Performance Improvement of Triplet-Triplet Annihilation-Based Upconversion Solid Films through Plasmon-Induced Backward Scattering of Periodic Arrays of Ag and Al.

The performance improvement of solid-state triplet-triplet annihilation-based photon upconversion (TTA-UC) systems is required for the application to various solar devices. The performance can be improved by making use of the local strong electric field generated through the excitation of localized surface plasmon (LSP) resonance of metal nanostructures. However, since the improvement is effective only within the limited nanospace around nanoparticles (i.e., the near-field effect), a methodology for improving the performance over a wider spatial region is desirable. In this study, a significant improvement in the threshold light excitation intensity (Ith) (77% decrease) as the figure of merit and the upconverted emission intensity (6.3 times enhancement) in a solid-state TTA-UC film with a thickness of 3 µm was achieved by stacking the film with periodic Ag half-shell arrays. The highest-enhanced upconverted emission was obtained by tuning the diffuse reflectance peak, which results from the excitation of LSP resonance of the Ag half-shell arrays, to overlap well with the photoexcitation peak of the sensitizer in the TTA-UC film. The intensity of the enhanced upconverted emission was independent of the distance between the lower edge of the TTA-UC film and the surface of half-shell arrays in the nanometer order. These results suggest that the performance improvement was attributed to the photoexcitation enhancement of the sensitizer by elongating the excitation light path length inside the TTA-UC film, which was achieved through a strong backward scattering of the incident light based on the LSP resonance excitation (i.e., the far-field effect). In addition, the upconverted emission was improved using half-shell arrays comprising low-cost Al, although the enhancement factor was 3.5, which was lower than that of Ag half-shell arrays. The lower enhancement may be attributed to a decrease in the backward scattering of the excitation light owing to the intrinsic strong interband transition of Al at long visible wavelengths.

An EMG-CT method using multiple surface electrodes in the forearm.

Electromyography computed tomography (EMG-CT) method is proposed for visualizing the individual muscle activities in the human forearm. An EMG conduction model was formulated for reverse-estimation of muscle activities using EMG signals obtained with multi surface electrodes. The optimization process was calculated using sequential quadratic programming by comparing the estimated EMG values from the model with the measured values. The individual muscle activities in the deep region were estimated and used to produce an EMG tomographic image. For validation of the method, isometric contractions of finger muscles were examined for three subjects, applying a flexion load (4.9, 7.4 and 9.8 N) to the proximal interphalangeal joint of the middle finger. EMG signals in the forearm were recorded during the tasks using multiple surface electrodes, which were bound around the subject's forearm. The EMG-CT method illustrates the distribution of muscle activities within the forearm. The change in amplitude and area of activated muscles can be observed. The normalized muscle activities of all three subjects appear to increase monotonically with increases in the load. Kinesiologically, this method was able to estimate individual muscle activation values and could provide a novel tool for studying hand function and development of an examination for evaluating rehabilitation.

Aggressive large cell medulloblastoma extending to the extracranial region in brain-dead state.

INTRODUCTION: The authors describe the case of a 29-month-old boy who presented with acute non-communicating hydrocephalus caused by a small tumor in the fourth ventricle. He became brain-dead immediately and remained stable in that condition. MATERIALS AND METHODS: Six months later, despite being in a brain-dead state, a rapid direct tumor extension from the intracranial to extracranial region was observed, and chemoradiotherapy was performed following tumor biopsy. The histopathological diagnosis was large cell medulloblastoma. Although treatment was initially effective, the tumor again aggressively invaded the cervical muscles via the spinal canal. Comparative genomic hybridization (metaphase) analysis revealed a pattern of aberrations predictive of a poor prognosis (+1q, ?17p, +17q, and probable amplification of c-myc gene), and he eventually died 11 months after onset. RESULTS: Direct invasion of medulloblastoma from the intracranial to extracranial region is extremely rare, and, to our knowledge, this is the first report of medulloblastoma exhibiting rapid extension to the extracranial region in brain-dead state. CONCLUSIONS: For patients with medulloblastomas, careful observation is needed even in brain-dead state. The etiology of this rare condition as well as the genetic characteristics responsible for aggressive tumor behavior are discussed.

