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Biomedical subjects

K Murase

Publications and source records attributed to K Murase.

At least 217 records · Page 12Linked to original sources
PubMed1989

Cholinergic effects on spinal dorsal horn neurons in vitro: an intracellular study.

The cholinoceptive properties of dorsal horn neurons (lamina III-V) were investigated by means of intracellular recordings from the rat isolated spinal cord slice preparation. In half of the neurons investigated, acetylcholine (ACh) evoked a dose-dependent slow depolarization and increase in excitability; hyperpolarization was observed in 10% of neurons. Acetyl-beta-methylcholine (MCh) similarly depolarized 39% and hyperpolarized 25% of neurons tested; depolarization was also observed following bethanechol. Responses to the muscarinic agonists were abolished by atropine (10(-5) M). Nicotine depolarized 84% of tested neurons; dihydro-beta-erythroidine (5 x 10(-5) M) and (+)-tubocurarine (10(-6) M) antagonized this depolarization. ACh-, MCh- and nicotine-induced depolarizations, associated with changes in input resistance, were maintained in the presence of tetrodotoxin (10(-6) M). Substance P, as well as repetitive electrical stimulation of the dorsal root, also evoked depolarization in ACh-sensitive neurons. Atropine, but not (+)-tubocurarine, diminished responses to both substance P and dorsal root stimulation. These results indicate that dorsal horn neurons are ACh-sensitive and possess both muscarinic and nicotinic receptors. In addition, the parallel sensitivity of neurons to muscarinic agonists, substance P and dorsal root stimulation, as well as the parallel antagonistic effect of atropine, are supportive of a common ionic mechanism underlying the activation of muscarinic and substance P receptors.

Action Potentials↗
PubMed1989

Excitatory and inhibitory amino acids and peptide-induced responses in acutely isolated rat spinal dorsal horn neurons.

The responses to excitatory and inhibitory amino acids and peptides were investigated in isolated rat spinal dorsal horn neurons (laminae I-V) of young rats using the whole-cell voltage-clamp technique. The treatment of spinal slices with low concentrations of enzymes and mechanical dissociation yielded isolated neurons that were sensitive to excitatory amino acids (glutamate, kainate, quisqualate and N-methyl-D-aspartate (NMDA), inhibitory amino acids (gamma-aminobutyric acid (GABA), glycine) and peptides (substance P, calcitonin gene-related peptide (CGRP). The responses of dorsal horn neurons to NMDA were potentiated by glycine and CGRP, whereas GABAA responses were enhanced by alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA). Our observations indicate that there is reasonable agreement between many of the responses of isolated neurons and those studied in in vivo and in vitro slice and culture preparations.

Amino Acids↗
PubMed1989

[Single photon emission computed tomography (SPECT) with N-isopropyl-p-(123I) iodoamphetamine in partial epilepsy--evaluation of delayed image].

Thirty eight patients with partial seizures in the interictal phase were studied using single photon emission computed tomography performed 30 min. (early image) and 4-4.5 hrs. (delayed image) after an injection of 111 MBq (3 mCi) N-isopropyl-p(123I) iodoamphetamine (IMP). Five types of distribution changes were observed on IMP-SPECT between the early and delayed images. Eight patients, Type 1, exhibited an unchanged distribution of IMP between the early and delayed images. Fifteen patients, Type 2, showed a smaller area of low uptake on the IMP-SPECT (delayed image) compared to that on the IMP-SPECT (early image)-redistribution. The Type 3 patients exhibited an initial uptake area on the IMP-SPECT (early image) which later became a lower uptake area on the IMP-SPECT (delayed image)-reversed redistribution. This type was further classified into three categories according to the initial uptake pattern including (a) Type 3A, 3 patients with increased uptake area, (b) Type 3B, 6 patients with normal uptake area, and (c) Type 3C, 6 patients with decreased uptake area. With Type 2, the epileptic findings on the present interictal electroencephalography (EEG) were shown in 11 of 15 patients. However, we could not find any other remarkable correlation among these 5 types and the clinical factors (the types of seizures, the X-CT findings, the present interictal EEG data, the present frequency of seizures, and the intervals from the last seizure). In 2 patients with Type 3B who suffered from simple partial seizures, a region of the normal distribution on the IMP-SPECT (early image) became a lower uptake area on the IMP-SPECT (delayed image), corresponding topologically to the ictal symptoms. In this experience, we determined that the IMP-SPECT (delayed image) could be useful in patients with the epileptic lesions unable to be detected on the IMP-SPECT (early image).

