Biomedical subjects

Y Ejima

Publications and source records attributed to Y Ejima.

At least 19 recordsLinked to original sources

PubMed2001

Clinical significance of serum pulmonary surfactant proteins a and d for the early detection of radiation pneumonitis.

PURPOSE: Radiation pneumonitis (RP) is one of the most serious complications for patients who receive thoracic irradiation. To avoid this, early diagnosis of radiation pneumonitis is extremely important. The purpose of the present study is to investigate whether serum pulmonary surfactant proteins A and D (SP-A and SP-D, respectively) could be useful markers for RP. METHODS AND MATERIALS: Eighty-six patients (lung cancer: 42 [primary: 39, metastatic: 3], breast cancer: 23, esophageal cancer: 21) who underwent radiation therapy were prospectively studied. Radiation doses ranged from 30-76 Gy (median, 58 Gy). Serum SP-A and SP-D levels were evaluated sequentially by a sandwich enzyme-linked immunosorbent assay (ELISA) method before, during, and throughout the follow-up period until the development of symptomatic RP or until one year after completion of radiotherapy. Specificity of the ELISA results was confirmed by Western blot analysis. Patients symptomatic for RP were graded according to the Common Toxicity Criteria. RESULTS: RP occurred in 19 patients. Serum SP-D levels of patients with RP were sequentially higher than those in patients without RP. In the monitoring, serum SP-D levels at 50-60 Gy showed greater sensitivity and positive predictive values for RP detection (74% and 68%, respectively) than SP-A (26% and 21%, respectively). Western blot analysis showed that the development of RP was due to overproduction, but not proteolysis of surfactant proteins. CONCLUSION: We confirm that serum SP-A and SP-D monitoring is a practical and useful diagnostic method for the early detection of RP.

Aged↗

PubMed2001

A VEP study on visual processing of figural geometry.

The possibility of a link between medial axes (hereafter called symmetries) and figure salience has recently been proposed [Vision Res. 38 (1998) 2323; Vision Res. 38 (1998) 2429]. In this paper we investigated the characteristics of transient visual evoked potentials (VEPs) associated with stimulus figures designed to have different symmetries. Significant trends were observed for VEP components N1 (160-190 ms) and P2 (220-250 ms). N1 and P2 had shorter peak latencies for stimuli with greater symmetry peak amplitudes.

Adult↗

PubMed2001

Hyperbaric oxygen therapy given 30 minutes after spinal cord ischemia attenuates selective motor neuron death in rabbits.

OBJECTIVE: Spinal cord ischemia sometimes causes paraplegia because the spinal motor neuron cells are vulnerable to ischemia. Although various protective remedies for spinal cord injury have been reported, there have been few established clinical methods. Although hyperbaric oxygen (HBO) has been used clinically as a treatment for ischemia, the reason for its effectiveness is still uncertain because sufficient experimental data are lacking. DESIGN: Prospective, randomized, controlled study. SETTING: Experimental animal research laboratory in a university research center. SUBJECTS: Twenty-three Japanese white rabbits, weighing 2-3 kg. INTERVENTIONS: A modified rabbit spinal cord ischemia model of infrarenal aortic occlusion for 15 mins was employed. Rabbits were randomly assigned to four groups; the rabbits in group A did not undergo ischemic insults (n = 5). The rabbits in groups B and C underwent ischemic insult for 15 mins, followed by 1 hr of HBO treatment at 3 atm absolute with 100% oxygen at 30 mins (n = 6) or 6 hrs (n = 7) after reperfusion, respectively. The rabbits in group D underwent ischemic insult for 15 mins without HBO treatment (n = 5). MEASUREMENTS AND MAIN RESULTS: We observed neurologic functions for 14 days. The sections of the spinal cords were stained with hematoxylin and eosin, and the number of spinal motor neurons in ventral region was counted by light microscopy. All rabbits in groups A and B could stand, whereas all rabbits in groups C and D showed irreversible paraplegia on days 2 and 14 after reperfusion. Spinal motor neurons in ventral gray matter in groups C and D decreased significantly compared with those in groups A and B. CONCLUSIONS: HBO therapy shortly after ischemic insult had protective effects against ischemic spinal cord damage. However, delayed treatment with HBO did not change the prognosis.

Animals↗

PubMed2001

Differences in respiratory parameters during continuous positive airway pressure and pressure support ventilation in infants and children.

