Characterization of unexpected postural changes during robot-assisted gait training in paraplegic patients.

STUDY DESIGN: This is a retrospective study. OBJECTIVES: The objectives of this study were to categorize unexpected postural changes (UPCs) during gait training in paraplegic patients with wearable gait-assist robots, to reveal the incidence of the UPC and its time-dependent changes during initial gait training period and to investigate neurological level-specific differences. SETTING: This study was conducted in Fujita Health University, Aichi, Japan. METHODS: We investigated five patients (46.2±14.6 years; lesion level: T6:3, T12:2). All patients had previously achieved gait with wearable robot and walker at supervision level. The UPCs were counted for 2 years and classified according to their type. The time-course data were calculated from the incidence of UPCs for 10 days from initial gait training with the walker. The neurological level-specific differences were investigated between T6 and T12 injuries. RESULTS: Eighty-five UPCs were observed and classified into three categories: anterior breakdown, posterior breakdown (PBD) and mal-timing. The average rate over the entire period was 0.96±0.62 (incidents/h/subject). PBD, which was defined as hyperflexion of both hip joints, occurred with the highest frequency (0.64±0.64 incidents/h/subject). During initial gait training, there was a gradual decrease in the occurrence of UPC. For neurological level-specific differences, UPCs were observed more frequently in T6 injuries (1.36±0.35 incidents/h/subject) compared with T12 injuries (0.36±0.31 incidents/h/subject). CONCLUSION: PBDs might be the result of near collisions between the trunk of the user and the walker, which make it difficult for the users to move their trunk over an anterior stance limb. Training that is focused upon well-timed forward movements of the walker might be required to avoid the occurrence of this common UPC.

Permanent acceptance of mouse cardiac allografts with CD40 siRNA to induce regulatory myeloid cells by use of a novel polysaccharide siRNA delivery system.

The CD40/CD154 co-stimulatory pathway is crucial in alloimmune response. We developed a novel small interfering RNA (siRNA) delivery system with a poly-dA extension at the 5'-end of the siRNA sense strand that was stably incorporated into 1,3-ß-glucan (schizophyllan, SPG). This was captured and incorporated into dendritic cells (DCs) through its receptor, Dectin-1, specifically silencing CD40 genes (siCD40) to exert immunoregulatory activity. siCD40/SPG-treated CBA mice permanently accepted B10 fully mismatched cardiac allografts. Consistent with graft survival, the infiltration of CD4(+), CD8(+) T cells into the graft was lower, and that the numbers of CD40(low)CD11c(+) DCs cells and CD4(+)Foxp3(+)cells were increased in both the graft and in the recipient spleen. In addition, naive CBA recipients given an adoptive transfer of splenocytes from the primary recipients with siCD40/SPG accepted a heart graft from donor-type B10, but not third-party Balb/c mice. In conclusion, the treatment with siCD40/SPG targeting DCs could generate antigen-specific Tregs, resulting in the permanent acceptance of mouse cardiac allografts. These findings have important implications for clarifying the mechanism underlying the induction of tolerance in DCs, and also highlight the potential of immunomodulation and the feasibility of siRNA-based clinical therapy in the transplantation field.

Evidence against a role of gap junctions in vestibular compensation.

Vestibular compensation following unilateral labyrinthectomy is associated with modifications of the membrane and firing properties of central vestibular neurons. To determine whether gap junctions could be involved in this process, immunofluorescent detection of neuronal connexin 36 and astrocytic connexin 43 was performed in the medial vestibular nucleus (MVN) of rats. In non-lesioned animals, strong staining was observed with anti-connexin 43 antibodies, while moderate staining was obtained with the anti-connexin 36 antibody. However, the expression of either type of connexin was not modified following unilateral labyrinthectomy. These morphological observations were complemented by pharmacological tests performed during extracellular recordings of MVN neurons in guinea pig brainstem slices. In non-lesioned animals, the gap junction blocker carbenoxolone reversibly decreased or suppressed the spontaneous discharge of about 60% of MVN neurons. This reduction was often associated with a long-duration disruption of the regularity of spike discharge. Both effects were mimicked by several other gap junction blockers, but not by glycyrrhizic acid, an analog of carbenoxolone that does not block gap junctions but reproduces its non-specific effects, nor by the selective inhibitor of astrocytic connexin-based networks endothelin-1. Similar effects of carbenoxolone were obtained on the spontaneous activity of ipsilesional MVN neurons recorded in brainstem slices taken from labyrinthectomized animals. Altogether, these results suggest that neuronal gap junctions are involved in shaping the spontaneous activity of MVN neurons. However, unilateral labyrinthectomy does not affect the expression of gap junctions in vestibular nuclei nor their implication in the regulation of neuronal activity.