Adolescent↗
PubMed1989

[Visualization of epileptic lesions using single photon emission computed tomography (SPECT) with N-isopropyl-p-(123I) iodoamphetamine after intravenous loading of bemegride--report of a case].

Single photon emission computed tomography (SPECT) was performed 30 minutes and 4 hours after injection of 111 MBq (3 mCi) N-isopropyl-p-(123I) iodoamphetamine (IMP) which was injected 5 minutes after the completion of intravenous bemegride loading. A 31-year-old female with simple partial seizures evolving to complex partial seizures evolving to generalized tonic-clonic convulsive seizures with a history of hospitalization, suffering from low-grade fever, generalized convulsive seizures, and impaired consciousness at the age of 27 years was studied. Angiographic examinations, X-CT, MRI, CSF examinations, and interictal neurological examinations were normal. She suffered from clonic convulsions in her right shoulder and arm, and hallucinations and dysmnesia which were characteristic of temporal lobe epilepsy. More recently she suffered from impaired consciousness once or twice a month. While the controlled IMP-SPECT study was normal, the IMP-SPECT study examined after the activation by intravenous bemegride loading showed the pattern of a regional increased uptake of IMP in the epileptic lesions corresponding with the epileptic symptoms, and a surrounding border of decreased uptake which might be the inhibition of surrounding neuronal activity and metabolism. In conclusion, the bemegride loading IMP-SPECT study could be a potential diagnostic method in patients with seizures whose epileptic lesions were not determined by the conventional methods or in whom the surgical interventions were considered, by reason of its capability to demonstrate positively the epileptic lesions.

Adult↗
PubMed1989

[Diagnostic value of the reflux sign in cholescintigraphy after administration of a gallbladder contracting agent--a comparison with X-ray cholangiography].

This study reviewed 25 patients with the reflux sign in cholescintigraphy to assess its diagnostic value in evaluating biliary passage. After at least 4-hour fasting 5 mCi of 99mTcPMT or p-butyl IDA was injected intravenously and serial images were recorded before and after intramuscular injection of 10 micrograms of ceruletide diethylamine (caerulein). The reflux sign was determined positive when increased radioactivities in the left hepatic duct (minor reflux; MIR) or more peripheral intrahepatic ducts (major reflux; MAR) were recognized after injection of caerulein. The reflux sign was found in 28 of 237 (12%) studies. Direct and/or indirect X-ray cholangiograms were available in 25 (MIR; 15, MAR; 10). They included common bile duct (CBD) stone in 4, dilated CBD in 4, biliary dyskinesia (BD) in 4, chronic pancreatitis (CP) in 4, gallbladder (GB) stone in 3, duodenal ulcer (DU) in 2, CBD adenoma, pancreatic pseudocyst (PP), duodenal diverticle (DD), and acute cholangitis (AC) in 1 each. Their serum bilirubin levels were within normal limit in all but 2 at the time of cholescintigraphy. Transit time of radionuclides to the duodenum was found prolonged more than 60 min in 17 (68%) patients and persistent pooling in the CBD was found in 8 (28%) patients on scintigrams. The diameter of the CBD on X-ray cholangiogram was ranged 4 to 17 mm. Dilated CBD of more than 10 mm was found in 13 (52%) patients and apparent stenosis of the CBD in 6 (24%) patients. MAR seemed to correspond to increased diameter of the common hepatic more than 2 mm after caerulein injection in DIC. No abnormal findings in X-ray cholangiography was found in 10 (40%) patients including 3 with BD, 2 with GB stone, 2 with DU, 1 each with CP, PP, and AC. All those patients demonstrated MIR. We concluded that major reflux (MAR) sign was helpful in detecting an incomplete obstruction of the CBD, especially in patients with slightly to mildly dilated CBD.

