Biomedical subjects

S Nishida

Publications and source records attributed to S Nishida.

At least 235 records · Page 13Linked to original sources

PubMed1994

Complete interocular transfer of motion aftereffect with flickering test.

It has been suggested that motion aftereffect with static test patterns (static MAE) reflects activities at a lower level system that dominantly processes first-order motion, while MAE with a directionally ambiguous test (flicker MAE) reveals a higher level system where second-order motion signals as well as first-order signals are available. To test this hypothesis, we examined interocular transfer of static and flicker MAE. Flicker MAE should transfer more efficiently than static MAE if it occurs at a higher level system. In the first experiment, the adaptation stimulus was a drifting luminance grating (first-order motion), or a drifting grating defined by flicker or texture difference (second-order motion). The test stimulus was a luminance grating, either static or counterphasing. The results indicated that static MAE, which was induced only by first-order motion, transferred partially, as has been reported in previous studies, but the transfer of flicker MAE was nearly perfect with either first- or second-order adaptation stimuli. The second experiment with varied adaptation contrast indicated that this complete transfer was not due to a ceiling effect. These results supported the hypothesis that the underlying mechanism for flicker MAE is located at a level higher than the mechanism for static MAE.

Adaptation, Physiological↗

PubMed1994

Automatic detection method of P300 waveform in the single sweep records by using a neural network.

Event-related potentials (ERPs) are responses related to the recognition of certain stimuli. P300 is the most important positive component in the ERP and appears around 300 ms after the target stimulus in the oddball paradigm. In our previous work, we proposed a method for the automatic detection of the P300 waveform in single-sweep records by using a correlation technique. However, determination of the threshold values of the P300 waveform for the correlation study was not an easy task. In skirting this problem, we developed an automatic method of detecting a single-sweep P300 waveform by using an artificial neural network. We selected appropriate characteristic parameters of positive peaks as input signals for the input layer units, and the weights between the layers were determined by using the back-propagation algorithm. The neural network for P300 detection was obtained automatically, based on the data of ERPs obtained from 11 healthy males, and gave substantial accuracy for P300 detection. Furthermore, by using this neural network we clarified the way in which the P300 waveform is judged visually by each inspector.

Acoustic Stimulation↗

PubMed1994

Automatic detection of P300 in single sweep records of auditory event-related potential.

In the conventional recording of event-related potentials (ERPs) by the "oddball" paradigm, the subject may employ different strategies for processing one stimulus from the other even within the same session because of variable psychological state. Hence, "averaging" may not necessarily be suitable for recording ERP. We have therefore established a method for single trial recording of auditory ERPs by processing the EEG data through discrete Fourier transform followed by inverse discrete Fourier transform with the low pass filter of 8 Hz (digital filter). Each single sweep response of the processed data was visually evaluated as to whether it contained P300 or not by three investigators who were made completely blind with respect to the category of each response. As the result, a positive peak at a latency of 200-500 ms was recognized in the single sweep responses to target stimuli at a significantly greater frequency (40-60%) than in those to nontarget stimuli (0-18%). Then a new method for the automatic detection of P300 was established based on the data of 11 subjects belonging to the training group, by taking into account, in addition to the correlation coefficient analysis in which the template was computed specifically for each subject, other criteria with respect to the amplitude and waveforms, so that a good agreement with the results of visual inspection as to the presence or absence of P300 could be achieved for both target and nontarget responses. This automatic analysis method was successfully applied to five other subjects of the test group. The peak latency and amplitude of the detected positive peaks significantly varied among single target responses even within the same session. The reaction time significantly correlated positively with the peak latency of the detected positive peaks and negatively with the amplitude of those peaks, supporting the usefulness of the present method.

Adult↗

PubMed1994

Does intravenous glutamine prevent bacterial translocation in hemorrhagic shock?

Bacterial translocation across the gut wall may be associated with insult to the latter. In this situation, intestinal flora can enter the blood stream and lymph nodes and be transported to other organs. Glutamine is a nonessential amino acid not presently included in total parenteral nutrition (TPN) preparations. The use of glutamine-enriched TPN in the rat has resulted in a significant reduction in bacterial translocation. This study attempted to evaluate the role of glutamine in preventing bacterial translocation following hemorrhagic shock in a rat model. Forty Sprague-Dawley rats were equally divided into two groups. The controls were given TPN solution, while the treated group had glutamine instead of the standard alanine present in TPN. Hemorrhagic shock was induced in both groups and blood cultures were performed. Glutamine-treated rats did not show a significant difference in survival suggesting that it is of no particular value in severe hemorrhagic shock in rats.