A sialic acid-binding lectin from the mushroom Hericium erinaceum.

A lectin was isolated from the mushroom Hericium erinaceum. This lectin is composed of two different subunits of 15 and 16 kDa and the molecular mass of the intact lectin was estimated to be 54 kDa by gel filtration. It exhibits specificity towards sialic acids, especially N-glycolylneuraminic acid.

Structural similarity of cytochrome c2 from Rhodopseudomonas viridis to mitochondrial cytochromes c revealed by its crystal structure at 2.7 A resolution.

The crystal structure of cytochrome c2 from Rhodopseudomonas viridis has been refined using molecular dynamics and restrained least-squares methods to a crystallographic R-factor of 0.216 at 2.7 A resolution. A structural comparison between Rps. viridis cytochrome c2 and the other bacterial cytochromes c2 or mitochondrial cytochromes c indicates that the overall protein foldings are very similar to each other with the exception of the surface loop and terminal region of the polypeptide chain. However, the position and hydrogen-bond pattern of the evolutionarily conserved water molecule buried within the heme binding pocket in Rps. viridis cytochrome c2 are common to those in the mitochondrial cytochromes c. This fact indicates that Rps. viridis cytochrome c2 is structurally more similar to mitochondrial cytochromes c than to the other bacterial cytochromes c2.

Role of cholinergic mossy fibers in medial vestibular and prepositus hypoglossal nuclei in vestibular compensation.

Several lines of evidence have suggested that acetylcholine is a possible neurotransmitter/neuromodulator involved in vestibular compensation. Further, the central vestibular system, oculo- and spino-motor neurons and peripheral vestibular efferents contain abundant cholinergic neurons. However, details of cholinergic effective sites during vestibular compensation remain to be clarified. In the present study, we selectively damaged rat vestibulo-floccular and vestibulo-uvulonodular cholinergic mossy fibers using ethylcholine mustard aziridinium ions. In these treated animals, unilateral labyrinthectomy caused more severe vestibulo-ocular deficits especially during the initial stage. From these findings we suggest that vestibulo-floccular and vestibulo-uvulonodular cholinergic mossy fibers contribute to the restoration of a balance between intervestibular nuclear activities for the induction of vestibular compensation during the initial stage.

Median sternotomy with bilateral bullous resection for unilateral spontaneous pneumothorax, with special reference to operative indications.

Simultaneous bilateral pulmonary operations were done through median sternotomy in 29 patients with unilateral spontaneous pneumothorax, because bullae and blebs of the lung are frequently bilateral. Bullous lesions on the contralateral lung were encountered in eight of 10 patients (80%) in whom no roentgenographic evidence of the additional lesions had been detected preoperatively. Postoperative examination of percent vital capacity was satisfactory (more than 80%) in 21 of 23 patients followed up over a month after operation, and this suggested that simultaneous bilateral thoracotomy through median sternotomy does not lead to a much greater decrease in postoperative pulmonary function than does unilateral operation. To determine the indications for this method of treatment, we investigated the frequency of subsequent development of contralateral pneumothorax in 178 patients who initially had unilateral spontaneous pneumothorax. The occurrence rate of contralateral pneumothorax with visible bullae on chest roentgenograms was as high as 60% and 33.3% in patients in their teens and in those in their 20s, respectively. In conclusion, therefore, the bilateral operative approach should be considered, especially in teenaged patients with contralateral bullae, in whom the highest contralateral occurrence rate of 60% was found.

Unilateral labyrinthectomy downregulates glutamate receptor delta-2 expression in the rat vestibulocerebellum.

The differential display method was applied to identify genes expression of which is altered in the flocculus after unilateral labyrinthectomy (UL). Total RNA from sham operated and labyrinthectomized rat flocculi was isolated, amplified by PCR using an arbitrary primer set and separated by electrophoresis on a polyacrylamide gel. PCR products the amounts of which were significantly lower in samples from labyrinthectomized animals than those from controls, were cut out of the gel and sequenced. One of the cDNA fragments showed 100% nucleotide sequence identity to the rat glutamate receptor (GluR) delta-2 subunit mRNA. In situ hybridization autoradiography showed that GluR delta-2 mRNA expression was intensely located to the floccular Purkinje cell layers. Furthermore, northern blot analysis showed that the delta-2 mRNA expression was decreased for at least two days after UL in accordance with diminishing UL-induced behavioral deficits. Therefore, it is suggested that the downregulation of delta-2 mRNA is involved in vestibular compensation. UL-induced spontaneous nystagmus (SN) was then examined in GluR delta-2 mutant mice. The frequency of SN in mutant mice was significantly more than that in wild mice until 12 h after UL. GluR delta-2-associated synaptic efficacy may be changed for the induction of vestibular compensation at the initial stage.