Adult↗
PubMed1989

SPECT volume measurement using an automatic threshold selection method combined with a V filter.

The volume measurement of various organs by single photon emission computed tomography (SPECT) has generally been performed by summing up the voxels lying within the outer edge of the organ determined by thresholding as a function of the maximum reconstructed counts within a volume of interest. The optimum threshold level, however, is influenced by various factors. To eliminate this problem, Mortelmans et al. (1986) proposed to use an automatic threshold selection method (ATSM) based on discriminant criteria and to correct the errors induced by the imperfect system response using the method based on linear regression analysis, which has some problems in practical application. We tried to use ATSM combined with a V filter. The correlation coefficient (r) and the regression equation between the true (x) and the calculated volume (y) obtained by experimentation using 22 phantoms with a volume ranging between 26 ml and 380 ml were as follows: r = 0.994 and y(ml) = 1.015 x +1.09 using ATSM combined with a V filter, while r = 0.993 and y(ml) = 1.110 x +30.55 using only ATSM. The relative error between the true and the calculated volumes decreased significantly (P less than 0.01) from 37.7% +/- 26.9% to 5.5% +/- 4.2%. The results suggest that ATSM combined with a V filter is useful for correcting the errors caused by an imperfect system response, and is available and reliable for SPECT volume determination even when the organ volume is small.

Filtration↗
PubMed1989

A unified computer program for assessment of attenuation correction and data acquisition methods in single photon emission computed tomography (SPECT).

A computer based simulation program was developed to assess the usefulness of various attenuation correction algorithms and data acquisition methods in single photon emission computed tomography (SPECT) in a unified approach. The program analytically calculated projection ray sums from a mathematical model with various distributions of activities and either uniform or non uniform attenuation coefficients by using the line integrals including the effect of attenuation. Data acquisition starting at arbitrary angles, various acquisition angles, including a 180 degree scan and a non circular orbit of a gamma camera, including an elliptical orbit can readily be taken into consideration in our simulation program. To simulate non circular orbit data acquisition, the resolution dependence on the object distance from the collimator surface was incorporated into the simulation. This computer based simulation program allows various combinations of attenuation correction algorithms such as hybrid methods, and data acquisition methods can be evaluated under a large number of study conditions. The usefulness of this computer based simulation program is shown with several representative examples.

Algorithms↗
PubMed1989

A unified design algorithm of two-dimensional digital filters for radioisotope image processing.

A unified design algorithm of two-dimensional digital filters for radioisotope image processing based on the Fourier-Bessel transform and the weighted least-squares method is described. The algorithm presented here can treat the various kinds of two-dimensional digital filters in a unified approach. Design examples are presented and several graphs are included to show the relationships between the design parameters as an aid in practical applications. The application of the method in radioisotope image processing is also presented. Several low-pass, Wiener and band-pass filters were designed using the method and applied to some clinical data in nuclear medicine including SPECT images. The digital filter design technique proposed here is considered to provide a powerful tool for extraction of additional qualitative information and improvement of the quality of nuclear medicine images both in research and in routine clinical work.

Algorithms↗
PubMed1989

Tachykinins modulate multiple ionic conductances in voltage-clamped rat spinal dorsal horn neurons.