Alanine↗

PubMed1994

Quantitative properties of plasma corticosterone elevation induced by naloxone-precipitated withdrawal in morphine-dependent rats.

Elevation of plasma corticosterone (PCS) has been used as an indicator of morphine withdrawal, but it is not clear whether the magnitude of elevation is related to the intensity of the dependence. The dose-dependent effects of naloxone on PCS and body weight were studied in male Sprague-Dawley rats rendered physically dependent on morphine by injecting increasing doses of 40-120 mg/kg/day, s.c. twice daily for 1-6 days. Naloxone (0.01-2.0 mg/kg, s.c.) was administered 3 hr after the last morphine administration. Naloxone elevated PCS levels in a dose-dependent manner in all groups treated with morphine, and the elevation was correlated with the number of days of morphine treatment. Naloxone also reduced dose-dependently the body weight in all groups treated with morphine; in this case, a reverse correlation was obtained between the body weight changes and the PCS levels. It was confirmed that PCS elevation is a quantitative sign of naloxone-precipitated morphine withdrawal and that the elevation is indicative of the degree of morphine physical dependence.

Analysis of Variance↗

PubMed1994

Effects of a mixture of peptidase inhibitors (amastatin, captopril and phosphoramidon) on Met-enkephalin-, beta-endorphin-, dynorphin-(1-13)- and electroacupuncture-induced antinociception in rats.

The effects of a mixture of three peptidase inhibitors (PIs), amastatin, captopril and phosphoramidon, on methionine-enkephalin (Met-enk)-, beta-endorphin (beta-end)-, dynorphin-(1-13) (Dyn)- and electroacupuncture (EA)-induced antinociception were compared in rats. EA was performed by passing electric pulses (3 Hz, 0.1-msec duration, for 45 min) through acupuncture needles inserted into the Hoku-point. The antinociceptive effect was estimated by the hind paw pressure test. The antinociceptive effects of Met-enk and beta-end injected i.c.v. or i.t. and of Dyn injected i.t. were clearly potentiated by the PIs pretreated by the same administration routes as used for the injection of opioid peptides. The antinociceptive effects of Met-enk, beta-end and Dyn injected i.c.v. were also potentiated significantly by i.t.-PIs. PIs injected into the periaqueductal gray (PAG) potentiated EA antinociception. However, the EA effect was not affected by i.t.-PIs and was rather attenuated by i.c.v.-PIs. These results suggest that: i) Met-enk hydrolyzing enzymes are involved in the degradation of not only Met-enk but also beta-end and Dyn in the rat central nervous system; ii) Met-enk and beta-end act on both supraspinal and spinal sites, while Dyn acts only on the spinal site; iii) EA antinociception is mediated by supraspinal Met-enk and/or beta-end; and iv) an anti-opiate peptide system may be activated by EA stimulation, being susceptible to Met-enk hydrolyzing enzymes.

Acupuncture Analgesia↗

PubMed1994

The dynamics of the visual system in combining conflicting KDE and binocular stereopsis cues.

The dynamics of the visual system in combining multiple depth cues were investigated by measuring the temporal change in the perceived 3-D shape of a random-dot stimulus with conflicting kinetic depth effect (KDE) and binocular stereopsis cues. The KDE shape perception dominated for the first few seconds, and then was gradually supplanted by the stereo shape perception. The effects of various pre-adaptation stimuli suggested that the temporal change in the perceived shape resulted from a self-adaptation of the KDE mechanism that occurs mainly at the levels of motion and relative motion detection.

Adult↗

PubMed1994

Perceived motion in structure from motion: pointing responses to the axis of rotation.

We investigated the ability to match finger orientation to the direction of the axis of rotation in structure-from-motion displays. Preliminary experiments verified that subjects could accurately use the index finger to report direction. The remainder of the experiments studied the perception of the axis of rotation from full rotations of a group of discrete points, the profiles of a rotating ellipsoid, and two views of a group of discrete points. Subjects' responses were analyzed by decomposing the pointing responses into their slant and tilt components. Overall, the results indicated that subjects were sensitive to both slant and tilt. However, when the axis of rotation was near the viewing direction, subjects had difficulty reporting tilt with profiles and two views and showed a large bias in their slant judgments with two views and full rotations. These results are not entirely consistent with theoretical predictions. The results, particularly for two views, suggest that additional constraints are used by humans in the recovery of structure from motion.

