Biomedical subjects

S Muraki

Publications and source records attributed to S Muraki.

At least 37 records · Page 2Linked to original sources

PubMed2000

Comparative study of AMP579 and adenosine in inhibition of neutrophil-mediated vascular and myocardial injury during 24 h of reperfusion.

OBJECTIVE: The purpose of this study was to compare protective effects of AMP579 and adenosine (Ado) at reperfusion (R) on inhibition of polymorphonuclear neutrophil (PMN) activation, PMN-mediated injury to coronary artery endothelium, and final infarct size. METHODS: In anesthetized dogs, 1 h of left anterior descending coronary artery occlusion was followed by 24 h R and drugs were administered at R. Control (n=8, saline control), AMPI (n=7, AMP579, 50 microg/kg i.v. bolus followed by 3 microg/kg/min for 2 h), AMPII (n=7, AMP579, 50 microg/kg i.v. bolus), AMPIII (n=7, AMP579, 3 microg/kg/min i.v. for 2 h), and Ado (n=7, adenosine, 140 microg/kg/min i.v. for 2 h). RESULTS: AMP579 in vitro directly inhibited superoxide radical (O(-)(2)) generation (nM/5x10(6) PMNs) from PMNs dose-dependently (from 17+/-1* at 10 nM to 2+/-0.2* at 10 microM vs. activated 30+/-2). However, inhibition of O(-)(2) generation by Ado at each concentration was significantly less than for AMP579. The IC(50) value for AMP579 (0.09+/-0.02 microM) on O(-)(2) generation was significantly less than that of Ado (3.9+/-1. 1 microM). Adherence of unstimulated PMN to postischemic coronary artery endothelium (PMNs/mm(2)) was attenuated in AMPI and AMPIII vs. Control (60+/-3* and 58+/-3* vs. Control 110+/-4), while Ado partially attenuated PMN adherence (98+/-3*). Accordingly, endothelial-dependent vascular relaxation was significantly greater in AMPI and AMPIII vs. Ado. At 24 h R, myocardial blood flow (MBF, ml/min/g) in the area at risk (AAR), confirmed by colored microspheres, in AMPI and AMPIII was significantly improved (0.8+/-0. 1* and 0.7+/-0.1* vs. Control 0.3+/-0.04). Infarct size (IS, TTC staining) in AMPI and AMPIII was significantly reduced from 38+/-3% in Control to 21+/-4%* and 22+/-3%*, respectively, confirmed by lower plasma creatine kinase activity (I.U./g protein) in these two groups (27+/-6* and 32+/-2* vs. 49+/-3). Cardiac myeloperoxidase activity (MPO, Abs/min) in the AAR was significantly reduced in AMPI and AMPIII vs. Control (36+/-11* and 35+/-10* vs. 89+/-10). However, changes in MBF, IS and MPO were not significantly altered by Ado. CONCLUSIONS: These data suggest that continuous infusion of AMP579 at R is more potent than adenosine in attenuating R injury, and AMP579-induced cardioprotection involves inhibition of PMN-induced vascular and myocardial tissue injury. *P<0.05 vs. Control.

Adenosine↗

PubMed2000

Effect of acute heat exposure on skin blood flow of the paralyzed thigh in persons with spinal cord injury.

