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Biomedical subjects

A Wakayama

Publications and source records attributed to A Wakayama.

At least 19 recordsLinked to original sources
PubMed2001

[Effect of stimulus size on binocular summation within the binocular visual field].

PURPOSE: To study the influence of stimulus sizes on binocular summation using the modified Octopus 201 combined with a space synoptophore. METHODS: Four normal subjects, aged 21 to 26 were tested. Using the SARGON program, we designed a new program to test 37 points in the central 6 degrees visual field. Sensitivity of the central 6 degrees visual field under monocular and binocular conditions was measured while the fusion patterns were displayed on the space synoptophore. The visual fields were measured at stimulus sizes 1, 3, and 5. RESULTS: The visual sensitivity under binocular conditions was higher than under monocular conditions for all the stimulus sizes. Binocular summation for stimulus size 1 was present in a flat form, for stimulus size 3 in a convex form, and for stimulus size 5 in a concave form in the central 6 degrees visual field. CONCLUSION: Binocular summation differed in stimulus size and retinal eccentricity. Binocular summation for stimulus size 3 increased in the fovea and it increased for stimulus size 5 in the peripheral area in the central 6 degrees visual field.

Adult↗
PubMed2000

Vitamin E supplementation attenuates leakage of enzymes following 6 successive days of running training.

The purpose of this study was to examine whether vitamin E supplementation in humans would attenuate an increase of serum enzymes as an indirect marker of muscle damage following a sudden large increase in the running distance in a 6-day running training or not. A randomized and placebo-controlled study was carried out on fourteen male runners who were supplied vitamin E (alpha-tocopherol 1200 IU x day(-1); E) or placebo (P) 4 weeks prior to (T1) and during 6 successive days of running training (48.3 +/- 5.7 km x day(-1), means +/- SD). Resting venous blood samples were obtained before maximal treadmill running, at T1, the day immediately before (T2), the next day (T3), and three weeks (T4) after the running training. Serum levels of alpha-tocopherol, lipid peroxidation products (thiobarbituric acid; TBA), creatine kinase (CK), lactate dehydrogenase (LDH), and LDH isozyme 1-5 were quantitatively analyzed. No significant difference was found in maximal oxygen uptake (VO2max) and maximal heart rates following the exhaustive exercise between the P and E group during the experiments. Vitamin E supplementation significantly increased serum alpha-tocopherol (p<0.001) and decreased TBA levels (p < 0.001) compared with pre-supplementation levels. Although serum CK and LDH activities increased significantly at T3 in either group, significantly lower CK (p < 0.05) and LDH (p < 0.001) levels were observed in the E group compared with the P group. The ratio of LDH1 to LDH2 (LDH1/LDH2) decreased significantly at T3 in either group compared with the T1 levels, since there was no significant difference in the LDH1/LDH2 between the P and E group throughout the experiments. These results indicate that vitamin E supplementation can reduce the leakage of CK and LDH following 6 successive days of endurance running. The protective effect of vitamin E against free radicals probably inhibits free-radical-induced muscle damage caused by a sudden large increase in the running distance.

Adult↗
PubMed1999

Combined transfrontal and endonasal endoscopic surgery of epidural abscess following frontal sinusitis. A case report.

A large epidural abscess secondary to frontal sinusitis in a previously healthy 19-year-old man was successfully treated with a small eyebrow incision using combined transfrontal and endonasal endoscopic technique. The abscess was resolved with concomitant pneumatization of the paranasal sinuses. The present case illustrates the promising use of endoscopy in the merging fields of neurosurgery and otorhinolaryngology.

Abscess↗
PubMed1999

Decrease in N-acetylaspartate without commensurate accumulation of acetate in focal cerebral ischemia in rat.

N-acetylaspartate (NAA) is a plausible marker of neuronal viability which decreases in a variety of neurodestructive conditions. To elucidate the mechanism that leads to NAA decline in two different types of cerebral ischemia in rats, we simultaneously determined cortical concentrations of NAA and its hydrolytic metabolites, aspartate, and acetate by high-resolution 1H-NMR spectroscopy. NAA decreased almost linearly up to 24 h in both decapitation induced global cerebral ischemia, and in ischemic cortices of focal ischemia. Acetate was increased continuously for up to 24 h of global ischemia, while in focal cerebral ischemia it was increased transiently at 6 h. Aspartate did not show any change in global ischemia, while it was decreased in focal ischemia. Although NAA decreased similarly in the brain with global and focal ischemia, temporal changes of two NAA hydrolytic metabolites were different in each type of ischemia. The present results suggest hydrolytic degradation of NAA may be modified alternatively under each pathophysiologic condition.

Acetates↗
PubMed1999

[Urodynamic studies on the untethering of spinal lipoma in the children].

