Biomedical subjects

M Tayama

Publications and source records attributed to M Tayama.

At least 19 recordsLinked to original sources

PubMed2003

[The analysis of renal function in off-pump coronary artery bypass grafting].

OPCAB (off-pump coronary artery bypass grafting) is useful for preventing post-operative neurologic complications. On the other hand, the effect of OPCAB on post-operative renal function is still unclear. We analyzed the post-operative renal function in 39 patients. Thirty-two patients had normal pre-operative renal function (CRE < or = 1.4 mg/dl). Thirty-one patients were doing well in terms of post-operative renal function. Only 1 patient needed hemodialysis (HD) because of systemic infection in early post-operative period. Another 7 patients had pre-operative renal dysfunction (CRE > or = 1.5 mg/dl). Three cases with high-grade pre-operative renal dysfunction (CRE > 3.0 mg/dl and CCR < 20 ml/min) needed temporary HD or continuous hemo-diafiltration (CHDF) in early post-operative period, and then they needed maintenance HD for the treatment of chronic renal failure within 3 weeks after OPCAB. Three of 4 cases with low-grade pre-operative renal dysfunction (CRE: 1.9-2.7 mg/dl and CCR: 22-42 ml/min) needed temporary HD or CHDF in early post-operative period. These 3 patients were relieved of the early post-operative renal failure, but required maintenance HD in the late periods. In summary, OPCAB could not prevent the development of acute renal failure in the patients with pre-operative renal dysfunction.

Aged↗

PubMed1999

Pulmonary blood flow distribution after the total cavopulmonary connection for complex cardiac anomalies.

In total cavopulmonary connection (TCPC), the anastomotic portion of the caval veins to the pulmonary artery (PA) is decided empirically based on personal experience. To compare the pulmonary flow distribution from both caval veins in various types of cavopulmonary anastomosis, intrapulmonary ventilation-perfusion distribution after TCPC was studied using lung scanning. We studied 11 patients, 2 to 37 years old, at 30-84 months after TCPC. Lung scanning was performed by administering 185 MBq of xenon-133 saline solution from their upper extremities and, after xenon-133 was washed out, from their lower extremities. Radionuclide counts on both lungs were obtained and intrapulmonary ventilation-perfusion distribution was assessed. In 4 patients whose superior vena cava (SVC)-PA anastomosis was on the right side of the inferior vena cava (IVC)-PA anastomosis, the blood flow distribution of the right and left lungs was 57.4%: 42.6%. In 3 patients whose SVC-PA anastomosis was on the left side of the IVC-PA anastomosis, the blood flow distribution of the right and left lungs was equal in both lungs (right, 53.1%; left, 46.9%). Systemic arterial oxygen saturation increased after TCPC (before TCPC, 85.3% +/- 2.7% and after TCPC, 89.8% +/- 2.3% (P < 0.05) in group R; before TCPC, 86.1% +/- 2.8% and after TCPC, 93.6% +/- 0.6% (P < 0.02) in group L). After TCPC, the value in group L had a tendency to be greater than that in group R (P < 0.04), in spite of the same values of systemic arterial oxygen saturation before TCPC and cardiac index (group R, 2.9 +/- 0.96; group L, 3.4 +/- 0.37). Lung scanning with xenon-133 revealed the distribution of pulmonary blood flow in the patients after TCPC quantitatively, and in the patients whose SVC-PA anastomosis was on the left side of the IVC-PA anastomosis, the right and left balance of the pulmonary blood flow distribution appeared to be more balanced compared with patients whose connection was done the opposite way.

Adolescent↗

PubMed1998

Effect of lidocaine on left ventricular pressure-volume curves during demand ischemia in pigs.