OBJECTIVES: To investigate whether increased body temperature during heat exposure promotes skin blood flow of the thigh (SBFT) in individuals with spinal cord injury at rest. STUDY DESIGN: A prospective study with high lesion and with low lesion. SETTING: Hiroshima University, Higashi-Hiroshima, Japan. METHODS: Seven male paraplegics (T5-L2) and seven able-bodied subjects volunteered to participate in the experiment. First the subject rested for 1 h at an ambient temperature (Ta) of 25 degrees C and a relative humidity (Rh) of 50%. Thereafter, the subject moved to a climatic chamber heated to Ta of 33 degrees C an Rh of 50 - 55% and was exposed to this environment for 1 h. SBFT, stroke volume, heart rate, the skin temperature of the medial thigh (Tthigh) and the tympanic membrane temperature (Tty) were assessed during the experiment. RESULTS: The four subjects with high lesions between Th6 and Th10 (HL) showed no increase in SBFT, while the remaining three subjects with low lesion at Th11 or Th12 (LL) showed increased SBFT in the hot environment. Although Tty increased with exposure time in heat, correlation between Tty and SBFT was not significant in either paraplegic group. However, correlation between SBFT and Tthigh was highly significant in both groups. The increase in Tthigh in LL was due to increased skin blood flow in the thigh, while in HL it was considered attributable to heat transfer from the environment to the skin. CONCLUSION: These findings indicate that SBFT during heat exposure was largely dependent on the level of spinal cord injury. SBFT with low lesions increased during heat exposure when the sympathetic cutaneous vasomotor supply of the thigh was preserved.

Adult↗

PubMed2000

The effect of frequency and mode of sports activity on the psychological status in tetraplegics and paraplegics.

OBJECTIVE: To examine whether the psychological benefits of sports activity differ between tetraplegics and paraplegics with spinal cord injury, and investigate the effect of frequency and modes of sports activity on the psychological benefits. METHODS: The Self-rating Depression Scale (SDS), State-Trait Anxiety Inventory (STAI) and Profiles of Mood States (POMS) were administered to 169 male individuals with spinal cord injury (mean age=42.7 years) including 53 tetraplegics and 116 paraplegics. The subjects were divided into four groups according to their frequencies of sports activity; High-active (more than three times a week; n=32), Middle-active (once or twice a week, n=41), Low-active (once to three times a month, n=32), and Inactive (no sports participation, n=64). RESULTS: Analysis of variance revealed significant differences in depression for SDS, trait anxiety for STAI and depression and vigor for POMS among the groups. High-active group showed the lowest scores of depression and trait anxiety and the highest score of vigor among the four groups. In contrast, no significant difference was found for any psychological measurements between tetraplegics and paraplegics. In addition, there was no significant difference for any psychological measurements among modes (wheelchair basketball, wheelchair racing, wheelchair tennis and minor modes). CONCLUSIONS: These findings demonstrated that sports activity can improve the psychological status, irrespective of tetraplegics and paraplegics, and that the psychological benefits are emphasized by sports activity at high frequency.

Adolescent↗

PubMed1998

Is atrial fibrillation resulting from rheumatic mitral valve disease a proper indication for the maze procedure?

BACKGROUND: There are a few patients without detectable atrial contraction despite restoration of atrial rhythm after the maze procedure for atrial fibrillation (AF) associated with mitral valve disease. METHODS: From January 1995 to March 1997, 29 consecutive patients with AF associated with mitral valve disease underwent our modified maze procedure combined with mitral or other valve operations. The causes of mitral valve disease were rheumatic mitral stenosis (n = 22) and nonrheumatic mitral regurgitation (n = 7). The 17 patients with postoperative atrial rhythm were divided into group I with rheumatic mitral stenosis (n = 10), and group II with mitral regurgitation of nonrheumatic origins (n = 7). RESULTS: Seventeen patients regained atrial rhythm, 2 patients had junctional rhythm, and another 10 remained in AF. Between the group of patients with restoration of atrial rhythm and that of patients remaining in AF, significant differences were found in the percentage with rheumatic disease, history of AF, and maximum f-wave voltage. The postoperative peak velocity of the atrial filling wave to peak velocity of early filling wave ratio for the left atrium measured using Doppler echocardiography was 0.25 in group I, which was significantly lower than that (0.42) in group II. CONCLUSIONS: Reconsideration of the indications for the maze procedure for AF associated with rheumatic mitral stenosis may thus be reasonable, particularly for cases in which replacement using a prosthetic valve is necessary, but we believe that patients with nonrheumatic mitral valve disease, especially those able to undergo reconstructive operations, are the best candidates for the maze procedure.

Adult↗

PubMed1998

Relationship between physical characteristics and physiological responses during maximal arm cranking in paraplegics.

