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Biomedical subjects

M Murase

Publications and source records attributed to M Murase.

At least 127 records · Page 7Linked to original sources
PubMed1990

Simulation of ciliary beating by an excitable dynein model: oscillations, quiescence and mechano-sensitivity.

Murase et al. (1989, J. theor. Biol. 139, 413) showed that an excitable dynein model can generate flagellar-like bending waves of low amplitude along an axoneme suspended in a viscous fluid. Either regular base-to-tip and irregular tip-to-base propagating waves can be produced. The present study shows that if the force-vs.-distance functions (or the potential energy functions as their integral form) that represent the functional properties of dyneins differ in the basal region, as compared with the rest of the active length of a short axoneme, and also differ between the opposing doublets, ciliary-like repetitive beats can be simulated. Depending on the parameter values, a cilium beats once and then becomes resting or quiescent, at the end of either its recovery or effective stroke. Interestingly, a quiescent cilium exhibits repetitive beats when a steady flow of water is applied to a part of the cilium in a suitable direction and at an appropriate speed. This kind of responsiveness to external stimuli, called directional mechano-sensitivity, may account for metachronal waves over a layer of cilia. As in the previous model for flagellar movement, the present model requires a passive region at the tip, but does not need a curvature feedback control, to generate ciliary-like beating patterns.

Animals↗
PubMed1990

[A successful surgical case of DeBakey IIIb dissecting aortic aneurysm in association with right aortic arch].

A case of chronic DeBakey IIIb dissecting aneurysm in association with right aortic arch is reported. A 49-year-old man having encountered an aortic dissecting episode two years ago, was examined more closely because the aneurysm became larger recently. Digital subtraction angiography (intra-venous and intra-aortic) showed DeBakey IIIb dissecting aneurysm associated with a right aortic arch with aberrant subclavian artery. The entry of the aneurysm was in the right descending aorta passing from left thorax to right. The operative indication was for enlarged false lumen in this case. Graft replacement of the aneurysm and closure of the false lumen in the right thorax was performed under partial cardiopulmonary bypass through right thoracotomy. Postoperative digital subtraction angiography showed that dissection was in the abdominal aorta but false lumen in the thorax was completely closed. The patient has made a comeback working. A case of dissecting aortic aneurysm associated with right aortic arch is extremely rare. To our knowledge, this is the third such case reported in Japan, but the first case of a successful graft replacement for dissecting aortic aneurysm associated with right aortic arch.

Aortic Dissection↗
PubMed1990

[Three operated cases of LMT-lesion with chief complaint of syncopal attack].

An urgent aorto-coronary bypass operation (AC-bypass) was made in three patients with unstable angina pectoris, suffering from stenosis of the left main trunk (LMT). All patients were admitted with chief complaints of chest discomfort and syncopal attack. Case 1 was a 71 year-old man who suffered with chest discomfort and syncopal attack. He was admitted to our emergency room by ambulance 40 minutes after the syncopal attack, on January 11, 1989. His blood pressure was 140/96; pulse 84 and regular. The electrocardiogram (ECG) showed right bundle branch block, ST elevation in aVR, aVL and ST depression in all other leads. Coronary arteriogram (CAG) was made urgently and showed 80% stenosis in LMT. The emergency AC-bypass operation was successfully carried out about 3 hours and 10 minutes after the onset of symptoms. Case 2 was a 51 year-old man who suffered from precordial oppression and syncopal attack. He was admitted to our emergency room by ambulance about 1 hour after the attack, on January 17, 1989. His blood pressure was 94/74; pulse 120 and irregular. Chest radiography showed a cardiothoracic ratio of 58% and the ECG disclosed atrial fibrillation, ST elevation in aVR and ST depression in I, II, III, aVF, V1-6. The echocardiogram revealed hypokinetic motion in the antero-lateral wall of the left ventricle. CAG was carried out without delay, and showed 70% stenosis with slit in LMT. An emergency AC-bypass operation was successfully carried out about 3 hours and 50 minutes after the onset of symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

[A surgical case of aortic regurgitation with Behçet disease].