1. The membrane actions of substance P (SP) and a related tachykinin, neurokinin A (NKA), have been investigated by means of a single-electrode, voltage-clamp technique in the immature rat dorsal horn neurons using an in vitro spinal cord slice preparation. 2. When the membrane potential was held at the resting level of between -75 and -55 mV, bath application of SP or NKA (10(-7) to 10(-5) M, for 1-3 min) induced an inward shift in the holding current lasting several minutes. The magnitude of this effect varied between 10 and 400 pA depending on the concentration of the peptides and the holding potential. 3. When a dorsal horn neuron was held at the resting level and subjected to 1-s depolarizing commands to membrane potentials between -60 and -35 mV, slow inward relaxations and inward tail currents, the latter on repolarization to the holding potential, were recorded. During the tachykinin-induced inward shift in the holding current, the inward relaxation and the tail current were augmented in a dose-related manner. 4. The SP-induced augmentation of the slow inward relaxation and the inward tail current is likely to be due to the enhancement of the activation of the Ca2+ current, because the effect was present, and even augmented in a zero-Ca2+, Ba2+-containing solution, it was reduced or completely abolished by zero-Ca2+, Co2+-, or Mg2+-containing solutions and is largely independent of the changes in external Na+, K+, or Cl- ions. Moreover, in the presence of the K+-channel blocker, tetraethylammonium (TEA), the effect is increased. 5. Depolarizing voltage commands to potentials positive to -35 mV evoked a large, outward K+ current response in the dorsal horn neurons, which was in part Ca2+-sensitive. The outward current response was augmented by SP. The SP effect persists, although being reduced in a zero-Ca2+, Ba2+- or Co2+-containing solutions. 6. In a zero-Ca2+ solution containing Co2+ and TEA, the augmentation of the Ca2+ current and the outward K+ current by SP was abolished. However, the SP-induced increase in a Ca2+-sensitive, voltage-insensitive conductance remained, although being reduced, and the response showed a reversal at about -28 mV. This current may be a result of a tachykinin-activated nonspecific increase in cationic permeability of the membrane of dorsal horn neurons, because the current is reduced by more than one-half when Na+ or Ca2+ is removed from the bathing medium.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

Pharmacological properties of YM-11124, a selective immunosuppressive agent for cell-mediated immunity.

Effect of YM-11124 on cell-mediated immune responses, type I to type III allergic reactions and inflammatory reaction was determined in mice, rats and guinea pigs. YM-11124 inhibited picryl chloride- and methylated bovine serum albumin-induced delayed-type hypersensitivity reactions by the treatment during both the sensitization and the elicitation phases in mice. Bilateral adrenalectomy did not prevent the suppression of DTH response by YM-11124. YM-11124 significantly prolonged the survival time of allogenic skin grafts in mice. Furthermore, YM-11124 inhibited the passive Arthus reaction in guinea pigs and the reversed passive Arthus reaction in rats. However, YM-11124 did not affect the passive cutaneous anaphylaxis reaction in rats, Forssman shock in guinea pigs and paw edema in rats. These results indicate that YM-11124 suppresses not only cell-mediated immune responses (type IV allergic reactions) but also type III allergic reactions without influence on types I and II allergic reactions as well as acute inflammation.

Animals↗
PubMed1989

Pilot study of recombinant human alpha-interferon for chronic non-A, non-B hepatitis.

Recombinant human alpha-interferon was administered to 15 patients with chronic non-A, non-B hepatitis as a part of a pilot study. Patients received injections of 2 million units per day of interferon three times weekly for 16 wk. The treatment schedule was completed in all but one, whose serum aminotransferase levels were continuously elevated during treatment. In seven of the 15 patients, elevated serum aminotransferase levels decreased rapidly during therapy and eventually fell into the normal or nearly normal range. However, once the therapy was stopped, a prompt return of aminotransferase levels to pretreatment values usually was observed. After 3 months of follow-up, aminotransferase activities remained normal in only two patients in whom liver histology showed marked improvement in intralobular degeneration and focal necrosis of hepatocytes. Anti-interferon antibody was detected in four patients at the end of therapy, and decreased 2',5'-oligoadenylate synthetase activity occurred in two patients and in another with relapsed aminotransferase level. Whether alpha-interferon therapy could control the disease activity in patients with chronic non-A, non-B hepatitis deserves further evaluation in a prospective controlled trial.

2',5'-Oligoadenylate Synthetase↗
PubMed1989

Reflux sign in cholescintigraphy after administration of a gallbladder contracting agent.

