalization in Intravenous Tissue Plasminogen Activator?

The aim of this study was to investigate the independent factors associated with the absence of recanalization approximately 24 h after intravenous administration of tissue-type plasminogen activator (IV TPA). The previous studies have been conducted using 1.5-Tesla (T) magnetic resonance imaging (MRI). We studied whether the characteristics of 3-T MRI findings were useful to predict outcome and recanalization after IV tPA. Patients with internal carotid artery (ICA) or middle cerebral artery (MCA) (horizontal portion, M1; Sylvian portion, M2) occlusion and treated by IV tPA were enrolled. We studied whether the presence of susceptibility vessel sign (SVS) at M1 and low clot burden score on T2*-weighted imaging (T2*-CBS) on 3-T MRI were associated with the absence of recanalization. A total of 49 patients were enrolled (27 men; mean age, 73.9 years). MR angiography obtained approximately 24 h after IV tPA revealed recanalization in 21 (42.9 %) patients. Independent factors associated with the absence of recanalization included ICA or proximal M1 occlusion (odds ratio, 69.6; 95 % confidence interval, 5.05-958.8, p = 0.002). In this study, an independent factor associated with the absence of recanalization may be proximal occlusion of the cerebral arteries rather than SVS in the MCA or low T2*-CBS on 3-T MRI.

The regional rate of serotonin synthesis estimated by the alpha-methyl-tryptophan method in rat brain from a single time point.

A simplified approach to the measurement of the rate of serotonin (5-HT) synthesis in laboratory animals is presented using autoradiography and labeled alpha-methyl-L-tryptophan. The method is based on the assumption that the volume of distribution of an apparent precursor pool is the same in all brain structures. The apparent distribution volume (Vapp) of the tracer was estimated from our previous data and found to be 0.45 +/- 0.1 ml g-1 (n = 147) as an average in all brain structures. When this value of Vapp was used, the rates of 5-HT synthesis in the rat brain structures, calculated from the single time point method, were not significantly different from those calculated by the dual time point method, where both Vapp and K* were estimated. The rates from the two approaches did not differ when compared by analysis of variance (p > 0.8), Mann-Whitney rank sum test (p > 0.11), Bonferroni-corrected two-tailed t test, or when the ratio between two groups was tested against the hypothesis of being 1. The agreement between rates of 5-HT synthesis estimated by the two methods was very good, suggesting that the simplified method proposed here is appropriate for these kind of measurements.

Microglial response to transient focal cerebral ischemia: an immunocytochemical study on the rat cerebral cortex using anti-phosphotyrosine antibody.

Microglial response to transient focal ischemia was examined using an immunohistochemical method with a monoclonal antibody to phosphotyrosine (P-Tyr). For this purpose, a rat model of reversible middle cerebral artery occlusion for 1 h was used. Compared with results in the noninsulted hemisphere, there was a significant increase in P-Tyr immunolabeling of the microglia in the insulted cerebral cortex 3 h postreperfusion. This microglial reaction progressed up to 24 h after ischemic insult. In the affected cerebral cortex, morphological changes of the microglial positive for P-Tyr were also observed, with shortened and thickened processes, enlarged cell bodies, and ameboid features. Cell density analysis did not show any apparent change in number of P-Tyr-positive microglia in the insulted cortex at 6, 12, and 24 h after reperfusion, suggesting that the cells with increased P-Tyr immunoreactivity were resident microglia. The present findings suggest that signal transduction mediated by tyrosine phosphorylation is involved in the microglial response to ischemic injury in the rat cerebral cortex.

A new method to measure brain serotonin synthesis in vivo. I. Theory and basic data for a biological model.