Nonthalamic generalization of ictal spikes in atypical absence seizures.

Reported here is the case of a boy who had a thalamic hemorrhage as a neonate and developed symptomatic focal epilepsy at 3 years of age. At the onset of focal epilepsy, the interictal spikes were localized in the occipital regions; over time, they gradually expanded, and atypical absences developed at the age of 6 years. When the patient was hospitalized at the age of 7 years 11 months, the spatiotemporal distribution of the synchronous spikes was assessed for each generalized spike-and-wave discharge observed on ictal electroencephalography. The occipital spikes were always the first to appear, and most spikes had posterior-to-anterior distribution. Occasionally, the frontopolar spikes appeared before the frontal spikes. These results indicate that the generalized spikes observed during atypical absences were formed by rapid generalization of the focally generated spikes from the occipital region through the cortex and the long association fibers, but not through the thalamus.

Interictal cerebral blood flow abnormality in cryptogenic West syndrome.

PURPOSE: To elucidate the abnormality of interictal regional cerebral blood flow (rCBF) of West syndrome at the onset. METHODS: Quantitative measurement of rCBF with an autoradiography method using N-isopropyl-((123)I) p-iodoamphetamine single photon emission computed tomography (SPECT) was performed on 14 infants with cryptogenic West syndrome. Regions of interest (ROIs) for rCBF were placed automatically using an automated ROI analysis software (three-dimensional stereotactic ROI template), and were grouped into 12 segments: callosomarginal, precentral, central, parietal, angular, temporal, posterior cerebral, pericallosal, lenticular nucleus, thalamus, hippocampus, and cerebellum. We compared rCBF between the patients and seven age-matched infants with cryptogenic focal epilepsy as a control group. The patients were divided into two groups according to the duration from onset to SPECT, to compare rCBF. RESULTS: Quantitative analysis revealed cerebral hypoperfusion in cryptogenic West syndrome with normal SPECT images under visual inspection. In bilateral central, posterior cerebral, pericallosal, lenticular nucleus, and hippocampus, and in the left parietal, temporal, and cerebellum, and in the right angular and thalamus segments there were statistical differences (p < 0.05). Compared with the duration from onset to SPECT, there were no significant differences of rCBF in all segments. DISCUSSION: Broad cerebral hypoperfusion with posterior predominance involving the hippocampus and lenticular nucleus implies that even cryptogenic West syndrome has a widespread cerebral dysfunction at least transiently, which would correspond to clinical manifestations of hypsarrhythmia and epileptic spasms. Hippocampal hypoperfusion suggests the dysfunction of hippocampal circuitry in the brain adrenal axis, and may contribute to subsequent cognitive impairment of cryptogenic West syndrome.

Gait posture estimation using wearable acceleration and gyro sensors.

A method for gait analysis using wearable acceleration sensors and gyro sensors is proposed in this work. The volunteers wore sensor units that included a tri-axis acceleration sensor and three single axis gyro sensors. The angular velocity data measured by the gyro sensors were used to estimate the translational acceleration in the gait analysis. The translational acceleration was then subtracted from the acceleration sensor measurements to obtain the gravitational acceleration, giving the orientation of the lower limb segments. Segment orientation along with body measurements were used to obtain the positions of hip, knee, and ankle joints to create stick figure models of the volunteers. This method can measure the three-dimensional positions of joint centers of the hip, knee, and ankle during movement. Experiments were carried out on the normal gait of three healthy volunteers. As a result, the flexion-extension (F-E) and the adduction-abduction (A-A) joint angles of the hips and the flexion-extension (F-E) joint angles of the knees were calculated and compared with a camera motion capture system. The correlation coefficients were above 0.88 for the hip F-E, higher than 0.72 for the hip A-A, better than 0.92 for the knee F-E. A moving stick figure model of each volunteer was created to visually confirm the walking posture. Further, the knee and ankle joint trajectories in the horizontal plane showed that the left and right legs were bilaterally symmetric.