Attention↗

PubMed1994

[Histopathological findings of human thyroid tumors and signal intensities of magnetic resonance imaging (MRI)].

We studied the correlation between postoperative thyroid histological findings and signal intensities of preoperative magnetic resonance (MR) imaging. The study subjects included 20 cases with thyroid diseases (7 with adenomatous goiter, 2 with follicular adenoma, 6 with papillary carcinoma, 5 with follicular carcinoma). Solid diseases excluding secondary changes (calcification, hemorrhage, necrosis and fibrosis) were investigated by T1 weighted imaging (T1WI) and T2 weighted imaging (T2WI). The results of this study showed that high signal intensities on T1 and T2 indicated preserved follicular structures with a full colloid and sparse atypical cells, in both benign and malignant diseases. Trabecular and microfollicular structures that showed destruction of follicular components and sparse colloid, had a tendency to show low approximately iso signal intensities on T1WI imaging. These results suggest that differentiated grades and the cell proliferative ability of thyroid tumors may be predictable with a combination of T1WI and T2WI.

Adult↗

PubMed1994

Collagen fibrils as skeletal frame in monkey trabecular meshwork.

In an attempt to identify the characteristic skeletal frame of the trabecular meshwork, the three-dimensional architecture of collagen fibrillar bundles (collagen bundles) was studied by applying the NaOH cell-maceration method to the anterior segment of cynomolgus monkey eyes. Collagen bundles in the trabecular meshwork were found to be continuous with thinner collagen lamellae in the peripheral cornea and with the collagen fibril plexus in the ciliary body. The collagen core in the uveal cord was columnar in shape and was arranged parallel to the long axis. Collagen bundles were arranged as the layered network forming the fundamental framework of the trabecular meshwork. Most collagen bundles of the corneoscleral sheet were arranged circularly, parallel to the circumference of the limbus, and numerous slender bundles were observed side by side, forming the flat and membranous configuration of the sheet. The endothelial meshwork consisted of a network of fine and sparse collagen fibrils forming extracellular spaces and intercommunicating openings. The inner wall of the canal of Schlemm was seen as a netlike surface of sparse collagen fibrils with variously sized circular openings. The openings suggested the possibility that development of giant vacuoles corresponds to the circular openings under the inner endothelial cell lining.

Animals↗

PubMed1994

Assessment of lupus nephritis activity using urinary retinol-binding protein.

We evaluated the presence of proximal renal tubular dysfunction as measured by urinary retinol-binding protein (RBP) in 70 patients with systemic lupus erythematosus. Renal disease activity was assessed using the British Isles Lupus Assessment Group (BILAG) index. This is a clinical-laboratory score based on the principle of the physician's intention to treat. Increased urinary RBP (> 400 micrograms/l) was detected in 17 of 22 (77%) patients with active nephritis, six of 18 (33%) patients with probably active nephritis, one of nine (12%) cases with stable renal disease, and one of 21 (5%) cases without apparent renal disease (P < 0.01). Compared to initial values, mean urinary RBP decreased significantly in six patients evaluated after improvement of the exacerbation of renal disease. There was a positive correlation between urinary RBP and 24-h proteinuria (r = 0.40, P < 0.01), and an inverse correlation between urinary RBP and creatinine clearance (r = -0.60, P < 0.01). In a multivariate analysis adjusting for duration of disease, blood pressure, 24-h proteinuria, and creatinine clearance, mean urinary RBP continued to be significantly and progressively greater for patients with no renal disease, stable renal disease, probably active and active nephritis. Proximal tubular dysfunction is frequent in patients with active lupus nephritis. This association cannot be completely explained by the effects of increased total proteinuria, reduced glomerular filtration rate, and systemic hypertension. Urinary RBP seems to be a marker of renal disease activity. This test may be clinically useful to differentiate patients with active lupus nephritis from those with stable or absent renal disease.

Adolescent↗

PubMed1994

[Objective evaluation of apparent accommodation of pseudophakic eyes].