Effect of glycosylation on carbamazepine-serum protein binding in humans.

Effect of glycosylation on carbamazepine-serum protein binding was investigated in vitro using the serum from 24 diabetics and 10 healthy subjects, and in vivo using the serum from 49 patients receiving carbamazepine. In both binding studies, nonglycosylated albumin levels were strongly correlated with the carbamazepine free fraction (%). To evaluate the effect of glycosylation in vivo, the patients were divided into two groups according to glycosylated albumin levels (%): a healthy group (10-15) and a high group (15 and over). The high group had decreased nonglycosylated albumin levels and an increased carbamazepine free fraction. Our results suggest that one should not use total concentrations for the monitoring of serum carbamazepine concentrations, but free concentrations, especially in poorly controlled diabetics.

Vestibular modulation of plasma vasopressin levels in rats.

Recent studies, which have shown an increase of plasma vasopressin (VP) in experimental motion sickness and the efficacy of VP antagonists for motion sickness, suggest an important role of VP in the development of vestibulo-autonomic responses. We have recently found evidence of the co-existence of vasopressinergic neurons with the stress-sensitive chemokinergic neuronal system in the hypothalamo-pituitary pathway in rats, which uses cytokine-induced neutrophil chemoattractant (CINC) as an effector molecule. In this study, to elucidate possible roles of VP and CINC in the vestibulo-autonomic responses, we simultaneously measured plasma VP and CINC concentrations after electrical or caloric vestibular stimulation in urethane-anesthetized rats. Electrical vestibular stimulation with more than 200 microA increased the plasma levels of VP in a current intensity-dependent manner, and stimulation with 500 microA increased the plasma VP levels to 350% of the normal control group, which received no stimulation. Caloric vestibular stimulation with cold water increased the plasma VP levels to 262% of the control group, which received caloric stimulation with water at 37 degrees C, and stimulation with warm water tended to increase the plasma VP levels. Plasma CINC levels were neither affected by electrical nor caloric vestibular stimulation. These findings indicate that vestibular stimulation increased plasma levels of VP but not CINC, and this vestibular-induced activation of VP neurons may be involved in a mechanism of vestibulo-autonomic responses.

Temporal stream of cortical representation for auditory spatial localization in human hemispheres.

We measured human evoked magnetic fields to binaural sounds with an interaural time delay as a cue for auditory localization. By analyzing the topography of auditory-evoked magnetic fields in the middle-latency, we demonstrated that particular cortical regions represent the direction of sound localization by their activity level. Upon presenting a binaural sound, the first representations were found in the middle frontal region as well as the superior temporal region of the right hemisphere approximately 19 ms after the stimulation, but their patterns differed. Other cortical regions including the prefrontal and parietal spatial areas were affected within roughly 60 ms. The results showed that the right hemisphere is dominant even in the preattentive stage of auditory spatial processing of sounds from different directions.

Effect of AF64A, a cholinergic neurotoxin, on footshock stimulation-induced locus coeruleus excitation in rats.

We studied the effect of ethylcholine mustard aziridinium ion (AF64A), a cholinergic neurotoxin, on the footshock stimulation (FS)-induced excitation of the locus coeruleus (LC) neurons in rats. The FS-evoked LC excitation was significantly reduced in AF64A-treated rats, in comparison with normal rats. In particular, the early component of LC excitation was less pronounced. The number of choline acetyltransferase immunoreactive neurons in the septal complex was significantly lower than those in normal rats, except for in the ventral subgroup. These findings suggest that the cholinergic neuron system is involved in the early component of LC excitation in rats.

A new liquid material for embolization of arteriovenous malformations.

We have developed a liquid material for embolization of arteriovenous malformations that is a mixture of ethylene vinyl alcohol copolymer and metrizamide dissolved in dimethyl sulfoxide. Upon contact with blood, dimethyl sulfoxide rapidly diffuses into the blood and forms an ethylene vinyl alcohol copolymer elastic soft sponge that obstructs both the feeder and the nidus. The material, which is not adhesive, was used for embolization of three left cerebral arteriovenous malformations with satisfactory results.

Single-photon emission CT and MR findings in Klüver-Bucy syndrome after Reye syndrome.

