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Biomedical subjects

S Uchida

Publications and source records attributed to S Uchida.

At least 235 records · Page 13Linked to original sources
PubMed1996

Computerization of Fujimori's method of waveform recognition. A review and methodological considerations for its application to all-night sleep EEG.

This article critically reviews 8 computer implementations of Fujimori's method for EEG waveform recognition, with methodological considerations for the application of this method to the analysis of all-night sleep EEG. Fujimori's method has been considered one of the most appropriate waveform analyses for EEG. This kind of analysis is advantageous for measuring frequency and amplitude of each EEG wave separately. However, current implementations have drawbacks which must be resolved before they can be used on all-night sleep EEG. An optimal sampling rate should be determined which is appropriate to the purpose of analysis. Amplitude thresholds for wave recognition, which are now set arbitrarily, should also be improved. Measurement of waves in higher orders of superimposition is also necessary, although existing systems are limited to the second order. Additional algorithms, such as for the separate detection of sleep slow waves, may be useful. Further applications for Fujimori's method are suggested.

Electroencephalography↗
PubMed1996

Stimulation of saphenous afferent nerve produces vasodilatation of the vasa nervorum via an axon reflex-like mechanism in the sciatic nerve of anesthetized rats.

The present study was intended to examine the physiological relevance of peptidergic afferent vasodilative fibers in the regulation of blood flow in the vasa nervorum, with special reference to the axon reflex. The response of nerve blood flow (NBF) in the sciatic nerve to electrical stimulation of saphenous nerve afferents was examined using laser Doppler flowmetry in anesthetized rats whose lumbosacral afferents and efferents had been disconnected from the spinal cord. Repetitive electrical stimulation of unmyelinated fibers in the central cut end of the saphenous nerve produced an increase in NBF in the sciatic nerve ipsilateral to the stimulation, independent of changes in mean arterial blood pressure. This increase was abolished by topical application of a calcitonin gene-related peptide (CGRP) receptor antagonist, hCGRP (8-37). In conclusion, NBF in the sciatic nerve is regulated via an axon reflex-like mechanism by unmyelinated afferent CGRP containing vasodilators with collaterals in the saphenous nerve.

Anesthesia↗
PubMed1996

Evidence of involvement of cytotoxic antibodies directed against patients's HLA class II produced by transfused donor-derived B cells in post-transfusion graft-versus-host disease.

Post-transfusion graft-versus-host disease (PTGVHD) is one of the most severe side-effects of blood transfusion. To characterize the effector cells causing this disease, we cloned lymphocytes from a PTGVHD patient's peripheral blood. T-cell and B-cell clones were established, the origins of which were proven to be transfused donor lymphocytes. It was found that the B cells produced IgG that mediated complement-dependent cytotoxicity to the cells bearing the patient's HLA class II genotype. Our results suggest, for the first time, the involvement of B-cell-produced cytotoxic antibodies directed against patient's HLA class II in the pathogenesis of PTGVHD.

Antibodies↗
PubMed1996

Deposition velocity of gaseous organic iodine from the atmosphere to rice plants.

To obtain parameter values for the assessment of 129I transfer from the atmosphere to rice, deposition of CH3I to rice plants has been studied. The mass normalized deposition velocity (VD) of CH3I for rough (unhulled) rice was 0.00048 cm3 g-1 s-1, which is about 1/300 of that of I2. Translocation of iodine, deposited as CH3I on leaves and stems, to rice grain was negligibly small. Distribution of iodine between hull and inner part of the grain was found to depend also on the chemical forms of atmospheric iodine to be deposited. The ratio of the iodine distribution in a grain exposed to CH3I was as follows: rough rice:brown rice (hulled rice):polished rice = 1.0:0.49:0.38. The distribution ratio in polished grains for CH3I exposed rice was about 20 times higher than that for I2.

Food Contamination, Radioactive↗
PubMed1996

Repressive regulation of the aquaporin-2 gene.