We performed conus untethering on 44 children with spinal lipoma. In this retrospective study, we studied urological examinations obtained in 36 consecutive patients. Urological examinations were ultrasonography of bladder and kidney, voiding cystourethrography (VCG), and urodynamic cystometry. In those of them, 6 patients had already had urinary dysfunction at preoperative stage, but 4 patients' spinal lipoma was one complication of cloaca exstrophy and 2 patients' spinal lipoma after repairment of their myelomeningocele. In the remaining 30 cases, 18 patients (60.0%) as the group 1 did not have urinary dysfunction and abnormality in any urological examinations. Another 7 patients (23.3%) as group 2 also did not have urinary dysfunction, but abnormal vesicoureteral reflux (VUR) was found out in their VCG examination. At postoperative stage, abnormal VUR resolved or improved in all these 7 cases, but one of them showed transient urinary retention. Two patients of 18 in the group 1 had to require clean intermittent self-catheterization at postoperative stage. These observations confirmed that children with spinal lipoma were more likely to present with urological findings, and so it was imperative that a diagnosis be made and treatment be instituted as early as possible.

Child, Preschool↗
PubMed1999

[Vein of Galen aneurysmal malformation: multi-staged feeder clipping in two neonatal cases with intractable heart failure].

The authors reported the surgical experience of two cases of vein of Galen aneurysmal malformation in the newborn, whose congestive high-output cardiac failure was intractable. Along with the intensive care to clinical manifestations of the heart failure, multi-staged feeder clipping was carried out to decrease the high-flow shunt of the malformation. As stages going on, heart failure was relieved gradually and cathecolamines were weaned. Although certain retardation became apparent in both cases, they are showing satisfactory development in the long-term follow up. By the recent advancement of the embolization technique, the embolization appears to have already taken place the treatment of choice for this malformation. According to the neonatal evaluation score of Lasjaunias, the embolization would no longer be recommendation in neonates, whose general condition scored less than eight points. The authors believe, based on our two cases, that multi-staged feeder clipping is one of the effective modality of treatment in neonates of the vein of Galen aneurysmal malformation with severe multiorgan failure.

Cardiac Output, High↗
PubMed1999

[Spinal lipoma in children: analysis of magnetic resonance image for upward displacement of medullary-conus on 44 consecutive surgical cases].

Medullary conus-untethering operation was conducted on 52 infants with spinal lipoma. Magnetic resonance (MR) image was used in order to evaluate the untethering results in 44 out of these 52 patients who could be followed-up after Osaka Medical Center & Research Institute for Maternal & Child Health was opened. Talking into account the changes in vertebral body during the growth period of infants, the authors studied the upward displacement of the conus-lipoma interface by four fractional MR sagittal image, using the vertebral body-intervertebral disc space as the baseline. Upward displacement was confirmed in 27 of 44 (61.4%). The mean, median and trimmed mean of upward displacement were 1.78 +/- 0.80, 2.0, 1.70 fractions, respectively. Sixteen (59.3%) were caudal type, 10 (37.0%) were transitional type and 1 (3.7%) was dorsal type. By type of spinal lipoma, upward displacement was observed in 16 of 23 caudal type patients (69.6%), 10 of 16 transitional type patients (62.5%) and 1 of 5 dorsal type patients (20%). While the rate of upward displacement was almost equal between the caudal and transitional type, that of dorsal type was lower. However, statistical analysis for the difference in population percentage of the three groups showed that significant difference existed only in the caudal type group.

Female↗
PubMed1999

Purely laparoscopic pylorus-preserving gastrectomy with extraperigastric lymphadenectomy for early gastric cancer: a case and technical report.

For the purpose of prevention of postgastrectomy syndrome and a less invasive and yet curative oncological resection, a purely laparoscopic pylorus-preserving gastrectomy with extraperigastric lymphadenectomy was performed for a patient with early gastric cancer located in the middle third of the stomach. The patient's postoperative course was uneventful. During his postoperative recovery, the patient experienced very little pain and used analgesic medication only one time. This operation appeared to be oncologically adequate. As of the seventh postoperative month, the patient never experienced dumping syndrome or alkaline reflux gastritis. This procedure is technically feasible and an excellent option because of its reduced surgical invasiveness and better postoperative quality of life.

Adenocarcinoma↗
PubMed1998

Identification of a receptor tyrosine kinase involved in germ cell differentiation in planarians.