We describe here an autoradiographic method to measure the in vivo rate of serotonin synthesis in rat brain. The method is based on the use of the L-tryptophan analogue alpha-methyl-L-tryptophan (alpha-MTrp), which is converted in vivo into alpha-methylserotonin (alpha-M5HT). Since alpha-M5HT is not a substrate for monoamine oxidase, it is accumulated in the brain tissue. Data are presented to confirm time-dependent conversion of alpha-MTrp into alpha-M5HT in the dorsal raphe nucleus and also in the pineal body, an organ outside the blood-brain barrier. It has also been shown that washing brain slices in 10% trichloroacetic acid results in less than 3% incorporation of alpha-MTrp into brain proteins. The rates of synthesis are calculated in several grossly dissected brain structures by using tracer kinetics and a three-compartment biological model. The half-life of the precursor pool is estimated to be approximately 20 min. The rate of serotonin synthesis is highest in the pineal body.

A new method to measure brain serotonin synthesis in vivo. II. A practical autoradiographic method tested in normal and lithium-treated rats.

We describe here a practical autoradiographic method to estimate the rate of serotonin synthesis in brain. A two-time point method (60 and 150 min after injection of alpha-[14C]methyl-L-tryptophan) was first evaluated in 14 normal rats (7 at each time point). After this the method was tested in lithium-treated rats. In normal rats the rate of serotonin synthesis measured by the two-time point method generally correlated with known concentrations of tryptophan hydroxylase. The rate of synthesis in lithium-treated rats was compared with that in sham-treated rats (NaCl treatment). The results showed a significant increase in the synthesis rate in some cerebral structures. The greatest increases in the serotonin synthesis rate, attributable to the lithium treatment, were observed in the parietal cortex (52%) and caudate nucleus (47%). This is the first investigation to demonstrate, with autoradiographic resolution (approximately 100 microns), the differential changes in the rate of serotonin synthesis in the brain. Lithium had no significant effect on the rate of synthesis in the pineal gland.

Hemifacial spasm due to contralateral acoustic neuroma: case report.

A patient with a large acoustic neuroma had contralateral hemifacial spasm. On CT, the brainstem was markedly displaced and distorted by the tumor. After total removal of the tumor the hemifacial spasm was temporarily worse, but disappeared 14 days after the operation.

Optimal timing of neutron irradiation for boron neutron capture therapy after intravenous infusion of sodium borocaptate in patients with glioblastoma.

PURPOSE: A cooperative study in Europe and Japan was conducted to determine the pharmacokinetics and boron uptake of sodium borocaptate (BSH: Na(2)B(12)H(11)SH), which has been introduced clinically as a boron carrier for boron neutron capture therapy in patients with glioblastoma. METHODS AND MATERIALS: Data from 56 patients with glioblastoma who received BSH intravenous infusion were retrospectively reviewed. The pharmacokinetics were evaluated in 50 patients, and boron uptake was investigated in 47 patients. Patients received BSH doses between 12 and 100 mg/kg of body weight. For the evaluation, the infused boron dose was scaled linearly to 100 mg/kg BSH. RESULTS: In BSH pharmacokinetics, the average value for total body clearance, distribution volume of steady state, and mean residence time was 3.6 +/- 1.5 L/h, 223.3 +/- 160.7 L, and 68.0 +/- 52.5 h, respectively. The average values of the boron concentration in tumor adjusted to 100 mg/kg BSH, the boron concentration in blood adjusted to 100 mg/kg BSH, and the tumor/blood boron concentration ratio were 37.1 +/- 35.8 ppm, 35.2 +/- 41.8 ppm, and 1.53 +/- 1.43, respectively. A good correlation was found between the logarithmic value of T(adj) and the interval from BSH infusion to tumor tissue sampling. About 12-19 h after infusion, the actual values for T(adj) and tumor/blood boron concentration ratio were 46.2 +/- 36.0 ppm and 1.70 +/- 1.06, respectively. The dose ratio between tumor and healthy tissue peaked in the same interval. CONCLUSION: For boron neutron capture therapy using BSH administered by intravenous infusion, this work confirms that neutron irradiation is optimal around 12-19 h after the infusion is started.

Calcineurin in the adult rat hippocampus: different distribution in CA1 and CA3 subfields.