The extubation criteria of pressure support ventilation (PSV) in infants and children were not yet established. We studied the differences in respiratory parameters during continuous positive airway pressure (CPAP) using a constant flow type ventilator and PSV using a demand valve type ventilator. Nineteen children (1.9+/-2.9 years old) who were ready to extubate were studied. All patients had recovered from their respiratory failure and had finished the weaning process of the ventilatory support. They were scheduled for extubation on the next day when their ventilatory mode had attained to a PSV of 3 cmH2O with a positive end-expiratory pressure (PEEP) of 3 cmH2O. On the extubation day, tidal volume (TV) and respiratory frequency (RR) were measured with a respiratory monitor at two modes (CPAP of 3 cmH2O and PSV), and the duty ratio (DR) and mean inspiratory flow (MF) were calculated. The sequence of the ventilatory mode was random. No case required reintubation. TV was 61.6+/-54.9 during CPAP and 67.7+/-61.4 ml during PSV, and RR was 38.5+/-10.6 and 37.1+/-8.8 beats/min., respectively. DR was 0.382+/-0.067 and 0.359+/-0.085, and MF was 96.6+/-78.3 and 101.0+/-69.0 ml/sec., respectively. The measured parameters and calculated values showed no significant difference between CPAP and PSV. It was found that the respiratory parameters were almost the same with CPAP and PSV immediately before the extubation, and the previous extubation criteria of CPAP can be used.

Blood Gas Analysis↗

PubMed2001

Evaluation of tube compensation in the Bennett 840 ventilator--a new ventilatory mode to support spontaneous breathing.

Respiratory care patients frequently require intubation with an endotracheal tube (ETT). Unfortunately, the ETT introduces a pressure drop (deltaPETT) that depends on the respiratory flow rate, thus increasing the work of breathing (WOB). Pressure support ventilation (PSV) cannot adequately compensate for this added WOB, because the degree of inspiratory assistance by PSV is fixed. Therefore, a technique called tube compensation (TC) has been developed to address deltaPETT. We examined the performance of TC and compared it with PSV of 5 cm H2O. The experimental system was constructed from a simulator, a test-lung, flow sensors, and a Bennett 840, and the respiratory parameters were studied. ETTs with IDs 6.5 and 8.0 mm were used. The quadratic approximation obtained for deltaPETT in the 6.5-mm ETT was 2.316 x flow + 7.910 x flow2, while that for the 8.0-mm ETT was 1.881 x flow + 3.353 x flow2. The maximum inspiratory flow (MIF) increased significantly with increasing TC, but tidal volume and inspiratory time did not show marked changes. The MIF for TC of 100% was larger than that for PSV of 5 cm H2O, when the 6.5-mm ID was used, but there was no significant difference between these modes when an ID of 8.0 mm was used. For both the 6.5 and 8.0-mm IDs, the PV loop corresponding to 100% TC was larger than that for PSV of 5 cm H2O. TC only compensated for the WOB caused by the ETT, whereas PSV compensated for the WOB caused by the ETT and the demand valve system. In clinical use, the differences between TC and PSV will demand attention.

Humans↗

PubMed2000

Aberrant splicing of the ATM gene associated with shortening of the intronic mononucleotide tract in human colon tumor cell lines: a novel mutation target of microsatellite instability.

Inherited mutations of the ATM gene are responsible for the human autosomal recessive disorder ataxia-telangiectasia (A-T) characterized by pleiotropic clinical manifestations. ATM mutations are also involved in the development of sporadic human cancers such as T-cell prolymphocytic leukemia and B-cell chronic lymphocytic leukemia. Little is known, however, on the association of ATM mutations with non-lymphoid malignancy. Here, we analyzed a panel of cell lines derived from human solid tumors for the presence of ATM mutations. PCR-SSCP analysis of 25 tumor cell lines revealed 50 sequence alterations in 16 cell lines. The most striking feature was a high frequency of deletions within the intronic mononucleotide tracts exclusively in the 5 colon tumor cell lines with microsatellite instability, which accounted for 62% of the sequence alterations observed here. Generation of aberrant splicing variants (497del22 or 1236del372) was associated with 2 such intronic deletions at splice acceptor sites preceding ATM exon 8 or exon 12, respectively. The level of ATM protein was partially depressed in the 3 cell lines where expression of protein-truncating 497del22 transcripts dominated. This implies that ATM is a novel mutation target of microsatellite instability where abnormal transcripts are generated indirectly by intronic mutations, which is distinct from the other mutation targets such as the type II TGF-beta receptor gene or BAX, where exonic repeats are directly affected.

Ataxia Telangiectasia Mutated Proteins↗

PubMed2000

Effects of roll and pitch components in retinal flow on heading judgement.