The purpose of this study was to elucidate the main physical factor(s) affecting cardiorespiratory responses during maximal arm cranking exercise in patients with paraplegia. Peak oxygen uptake (peak Vo2), peak pulmonary ventilation (peak VE) and peak heart rate (peak HR) were measured during maximal arm cranking exercise in 28 Japanese male patients. A cluster analysis was applied to the data for peak Vo2, peak HR and peak VE, and then the subjects were classified into four groups (A, B, C and D). Group A showed high peak VE and peak HR and low peak Vo2, Group B low peak Vo2 and high values for other parameters, Group C the greatest physiological values for all measurements among the groups and, in contrast, Group D showed low peak Vo2 and the lowest peak VE and peak HR among the groups. The subjects in Group C had low level of spinal cord injury and were sports participants. On the other hand, duration since injury was not related to the cardiorespiratory responses during maximal arm cranking. These findings indicate that the effects on these responses of years since injury are subordinate to those of the level of spinal cord injury and training.

Adult↗

PubMed1998

Inhaled nitric oxide therapy via nasopharyngeal tube in an infant with end-stage pulmonary hypertension.

The delivery of nitric oxide (NO) via a nasopharyngeal tube is an alternative to endotracheal intubation. A male infant with end-stage pulmonary hypertension (PH) due to a severe hypoplastic lung developed a PH crisis on day 145 and received NO inhalation via a nasopharyngeal tube. Clinical improvement was maintained for 7 days with 18-22 ppm NO inhalation. The patient remained in close physical contact with his parents without the use of sedation. Blood methemoglobin levels remained below 1%. The environmental NO levels were less than 0.06 ppm and NO2 less than 0.3 ppm throughout the treatment, well within the safety margin. On day 152, the patient succumbed to hypoxemia and heart failure. The use of a nasopharyngeal NO delivery system without sedation, as an alternative to endotracheal intubation with sedation, was a practical method in treating a patient with PH while maintaining a certain quality of life for the patient and the family.

Administration, Inhalation↗

PubMed1998

Functional evaluation of the bileaflet mechanical valve in the aortic position using dobutamine-stress echocardiography: is a 23-mm prosthetic valve adequately large enough?

The issue of valve prosthesis-patient mismatch in small annular patients is still controversial. The hemodynamic function of bileaflet mechanical valves in the aortic position was examined using dobutamine-stress echocardiography. Forty-four patients were enrolled in the study and divided into 5 groups, according to prosthesis size, from 21 mm to 29 mm. The aortic peak pressure gradient (APG) increased significantly in all groups with dobutamine-stress and exceeded 50 mmHg in 83% of the 21-mm group, in 64% of the 23-mm group, and in 33% of the 25-mm group. The APG even exceeded 80 mmHg in 22% and 18% of the 21-mm and 23-mm groups, respectively. In these cases, the potential of 'valve prosthesis-patient mismatch' was considered. From the relationship between the APG and the prosthesis valve area index (VAI), 'critical VAIs' were found where patients were likely to enter the 'mismatch' status; that is, 1.22 and 1.77 cm2/m2, respectively, for the 5 and 10 microg/kg per min stages of dobutamine stress. This critical VAI range is useful in predicting the 'mismatch' patients preoperatively. Alternative procedures or prostheses should then be selected for them.

Adult↗

PubMed1998

[A case report of aortic valve replacement and ascending + hemi aortic arch replacement for congenital bicuspid aortic stenosis with poststenotic dilatation of ascending aorta].

The patient of 21-year-old female, who had undergone VSD closures at the age 5 and had been pointed out to have aortic valve stenosis at that time, was admitted to our hospital with complaints of palpitation and easy fatigability. Pressure gradient of 140 mmHg between left ventricle and ascending aorta, and poststenotic dilatation of max 55 mm in diameter from ascending aorta to hemi aortic arch was recognized by cardiac catheterization and aortogram. For fear of aortic dissection in late phase caused by dilatation of ascending aorta left over, graft replacement from ascending aorta to hemi aortic arch was carried out simultaneously adding to aortic valve replacement (AVR). We are of the opinion that not only AVR but also simultaneous graft replacement should be performed actively on the case with dilatation of ascending aorta of over 55 mm in diameter in order to prevent aortic dissection.