We examined the immunohistochemical regional distribution of calcineurin (Ca2+/calmodulin-dependent protein phosphatase) in the adult rat hippocampus, following various regional destruction. In the normal adult rat hippocampus, the calcineurin immunoreactivity showed a characteristic pattern. This protein phosphatase was detected in all layers of the CA1 subfield, including the cytoplasm of the pyramidal cells, whereas it was strongly evident in the stratum lucidum and moderately so in the cytoplasm of pyramidal cells in the CA3 subfield. Seven days after transient forebrain ischemia, which induced destruction of CA1 pyramidal cells, the calcineurin immunoreactivity decreased in all layers of the CA1 subfield, while the immunoreactivity for synapsin I, a marker of the presynaptic site, was preserved. Seven days after the intraventricular injection of kainate, which induced destruction of CA3 pyramidal cells, the calcineurin immunoreactivity in the stratum lucidum was preserved, although the immunostaining pattern of the stratum lucidum changed when CA3 pyramidal cells were destroyed. Seven days after mechanical destruction of the dentate gyrus and CA4 subfield, which induced destruction of mossy fibers, the calcineurin immunoreactivity in the stratum lucidum was lost, except in the far site of the stratum lucidum. In the CA1 subfield, calcineurin was mainly located in postsynaptic sites, while it was mainly located in the presynaptic sites in the mossy fibers of the CA3 subfield. The immunohistochemistry of adjacent sections with antibodies of microtubule-associated protein 2 and synapsin I, which are markers of postsynaptic and presynaptic sites respectively, supports these results. Thus, calcineurin has a different synaptical distribution in the rat hippocampus.

Cellular localization of type II Ca2+/calmodulin-dependent protein kinase in the rat basal ganglia and intrastriatal grafts derived from fetal striatal primordia, in comparison with that of Ca2+/calmodulin-regulated protein phosphatase, calcineurin.

We investigated immunohistochemically the cellular localization of multifunctional type II Ca2+/calmodulin-dependent protein kinase in the rat basal ganglia and intrastriatal grafts derived from fetal striatal primordia, in comparison with that of calcineurin, a reliable marker for striatal medium-sized spinous neurons. The type II Ca2+/calmodulin-dependent protein kinase-positive neurons were of medium size, with a mean diameter of 16.1 +/- microns (average +/- S.D., n = 72, range 13.6-18.3 microns) and comprised approximately 70% of the total neuronal population in the striatum. Light microscopy showed that the type II Ca2+/calmodulin-dependent protein kinase-positive cells had round, triangular or polygonal cell bodies with relatively little cytoplasm. Analysis of serial sections showed that type II Ca2+/calmodulin-dependent protein kinase and calcineurin immunoreactivities were co-localized in the striatal neurons examined with a similar distribution pattern. Type II Ca2+/calmodulin-dependent protein kinase-positive cells were always immunoreactive for calcineurin and cells negative for type II Ca2+/calmodulin-dependent protein kinase showed no apparent calcineurin immunoreactivity. Type II Ca2+/calmodulin-dependent protein kinase-positive nerve fibers in the globus pallidus and substantia nigra almost disappeared following striatal ischemic injury produced by transient middle cerebral artery occlusion and cerebral hemitransection, respectively, suggesting that these immunopositive fibers were striatal projections. Thus, most type II Ca2+/calmodulin-dependent protein kinase-positive neurons in the rat striatum are considered to be of the medium-sized spinous type. Type II Ca2+/calmodulin-dependent protein kinase or calcineurin immunoreactivity was also observed in a large number of neurons in transplants derived from fetal striatal primordia grafted into striatal ischemic lesions. In addition, type II Ca2+/calmodulin-dependent protein kinase- or calcineurin-immunoreactive nerve fibers appeared in the deafferented globus pallidus of the host rats, suggesting that the striatopallidal pathway was reformed by striatal projection neurons of the transplants. This finding may also indicate that Ca2+/calmodulin-regulated enzymes are useful for tracing striatal projection fibers as endogenous marker proteins.