We investigated effects of roll (rotation around line of sight) and pitch (rotation around the horizontal axis) components of retinal flow on heading judgement from visual motion information. It was found that performance level of human observers for yaw (rotation around the vertical axis) plus pitch is little different from that for only yaw although there is bias in perceived heading toward the fixation point, and that heading judgement is fairly robust with respect to roll. It was also found that there are some observers who can perceive heading with pitch, yaw and roll at a roll rate of 11.5 degrees /s without extra-retinal information. It suggests that there exist compensation mechanisms for roll in the human visual system.

Algorithms↗

PubMed2000

Heading judgement from second-order motion.

We examined human heading judgement from second-order motion which was generated by random-dots with the contrast polarity determined randomly on each frame. It was found that human observers can judge heading fairly accurately from second-order motion when pure translation is simulated or when self-motion toward a ground plane with gaze rotation is simulated but they cannot when self-motion toward cloud-like random dots with gaze rotations is simulated. It is suggested that the human visual system cannot decompose the flow fields into rotational and translational components by using second-order motion information alone, but it can do in some ways from the flow field of the ground plane.

Contrast Sensitivity↗

PubMed2000

A model of human heading judgement in forward motion.

We developed a new computational model of human heading judgement from retinal flow. The model uses two assumptions: a large number of sampling points in the flow field and a symmetric sampling region around the origin. The algorithm estimates self-rotation parameters by calculating statistics whose expectations correspond to the rotation parameters. After the rotational components are removed from the retinal flow, the heading direction is recovered from the flow field. Performance of the model was compared with human data in three psychophysical experiments. In the first experiment, we generated stimuli which simulated self-motion toward the ground, a cloud or a frontoparallel plane and found that the simulation results of the model were consistent with human performance. In the second and third experiment, we measured the slope of the perceived versus simulated heading function when a perturbation velocity weighted according to the distance relative to the fixation distance was added to the vertical velocity component under the cloud condition. It was found that as the magnitude of the perturbation was increased, the slope of the function increased. The characteristics observed in the experiments can be explained well by the proposed model.

Computer Simulation↗

PubMed2000

Summation between nearby motion signals and facilitative/inhibitory interactions between distant motion signals.

To explain the finding that motion assimilation was dominant between nearby motion signals while motion contrast between distant ones, a center-surround antagonistic mechanism was proposed [Nawrot & Sekuler (1990). Vision Research, 30, 1439-1451]. However, motion assimilation occurred not only between nearby signals but also between distant ones, suggesting the existence of a center-surround non-antagonistic mechanism [Ido. Ohtani & Ejima (1997). Vision Research, 37, 1565-1574]. The present study was designed to provide direct evidence for the non-antagonistic mechanism, and to examine further the motion interactions which operate in different spatial scales. The nature of motion interaction between the test and the inducer was examined by varying the size, the number of frames, the frame duration and the inter-frame displacement of random-dot kinematograms. The results were consistent with the notion that there are three types of interactions in human motion processing; one is a summation process effective within nearby regions, and the other two are facilitative and inhibitory induction processes operating over larger spatial scales. Analysis of the results in terms of the Fourier components suggests that the facilitative and the inhibitory induction processes may be sensitive, respectively to the lower and the higher temporal frequency components of the stimulus.

Humans↗

PubMed2000

Combined therapy with hypothermia and anticytokine agents in influenza A encephalopathy.

Two children with influenza A-related encephalopathy were treated with a combination of mild hypothermia (deep body temperature of the forehead: 35 degrees C) and anticytokine agents (high-dose methylprednisolone and ulinastatin), while receiving amantadine. One of the cases exhibited acute necrotizing encephalopathy on computed tomography (CT). Although no severe complications occurred, correctable hypokalemia and hyperglycemia occurred in both cases. Both patients recovered without any neurological sequelae. Our therapeutic protocol appears to be effective for managing influenza A-related encephalopathy.

Amantadine↗

PubMed2000

The patchwork engine: image segmentation from shape symmetries.