Expression of aquaporin-2 (AQP2) is exclusively limited to kidney collecting duct cells, and this strictly limited expression could be mediated by transcription of the gene. We first examined AQP2 mRNA expression in many cultured epithelial cells derived from kidney. Northern blot using OK, LLC-PK1, Madin-Darby canine kidney, and outer medullary collecting duct (OMCD) cells and primary culture of inner medullary collecting duct (IMCD) cells did not reveal any significant signal. A more sensitive method, ribonuclease protection assay, could detect a faint signal in OMCD cells when they were bathed in a hypertonic medium. Reverse-transcribed polymerase chain reaction applied to primary culture of IMCD cells showed a rapid dissipation of AQP2 mRNA within 4 days after culture. A reporter gene assay performed in the 1st day of primary culture of IMCD cells showed that the 5' region up to -2.9 kb worked as a promoter. Deletion experiments showed that at least two regions, from -434 to -364 and from -153 to -84, contain negatively acting cis-elements. When connected to a heterologous promoter, these regions repressed the activity in an orientation-dependent manner. These results suggest that transcription of AQP2 gene is strictly regulated and its ability is rapidly depressed in culture condition. This cell differentiation-specific expression of the gene may be, at least in part, mediated by the repressors present in its 5'-flanking region.

Animals↗
PubMed1996

Reflex modulation of catecholamine secretion and adrenal sympathetic nerve activity by acupuncture-like stimulation in anesthetized rat.

The effects of acupuncture-like stimulation of the abdomen and a hindlimb on the secretion rates of adrenal medullary catecholamine hormones (adrenaline and noradrenaline) and adrenal sympathetic efferent nerve activity were studied using urethane-anesthetized rats. Acupuncture needles (diameter of 340 microns) were inserted into the skin and underlying muscles of either the abdomen or a hindlimb to a depth of 10 mm and then twisted at a frequency of about 1 Hz for 90 s. The stimuli induced three types of response in both catecholamine secretion and adrenal sympathetic nerve activity (i.e., decrease, increase, and no change). These different responses corresponded with three similar types of response in mean arterial pressure. In spinalized animals, the stimuli produced only increases in both catecholamine secretion and nerve activity, and abdominal stimulation elicited a larger response than hindlimb stimulation. The responses of adrenal nerve activity were eliminated after surgically severing the afferent nerves innervating the abdomen and hindlimb. These findings indicate that the secretion of adrenal medullary hormones is controlled reflexively by acupuncture-like stimulation via excitation of somatic afferent nerves and also via the reflex responses of adrenal sympathetic efferent nerves. Both the spinal cord and supraspinal structures act as reflex centers. The excitatory reflex properties at the propriospinal and segmental levels are modified into a generalized, either excitatory or inhibitory, response by supraspinal structures.

Abdomen↗
PubMed1996

Alterations in calcium antagonist receptors and calcium content in senescent brain and attenuation by nimodipine and nicardipine.

Characteristics of L- and N-type calcium (Ca++) channel antagonist receptors in brains of senescence-accelerated prone mouse (SAMP8) showing age-related deterioration of learning and memory were examined by using (+)-[3H]PN 200-110 and [125I]omega-conotoxin GVIA as radioligands. There was a tendency toward consistent decrease in Bmax for both radioligands in seven brain regions of SAMP8 compared with the control mouse. The reduction in (+)-[3H]Pn 200-110 binding sites was statistically significant in the hippocampus, midbrain and pons/medulla oblongata, and that in [125I]omega-conotoxin binding sites was significant in the cerebral cortex, corpus striatum and pons/medulla oblongata. On the other hand, there was a marked elevation in Ca++ content in the brain of SAMP8. Chronic p.o. administration (0.3, 1 and 3 mg/kg/day for 3 weeks) of nimodipine and nicardipine to SAMP8 caused a significant increase in the Bmax values of (+)-[3H]PN 200-110 binding in the cerebral cortex and hippocampus. This may reflect up-regulation of brain Ca++ channel antagonist receptors as a result of the prolonged blockade by nimodipine and nicardipine. On the other hand, similar administration of amlodipine and nilvadipine failed to produce an enhancement of Bmax values of (+)-[3H]PN 200-110 binding, whereas both drugs at high doses evoked a significant increase in the apparent dissociation constant. Furthermore, the brain Ca++ content in SAMP8 was markedly reduced by chronic p.o. administration of Ca++ channel antagonists, and the decrease was equivalently observed for all of four 1,4-dihydropyridine antagonists in spite of the difference in the effect on brain receptors. In conclusion, the present study suggests that there is an altered Ca++ homeostasis in the SAMP8 brain that is effectively attenuated by chronic administration of nimodipine and nicardipine. Hence SAMP8 may be a suitable animal model for evaluating the therapeutic effects of Ca++ channel antagonists on neurological disorders associated with the aging brain.