A case of Behçet disease associated with aortic valve regurgitation treated with aortic valve replacement is reported. The patient was treated successfully with special surgical techniques for prevention of post operative paravalvular leakage and occurrence of pseudo aneurysm because the patient was under long-term steroid therapy for Behçet disease.

Aortic Valve↗
PubMed1990

[A case of holoprosencephaly with a flat electroencephalogram].

A case of alobar type of holoprosencephaly, a severe impairment of the development of central nervous system, is presented. This is a case report of 2-month-old boy who had a peculiar physiognomy with a microcephalus and an undeveloped forehead. Echoencephalography showed a defect of almost all cerebellum and a singular ventricle accompanied with severe hydrocephalus. However, his brain stem and cerebellum could be confirmed. His electroencephalogram showed complete flat waves and failed to respond to visual evoked potential test (VEP) and auditory brain stem response test (ABR). Any chromosomal abnormalities were not found.

Echoencephalography↗
PubMed1990

S-100ao protein in serum during acute myocardial infarction.

Concentrations in serum of S100ao protein (alpha alpha form of S-100 protein, which is present at high concentrations in heart muscle) were successively measured by enzyme immunoassay in 21 patients with acute myocardial infarction (AMI) and six with angina pectoris (ANP). Results were compared with measurements of creatine kinase isoenzyme MB (CK-MB) concentrations in the same specimens. Mean S100ao concentrations in sera from 100 healthy adults were 0.12 (SD 0.08) microgram/L. In patients with AMI, S100ao concentrations were 4.74 +/- 5.27 micrograms/L at admission, peaked 8 h after admission (23.5 +/- 27.7 micrograms/L), then decreased gradually. Among nine AMI patients who were admitted within an hour after their attack, eight showed abnormally high concentrations of S100ao in serum (greater than 0.5 microgram/L), whereas only four showed abnormally high CK-MB concentrations (greater than 5 micrograms/L) in sera at the time of admission. Serum S100ao concentrations remained within the normal range in all six patients with ANP; however, serum CK-MB concentrations were increased in two of them. Therefore, serum S100ao is useful not only for detection of AMI but also for differentiating AMI from ANP.

Acute Disease↗
PubMed1990

[Clinical effect of norfloxacin in pediatric field].

We have investigated bioavailability, clinical efficacy, side effect and antimicrobial activity of norfloxacin (NFLX) to evaluate the efficacy and safety in the pediatric field. Results are summarized as follows 1. After oral administration of 100 mg, Tmax was 2 hours and T 1/2 were 4.2 and 2.6 hours in 2 cases. 2. In 10 cases of urinary tract infection (UTI) and 4 cases of intestinal tract infection (ITI), clinical efficacy rate was 100% (14/14). 3. In UTI, causative bacteria were all eradicated. In ITI, 1 case with Campylobacter jejuni remained unchanged. Overall eradication rate was 92.9% (13/14). 4. Antimicrobial activities to clinically isolated organisms such as Gram-negative rods or Staphylococcus aureus, MIC of NFLX was clearly superior to those of cefaclor, amoxicillin, nalidixic acid, fosfomycin and erythromycin. 5. Side effect of dipsia was observed in 1 case and eosinophilia was found in 1 case. But these reactions were mild and we were able to continue the administration of the drug. The above results suggest that NFLX is a useful and safe drug for the therapy of UTI and ITI in the pediatric field.

Adolescent↗
PubMed1989

Properties of an excitable dynein model for bend propagation in cilia and flagella.