We propose blind segmentation of images into shape-related 'patches' based on pre-calculated local symmetries (Van Tonder, G.J. & Ejima, Y. (1999). (Forthcoming a) Flexible computation of shape symmetries. Submitted for publication) in shape boundary contours. First, lateral weights between all points in the boundary contour map are assigned analogous to Euclidean distance maps in watershed segmentation (Beucher, S. & Lantejoul, C. (1979). Use of watersheds in contour detection. Proceedings of the International Workshop on Image Processing, CCETT, Rennes, France.). Lateral weights are then used to: (1) extract local maxima in symmetries; (2) link maxima within locally enclosed boundary contours; and (3) reconstruct shape contours using symmetry maxima as 'seeds'. The new model overcomes weaknesses of watershed segmentation. The new model closes gaps in relatively more solid image contours, but it is fundamentally different from methods based on contour interpolation (Grossberg, S., Mingolla, E. & Todorovć, D. (1989). A neural network architecture for preattentive vision, IEEE Transactions on Biomedical Engineering 36, 65-84; Heitger, F. & von der Heydt, R. (1993). A computational model of neural contour processing: figure-ground segregation and illusory contours. Proceedings of the Fourth International Conference on Computer Vision, IEEE Computer Society Press, Washington D.C. (pp. 32-40)). Images are segmented into shape-relevant color-by-number-like patches which compare well to related methods (Gauch, J. & Pizer, M. (1993). The intensity axis of symmetry and its application to image segmentation, IEEE Transactions on Pattern Analysis and Machine Intelligence, 15 (8), 753-770; Ilg, W. & Ogniewicz, R. (1995). The application of Voronoi skeletons to perceptual grouping in line images, Proceedings of the 11th International Conference on Pattern Recognition, The Hague, The Netherlands, pp. 382-385; Zhu, S.C. & Yuille, A.L. (1996) FORMS: a flexible object recognition and modeling system, International Journal of Computer Vision, 20 (3), 187-212.). Two primitive operations, comparison and merging of patches, are proposed as drives for exposing more global shape contours from patches. We conclude that symmetry goes beyond abstract shape morphology: it can contribute to figure-ground segmentation in early vision and form part of primitive operations needed to create hypotheses of complex shape.

Animals↗

PubMed2000

Bottom-up clues in target finding: why a Dalmatian may be mistaken for an elephant.

We provide informal psychophysical support for a strategy where bottom-up features guide attention toward a target, and the top-down path interprets hypothetical shapes at the target location--as opposed to a dominant top-down approach. In our survey, for which we used the familiar picture of a Dalmatian dog against a dappled background, (i) 75% of subjects initially found a bulging body which overlaps that of the dog, but final 'top-down' percepts were unexpected: nearly all subjects assigned an incorrect head and limbs to the body; (ii) after random rotation of texture elements overlapping computed features only 45% of subjects reported a bulging body, with a few adding limbs etc. The picture of the Dalmatian dog must therefore contain many bottom-up features--a top-down strategy may find 'incorrect' targets at correct target locations. Computational support for these claims is more easily constructed than one may expect. We could compute at least two bottom-up features, both useful in 3-D surface interpolation from 2-D scenes, which yielded significant values at the location of the Dalmatian dog: anisotropic texture compression and affine texture distortion cues. We therefore conclude that the role of top-down processing is overstated in a traditional example such as the Dalmatian dog picture.

Cues↗

PubMed2000

From image segmentation to anti-textons.

We apply the 'patchwork engine' (PE; van Tonder and Ejima, 2000 Neural Networks forthcoming) to encode spaces between textons in an attempt to find a suitable feature representation of anti-textons [Williams and Julesz, 1991, in Neural Networks for Perception volume 1: Human and Machine Perception Ed. H Wechsler (San Diego, CA: Academic Press); 1992, Proceedings of the National Academy of Sciences of the USA 89 6531-6534]. With computed anti-textons it is possible to show that tessellation and distribution of anti-textons can differ from that of textons depending on the ratio of texton size to anti-texton size. From this we hypothesise that variability of anti-textons can enhance texture segregation, and test our hypothesis in two psychophysical experiments. Texture segregation asymmetry is the topic of the first test. We found that targets on backgrounds with regular anti-textons segregate more strongly than on backgrounds with highly variable anti-textons. This neatly complements other explanations for texture segregation asymmetry (e.g. Rubenstein and Sagi, 1990 Journal of the Optical Society of America A 7 1632-1643). Second the relative significance of textons and anti-textons in human texture segregation is investigated for a limited set of texture patterns. Subjects consistently judged a combination of texton and anti-texton gradients as more conspicuous than texton-only gradients, and judged texton-only gradients as being more conspicuous than anti-texton-only gradients. In the absence of strong texton gradients the regularity versus irregularity of anti-textons agrees with perceived texture segregation. Using PE outputs as anti-texton features thus enabled the conception of various useful tests on texture segregation. The PE is originally intended as a general image segmentation method based on symmetry axes. With this paper we therefore hope to relate anti-textons with visual processing in a wider sense.

Contrast Sensitivity↗

PubMed2000

WAF1 accumulation by carbon-ion beam and alpha-particle irradiation in human glioblastoma cultured cells.