A patient with early onset Huntington disease and severe cerebellar atrophy.

We report on a girl with early onset Huntington disease (HD). Her initial symptoms at 2 years of age included oral motor dysfunction and gait disturbance. Magnetic resonance imaging of the head revealed severe atrophy of both the vermis and the cerebellar cortex in addition to the common findings of basal ganglia including the caudate nuclei, putamen, and globus pallidus. Molecular analysis showed 160 CAG repeats in the HD gene. This mutation was inherited from her mother who was also affected, with a HD CAG expansion of 60 repeats. Cerebellar symptoms should be considered as a manifestation of early onset HD.

Gait analysis using gravitational acceleration measured by wearable sensors.

A novel method for measuring human gait posture using wearable sensor units is proposed. The sensor units consist of a tri-axial acceleration sensor and three gyro sensors aligned on three axes. The acceleration and angular velocity during walking were measured with seven sensor units worn on the abdomen and the lower limb segments (both thighs, shanks and feet). The three-dimensional positions of each joint are calculated from each segment length and joint angle. Joint angle can be estimated mechanically from the gravitational acceleration along the anterior axis of the segment. However, the acceleration data during walking includes three major components; translational acceleration, gravitational acceleration and external noise. Therefore, an optimization analysis was represented to separate only the gravitational acceleration from the acceleration data. Because the cyclic patterns of acceleration data can be found during constant walking, a FFT analysis was applied to obtain some characteristic frequencies in it. A pattern of gravitational acceleration was assumed using some parts of these characteristic frequencies. Every joint position was calculated from the pattern under the condition of physiological motion range of each joint. An optimized pattern of the gravitational acceleration was selected as a solution of an inverse problem. Gaits of three healthy volunteers were measured by walking for 20s on a flat floor. As a result, the acceleration data of every segment was measured simultaneously. The characteristic three-dimensional walking could be shown by the expression using a stick figure model. In addition, the trajectories of the knee joint in the horizontal plane could be checked by visual imaging on a PC. Therefore, this method provides important quantitive information for gait diagnosis.

[Epileptic spasms without hypsarrhythmia showing astatic seizures in clusters].

It is difficult to differentiate astatic seizures among atonic, myoclonic and tonic seizures without the help of ictal polygraphic recordings. We described a girl with epilepsy presenting periodic astasia caused by epileptic spasms. Her seizures had occurred in clusters since 1-year and 7-month of age. Her interictal electroencephalogram (EEG) showed intermittent diffuse (poly) spike (s) and wave discharges, without a trace of hypsarrhythmia. She had a diagnosis of epilepsy with myoclonic-astatic seizures at a previous hospital, and her seizures had been resistant to multiple antiepileptic agents. After she was referred to our hospital, the ictal video-EEG recordings were made before and after ACTH administration, which revealed that her astatic seizures were epileptic spasms with presumed cortical origin. We should carefully evaluate the astatic seizures during early childhood which may be an atypical presentation of epileptic spasms.

Developmental outcomes of cryptogenic West syndrome.

OBJECTIVE: To elucidate factors affecting the developmental outcome of cryptogenic West syndrome. STUDY DESIGN: Medical records of 32 patients, who were followed-up regularly for more than 1 year, were reviewed for clinical features: treatment lag, electroencephalography findings, and seizure evolution. Those features were compared between the normal outcome group (12 patients) and the delayed outcome group (20 patients). The outcomes were determined at the average age of 8.6 +/- 4.7 years. RESULTS: The duration from onset to any treatment of the delayed group was longer than that of the normal group (P < .05). Evolution of electroencephalographic findings showed that paroxysmal discharges reappeared in frontal regions more frequently in the delayed group than in the normal group (P < .05). In the delayed group, other types of seizure except for spasms occurred more commonly than in the normal group (P < .05). More patients of the delayed group evolved to focal epilepsy than those of the normal group (P < .05). CONCLUSIONS: Shorter treatment lag might be associated with a favorable outcome in cryptogenic West syndrome. Reappearance of paroxysmal discharges in the frontal regions and evolution to other types of seizure may be associated with undetectable lesions in the frontal regions.