Adult↗

PubMed1997

Characteristics of physical health conditions in middle-aged and elderly joggers.

To clarify the characteristics of physical health conditions in middle-aged and elderly joggers who run regularly, they were compared with middle-aged and elderly people who did not exercise routinely. The physical health conditions were investigated by a questionnaire survey sent by mail. The subjects were 316 joggers (230 men and 86 women) and 272 non-joggers (173 men and 99 women). The number of joggers having any illness was lower than that of non-joggers in both men and women. In contrast, there was no significant difference in type of illness between joggers and non-joggers. Concerning symptoms, the number of joggers who complained of lumbar pain and shoulder stiffness was low, but the number of joggers with symptoms including knee joint pain and muscle pain as well as injury was high compared to non-joggers. While the results of this study reconfirm that continuous jogging in middle-aged and elderly people may effectively improve their physical condition, based on the finding that the morbidity was low, it appears that many joggers have knee joint pain, a typical disorder due to running.

Aged↗

PubMed1997

[Functional MRI employing diazepam; a proposal of neuropharmacological fMRI].

Employing the active benzodiazepine receptor (BZR) ligands, we have used BOLD fMRI to elucidate the effects of these drugs on brain function. The sequential MRI was performed with a 1.5T clinical scanner (Philips GYROSCAN) using a FLASH sequence with the following parameters: TR/TE, 100/45 msec; flip angle, 25 degrees; matrix size, 128*128; 2 averages; for 64 image acquisitions in 32 min. First, 2 mg of diazepam was administrated intravenously at the beginning of the 5th, 15th, 25th, and 35th acquisitions. Then, flumazenil was administrated at the beginning of the 45th (0.2 mg) and 55th (0.3 mg) acquisitions in order to reverse the effect of diazepam. Data processing was made employing Akaike Information Criterion to detect if there were intensity changes after the medication among the trends of intensity changes. Diazepam administration decreased the intensity for a while and flumazenil increased one. In the case of the left frontal glioma with focal epileptogenicity, intensity changes were detected around the tumor. Since the neuronal function consists of the trans-neuronal communications employing neurotransmitters, the result on the modulation of this passage depends on the neuronal function related to the transmitter: gamma-amino butyric acid (GABA) in this instance for the effects of these medications to epilepsy. The change in the local blood flow is the result of the local neuronal activity. Therefore, we speculate that this neuropharmacological functional MR image may reflect the neuronal function related to the GABAegic neurotransmitter system. In addition to elucidating basic neurotransmitter function mechanisms, we believe this technique may have clinical utility in the pre-surgical evaluation of patients with intractable seizure disorders. In this respect, this paper presents a new spectrum of fMRI that is capable to study a part of neurotransmitter function employing the BZR ligands, reversing the effect of the agonist with the competitive antagonist, for the first experience, to propose the neuropharmacological functional MR images to have clinical utility in patients with intractable epilepsy in the interictal state.

Anti-Anxiety Agents↗

PubMed1996

Cardiovascular and respiratory responses to passive leg cycle exercise in people with spinal cord injuries.

The purpose of this study was to determine the effect of passive leg cycle exercise (PLE) on cardiovascular and respiratory responses in people with spinal cord injuries (PSCI). Eight PSCI with lesions from T8 to L1 and five control subjects (CS) performed PLE at pedalling frequencies of 20 or 40 rpm for 7 min at room temperature of about 25 degrees C. We measured, at rest and during PLE, the pulmonary ventilation (VE), oxygen uptake (VO2), cardiac output (Q), stroke volume (SV), heart rate (HR) and arterial blood pressure, as well as the skin blood flow (SBF) in the lower limb after PLE. An increase in pedalling frequency promoted an increase in VE and VO2 in both groups. Compared with the CS, the PSCI showed significantly smaller increases in VO2 (P < 0.05). The Qc was significantly elevated during PLE at 20 and 40 rpm in CS, and at 40 rpm in PSCI (P < 0.05). In CS, it resulted from increases in both SV and HR, whereas in PSCI, it was contributed to by a greater increase in SV without a rise in HR. In CS, the increase in pedalling frequency promoted the increases in SV and HR and consequently in Qc. In PSCI, however, the values remained constant irrespective of pedalling frequency. The arterial blood pressure and SBF in the lower limbs were unchanged by PLE in both groups. These results would suggest that passive leg exercise promotes venous return from the paralyzed lower limbs in PSCI.