PURPOSE: There have been no reports about the effects of heavy-ion beams on the expression of the WAF1 gene, although ionizing radiation such as y-rays and X-rays is well known to induce WAF1 (p21/CIP1/sdi1) gene expression in a p53-dependent manner. In the present study, it was examined whether WAF1 accumulation was induced after carbon-ion (C-) beam or alpha-particle irradiation in four glioblastoma cell lines. MATERIALS AND METHODS: A colony assay for radiosensitivity and Western blot analysis of WAF1 were applied to two human glioblastoma cell lines, A-172 bearing wild-type p53 (wtp53) and T98G bearing mutated p53 (mp53). A-172/neo and A-172/mp53 were transfected with a control vector (containing only a neo selection marker) and a mp53 expression vector respectively. RESULTS: The amount of WAF1 increased markedly after X-ray irradiation in A-172 and A-172/neo cells but not in T98G and A-172/mp53 cells. The level of WAF1 reached a plateau at 3-10 h after X-ray irradiation at 5 Gy in A-172 and A-172/neo cells. Likewise, the levels of WAF1 in A-172 and A-172/neo cells reached a plateau at 3-10 h and 6-24 h after C-beam (3.0 Gy) and alpha-particle (4.5 Gy) irradiation respectively. The amount of WAF1 increased markedly in a dose-dependent manner 10 h after X-ray, C-beam or alpha-particle irradiation in A-172 and A-172/neo cells but not in T98G or A-172/mp53 cells. In addition, cell survival assay showed that these cell lines were most sensitive to C-beams, less sensitive to alpha-particles and least sensitive to X-rays at 10% survival. There was no difference in sensitivity among these cell lines against C-beam and alpha-particle irradiation whereas wtp53 cells (A-172 and A-172/neo) were more sensitive to X-rays than mp53 cells (A-172/mp53 and T98G). CONCLUSIONS: These results indicate that C-beams and alpha-particles induce p53-dependent WAF1 accumulation as well as is the case with X-rays, suggesting that WAF1 protein accumulation may not contribute to cell killing.

Alpha Particles↗

PubMed2000

Method for recovery of heading from motion.

A new method for recovery of heading from motion is developed on the basis of Longuet-Higgins and Prazdny's algorithm [Proc. R. Soc. London Ser. B 208, 385 (1980)]. In the algorithm a radial virtual flow field is generated and the difference between the original velocity field and the virtual radial field is computed. The difference vectors, which are directed to the heading point in the projected plane, allow us to estimate the direction of heading. The simulations of the algorithm were performed, and it was shown that the method estimates the direction of heading accurately.

Algorithms↗

PubMed2000

[Anesthetic management of a patient with hemophilia A for left modified Blalock-Taussig shunt].

We gave anesthesia to a patient with hemophilia A for left modified Blalock-Taussig shunt. The patient was a twenty five-day-old boy with pulmonary atresia. We performed the bolus injection test of factor VIII concentrate in preoperative period. His factor VIII activity increased from 9.3 to 113.3% after a bolus injection of 165 units. To keep his factor VIII activity above 80% in perioperative period, a bolus of 125 units of recombinant factor VIII concentrate was injected at anesthesia induction, 125 units 2 hours after the start of the operation, and 125 units 6 hours after the end of the operation. Factor VIII activity 2 hours after anesthesia induction increased only 37.8%, and we had to infuse recombinant factor VIII concentrate additionally. We measured factor VIII activity during operation, and he finally received total of 415 units of factor VIII concentrate. Hydroxyethyl starch infusion, blood transfusion and bleeding in the perioperative period might have caused the factor VIII activity to decrease beyond our expectation. We should infuse factor VIII concentrate properly measuring the factor VIII activity during this operation.

Anastomosis, Surgical↗

PubMed1999

Effect of high-density extremely low frequency magnetic field on sister chromatid exchanges in mouse m5S cells.

The induction of sister chromatid exchanges (SCEs) was evaluated in the cultured mouse m5S cells after exposure to extremely low frequency magnetic field (ELFMF; 5, 50 and 400 mT). Exposure to 5 mT and 50 mT ELFMF led to a very small increase in the frequency of SCEs, but no significant difference was observed between exposed and unexposed control cells. The cells exposed to 400 mT ELFMF exhibited a significant elevation of the SCE frequencies. There was no significant difference between data from treatments with mitomycin-C (MMC) alone and from combined treatments of MMC plus ELFMF (400 mT) at any MMC concentrations from 4 to 40 nM. These results suggest that exposure to highest-density ELFMF of 400 mT may induce DNA damage, resulting in an elevation of the SCE frequencies. We suppose that there may be a threshold for the elevation of the SCE frequencies, that is at least over the magnetic density of 50 mT.

Animals↗