The diastolic pressure-volume curve shifts upward during demand ischemia, most likely because of changes in Ca2+ dynamics within the sarcomere. It is possible that agents that affect Na+/Ca2+ exchange, such as lidocaine, a class 1b-type Na+-channel blocker that decreases intracellular Na+, could affect the diastolic pressure-volume relationship because of indirect effects on intracellular Ca2+. Lidocaine is a drug widely used to treat arrhythmias in patients with myocardial ischemia. We studied the effects of lidocaine on diastolic dysfunction associated with demand ischemia. We compared diastolic (as represented by the shift in the diastolic pressure-volume relationship) and systolic function during demand ischemia before and after lidocaine injection. We created demand ischemia in pigs before and after administering lidocaine (5 mg/kg) in eight open-pericardium anesthetized pigs. Demand ischemia was induced by constricting the left anterior descending coronary artery and then pacing at 1.5-1.8 times the baseline heart rate for 1.5-3 min. Hemodynamics were recorded during baseline, demand ischemia, baseline after lidocaine injection, and demand ischemia after lidocaine. Lidocaine did not affect systolic function or the time constant of isovolumic relaxation, but it increased the upward shift of the diastolic pressure-volume curve during demand ischemia compared with the increase that occurred before lidocaine was administered. This result suggests that lidocaine could aggravate diastolic dysfunction in patients with ischemic heart disease.

Animals↗

PubMed1997

Differences in brain metabolites between patients with autism and mental retardation as detected by in vivo localized proton magnetic resonance spectroscopy.

We performed volume-selective proton magnetic resonance spectroscopy (1H-MRS) of the brain with a 1.5 T magnet in 28 patients with autism, and compared the results with those from 28 age-matched patients with unclassified mental retardation and 25 age-matched healthy children. Peaks for N-acetylaspartate, choline and creatine, but not lactate, were observed in each group on 1H-MRS. The N-acetylaspartate/choline ratio was lower in patients with mental retardation than in patients with autism and controls (P = .05, respectively). However, there were no differences in the N-acetylaspartate/ choline ratios between patients with autism and controls, and the N-acetylaspartate/creatine and choline/creatine ratios did not differ among the three groups. These results suggest that N-acetylaspartate is decreased in patients with mental retardation and that a disorder or dysfunction of neurons in the brain exists. There also appear to be differences in the brain lesions or dysfunctions found in patients with autism and mental retardation.

Aspartic Acid↗

PubMed1995

Development of the brainstem and cerebellum in autistic patients.

Studies of magnetic resonance images have revealed morphological disorders of the brainstem and cerebellum in autistic children and adults. When we studied development of the brainstem and cerebellum in autistic patients, we found that although the brainstem and cerebellum significantly increased in size with age in both autistic patients and controls, these structures were significantly smaller in autistic patients than in controls. The speed of development of the pons, the cerebellar vermis I-V and the cerebellar vermis VI-VII was significantly more rapid in autistic patients than in the controls. However, the speed of development of the other brain structures in the posterior fossa did not differ between autistic patients and controls. The regression intercepts of the brainstem and cerebellum as well as those of their components were significantly smaller in autistic patients than in controls. Results suggest that brainstem and vermian abnormalities in autism were due to an early insult and hypoplasia rather than to a progressive degenerative process.

Adolescent↗

PubMed1995

Proton magnetic resonance spectroscopy of brain in congenital myotonic dystrophy.

Volume selective proton magnetic resonance spectroscopy of brain was performed on a 1.5 T magnet in 5 patients with congenital muscular dystrophy and compared to the results in 46 healthy children and 1 healthy adult. Peaks of N-acetyl aspartate, choline, and creatine but not lactate, were observed in both groups on proton magnetic resonance spectroscopy. Spectroscopy of controls revealed an increase with advancing age in the ratio of N-acetyl aspartate/choline and N-acetyl aspartate/creatine and a decrease in the choline/creatine ratio. In patients with congenital myotonic dystrophy, the N-acetyl aspartate/choline ratio did not increase with advancing age, but the N-acetyl aspartate/creatine ratio did. The choline/creatine ratio decreased with advancing age, which matched the results of controls. At any age older than 4 years, the N-acetyl aspartate/choline and N-acetyl aspartate/creatine ratios were lower in patients with congenital myotonic dystrophy than in controls. The choline/creatine ratio did not differ between congenital myotonic dystrophy and controls. These results suggest that in patients with congenital myotonic dystrophy N-acetyl aspartate decreases and there exists a developmental disorder of neurons in brain.