Murase & Shimizu (1986, J. theor. Biol. 119, 409) introduced an excitable dynein-microtubule system based on a three-state mechanochemical cycle of dynein to demonstrate bend propagation in the absence of a curvature control mechanism. To examine the essential behavior of this class of models in a viscous fluid, we have represented the force generated by the complex dynein mechanochemistry by a formal model consisting of "force" and "activation" functions vs. sliding distance. Since the model has excitable properties with threshold phenomena and hysteresis switching between two opposed subsystems, it closely resembles the more realistic dynein kinetic scheme in its overall properties but is specified by fewer parameters. This model displays both bend initiation and bend propagation when the filaments at the basal end are either fixed or free to slide. A passive region is necessary at one end of the axoneme in order to obtain stable wave propagation; bends propagate towards the end with the passive region. Stable bend propagation is highly sensitive to small perturbations in external force distribution.

Adenosine Triphosphatases↗
PubMed1989

Neuromagnetic study of the auditory responses in right and left hemispheres of the human brain evoked by pure tones and speech sounds.

Neuromagnetic responses in the human auditory cortex evoked by various burst stimuli of pure tones and monosyllable speech sounds were measured separately from two hemispheres. Both the pure tones and speech sounds elicited clear responses with two main peaks. The field patterns over the scalp at the peak latencies indicated a single current dipole as an equivalent field generator. The depth of the current dipoles computed from the mapped field data was deeper from the scalp for a tone stimulus of higher frequency, which confirms the tonotopic organization in the auditory cortex. A difference was found in the dipole locations in the horizontal plane for the speech stimuli of a vowel and a consonant-vowel /a/ and a consonant-vowel /ka/. It suggests the sensitivity of the magnetic responses to the acoustic structure of the speech sound.

Adult↗
PubMed1989

Locating accuracy of a current source of neuromagnetic responses: simulation study for a single current dipole in a spherical conductor.

The locating accuracy of a current dipole of neuromagnetic responses in a spherical conductor was examined in terms of the residual field which was a difference between the measured and calculated magnetic fields in a least squares fitting. Characteristics of the residual field as a function of the noise field, dipole depth, and number of measurement points were studied by computer simulations. The confidence region of the dipole location was determined by changing a dipole parameter along a coordinate axis until the sum of squares of the residual field increased by a factor given for each axis. As an example for a dipole at 2.4 cm depth, 95% confidence limits extend 2 mm along the transverse axis, 6 mm along the longitudinal axis, and 5 mm along the radial axis when the signal-to-noise ratio is 2.5 and the measurement points are 42. The method was applied to auditory evoked magnetic responses to examine location differences of the dipoles for different stimuli in the auditory cortex.

Auditory Cortex↗
PubMed1989

Beta-enolase in blood plasma during open heart surgery.

The enolase isoenzyme composed of the beta subunit (alpha beta or beta beta enolase) is distributed predominantly in the heart and skeletal muscles. To see whether it may be a useful indicator of myocardial damage, concentrations of beta-enolase (the beta subunit of enolase) were determined in serial blood samples taken from 18 patients who underwent mitral valve replacement, using a highly sensitive enzyme immunoassay method. They were compared with those of creatine kinase MB isoenzyme (CK-MB) in the same samples. The mean arterial beta-enolase concentration was 6.60 (SD 3.84) ng.ml-1 at the beginning of anaesthesia. It increased rapidly after reperfusion and rose to greater than 100 ng.ml-1 at 2 h post-reperfusion. It remained high until 12 h post-reperfusion, and then decreased slowly. The plasma beta-enolase concentrations were significantly higher in coronary sinus samples than in arterial samples in the early phase after reperfusion. Since plasma carbonic anhydrase III, which is known to be localised only in the skeletal muscle, did not increase during the surgery, we suggest that the major portion of the elevated plasma beta-enolase was derived from heart muscle. Plasma concentrations of beta-enolase increased as quickly as those of CK-MB after reperfusion. The CK-MB concentrations had returned to normal at 2 d but the beta-enolase concentrations remained elevated up to 7 d. These results show that the determination of beta-enolase in plasma may be useful for estimating myocardial damage during open heart surgery.