In 23 (9 males and 14 females) pseudophakic eyes which had a biconvex type intraocular lens (IOL) implanted after cataract extraction, we objectively measured changes in the anterior chamber (AC) depth caused by axial movement of the IOL accompanying accommodation of the contralateral phakic fellow eye, using a Schimpflug slit image with an anterior eye segment image analysis system (Nidek, EAS-1000, Japan). In 114 phakic eyes of 57 persons as controls, AC depths accompanying accommodation from distances of 5 m to 30 cm and 10 cm decreased with increasing age. The decreased mean value of AC depth with accommodation from distances of 5 m to 30 cm was 0.17 mm in patients in their teens, 0.15 mm in patients in their 20 s, 0.10 mm in the 30 s, 0.06 mm in the 40 s, 0.05 mm in the 50 s, and 0.03 mm in the 60 s. The decrease of AC depth with accommodation at a distance of 10 cm was 0 in patients in their 60 s. In the pseudophakic eye changes in anterior chamber depth caused by focusing at short distances were less than 0.04 mm, and decreasing rate of anterior chamber depth (DRAC) was less than 1% in all the pseudophakic eyes. Movement of IOL on the optical axis was too subtle to account for apparent accommodation of the pseudophakic eye.

Accommodation, Ocular↗

PubMed1994

[Analysis of foetal death rates in Japan based on legitimacy status of foetus and period of gestation].

The purpose of this study was to analyze spontaneous and artificial foetal death rates from the context of legitimacy status of the foetus and period of gestation. Data over five years, 1985 to 1989, were averaged and mainly used for analysis and compared to reference data for five other years, 1970 to 1974, with the following results. In the latter half of the 1980's, spontaneous foetal death rates for the illegitimate were very high compared to the legitimate. In all periods of gestation, spontaneous foetal death rates of the illegitimate were higher than those of the legitimate. For the 16th to the 31st week of gestation especially, rates of the illegitimate were ten times or more that of the legitimate. Spontaneous foetal deaths before the 24th week of gestation constituted nearly 90% of all spontaneous foetal deaths in the illegitimate. By comparison, the percentage was 66% in the legitimate. This data suggests that some artificial foetal deaths were being notified as spontaneous and this phenomenon caused the differences mentioned above. Artificial foetal death rates of the illegitimate were very high compared to the legitimate. Before the 24th week of gestation, artificial foetal death rates were 50 to 100 times that of the legitimate. These characteristics observed in the latter half of the 1980's, were also seen in the first half of the 1970's. From the comparison of the two observation periods, the registration of foetal deaths appears to be improving, especially in the period of 12 to 15 weeks of gestation.

Abortion, Induced↗

PubMed1993

Human plasma alpha 2-macroglobulin and von Willebrand factor possess covalently linked ABO(H) blood group antigens in subjects with corresponding ABO phenotype.

We recently identified ABO(H) blood group structures in Asn-linked sugar chains of human von Willebrand factor (vWF) purified from factor VIII concentrates (J Biol Chem 267:8723, 1992). We surveyed plasma glycoproteins carrying ABO(H) blood group antigens by Western blotting analysis and sandwich enzyme-linked immunosorbent assay using blood group-specific monoclonal antibodies (MoAbs) and a lectin. Two major plasma proteins showing apparent molecular weight of about 180 Kd and 270 Kd by sodium dodecyl sulfate polyacrylamide gel electrophoresis reacted with blood group-specific MoAbs and Ulex europaeus lectin I in accordance with donor blood group. Direct sequence analysis of the protein bands showed their identity with the N-terminal sequences of alpha 2-macroglobulin (alpha 2M) and vWF, respectively. The two bands also reacted with anti-alpha 2M and anti-vWF antibodies. The alpha 2M and vWF prepared from plasma by immunoprecipitation showed the appropriate blood group antigenicity. After incubation with endoglycosidase F, both alpha 2M and vWF lost almost all reactivity with anti-blood group reagents. About 90% of plasma vWF, but only approximately 10% of alpha 2M, was immunoprecipitated with anti-blood group antibody. These results indicate that at least two plasma glycoproteins, vWF and alpha 2M, possess Asn-linked ABO(H) blood group antigens in normal individuals with corresponding ABO phenotype. Therefore, ABO(H) blood group antigens in plasma glycoproteins should be considered during preparation of plasma materials for therapeutic use.

ABO Blood-Group System↗

PubMed1993

Manganese superoxide dismutase content and localization in human thyroid tumours.