Adolescent↗

PubMed1995

Reduced N-acetylaspartate in the brain observed on in vivo proton magnetic resonance spectroscopy in patients with mental retardation.

Volume-selective proton magnetic resonance spectroscopy (1H-MRS) of the brain was performed with a 1.5T magnet in 28 patients with unclassified mental retardation (MR) and in 25 age-matched healthy children. Peaks of N-acetylaspartate (NAA), choline (Cho), and creatine (Cr), but not of lactate, were observed in both groups on 1H-MRS. In all our subjects of this age range, 1H-MRS revealed an increase with advancing age in the ratio of NAA/Cho (P = .0031), but no developmental change in the NAA/Cr and Cho/Cr ratios. The NAA/Cho ratio was lower in patients with MR than in controls (P = .0016). The NAA/Cr ratio tended to be lower in the MR group, and the Cho/Cr ratio did not differ between patients with MR and controls. These results suggest that in patients with MR, NAA decreases and a disorder and/or dysfunction of neurons in the brain exists.

Adolescent↗

PubMed1995

Developmental brain changes investigated with proton magnetic resonance spectroscopy.

Volume-selective proton magnetic resonance spectroscopy (1H-MRS) of the brain was performed with a 1.5 Tesla magnet in 47 healthy children and in six healthy adults. Peaks of N-acetylaspartate (NAA), choline (Cho) and creatine (Cr) were observed in all cases, but a lactate peak was not observed. In the right parietal region. 1H-MRS revealed increases in the rations of NAAJCho and NAA/Cr and a decrease in Cho/Cr with advancing age. The most rapid changes were noted between one and three years of age. 1H-MRS of the right frontal region also was performed in 21 cases (20 children and one adult). In the right frontal region, there was an increase in the ratio of NAA/Cho and a decrease in Cho/Cr with advancing age, while a developmental change was not observed in the ratio of NAA/Cr. The ratios of both NAA/Cho and NAA/Cr were lower in the right frontal region than in the right parietal region. These results show that developmental changes and regional variation of metabolites are observed in 1H-MRS of the brain, and need to be considered in its application.

Adolescent↗

PubMed1995

[Proton MR spectroscopy of the brain in patients with congenital myotonic dystrophy].

Volume selective proton MR spectroscopy (1H-MRS) of the brain was performed on a 1.5T magnet in five patients with congenital muscular dystrophy (CMyD), 46 healthy children, and one healthy adult. Peaks of N-acetylaspartate (NAA), choline (Cho) and creatine (Cr) were observed in both patients and control groups on 1H-MRS, but lactate was not observed. 1H-MRS revealed an increase in the ratio of NAA/Cho and NAA/Cr, and a decrease in Cho/Cr ratio with age in control subjects. In patients with CMyD, the values of NAA/Cho ratio did not increase with age. The values of NAA/Cr ratio decreased with age. The values of Cho/Cr ratio decreased with age in both patient and control groups. At age more than 4 years, the values of NAA/Cho and NAA/Cr ratios were lower in patients with CMyD than in controls. The values of Cho/Cr ratio did not differ between CMyD and controls. These results suggest that in patients with CMyD, there is an NAA decrease and a developmental disorder of neurons in the brain.

Adolescent↗

PubMed1994

Needs of physiological and psychological research using artificial gravity.

In the next century, mankind will expand its activity to the moon and Mars. At that time, humans will be exposed to a low and micro-gravity environment in long term which causes physiological and psychological problems. The authors propose an artificial gravity space station for a research laboratory on human physiology and psychology at various gravity levels. The baseline specifications and the configuration of the space station are shown. Reviewing the history of manned space flight, the necessity of the research on an artificial gravity space station is discussed, including themes of research to be conducted on the station and the application of its results. Technical issues for realization of the space station such as environmental factors, system function and assembly scenario are also discussed.