Aging↗
PubMed1996

[A study on relapse of schizophrenic patients--10-year-follow-up investigation after initial admission].

Ten year prognosis of schizophrenic patients after their initial admission was studied. The subjects of the present investigation were 106 schizophrenic patients who fulfilled the criteria for schizophrenia of DSM-III-R and were initially admitted to a hospital between January 1979 and December 1984. They were classified into following five groups: 1) a discontinuing group (39 patients who could not be followed up because of changing the hospital or ceasing outpatient treatment), 2) an unrelapsing group (29 patients who had no relapse in continuing medication), 3) an A group (13 patients who relapsed in spite of continuing medication), 4) a B group (22 patients who relapsed only after discontinuing medication), and 5) a C group (3 patients who relapsed in continuing medication as well as after discontinuing medication). These groups were compared in multiple domains such as age at onset, age on initial admission, duration from onset to initial admission, etc. The average age at onset was significantly older in the unrelapsing group (29.0 years) than in the A group (22.1 years) (p < 0.05). The average age on initial admission was significantly older in the unrelapsing group (35.2 years) than in the A group (25.0 years) (p < 0.01). Furthermore the average duration from onset to initial admission was significantly longer in the unrelapsing group (70.9 months) than in the A group (23.8 months) (p < 0.05). Assuming theoretical groups considered in points of tendency of relapse and the effect of neuroleptics on the prevention in each patient, as well as theoretical subgroups considered in points of biological pathology and nonbiological pathology as factors of relapse, the following two subgroups were abstracted from the groups of this study: a subgroup with a high effect of medication on the prevention of relapse and the other with a low effect. There were significant differences in the average age at onset, age on initial admission, duration from onset to initial admission, and duration of initial admission between these two subgroups. These different onset pattern suggest that the effect of medication on relapse is different among patients. Our results indicate existence of a group of schizophrenic patients whose relapse can not be prevented by current neuroleptic therapy.

Adult↗
PubMed1996

Chloride transport across kidney epithelia through CLC chloride channels.

This review summarizes recent progress in elucidating the chloride-transporting mechanisms in kidney epithelia, focusing particularly on those which act through the newly identified chloride channels. A family of chloride channel proteins (ClC chloride channels) consisting of at least 9 members (ClC-1, 2, 3, 4, 5, 6, 7, K1 and K2) has recently been identified in mammals. Although all of these ClC channels, except for skeletal muscle-specific ClC-1, are expressed in the kidney, only ClC-K1 and K2 are kidney-specific ClC chloride channels, suggesting that they play an important role in the kidney. The functional properties and intrarenal localization of these chloride channels are summarized, and their involvement in certain tubular dysfunctions and physiological roles are discussed in this report.

Biological Transport↗
PubMed1996

[Prospective clinical study of the combination therapy of auranofin and methotrexate for rheumatoid arthritis--a multi-center study].

In a study to evaluate the usefulness of DMARDs combination therapy for RA, AF and MTX were concurrently given to RA patients who had responded poorly to over three months of monotherapy of either AF or MTX. The study was composed of two stages. In the first stage, patients were concurrently given AF and MTX for six months in order to evaluate the efficacy of combination therapy. In the second stage, patients who had responded to the earlier combination therapy were again put on monotherapy of the additive DMARD. Safety evaluation was conducted with 126 patients, and both efficacy and utility were evaluated in 100 patients. Lansbury index for RA significantly improved in both groups of patients starting with the AF and followed by the MTX combination (Group I) and those who started with MTX alone followed by the AF combination (Group II). The ratio of patients who achieved slight improvement or better in the overall improvement rating was significantly higher in Group I at 74.6%, vs. 51.1% in Group II patients. Ten patients (16.9%) and 2 patients (4.9%) were switched to their additive DMARD monotherapy of MTX and AF respectively, having responded to the combination therapy in stage I with slight improvement or a better rating. Adverse events were observed in 44 patients (34.9%), but the combination therapy neither increased the incidence of adverse events nor caused new adverse events. Combination therapy of AF and MTX appeared to be useful both in terms of efficacy and safety for patients who have experienced the dwindling effect of monotherapy.