Adult↗

PubMed1996

Relationship between core temperature and skin blood flux in lower limbs during prolonged arm exercise in persons with spinal cord injury.

The purposes of the present study were to examine the response of the skin blood flux (SBF) in the paralyzed lower limbs of persons with spinal cord injury (PSCI) and to clarify the relationship between the SBF and core temperature during prolonged arm exercise. Eight male PSCI with lesions from T6 to L5 and six male control subjects (CS) participated in this study. The subjects rested for 60 min and then performed arm-cranking exercise at 20 W for 30 min at 25 degrees C. The tympanic membrane temperature (Tty) and SBF in the anterior thigh (SBFT) and in the posterior calf (SBFC) were continuously measured throughout the experiment. The SBFC did not change in either PSCI or CS during the experiment. The SBFT in four PSCI with high lesions (T6 to T12), remained unchanged during exercise. The SBFT in the other four PSCI with low lesions (T12 to L5, delta SBFT+) began to elevate markedly when the Tty exceeded a threshold temperature of 36.69 degrees C. The pattern of increase of SBFT in delta SBFT+ was similar to that in CS, although onset of the increase in SBFT was delayed and the peak of SBFT during exercise was significantly lower in comparison with the CS. We consider that these differences between the delta SBFT+ and CS were largely attributable to the lower Tty in the former group, which took a prolonged time to reach the threshold of 36.69 degrees C.

Adult↗

PubMed1996

Effect of maximal arm exercise on skin blood flux in the paralyzed lower limbs in persons with spinal cord injury.

The purpose of the present study was to examine the effect of maximal arm exercise on the skin blood circulation of the paralyzed lower limbs in persons with spinal cord injury (PSCI). Eight male PSCI with complete lesions located between T3 and L1 performed graded maximal arm-cranking exercise (MACE) to exhaustion. The skin blood flux at the thigh (SBFT) and that at the calf (SBFC) were monitored using laser-Doppler flowmeter at rest and for 15 s immediately after the MACE. The subject's mean peak oxygen uptake and peak heart rate was 1.41 +/- 0.22 l.min-1 and 171.6 +/- 19.2 beats.min-1, respectively. No PSCI showed any increase in either SBFT or SBFC after the MACE, when compared with the values at rest. These results suggest that the blood circulation of the skin in the paralyzed lower limbs in PSCI is unaffected by the MACE.

Adult↗

PubMed1996

[Surgical treatment of primary mediastinal tumors in children].

Twenty children with primary mediastinal tumor underwent surgical treatment. Ten patients had benign tumor and the other patients were malignant. Seven of ten patients with malignant tumor were neurogenic, and 3 patients were of germ cell tumor. In the clinical manifestation, 11 patients were asymptomatic. All of benign tumors were resected completely, but in a few patients with malignant tumors, the complete resection not possible. However, except for one patient with immature teratoma, all patients with malignant tumor have been surviving following postoperative chemotherapy and radiotherapy. Two infants with bronchogenic cyst were operated on their respiratory distress syndrome in emergency, and have been salvaged.

Adolescent↗

PubMed1996

[A case report of a pseudoaneurysm of the thoracic aorta (thrombotic closure type) showing like a mediastinal tumor--value of endoscopic ultrasonography in differential diagnosis].