Aerospace Medicine↗

PubMed1994

Infantile spasms with predominantly unilateral cerebral abnormalities.

To investigate the pathogenesis of infantile spasms, 12 children underwent a combination of neurophysiologic and neuroimaging studies including brainstem evoked potentials and single photon emission computed tomography with 99mTcHMPAO. Three of the children had localized cerebral abnormalities on neuroimaging, i.e. right frontotemporal cortical microdysgenesis, left frontotemporal polymicrogyria, and right parietooccipitotemporal porencephalic cyst. Neurophysiologic studies also indicated that a single cerebral hemisphere was predominantly involved, while the other hemisphere and the brainstem were relatively spared, a result compatible with the clinical findings of hemiparesis and hemiconvulsion. In these three patients, administration of carbamazepine was followed by marked improvement of the clinical and electroencephalographic findings. Our results suggest that a combination of noninvasive examinations can distinguish a particular subtype of infantile spasms associated with a localized cerebral abnormality and responsive to carbamazepine.

Carbamazepine↗

PubMed1994

[Development of the brainstem and cerebellum in autistic children].

Studies of magnetic resonance images have revealed morphological disorders of the brainstem and cerebellum in autistic children and adults. When we studied development of the brainstem and cerebellum in autistic patients, these structures were significantly smaller in autistic patients than in controls. Although the brainstem and cerebellum significantly increased in size with age in both groups, the development of the pons, cerebellar vermis I-V and cerebellar vermis VI-VII was significantly more rapid in autistic patients than in controls. However, the development of the other brain structures in the posterior fossa did not differ between autistic patients and controls. The regression intercepts of the brainstem and cerebellum as well as those of their components were significantly smaller in autistic patients than in controls. These results suggested that significant anatomical changes took place in the posterior fossa brain structures in the prenatal period in autistic children, but were not progressive.

Adolescent↗

PubMed1994

[Neurophysiologic studies on patients with migration disorder].

Neurophysiologic studies on six patients (five lissencephaly and one schizencephaly) with migration disorder were performed in order to evaluate the CNS function by multimodality evoked potentials. All cases revealed abnormalities in SSEP, four cases lost components below P 3 or had low voltage of P 3 indicating brainstem dysfunction in the somatosensory pathway. Two cases lost component below N 1 indicating sensory cortical dysfunction. Three cases revealed ABR abnormalities including a low amplitude of wave V, and one case revealed a prolonged peak latency of wave I and a low amplitude of all components. Two cases revealed abnormalities of poor cortical components in SEP, two cases in VEP, and three cases in MLR. Five cases had normal findings in P-SEP and three cases in VEP. The result of this study demonstrates that patients with migration disorder are frequently associated with cortical, brainstem and peripheral dysfunctions and has heterogeneity in pathophysiology.

Brain↗

PubMed1994

[Infantile spasms with localized cerebral lesion detected by 99mTcHMPAO-SPECT].

We experienced a 6-month-old girl with infantile spasms who had localized cerebral lesion detected by 99mTcHMPAO-SPECT. She was born vaginally after a full term uncomplicated delivery with a birth weight of 3,100 g. She developed emprosthotonic spasms with series formation and EEG showed asymmetric periodic hypsarrhythmia which was predominant in the right hemisphere. While MRI could not detected any focal lesion, 99mTcHMPAO-SPECT disclosed hypoperfusion at the right anterior temporal and frontal areas. Although vitamin B6, clonazepam and sodium valproate were administered with no remarkable benefit, the treatment with ACTH-Z or carbamazepine resulted in cessation of spasms and improvement of the EEG findings. Consequently, the study with 99mTcHMPAO-SPECT was useful to clarify the pathology of infantile spasms, and we concluded that a patient with localized cerebral lesions should be given carbamazepine.

Brain↗

PubMed1994

[Developmental changes in proton MR spectroscopy of the brain].