Regional cerebral blood flow and developmental outcome in cryptogenic West syndrome.

PURPOSE: To elucidate the relation between alterations of regional cerebral blood flow (rCBF) by adrenocorticotropic hormone (ACTH) therapy and developmental outcomes of cryptogenic West syndrome. METHODS: Quantitative measurement of rCBF, with autoradiography method using N-isopropyl-((123)I) p-iodoamphetamine single photon emission computed tomography before and after ACTH therapy, was performed on 17 infants with cryptogenic West syndrome. Regions of interest for rCBF were placed bilaterally in the cerebellum, the thalamus, the caudate nucleus, and the frontal, temporal, and occipital cortices. RCBFs and the alteration ratios calculated from rCBFs before and after ACTH therapy were compared between two groups: the normal and delayed groups, which were divided by developmental outcome at 2 years old. RESULTS: RCBFs before the therapy were not different statistically between the normal and delayed groups, and between those groups and the control group also. RCBFs after ACTH therapy of the occipital, thalamic and cerebellar regions were different between the normal and delayed groups (p < 0.05). Alteration ratios were different between the normal and delayed groups, in all of the regions but the frontal region (p < 0.05). CONCLUSIONS: This study showed the differences of rCBF response by ACTH therapy between the normal and delayed groups of cryptogenic West syndrome. The difference of rCBF alteration might be associated with maturation of the cerebrovascular system, or influence of corticotropin-releasing hormone regarding the brain-adrenal-axis.

Human herpesvirus 6 encephalopathy predominantly affecting the frontal lobes.

Isolated cases of human herpesvirus 6 encephalopathy have recently been reported, although the pathophysiology remains largely unknown. To elucidate the changes specific to human herpesvirus 6 encephalopathy on diagnostic images, this study investigated magnetic resonance imaging findings in 10 patients with a diagnosis of human herpesvirus 6 encephalopathy including diffusion-weighted imaging in 6 of 10, and findings of cerebral blood flow imaging by single-photon emission computed tomography in 9 of 10 patients. No abnormalities were evident on T(1)-weighted, T(2)-weighted, or fluid-attenuated inversion-recovery magnetic resonance imaging during acute phases; however, diffusion-weighted imaging indicated abnormal hyperintensity in the subcortical white matter of the frontal lobes in all six patients during the acute phase. Cerebral blood flow single-photon emission computed tomography revealed decreased perfusion, predominantly in the frontal region of all nine patients during their clinical course. Disturbances predominantly affecting the frontal lobes (region) on magnetic resonance imaging and cerebral blood flow single-photon emission computed tomography were common in all patients, suggesting that the findings may be characteristic of human herpesvirus 6 encephalopathy.

Alteration of regional cerebral blood flow to thyrotropin-releasing hormone therapy in acute encephalitis and encephalopathy during childhood.