A simple enhancement method for the silver-gold-intensified diaminobenzidine reaction in the light microscopic immunoperoxidase technique.

We describe a simple and sensitive method for enhancement of the silver-gold-intensified 3,3'-diaminobenzidine (DAB) reaction demonstrating peroxidase activity. After completing silver-gold intensification of the preparations immunostained by the avidin-biotin-peroxidase method with DAB as the chromogen, the preparations were immersed in a solution containing uranyl nitrate. This new method appeared to increase the sensitivity by at least one order of magnitude as compared with silver-gold intensification alone.

Correlation of sequential magnetic resonance imaging of experimental brain ischemia with histologic changes in gerbils.

RATIONAL AND OBJECTIVES: To characterize Gd-DTPA-enhanced T1-weighted images (Gd-T1WI) in the acute phase of cerebral ischemia, sequential magnetic resonance images of 84 Mongolian gerbils with occlusion of the left common carotid artery were evaluated. METHODS: Twelve gerbils were used for each group, among which the occlusion time (5-180 minutes, permanent) varied. Histopathologic changes developing within the first 2 weeks were compared with patterns on T2-weighted images and Gd-T1WI on a 7.05-Tesla system. RESULTS: Although T2-weighted images and Gd-T1WI both demonstrated abnormal findings as early as 3 hours after occlusion, Gd-T1WI demonstrated more definite abnormalities with shorter occlusion than T2-weighted images (especially when there were only mild histologic changes). The earliest changes were an abnormal enhancement around and within the lateral ventricles in temporary occlusions; this was not demonstrated in permanent occlusions. CONCLUSIONS: Magnetic resonance images using Gd-DTPA demonstrated abnormal permeability within 3 hours after occlusion, and the pattern is correlated with intensity of ischemia.

HLA-mismatched CD34-selected stem cell transplant complicated by HHV-6 reactivation in the central nervous system.

We report here a patient who suffered from PCR- confirmed human herpesvirus type 6 (HHV-6) meningoencephalitis after allogeneic purified CD34+ cell transplantation from his HLA-mismatched sibling donor, even though he had been on intense prophylaxis with i.v. ganciclovir (GCV), acyclovir (ACV) and gamma-globulin containing a specific antibody against HHV-6. Serological evaluation disclosed that both the donor and recipient had IgG antibody against HHV-6 before transplantation. His blood WBC count started to transiently increase on day 10, and all blood components had decreased by day 20. He then developed a severe headache and high blood pressure, and sporadic abnormal neurological findings including nystagmus and delirium. An analysis of cerebrospinal fluid (CSF) revealed 8 cells/microl, a glucose level of 130 mg/dl and a protein level of 201 mg/dl (normal, 50 mg/dl) on day 26. At the time, HHV-6 was detected only in CSF by a PCR-based method and he was diagnosed as having meningoencephalitis due to the local reactivation of HHV-6. Although he failed to respond to high-dose therapy with ACV (60 mg/kg/day) and gamma-globulin, the DNA of this virus disappeared from the CNS upon treatment with GCV (30 mg/kg/day) combined with the intraventricular infusion of alpha-interferon. His clinical course was further complicated with meningoencephalitis due to staphylococcus epidermidis, and he died of tentorial herniation on day 79 without the recovery of blood components. This experience may indicate that intense prophylaxis to prevent reactivation of HHV-6 in the CNS is essential for the management of such profoundly immunosuppressed patients.

Changes of immunoreactivity for synaptophysin ('protein p38') following a transient cerebral ischemia in the rat striatum.