Adult↗
PubMed1996

[Structure and function of ClC chloride channels].

ClC chloride channels form a voltage-gated chloride channel family. It consists of at least 8 members of chloride channel, including the skeletal muscle-specific ClC-1 and the two very homologous kidney-specific chloride channels, ClC-K1 and ClC-K2. The dysfunction of ClC-1 is shown to lead to myotonia. Both ClC-K1 and ClC-K2 are involved in the transcellular chloride transport in the different nephron segments and may be involved in certain disorders of tubular function. This review focuses on (1) the structure and function of ClC chloride channels and (2) the involvement of ClC chloride channels in human diseases.

Animals↗
PubMed1996

[The relation of retinal vascular occlusion and carotid artery stenosis].

We evaluated carotid ulceration and stenosis in 16 patients with central retinal artery occlusion (CRAO), 13 patients with branch retinal artery occlusion (BRAO), and 27 patients with central retinal vein occlusion (CRVO). One of three kinds of angiography was selected according to the patient's condition. These included conventional cerebral angiography, intravenous digital subtraction angiography (IVDSA), and magnetic resonance angiography (MRA). Carotid artery stenosis (50% or greater) was noted in 37.5% (6/16) of the patients with CRAO and in 23.1% (3/13) of the patients with BRAO. Only one of 27 patients with CRVO had a contralateral 50% carotid artery stenosis. In order to detect an underlying systemic disease in evaluating patients with retinal artery occlusion, examination of the carotid vessels is essential. It may also be helpful to estimate the risk of cerebral stroke for patients with retinal stroke.

Adult↗
PubMed1995

Receptor occupation and pharmacokinetics of MPC-1304, a new Ca2+ channel antagonist, in spontaneously hypertensive rats.

MPC-1304, (+/-)-methyl 2-oxopropyl 1,4-dihydro-2,6-dimethyl-4-(2-nitrophenyl)-3,5-pyridinedicarbonate , is a novel 1,4-dihydropyridine Ca2+ channel antagonist with potent and long-lasting antihypertensive effects. We characterized the ex vivo and in vivo binding properties of MPC-1304 to Ca2+ channel antagonist receptors in myocardial, aortic and brain tissues of spontaneously hypertensive rats (SHR) by radioreceptor assay using [3H](+)-PN 200-110 ([5-methyl-3H](+)-PN 200-110 (4-(2,1,3-benzoxadiazol-4-yl)-1,4,-dihydro-5-methoxycarbonyl-2,6-d imethyl-1,4-dihydro-3-isopropylcarbonylpyridine-5-carboxylic acid methyl ester)). At 1 and 6 h after oral administration of MPC-1304 (10 mg/kg) in SHR, there was significant decrease (48%) in the number of [3H](+)-PN 200-110 binding sites (Bmax) in myocardial membranes compared to control values. The plasma concentration of MPC-1304 in SHR correlated significantly with the occupation by this drug of myocardial Ca2+ channel antagonist receptors. The in vivo specific binding of [3H](+)-PN 200-110 in particulate fractions of aorta of SHR was significantly reduced (74.8 and 37.9%, respectively) at 1 and 6 after oral administration of MPC-1304 (3 mg/kg), while the myocardial [3H](+)-PN 200-110 binding was decreased only at 1 h later. In these rats, there was little change in cerebral cortical [3H](+)-PN 200-110 binding. In conclusion, MPC-1304 exerted more selective and sustained occupation in vivo of Ca2+ channel antagonist receptors in vascular tissues of SHR than in those of myocardial and brain tissues.

Administration, Oral↗