Adult↗
PubMed1989

Malignant peripheral nerve sheath tumor (MPNST) showing perineurial cell differentiation.

We report a malignant peripheral nerve sheath tumor (MPNST) showing the unusual immunohistochemical feature of epithelial membrane antigen (EMA) immunoreactivity in a 52-year-old man. The tumor, located in the left paravertebral muscles, was composed of both cellular and myxoid areas. Spindle-shaped tumor cells were arranged in longitudinal cell cords, in a storiform pattern, and in whorled structures. Ultrastructurally, the tumor cells had many interdigitating cell processes, primitive cell junctions, and discontinuous external laminae. These histological and ultrastructural features were most consistent with those of an MPNST; but on immunohistochemistry, the tumor cells reacted for epithelial membrane antigen rather than for S-100 protein or Leu-7. Because EMA-immunoreactivity was recently demonstrated in perineurial cells, we concluded that the tumor was an MPNST mainly composed of tumor cells showing perineurial cell differentiation.

Cell Differentiation↗
PubMed1989

Usefulness of rate responsive atrial pacing in patients with sick sinus syndrome.

We studied heart rate response and blood lactate changes during treadmill exercise testing in 10 patients with sick sinus syndrome (SSS) and normal atrioventricular (AV) conduction in whom an activity detecting multi-programmable rate responsive pacemaker was implanted for atrial pacing (AAI pacing). Treadmill exercise testing was performed twice in each patient under the two different AAI pacing modes: rate responsive function off (fixed rate 60 pulses per minute [ppm]; RR-off) and rate responsive function on (rate response 10, activity threshold medium, basic rate 60 ppm, and maximum rate 150 ppm; RR-on). Chronotropic response and blood lactate change during exercise were compared among patients under each pacing mode and eight healthy volunteers of ages matching those of the patients. In patients under the RR-off pacing mode (RR-off patients), chronotropic response was lower (P less than 0.01) and blood lactate level was higher (P less than 0.05) than those in patients under the RR-on pacing mode (RR-on patients) and volunteers during exercise. In RR-on patients, however, both chronotropic response and lactate level changes during exercise were comparatively improved, with no significant differences between RR-on patients and volunteers. These data suggested that improvement of chronotropic response by rate responsive pacing, in comparison with nonrate responsive pacing, increased the blood supply to the working muscles and resulted in less lactate production during exercise. It was concluded that rate responsive AAI pacing which could maintain AV synchrony and normal intraventricular conduction was an optimal physiological pacing mode for SSS patients with normal AV conduction.

Adult↗
PubMed1989

Creatine kinase BB isozyme in the blood during open heart surgery--comparison with creatine kinase MB and MM isozymes.

By using a recently developed highly sensitive enzyme immunoassay method, concentrations of the 3 forms of cytoplasmic creatine kinases (CK-BB, CK-MB and CK-MM) were determined in blood samples serially taken from 18 patients who received mitral valve replacement. Blood CK-BB levels, 0.64 +/- 0.32 ng/ml at the beginning of anesthesia, rose sharply after reperfusion reaching the peak level (23.3 +/- 7.56 ng/ml) 2 hours after reperfusion, and then fell rapidly. The response of CK-BB in blood was rapider and more sensitive than that of CK-MB or CK-MM. The CK-BB concentrations were significantly higher in coronary sinus samples than in arterial samples. These results suggest that the major portion of elevated blood CK-BB level in the early phase after reperfusion are derived from the heart muscle.

Cardiopulmonary Bypass↗
PubMed1989

[Transvenous permanent pacemaker implantation for Fabry's disease. 3 cases report].