We present the MR and single-photon emission CT findings in a 3-year-old patient in whom Klüver-Bucy syndrome developed after Reye syndrome. MR images showed diffuse brain atrophy, which was predominant in the temporal lobes, and single-photon emission CT scans showed decreased cerebral perfusion in the bilateral temporal lobes and associated cortical areas.

Intracranial and orbital cavernous angiomas. A review of 30 cases.

The authors review 30 documented cases of intracranial and orbital cavernous angiomas treated at their institution between 1965 and 1984. The diagnosis was based on computerized tomography (CT) or surgery; three patients were treated in the pre-CT era (1965 to 1976) and 27 since the advent of CT. The number of cases diagnosed preoperatively markedly increased after the introduction of CT, and 22 cases were verified histopathologically at surgery. Six cases were in children (aged 2 months to 17 years) and 24 in adults (aged 19 to 73 years). There was no significant sex difference (male:female ratio was 14:16). Nineteen lesions were intraparenchymal, five were intraventricular, three were in the middle fossa, two were intraorbital, and one originated from the tentorium. Symptoms varied according to the site of the lesion; hemorrhage occurred in 11 cases. Calcifications were seen on CT scans in all cases, but on plain skull films in only two. Angiography revealed hypovascular masses in all cases excluding those with lesions in the middle fossa; in two cases, tumor stain could be detected only with prolonged-injection angiography. Radionuclide brain scanning showed a dense hot area in eight of 19 patients. Recent experience has shown that magnetic resonance imaging clarified anatomic relationships that were obscure on CT. The overall outcome was favorable except for one patient who died in the postoperative period. The clinical results in this series are summarized and some diagnostic and therapeutic problems are discussed.

Role of asparagine-linked carbohydrates in pulmonary metastasis of B16-F10 murine melanoma cells: implication through glycosylation inhibition by nojirimycin.

N-linked oligosaccharide moieties of cell surface glycoconjugates may be involved in the metastatic potential of tumour cells. Many studies have examined the anti-metastatic properties of inhibitors of carbohydrate synthesis or processing in vitro. However, there has so far been little evidence of such inhibitory factors on metastasis in vivo because of the general high toxicity of the inhibitors. In this study, we found nojirimycin (NM) to be a substantially non-toxic carbohydrate synthesis inhibitor that inhibited the experimental metastasis of B16-F10 melanoma cells not only in vitro but also in vivo. When NM was administered intraperitoneally to syngeneic C57BL/6 mice, the inhibition was dose-dependent, with 40-75% suppression of pulmonary colonization observed after 5 days exposure to NM (at 0.4 or 4 mg/day). An in vitro lectin sensitivity assay showed that NM-treated B16-F10 cells were less susceptible to the lectin concanavalin-A, suggesting alteration or decrease of high mannose-type carbohydrate moieties on the cell surface. Further in vitro analysis of adhesiveness between B16-F10 cells and endothelial cells demonstrated that NM treatment causes reduced binding of B16-F10 cells to endothelial cells. We have also studied the effect of NM on natural killer (NK) cells in mice. NM treatment elicited no substantial increase in the cytotoxic activity of splenic NK cells against YAC-1 target cells. These results indicate that NM acts on the process of adhesion and that specific structures of the cell surface carbohydrate moieties may be involved in the colonization phase of metastasis in vivo.

Histamine release from the hypothalamus induced by gravity change in rats and space motion sickness.

Freely moving rats were exposed to 2 g hypergravity in an animal centrifuge device to produce motion sickness. Histamine release from the anterior hypothalamus of the rats was measured in vivo with a microdialysis technique. After a 2-h load of 2 g hypergravity, rats ate kaolin. Because pica, eating a nonnutritive substance such as kaolin, is a behavioral index of motion sickness in rats, this finding indicates that the rats suffered from motion sickness. During 2 g hypergravity for 2-h, histamine release from the hypothalamus was transiently increased. In contrast, neither the transient increase of histamine release nor the kaolin consumption were induced by 2 g hypergravity in bilaterally labyrinthectomized rats. Pretreatment with alpha-fluoromethylhistidine, an inhibitor of histamine-synthesizing enzyme, decreased both the basal and hypergravity-induced releases of histamine from the hypothalamus and suppressed the kaolin consumption induced by hypergravity. Taken together, these findings suggest that the vestibular information of changes in gravity activate the histaminergic neuron system, resulting in the development of motion sickness. More prolonged stimulation, a 4-h load of 2 g hypergravity, induced significant increase of kaolin consumption on postdays 1-3, though rats ate kaolin on postdays 1-2 after 2 g hypergravity for 2 h. During 2 g hypergravity for 4 h, the initial transient increase of histamine release was followed by the gradual increase of histamine release after the end of centrifugation. It is suggested that rats adapted to the hypergravity environment after centrifugation for 4 h, but not 2 h, so that the change in gravity from 2 g to 1 g became a provocative stimulation. We, therefore, concluded that motion sickness in rats induced by a negative change in gravity can be used as a simulation of space motion sickness, which is induced by exposure to microgravity. Histaminergic activation in the development of motion sickness induced by negative change in gravity might be an underlying mechanism of space motion sickness.