A 65-year-old male patient was refered to our hospital for abnormal mediastinal shadow. CT and MRI study showed an inhomogeneous mediastinal tumor simulating neoplasm neighboring the aortic arch. Thoracic aortogram did not revealed the existence of thoracic aortic aneurysm. But the endoscopic ultrasonography (EUS) showed a pseudoaneurysm with a 2 cm entry site. The diagnosis of pseudoaneurysm was therefore proved, so the patient underwent the operation safely with preparation for extracorporeal circulation. Some patients with chronic thoracic pseudoaneurysm has no history of chest trauma and other causes. It is valuable to perform EUS for the differential diagnosis of abnormal mediastinal shadow which shows like a mediastinal tumor.

Aged↗

PubMed1995

Effect of arm cranking exercise on skin blood flow of lower limb in people with injuries to the spinal cord.

The purpose of this study was to examine whether arm cranking exercise induces changes in skin blood flow in the paralyzed lower limbs of people with injuries to the spinal cord (PISC). Ten PISC with lesions located between Th5 and L5 and six control subjects performed arm cranking exercise for 6 min at three intensities, 10, 30 and 50 W, at a room temperature of 25 degrees C. Oxygen uptake (Vo2) and heart rate (HR) were measured for the last 2 min of each exercise period. The skin blood flow at the anterior thigh (BFsk,t) was continuously monitored using laser Doppler flowmetry for the whole 6-min period and for the first 10 min of recovery following exercise. During exercise, the PISC showed lower Vo2 and greater HR than the control subjects. No increase in BFsk,t was found in six of the PISC with lesions at or above Th12, irrespective of the exercise intensity. On the other hand, in PISC with lesions at L1 or below, BFsk,t increased significantly (P < 0.05) with an increase in Vo2 and HR, although the BFsk,t at a given Vo2 and HR was lower than that in the control subjects. These results would suggest that arm exercise can promote the blood circulation in the skin of the lower limbs if the injury level is below L1.

Adult↗

PubMed1995

Effects of upper limb exercise on thermoregulatory responses in patients with spinal cord injury.

We evaluated changes in body temperature, heart rate, and oxygen uptake during arm cranking exercise (20 watts, 30 min) in an artificial climate room at a temperature of about 25 degrees C or 35 degrees C (relative humidity, about 50%) in 5 patients with paraplegics due to spinal cord injury (SCI). The tympanic temperature (Tty) was significantly higher from rest to recovery at 35 degrees C than at 25 degrees C. The mean Tty after 10 minutes of rest was 36.68 degrees C +/- 0.396 (mean +/- SD) at a room temperature of 25 degrees C and 37.25 degrees C +/- 0.253 at 35 degrees C, showing a difference of about 0.5 degrees C. This difference was maintained during exercise and recovery. The Tty at the end of exercise was higher than that at the start of exercise by 0.66 degrees C +/- 0.218 (mean +/- SD) at 25 degrees C and by 0.59 degrees C +/- 0.210 at 35 degrees C. The skin temperature (Tsk) in each measurement area (the head, arm, chest, thigh, shin, and calf) was significantly higher at 35 degrees C. Oxygen uptake did not differ between 25 degrees C and 35 degrees C. The heart rate was significantly higher at 35 degrees C than at 25 degrees C during rest and at the start of exercise but did not differ during exercise and recovery. Thus, mild-moderate exercise in this study did not cause marked changes such as increases in body temperature and heart rate that affect biological function in SCI.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

[Malignant mediastinal lesions with invasion to the superior vena cava].

Four patients underwent resection of mediastinal malignant tumors with invasion to the superior vena cava. Two patients had invasive thymoma, one seminoma, and one metastatic mediastinal lymph nodes of unknown origin. Prior to resection of the tumor, an ePTFE graft was anastomosed between the innominate vein and the right atrium to maintain the venous drainage from the brain and the upper extremities. In two patients, the superior vena cava was reconstructed by patch angioplasty after the tumor with a part of the vena cava was safely resected. One patient died of acute respiratory failure, but the other three are alive and well without any evidence of graft obstruction. This safe and useful method in order to prevent cerebral congestion during and after resection of the tumor.

Adult↗