To investigate external signals involved in germ cell differentiation from somatic stem cells, we have tried to identify protein kinases whose expression is regulated during the process of sexualization of asexual-state planarians. It is known that in planarians germ cells differentiate from totipotent somatic stem cells called "neoblasts" during sexualization. As a first step, we have isolated twelve protein kinase genes from cDNAs of sexual-state planarians, including three non-receptor tyrosine kinases, three receptor-tyrosine kinases and three non-receptor serine/threonine kinases, and then analyzed their expression patterns during sexualization. One of them, the DjPTK1 gene, is specifically expressed in germ cells of sexual-state planarians. DjPTK1-positive cells were also detected in the mesenchymal space during the process of sexualization, and it appears that these cells migrate to the dorsal side and then differentiate into spermatogonia/spermatocytes in testis. Sequence analysis indicated that the DjPTK1 gene encodes a receptor protein tyrosine kinase belonging to the FGFR/PDGF family. These results suggest that a receptor tyrosine kinase system may be involved both at an early stage of germ cell differentiation and in a step of germ cell maturation in planarians.

Amino Acid Sequence↗
PubMed1998

Changes in brain organic osmolytes in experimental cerebral ischemia.

The cell volume is regulated not only by inorganic ions, but also by organic osmolytes, such as amino acids, methylamines, and polyhydric alcohols (polyols). Using proton nuclear magnetic resonance spectroscopy (1H-NMR), we measured the tissue concentrations of amino acids (alanine, aspartate, gamma-aminobutyric acid (GABA), glutamate, glutamine, N-acetyl-aspartate (NAA), taurine), methylamines (glycerophosphorylcholine (GPC), creatine+phosphocreatine (total creatine, tCr)), and polyols (myo-inositol) in the rat brain after middle cerebral artery occlusion (incomplete focal ischemia) or after decapitation (complete global ischemia). The total osmolytes expressed as a sum of total amino acids, total methylamines, and total polyols were significantly decreased at 24 h of focal ischemia (58.7% of control value, P=0.0025) whereas they were not changed following decapitation. The water content was increased from control value of 77.9%-84.1% after focal ischemia (P<0.0001) but not after decapitation. These results suggest that the brain organic osmolytes are involved in the process of edema formation following focal cerebral ischemia. Further elucidation of the cellular mechanisms regulating these organic osmolytes in cerebral ischemia may promote greater understanding of the pathophysiology involved in the evolution of brain edema.

Alanine↗
PubMed1997

[Anesthetic and perioperative management of a neonatal vein of Galen malformation with multiple organ failure].

We treated a neonate in intractable cardiac failure due to a vein of Galen malformation. She manifested severe multiple organ failure. Perioperative problems are cardiac failure, respiratory failure, renal as well as hepatic dysfunction, and coagulopathy. Direct clipping of the feeding arteries improved her symptoms. Anesthetic problems encountered in this patient are massive bleeding and drastic circulatory changes while clipping the feeding arteries, increased intracranial pressure and brain ischemia, and other underlying complications; hepatic and renal dysfunction, respiratory failure and coagulopathy.

Anesthesia, General↗
PubMed1996

[Clinical and electroencephalographic studies in children with hemimegalencephaly].

Clinical and electroencephalographic (EEG) studies were performed in two children with hemimegalencephaly. The ages of seizure onset were 44 hours after birth in one infant and 33 days of postnatal life in the other patient. In both children, infantile spasms (IS) associated with hemihypsarrhythmia, developed at 1.5 months and 4 months, respectively. The subsequent clinical courses in these children were notable for frequent, intractable seizures. The seizures consisted of either generalized or partial seizures which originated from not only the hemimegalic hemisphere but also the contralateral one. Later, the clinical and EEG findings in one child indicated the development of Lennox-Gastaut syndrome (LGS). These findings suggested that the lesions of epileptogenesis in patients with hemimegalencephaly involved not only the pathological hemisphere, but also the contralateral hemisphere and subcortical structures. A detailed neurophysiological investigation in hemimegalencephaly could help the elucidation of the pathophysiology of intractable epilepsies, such as IS or LGS.

Brain↗
PubMed1993

Two-step procedure for early neonatal surgery of fetal hydrocephalus.

This retrospective study analyzed the diagnosis and treatment of 36 infants with central nervous system anomalies diagnosed antenatally by ultrasonographic studies between December, 1987 and December, 1990. Magnetic resonance imaging of the fetuses without maternal or fetal sedation/anesthesia was very useful, as the fetal ventricular system was depicted clearly. Twenty-three infants with hydrocephalus underwent early postnatal surgical emplacement of a miniature Ommaya's reservoir. Continuous cerebrospinal fluid aspiration was combined with intracranial pressure monitoring. Observation of the ventricular size used ultrasonography through the anterior fontanelle. This technique controlled the intracranial pressure during the early neonatal period without serious complications. A ventriculoperitoneal shunt was emplaced 1 month later as the second, more permanent treatment. This two-step procedure achieves brain reconstitution and prevents irreversible neurological damages. Clinical and radiographic findings are presented to illustrate the effectiveness of this approach.