This study reviewed 12 patients with the reflux sign in cholescintigraphy to assess its diagnostic usefulness in evaluating biliary passage. The reflux sign was determined by appearance or increase of the radioactivity in peripheral intrahepatic bile ducts after intramuscular injection of 10 micrograms of ceruletide diethylamine (caerulein). Of the 12 patients, there were common bile duct (CBD) stone in four, chronic pancreatitis in two, biliary dyskinesia in two, papillary adenoma of the CBD, dilated CBD, papillitis, and juxtapapillary duodenal diverticulum in one each. Cholangiographically, dilated caliber of the CBD more than or equal to 12 mm was found in five and equivocal caliber of 8 to 11 mm was in the remaining seven. Apparent stenosis of the CBD was found in four with dilated CBD. There were two patients who had CBD stone with equivocal caliber of the CBD. The reflux sign seems to be a sensitive finding indicating the presence of biliary dysfunction, and would be helpful for the detection of incomplete obstruction of the CBD or CBD stone, especially in a patient with equivocal caliber of the CBD.

Adult↗
PubMed1988

Calcitonin gene-related peptide enhances calcium current of rat dorsal root ganglion neurons and spinal excitatory synaptic transmission.

The actions of calcitonin gene-related peptide (CGRP) were examined on Ca2+-dependent action potentials and voltage-dependent Ca2+ currents in rat dorsal root ganglion (DRG) neurons in vitro. In addition, we tested the effect of CGRP on excitatory synaptic transmission in the rat spinal dorsal horn. CGRP produced a reversible increase in the amplitude and the duration of the Ca2+ spike of DRG neurons and directly increased the voltage-dependent Ca2+ current by enhancing both the transient and the sustained components of the current. The increase in the Ca2+ current is likely to be responsible for the increase in the Ca2+ spike and facilitation of excitatory synaptic transmission.

Action Potentials↗
PubMed1988

Actions of calcitonin gene-related peptide on rat spinal dorsal horn neurons.

The membrane actions of calcitonin gene-related peptide (CGRP) and the effect on the Ca-dependent action potential of dorsal horn neurons have been investigated by means of an intracellular recording technique in the immature rat in vitro spinal cord slice-dorsal root ganglion preparation. Bath application of CGRP (10(-8)-10(-6) M for 1-10 min) produced a slow reversible depolarization in about one-third of the cells examined. Biphasic membrane response consisting of an initial hyperpolarization followed by a late prolonged depolarization was seen in a smaller proportion of tested cells. Both membrane responses were present, and even enhanced, when synaptic transmission and Na spikes were blocked by perfusing the slice with a TTX-containing Krebs solution. The CGRP-induced membrane changes were also present in media containing TTX and TEA. The CGRP-evoked depolarization was associated with an increase in the input resistance, and enhanced excitability in a majority of neurons tested. In addition, CGRP modified the duration of Ca-dependent action potentials of dorsal horn neurons, the most consistent change being a prolonged increase in the spike duration. Our results are consistent with a neurotransmitter or neuromodulator role for CGRP in the rat spinal dorsal horn.

Action Potentials↗
PubMed1988

Quantitative aspect of two-factor analysis applied to radionuclide gated cardiac studies.

The quantitative aspect of two factor analysis (TFA) applied to radionuclide gated cardiac studies was investigated using clinical data and a computer based simulation method. In the clinical investigation, the ejection fraction (EF) calculated from the extracted ventricular pattern (EVP) significantly correlated with the left ventricular EF(LVEF) determined from multiple gated cardiac blood pool scans (MUGA), while the regression line deviated considerably from the line of identity. The contribution of the EVP(CEVP) to the total information inversely correlated significantly with the LVEF. In the computer simulation, a model simulating the atrial, ventricular, and background regions was studied. In the case with no statistical noise and constant background, the EF calculated from the EVP was nearly equal to the true EF, and the CEVP decreased as the EF increased. The statistical noise increased the EF and decreased the CEVP, this tendency was most marked when the true EF was less than about 50%. When background varied largely with time, the quantitative aspect deteriorated considerably. In conclusion, the clinical investigation results suggest that TFA has some possible use in quantitative analysis, however, the stimulation results suggest that it should be used carefully because its quantitative aspect is affected by various factors.

Algorithms↗