We assessed the chronological change of the expression of synaptophysin, an integral glycoprotein on the presynaptic vesicles, after a transient cerebral ischemic insult in the rat. The ischemic lesion was consistently localized in the dorsolateral part of the striatum, which was clearly visualized by a depletion of calcineurin immunostaining or increases of immunoreactivities for glial fibrillary acidic protein and tyrosine hydroxylase. Immunoreactivity for synaptophysin was transiently increased in the ischemic lesions from 3 to 7 days after cerebral ischemia. Thereafter, synaptophysin immunostaining in the damaged areas gradually decreased and finally almost disappeared one month after surgery. Because synaptophysin is located in the presynaptic vesicle, and thought to be involved in presynaptic functions such as vesicle-membrane fusion and release of neurotransmitters, present findings suggest that loss of the postsynaptic site after ischemic insult induces a transient increase of the presynaptic functions, followed by a decrease of functional presynaptic activity or trans-synaptic retrograde degeneration of axon terminals.

Increased expression of growth-associated protein GAP-43/B-50 following cerebral hemitransection or striatal ischemic injury in the substantia nigra of adult rats.

The substantia nigra receives massive inhibitory gamma-aminobutyric acid (GABA)-ergic inputs, deafferentation of which is supposed to lead to anterograde transsynaptic regression of the nigral neurons. An immunohistochemical technique was used to examine growth-associated protein GAP-43 expression following cerebral hemitransection or transient middle cerebral artery occlusion (MCAO) in the substantia nigra of adult rats. GAP-43 expression was transiently elevated in the substantia nigra pars reticulata (SNr) neurons, but not in the pars compacta neurons at 3 and 4 days post-hemitransection. Massive striatal ischemic injury produced by transient MCAO also caused an increase in GAP-43 synthesis in the SNr neurons at 3 and 4 days after operation. The present findings raise the possibility that deafferentation of the GABAergic inputs leading to transneuronal regression of the SNr neurons is responsible for the elevated expression of GAP-43 in the substantia nigra of adult rats.

Non-invasive in-vivo autoradiographic method to measure axonal transport in serotoninergic neurons in the rat brain.

We studied axonal transport of serotoninergic neurons by autoradiography following intravenous administration of alpha-[14C]methyl-L-tryptophan (alpha-[14C]MTrp). Autoradiograms obtained 24 h after intravenous injection of the tracer demonstrated clearly all raphe nuclei and the major ascending pathway, the medial forebrain bundle (MFB). From these autoradiograms it was clear that radioactivity traveling along the MFB had already reached the substantia nigra and ventrolateral geniculate body nuclei, terminal field. The whole route of the MFB was well visualized from an axial cross-section of a three-dimensional display of data. Autoradiograms obtained at 6 h after injection revealed only the caudal part of the MFB but all raphe nuclei were labelled, indicating that the tracer was in the process of being transported, probably as an alpha-methyl-5-hydroxytryptamine, via the MFB. The axonal transport rate was estimated from the brain autoradiograms of 4 rats killed 6 h after injection of the tracer. The mean distance of the tracer transported via the medial forebrain bundle in 4 rats was 3.8 +/- 0.4 (S.D.) mm, which corresponded to the level of the posterior to mid-hypothalamus. The axonal transport rate calculated from this distance from the medial raphe was 0.63 +/- 0.07 mm/h (14 mm/day). There was no significant difference in the axonal transport rate between the right and left side of the MFB.

Neuronal induction of 72-kDa heat shock protein following methamphetamine-induced hyperthermia in the mouse hippocampus.

By means of an immunohistochemical technique, we examined the neuronal induction of 72-kDa heat shock protein (HSP72) in response to methamphetamine-induced hyperthermia in the mouse hippocampus. Strong HSP72 immunoreactivity (ir) was found in the neurons of hippocampus proper, particularly in the CA1/2 and medical CA3 subfields, at 10 h after drug injection. By 18 h, those neurons still revealed HSP72-ir, while neurons of the dentate gyrus also appeared positive for HSP72. At this stage, intense HSP72-ir was first detected in non-neuronal cells, i.e. glial and vascular endothelial cells. At 24 h, no apparent HSP72-ir was found in the hippocampal neurons, while only non-neuronal cells still revealed immunoreactivity for HSP72. In addition, no morphological evidence of cell degeneration or loss was noted in the CA1 sector or other hippocampal regions at 5 days after hyperthermic insult. In conclusion, (1) methamphetamine-induced hyperthermia per se is a stressful stimulant causing neuronal induction of HSP72 in the hippocampus neurons, particularly of CA1/2 and medial CA3 sectors, but does not prove fatal to the cells; (2) there is a cell type-specific difference in response to hyperthermic insult by inducing HSP72 and the timing of the induction response in the hippocampal formation; and (3) the animals that underwent drug-induced hyperthermia may be useful as an experimental model for the study of the protective mechanism of heat shock proteins against subsequent harmful stimuli.