Brain↗
PubMed1993

Evaluation of masked neurological disorders in the chronic stage after middle cerebral artery occlusion in rats--methamphetamine-induced rotation and regional glucose metabolism in basal ganglia.

Neurofunctional changes in rats in the chronic stage of focal cerebral ischemia induced by left middle cerebral artery (MCA) occlusion were examined. Neurological disorders and behavioral changes were observed with or without methamphetamine administration. Metabolic changes in the basal ganglia following methamphetamine intraperitoneal injection were evaluated by [14C]deoxyglucose autoradiography 30 days after occlusion. Neurological examination revealed persistent spontaneous rotation to the lesioned side in two of 18 rats, and forelimb flexion to the lesioned side in nine of 18 rats during a 28-day observation period after occlusion. Intraperitoneal administration of methamphetamine (4 mg/kg) induced full 360 degrees rotation toward the lesion side in 14 of 17 rats. The number of rotations was inversely correlated with the size of the intact striatum on the lesion side, especially in rats with cerebral infarct located only in the striatum. Rats with extensive cortical lesion in addition to striatal lesion did not demonstrate this relationship. Deoxyglucose autoradiography in methamphetamine-untreated rats showed symmetrical local cerebral glucose utilization in the basal ganglia except for the subthalamic nucleus, striatum and sensorimotor cortex. Autoradiography in methamphetamine-treated and MCA-occluded rats showed a remarkable increase in glucose utilization in the anterior striatum, entopeduncular nucleus, substantia nigra pars reticulata, and sensorimotor cortex contralateral to the occlusion side, but not on the lesioned side. Rotational movements observed in methamphetamine-treated rats are related to lack of stimulation of the basal ganglia system on the ischemic side.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

[Perinatal neurosurgical care for one fetal hydrocephalus on twin gestation].

Twin gestations are responsible for a disproportionate amount of perinatal mortality and morbidity. Such gestations may impose greater demands on maternal and child physiologic systems than singleton pregnancies. The most common antenatal complications were preterm labor. The clinical record of myelomeningocele infant presenting with overt hydrocephalus in utero at 27 weeks of twin gestation and operated miniature Ommaya's reservoir placement early after birth and intentional delayed back closure for myelomeningocele was reported. Although perinatal neurosurgical care for one fetal hydrocephalus on twin gestation is clearly advantageous, it alone is relatively ineffective in reducing the incidence of the complication, preterm labor.

Diseases in Twins↗
PubMed1991

[Extremely low birth-weight infant with hydrocephalus; management of hydrocephalus using a miniature Ommaya's reservoir].

Use of the miniature Ommaya's reservoir in the treatment of extremely low birth-infant (under 1,000 mg) with hydrocephalus was studied in a series of five patients. The reservoir has a small-caliber with a 3 cm ventricular catheter. For these infants, this miniature Ommaya's reservoir is extremely useful for protection of the cortical mantle until a definitive procedure can be carried out after increase of body weight. The clinical course in five cases are summarized.

Cerebrospinal Fluid Pressure↗
PubMed1990

Functional impairment due to white matter ischemia after middle cerebral artery occlusion in cats.

We recorded regional cerebral blood flow, somatosensory evoked potentials, and auditory evoked potentials in the thalamic relay nuclei (ventral posterior lateral nucleus and medial geniculate body) and in the somatosensory and auditory cortices during and after 1 hour of transient left middle cerebral artery occlusion in nine cats. Regional cerebral blood flow was also measured in the thalamocortical tracts of five of these cats. Additionally, the integrity of thalamocortical connections was tested by retrograde labeling of the thalamic nuclei with horseradish peroxidase in eight cats (three of which experienced no ischemia). Regional cerebral blood flow was severely reduced during middle cerebral artery occlusion in the left primary auditory cortex (8.5 ml/100 g/min) and in white matter pathways (6.4-7.6 ml/100 g/min). In contrast, regional cerebral blood flow did not change significantly in the somatosensory cortex or in either thalamic nucleus. Evoked potentials were abolished in both cortices but remained unchanged in the thalamic nuclei. Cortical somatosensory evoked potentials disappeared 5-8 minutes later than auditory evoked potentials. Recirculation after 1 hour of ischemia resulted in rapid and almost complete recovery (94%) of somatosensory evoked potentials and little recovery (18.4%) of auditory evoked potentials. We conclude that in the auditory pathway both cortical and fiber tract ischemia are (perhaps synergistically) responsible for dysfunction, while in the somatosensory cortex evoked potentials are abolished due to white matter ischemia. The delayed disappearance and better recovery of somatosensory than of auditory evoked potentials indicate that ischemic tolerance is higher in fiber tracts than in cortex.

Animals↗