Neural mechanisms of motion sickness.

Three kinds of neurotransmitters: histamine, acetylcholine and noradrenaline, play important roles in the neural processes of motion sickness, because antihistamines, scopolamine and amphetamine are effective in preventing motion sickness. Histamine H1-receptors are involved in the development of the symptoms and signs of motion sickness, including emesis. On provocative motion stimuli, a neural mismatch signal activates the histaminergic neuron system in the hypothalamus, and the histaminergic descending impulse stimulates H1-receptors in the emetic center of the brainstem. The histaminergic input to the emetic center through H1-receptors is independent of dopamine D2-receptors in the chemoreceptor trigger zone in the area postrema and serotonin 5HT3-receptors in the visceral afferent, which are also involved in the emetic reflex. Antihistamines block emetic H1-receptors to prevent motion sickness. Scopolamine prevents motion sickness by modifying the neural store to reduce the neural mismatch signal and by facilitating the adaptation/habituation processes. The noradrenergic neuron system in the locus coeruleus is suppressed by the neural mismatch signal. Amphetamine antagonizes mismatch-induced suppression of noradrenergic neural transmission, resulting in preventing motion sickness.

Sound lateralization in patients with lesions including the auditory cortex: comparison of interaural time difference (ITD) discrimination and interaural intensity difference (IID) discrimination.

We examined sound lateralization using dichotic presentation of noises in 15 patients with left unilateral (12 patients) or bilateral (3 patients) temporal lobe lesions, that included the auditory cortex, and evaluated their abilities to discriminate interaural time and intensity difference (ITD, IID) separately. On the ITD discrimination test, discrimination thresholds in patients with left unilateral lesions were significantly higher than those in normal subjects, but all patients with left unilateral lesions could detect ITD. However, none of 3 patients with bilateral lesions could detect ITD. On the IID discrimination test, all patients with either unilateral or bilateral lesions could detect IID. IID discrimination thresholds in these patients were significantly higher than those in normal subjects. The auditory cortex plays an important role in discriminating both cues, but appears to be necessary for discriminating ITD.

Age-related alteration of carbamazepine-serum protein binding in man.

To determine whether biological maturation influences the kinetics of carbamazepine-serum protein binding, the carbamazepine free fraction (%) was investigated in the serum of 66 patients, ranging from 4 to 83 years, with epilepsy or trigeminal neuralgia, treated with carbamazepine alone or carbamazepine in combination with phenytoin, phenobarbital, and/or valproic acid, over a relatively long period. Biochemical parameters such as levels of albumin and non-glycated albumin showed a significant relationship with carbamazepine free fraction (r = -0.521, P < 0.001 for albumin; r = -0.700, P < 0.001 for non-glycated albumin). Non-glycated albumin was more strongly correlated with carbamazepine free fraction. The biochemical parameters showed a significant relationship with age (r =-0.243, P < 0.1 for albumin; r =0.666, P < 0.001 for glycated albumin; r = -0.459, P < 0.001 for non-glycated albumin; r = 0.640, P < 0.001 for carbamazepine free fraction). Glycated albumin (%), non-glycated albumin and carbamazepine free fraction (%) were strongly correlated with age, whereas albumin showed only a weak correlation with age. To evaluate the effects of ageing on carbamazepine-serum protein binding, the patients were divided into three groups according to age: children, 4-15 years; adults, 16-64 years; elderly, 65-83 years. Albumin and non-glycated albumin were much lower, and glycated albumin (%) and carbamazepine free fraction (%) much higher in the elderly group than in the other two groups. The results of this study showed that the major ligand of carbamazepine in the serum was non-glycated albumin, which decreased with age. These observations suggested that in elderly patients, the elevation of free carbamazepine concentrations in the serum caused by reduced non-glycated albumin levels, induces increases in the sensitivity of the pharmacological effects of carbamazepine and the risk of drug interactions.