BACKGROUND: Thyrotropin-releasing hormone (TRH) is now used as a therapeutic agent for various neurological disorders. Animal study has shown that TRH was attributable to increased cerebral blood flow (CBF). AIMS: There have been occasional reports that TRH therapy was effective for improving symptoms of persistent disturbance of consciousness after acute encephalitis or encephalopathy during childhood. To determine whether TRH has an effect on increasing CBF to patients who have consciousness disturbance caused by acute encephalitis or encephalopathy, and to determine the optimal method of administration. METHODS: Sixteen patients aged 0.7-10.9 years (mean age, 3.2+/-3.1 years) who presented with persistent disturbance of consciousness resulting from acute encephalitis or encephalopathy and were treated with TRH. Regional CBF (rCBF) was measured by single photon emission computed tomography before and after TRH therapy. The alteration rates of rCBF were compared between the divided two groups concerning the dose levels, dosing periods, and treatment lags. RESULTS: The alteration rates of rCBF of the high dose group were higher than those of the low dose group. Differences in the dosing periods and treatment lags did not cause any significant difference of the alteration rates of rCBF. CONCLUSION: The study showed that higher alteration rates of the CBF were observed in the higher dosing group, and TRH have the potency of increasing CBF. TRH therapy would have the potential for effective treatment of persistent consciousness disturbance caused by childhood acute encephalitis or encephalopathy.

Therapeutic efficacy and adverse effects of adrenocorticotropic hormone therapy in west syndrome: differences in dosage of adrenocorticotropic hormone, onset of age, and cause.

OBJECTIVES: To determine the dosage and factors influencing efficacy of adrenocorticotropic hormone (ACTH) for West syndrome. STUDY DESIGN: A retrospective study of 135 patients receiving ACTH therapy with a synthetic analogue for initial effect, seizure outcome 1 year after therapy, and adverse effects. Efficacy and adverse effects were compared among the groups divided by clinical factors: dosage, treatment lag, onset age, and cause. RESULTS: One hundred thirteen patients had seizure control with ACTH. For more than 1 year after ACTH, 59 remained seizure free. Adverse effects were observed in 57, and ACTH therapy was discontinued in 23. The lowest dosage group (0.0125 mg/kg/d) had fewer episodes of discontinuation (P<.05), whereas differences in efficacy between different dosages were insignificant. None of the clinical factors correlated with initial effect. The earlier-onset group (<4 months) showed unfavorable seizure outcome 1 year after ACTH (P<.01). The cryptogenic patients showed better seizure outcome (P<.05) compared with the symptomatic. CONCLUSION: Synthetic ACTH therapy at a lower dosage is as effective as natural ACTH therapy at a higher dosage. Considering the adverse effects and the benefits for seizure control, the ACTH dosage of 0.0125 mg/kg/d (synthetic analogue) is more favorable than larger dosage.

Intravenous lidocaine for status epilepticus during childhood.

The clinical efficacy of lidocaine for convulsive status epilepticus in 53 convulsive episodes was examined in 37 children (17 males, 20 females). Mean age of patients receiving lidocaine was 3 years 7 months (SD 3y 5mo). Lidocaine administration achieved control of status epilepticus in 19 of 53 convulsive episodes (35.8%). Seizures ceased within 5 minutes of lidocaine administration in all 19 patients who were responsive to the drug. Regarding aetiology of status epilepticus and types of seizures, there was no statistical difference in effectiveness. Mild decrease of oxygen saturation, monitored by pulse oximetry, was observed in one patient, which improved by oxygenation using a mask. Lidocaine is a useful anticonvulsive agent; however, the response rate to lidocaine appears to be quite low, as less than half of the seizures were effectively controlled by lidocaine. Favourable properties of the drug include prompt responses, less alteration of consciousness, and fewer adverse effects, including less respiratory depression.

[MRI-diffusion weighted images of encephalopathy associated with human herpesvirus 6 infection].

Encephalopathy associated with human herpes virus 6 infection (HHV-6 encephalopathy) is not rare. The pathophysiology of HHV-6 encephalopathy has not been clearly established and diagnosis in the early stages is difficult. To elucidate the diagnostic value of MRI in the early stages of HHV-6 encephalopathy, we performed MRI including diffusion weighted imaging (DWI) on 6 patients. No abnormalities were found in the T1, T2 weighted images and fluid attenuated inversion recovery (FLAIR) images of any of the patients. DWI revealed an increase of signal in the subcortical white matter of the frontal lobes during the acute phase in all 6 patients. Follow-up MRI in two patients showed lesions expanded to the cortical regions, and disappearance of high signal-lesions followed by atrophy of the corresponding areas in 2 patients. To our knowledge, these findings have not previously been reported in acute encephalopathy and encephalitis and may be characteristic of HHV-6 encephalopathy. DWI may be a useful diagnostic procedure in the early stages of HHV-6 encephalopathy.