Three men with Fabry's disease (angiokeratoma corporis diffusum universal ) are described. In the first patient, atrial fibrillation appeared, and a permanent cardiac pacemaker (VVI) was implanted. Sick sinus syndrome with complete atrioventricular block was occurred on the second patient. Transvenous pacemaker (DDD) implantation was performed for him. The last patient was younger brother of the second patient. He demonstrated complete atrio-ventricular block, so cardiac pace maker (VAT) was implanted. They showed a low value of granulocyte's alpha-galactosidase activity. During 1 to 4 year follow up period, they showed no trouble about pacemaking. Fabry's disease is an disorder of glycosphingolipid metabolism. This disorder is characterized by the accumulation of trihexosyl ceramide in many sites. Cardiac involvement and abnormal electrocardiographic manifestations are common in this disorder. Permanent cardiac pacemaker is necessary for severe bradycardia caused by this disorder.

Adult↗
PubMed1989

[Beta-enolase in blood plasma during open heart surgery--comparing with CK-MB and CA-III in blood plasma].

Enolase isozyme composed of the beta subunit (alpha beta or beta beta enolase) is distributed predominantly in the heart and skeletal muscles. Concentrations of beta-enolase (beta subunit of enolase) in blood plasma samples serially taken from 18 patients, who received mitral valve replacement, were estimated by using a highly sensitive enzyme immunoassay method and compared with those of CK-MB in the same samples. Plasma beta-enolase levels, that were 6.60 +/- 3.84 ng/ml at the beginning of anesthesia, increased rapidly after reperfusion reaching the plateau more than 100 ng/ml between 2 to 12 hours, showing two peak (116 +/- 45.7 ng/ml at 4 hours and 112 +/- 48.1 ng/ml at 12 hours after reperfusion), and then decreased slowly remaining high levels even when plasma CK-MB levels became normal. The beta-enolase concentrations were significantly higher in coronary sinus samples than in arterial samples early after reperfusion. Since plasma carbonic anhydrase III, which is known to be localized only in the skeletal muscle, did not increase during the surgery, it is suggested that the major portion of elevated plasma beta-enolase levels were derived from the heart muscle. Plasma levels of beta-enolase increased as quickly as those of CK-MB after reperfusion and kept high levels longer than those of CK-MB. These results indicate that the determination of beta-enolase in plasma may be useful for estimating the myocardial damage during open heart surgery.

Carbonic Anhydrases↗
PubMed1989

[Basic and clinical studies on use of clarithromycin granules in pediatrics].

Studies were conducted on in vivo pharmacokinetics of clarithromycin (TE-031, A-56268) in children and also on the efficacy and the safety of this macrolide antibiotic in the treatment of bacterial infections in children. The results obtained are summarized as follows: 1. TE-031 granules were orally administered to 5 children in a dosage of 5 mg/kg before meal. Maximum drug concentrations (range: 0.29-2.0 micrograms/ml) in the serum occurred during a period from 30 minutes to 1 hour after administration, but there were clear differences in blood concentrations among the individuals. 2. TE-031 granules were orally administered in a average dosage of 20 mg/kg/day to a total of 17 patients, consisting of 14 children with respiratory tract infections and 3 children with intestinal infections. The clinical efficacy evaluation resulted in 10 excellent cases, 6 good cases and 1 fair case, for an efficacy rate of 94.1%. 3. Studies on the bacterial efficacy were carried out for 10 cases. The TE-031 bacteriological efficacy evaluation showed elimination in 7 cases, a decreased bacterial count in 2 cases, and no change in 1 case. The elimination rate was, thus, 70.0%. Elimination rates according to different species of bacteria were 66.7% (2 of 3 strains) for Staphylococcus aureus, 100% for both Streptococcus pneumoniae (3 of 3) and Streptococcus pyogenes (1 of 1), and 42.9% (3 of 7) for Haemophilus influenzae. 4. There were no symptoms which were attributable to side effects of the TE-031 therapy. The only laboratory test abnormality detected was eosinophilia in 1 patient.

Age Factors↗