Manganese-containing superoxide dismutase (Mn-SOD) content and its immunohistochemical localization in human thyroid tumours and some other thyroid diseases were examined and compared with adjacent normal thyroid tissue. Enzyme-linked immunosorbent assay (ELISA) was used in this study for the measurement of Mn-SOD. The content of Mn-SOD tended to increase in diffuse hyperplasia, adenomatous goitre, and follicular adenoma. In papillary carcinoma, it was significantly higher than in adjacent normal thyroid tissue. Follicular carcinoma also revealed a markedly high Mn-SOD content. In the immunohistochemical study, adjacent normal thyroid tissue showed granular positive staining of Mn-SOD in the cytoplasm. An increase of Mn-SOD was observed in the papillary proliferative lesion of diffuse hyperplasia and in the follicles adjacent to lymphoid tissue in chronic thyroiditis with hypothyroidism. Strong positive staining of Mn-SOD was observed in papillary and follicular carcinomas, whereas in anaplastic carcinoma staining was markedly less intense. These results indicate that the Mn-SOD content varies according to the degree of differentiation of thyroid carcinomas.

Adenoma↗

PubMed1993

Potential bile acid metabolites. 19. The epimeric 3 alpha,6,7 beta-trihydroxy- and 3 alpha,6,7 beta,12 alpha-tetrahydroxy-5 alpha-cholanoic acids.

Syntheses by a new procedure of the known 3 alpha,6 alpha,7 beta- and 3 alpha,6 beta,7 beta-trihydroxy-5 alpha-cholanoic acids, and of the once-reported analog 3 alpha,6 alpha,7 beta,12 alpha-, as well as the new 3 alpha,6 beta,7 beta,12 alpha-tetrahydroxy-5 alpha-cholanoic acids, are described. Key intermediates of the syntheses are the 6-oxo-7 beta-ols of the respective 5 alpha-cholanoic acids (and their methyl esters) prepared by allomerization at C-5 of appropriate 6-bromo-7-oxo derivatives of the corresponding 5 beta-acids. Successful reduction of the 6,7-ketols to the desired products depended on the proper choice of reagents, either Zn(BH4)2 or Li/NH3/MeOH.

Ammonia↗

PubMed1993

Method for single-trial recording of somatosensory evoked potentials.

Evoked potentials (EPs) in response to stimuli are recorded from a human scalp contaminated with noise. To improve the signal-to-noise ratio, averaging methods have been widely used for the recorded data. However, when the waveforms of EP for each stimulus are not identical, the average waveform of the EP deteriorates. Variation of the EP waveform to each stimulus itself is important information for the EP. In this paper, a recording method for single somatosensory evoked potential (SEP) waveform is proposed, in which three kinds of band-pass filters were selectively used during three specific time sectors for each interstimulus interval. For the late section of the interval, an EEG waveform prediction method was applied to eliminate contaminated alpha rhythm components. By using the proposed method, we were successful in detecting the single SEP waveform.

Adult↗

PubMed1993

Primary structures of platelet aggregation inhibitors (disintegrins) autoproteolytically released from snake venom hemorrhagic metalloproteinases and new fluorogenic peptide substrates for these enzymes.

A hemorrhagic protein (60 kDa), HR1B, present in the venom of Trimeresurus flavoviridis is a mosaic protein consisting of an NH2-terminal metalloproteinase-domain, a disintegrin (platelet aggregation inhibitor)-like domain, and a unique COOH-terminal Cys-rich domain. Since the gross structures of HR1B and protein precursors of disintegrins, trigramin, and rhodostomin, all of which contain the metalloproteinase domain, are similar, many disintegrins so far detected in snake venoms are assumed to be autoproteolytic fragments released from precursors. In ongoing related experiments, the newly purified hemorrhagic metalloproteinases, HR1A from T. flavoviridis venom and HT-1 from Crotalus ruber ruber venom, in addition to HR1B, were autoproteolyzed, in the absence of Ca2+, at 37 degrees C for 3-12 h. Under these conditions, HR1A, HR1B, and HT-1 each released a single major fragment of 32, 34, and 31 kDa, respectively. The entire amino acid sequences of the isolated fragments indicated the presence of disintegrin-like and Cys-rich domains in the COOH-terminal regions of HR1A, HR1B, and HT-1, respectively. It seems likely that so-called disintegrins probably originate from various metalloproteinases present in venom. On the bases of peptide sequences close to the autoproteolytic cleavage sites of these metalloproteinases and the sites of fibrinogen cleaved by these enzymes, we synthesized new intramolecularly quenched fluorogenic peptide substrates. Among the 10 peptides tested, 2-aminobenzoyl (Abz)-Ser-Pro-Met-Leu-2,4-dinitroanilinoethylamide (Dna) proved to be the best substrate for venom metalloproteinase, as deduced from kinetic analyses.

Amino Acid Sequence↗