[Choice and administration sequence of antiepileptic agents for status epilepticus and frequent seizures in children].

We investigated the sequence of the administration, the efficacy and the safety of antiepileptic drugs (AED) given intravenously for the treatment of status epilepticus and frequent seizures in children. Our institute has a recommended sequence of AED administration for treatment of status epilepticus: the first-line agent is diazepam (0.3 - 0.5 mg/kg administered intravenously, once or twice). The second-line drugs include midazolam (0.15 - 0.4 mg/kg intravenously, once or twice, and if necessary, followed by continuous infusion at 0.06 - 0.18 mg/kg/hour), lidocaine (1 - 2 mg/kg intravenously, once or twice, and if necessary, followed by continuous infusion at 2 - 4 mg/kg/hour) and phenytoin (10 - 20 mg/kg, infused slowly). For those patients who previously experienced a seizure which was refractory to diazepam but responsive to the second-line agent, it was recommended to use the second-line agent as a first-line agent. When seizures were refractory to the first and second-line agents, thiopental was administered (3 - 10 mg/kg intravenously, and if necessary, followed by continuous infusion at 2 -5 mg/kg/hour). The etiologies of 177 occasions of status epilepticus and frequent seizures were categorized into two groups:epilepsy (n = 95) and situation-related seizures (n = 82). Situation-related seizures included febrile seizures (n = 44), acute encephalopathy/encephalitis (n = 31) and benign infantile convulsions (n = 7). The ages of the patients ranged from 0.1 to 18.4 years (average +/- SD:3.69 +/- 3.15 years). Diazepam was administered as the first-line drug on 157 of 177 occasions (88.7%). On 116 occasions the second-line agents were administered. Midazolam and lidocaine were injected as the second-line agent on 54 (46.6%), and on 33 (28.4%) occasions, respectively, although both midazolam and lidocaine injections were off-label use for seizure control in Japan. Thiopental was used as the third to fifth-line agent. Effective ratios (effective occasions/total occasions) of each drug were the following: thiopental 19/21 (90.4%), midazolam 57/99 (57.6%), lidocaine 25/60 (41.7%), phenytoin 16/41 (39.0%), diazepam 59/164 (36.0%). Thiopental was statistically more effective than midazolam, lidocaine, diazepam or phenytoin (p < 0.01), and midazolam was statistically more effective than diazepam (p < 0.01) or phenytoin (p < 0.05). Administration of thiopental caused complications more frequently than the other agents (p < 0.01): The complications by thiopental were severe in some cases requiring intratracheal intubations and artificial ventilation. From the viewpoint of both efficacy and safety, midazolam should be recommended as one of the first-line agents for status epilepticus.

[Single photon emission computed tomography findings in a case of alternating hemiplegia of childhood in relation to migraine].

Single photon emission computed tomography (SPECT) was performed 3 times during attacks and performed 4 times during postictal periods on a case of alternating hemiplegia of childhood. Hyperperfusion of the corresponding hemisphere to hemiparesis was suggested by asymmetric increase RI uptake during the ictal scans, whereas interictal scans showed symmetric topography of cerebral blood flow. Manifestations except hemiplegia included loss of consciousness and vomiting. These manifestations and ictal SPECT findings are the same evidence as hemiplegic migraine. It suggests that these two disorders have a similar pathophysiology. There are two interesting findings regarding this patient. The first finding is magnetic resonance imaging showed progressive cerebellar atrophy. Second finding is interictal SPECT showed a progressive decrease of cerebral perfusion, especially in cerebellar hemispheres. These two findings suggest alternating hemiplegia of childhood may be a chronic progressive disorder.