Volume-selective proton MR spectroscopy (1H-MRS) of the brain was performed on a 1.5 T magnet in 31 healthy children aged from 1 month to 15 years and one healthy adult. Peaks of N-acetylaspartate (NAA), choline (Cho) and creatine (Cr) were observed in all cases on 1H-MRS, but not lactate. On 1H-MRS of the right parietal region, with advancing age, 1H-MRS revealed an increase in the ratios of NAA to Cho and NAA to Cr and a decrease in Cho to Cr. The most rapid change was noted during the first one to three years of life. 1H-MRS of the right frontal region was also performed in eleven cases. The ratio of NAA/Cho was smaller in the right frontal region than in the right parietal region. From this result, it may be suggested that the neuronal maturation in the frontal region delays as compared with the parietal region.

Adolescent↗

PubMed1994

[MRI measurements of the brain stem and cerebellum in high functioning autistic children].

To determine involvements of the brain stem and/or cerebellum in autism, we compared midsagittal magnetic resonance images of the brains of high functioning autistic children with those of normal controls. We found that the midbrain and medulla oblongata were significantly smaller in these autistic children than in the control children. The pons area did not differ between the two groups, nor was there any difference in the cerebellar vermis area. The ratio of the brain stem and cerebellum to the posterior fossa area did not differ significantly between the high functioning autistic and the control children. The development of the cerebellar vermis area was delayed in autistic children as compared with that in the control children. Thus, it was suggested that significant anatomical changes in the midbrain and medulla oblongata existed in the autistic children.

Aging↗

PubMed1993

Effect of saposins on acid sphingomyelinase.

The effect of saposins (A, B, C and D) on acid sphingomyelinase activity was determined using a crude human kidney sphingomyelinase preparation and a purified sphingomyelinase preparation from human placenta. Saposin D stimulated the activity of the crude enzyme by increasing its apparent Km and Vmax. values for sphingomyelin hydrolysis. Unlike the crude enzyme, the activity of the purified enzyme was strongly inhibited by saposin D as well as other saposins. Saposin D decreased the apparent Km and Vmax values of purified sphingomyelinase activity. The effects of saposin D on the activity of different sphingomyelinase preparations appear to depend on Triton X-100, which is present in the crude enzyme but not in the purified enzyme. When the detergent was removed from the crude preparation, the effect of saposin D changed from being stimulatory to inhibitory. Conversely, when the detergent is added to the purified enzyme, the effect of saposin D on sphingomyelinase activity changed from being inhibitory to stimulatory. While other saposins were inhibitory or had no effect on sphingomyelinase activity in the above assay system, not only saposin D but also saposins A and C exhibited a stimulatory effect upon purified sphingomyelinase activity when the substrate, sphingomyelin, was added in the form of liposomes without detergent. Saposin B was not only inhibitory in the liposome system, but also reduced the stimulatory effect of saposins A, C and D. These observations indicate that the stimulatory effect of saposins A, C and D on acid sphingomyelinase activity is greatly influenced by the physical environment of the enzyme and suggest that similar effects by saposins may be exerted in lysosomal membranes.

Detergents↗

PubMed1993

Brainstem involvement in infantile spasms: a study employing brainstem evoked potentials and magnetic resonance imaging.

Ten patients with infantile spasms underwent brainstem evoked potentials and magnetic resonance imaging (MRI) examination to evaluate brainstem involvement. Short latency somatosensory evoked potentials and auditory brainstem responses were abnormal in seven and five of the 10 patients, respectively. MRI findings were abnormal in nine of the 10 patients. Six patients demonstrated various degrees of atrophy of the brainstem. In all of these cases brainstem evoked potentials were abnormal. This study demonstrates that infantile spasms are frequently associated with brainstem dysfunction and raises the hypothesis that brain atrophy involving the brainstem might be a cause of infantile spasms. In addition, this study also documents the combination of brainstem evoked potentials and MRI examination is valuable tool in the evaluation of brainstem involvement in infantile spasms.

Adrenocorticotropic Hormone↗