Disruption of the blood-cerebrospinal fluid barrier by transient cerebral ischemia.

The influence of transient cerebral ischemia on blood-brain and blood-cerebrospinal fluid (CSF) barrier permeability was studied sequentially by magnetic resonance imaging (MRI) contrast enhancement using gadolinium-diethylene triamine pentaacetic acid (Gd-DTPA) in rats. The unilateral internal carotid and middle cerebral arteries were transiently occluded by inserting a nylon thread into the carotid artery and removing it following a variable interval of 5 to 60 min. Contrast enhancement of the lateral ventricle on the affected side was seen in the enhanced T1-weighted image at the early stage of reperfusion 6 h after the start of ischemia in most of the rats subjected to 30- and 60-min ischemia, and in 3 of 6 rats in the 15-min ischemia group. Autoradiograms of Gd-[14C]DTPA in rats subjected to 60-min ischemia demonstrated that the tracer strongly accumulated in the choroid plexus, the wall of the lateral ventricle and its surrounding brain tissue. On the other hand, parenchymal enhancement of the striatum was seen only in the 60-min ischemia group and appeared later on Day 1 or Day 7. These results indicate that ventricular enhancement on MRI in this model is caused by disruption of the blood-CSF barrier at the choroid plexus of the lateral ventricle. This is the first reported study to demonstrate blood-CSF barrier disruption by transient ischemia.

Activities of calcineurin and phosphatase 2A in the hippocampus after transient forebrain ischemia.

We investigated the changes in the enzyme activity and immunoreactivity of calcineurin in the rat hippocampus after transient forebrain ischemia. Immediately after 20-min transient forebrain ischemia, calcineurin activity decreased to about 40% of the control in the CA1 region and to about 55% in other regions. Protein phosphatase 2A activity showed no remarkable changes. By 12 h after ischemia, calcineurin activity recovered, more in the CA1 region than in other regions. At 24 h it decreased again, but only in the CA1 region. Immunohistochemical- and immunoblot analyses showed no remarkable change in calcineurin in any region of the hippocampus within 12 h after ischemia. Thus, the activity of calcineurin is dissociated from its immunoreactivity and quantity. Several studies have suggested that unknown inhibitory factor(s) and/or reversible changes in calcineurin act to modify enzyme activity after ischemia. In contrast, phosphatase 2A activity underwent no obvious changes during the post-ischemia period we examined. This unique time course of calcineurin activity may contribute to the mechanism of ischemic neuronal injury.

Calcineurin, a calcium/calmodulin-regulated protein phosphatase, in mammalian neuroendocrine cells and neoplasms.

Calcineurin is a calcium/calmodulin-regulated protein phosphatase. By using enzyme-immunoassay and immunocytochemistry with an affinity-purified specific antibody to this protein, we have found that calcineurin is expressed in the central and peripheral neuroendocrine cells, also termed amine precursor uptake and decarboxylation cells. In addition, calcineurin immunoreactivity was found in the central neuroendocrine neoplasms such as pineocytoma, olfactory neuroblastoma and paraganglioma. The present findings indicate that the activity of phosphatase regulated by calcium and calmodulin is involved in neuroendocrine functions, and that the enzyme can be useful for the identification and characterization of neuroendocrine cell tumors.