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Biomedical subjects

K Ehara

Publications and source records attributed to K Ehara.

29 records · Page 2Linked to original sources
PubMed1990

Changes in free water content and energy metabolism of the brain in experimental hydrocephalus.

In acute and subacute hydrocephalus periventricular oedema is most prominent. At these stages of hydrocephalus, the free water content is increased and the bound water content, to the contrary, significantly decreased in the periventricular white matter. The bioenergetic state is also altered. In the chronic stage the ratio of free-to-bound water content returns to a level near the control value, leading to a decrease of periventricular oedema by formation of alternative pathways of CSF absorption. The bioenergetic state was slightly altered at this stage.

Acute Disease↗
PubMed1990

Factors affecting prognosis of intrauterine hydrocephalus diagnosed in the third trimester--computerized data analysis on controversies in fetal surgery.

Twenty hydrocephalic patients diagnosed in the third trimester of fetal life were evaluated and followed during a 7-year period. The factors affecting the prognosis, including the type of hydrocephalus, underlying conditions, associated anomalies, time of diagnosis and delivery, fetal period after diagnosis, head circumference and degree of ventriculomegaly at birth, and age at treatment, were comprehensively analyzed. The difference between final outcomes as assessed by developmental quotient (DQ) or intelligence quotient (IQ) were statistically tested with computation by means of STAX packages in an NEC 9801 VX. Hydrocephalus as an isolated defect occurred in six cases (30%), was associated with other central nervous system anomalies in nine (45%), and was secondary to intrauterine intraventricular hemorrhage or brain tumor in five (25%). The average age at the time of diagnosis was 33.9 weeks of gestation (range, 27-40 weeks). One fetus was treated by transabdominal cephalocentesis, but the majority of patients underwent ventriculoperitoneal shunt postnatally. The final IQ or DQ scores ranged from 20 to 120 (mean score, 50.6). The data analyses revealed that the only significant factor affecting outcome was the fetal period after diagnosis of hydrocephalus (r = -0.5076, p less than 0.01). Our data supports the fact that the results of an on-going hydrocephalic state may become irreversible during fetal life. It is emphasized that establishment of a more precise pathophysiological evaluation, and a less invasive but more reliable decompressive technique for fetal hydrocephalus, is urgent.

Chi-Square Distribution↗
PubMed1990

Changes in the components and content of biological water in the brain of experimental hydrocephalic rabbits.

Changes in biological water components and their respective content in the cortical gray matter and periventricular white matter were studied in rabbits rendered hydrocephalic by intracisternal kaolin injection. There was no change in either total water content or free or bound water content in the cortical gray matter at the various stages of hydrocephalus development. While there was no significant change in total water content in the periventricular white matter at any stage of hydrocephalus, free water content was significantly elevated and bound water content was decreased at the acute and subacute stages, with a return to relatively normal levels at the chronic stage. It is concluded that in the periventricular white matter, free water enters the brain across the ependymal lining during the acute and subacute stages of experimental hydrocephalus with a simultaneous reduction in the bound water and that there is some recovery at the chronic stage. It is suggested that alternative drainage pathways may develop in chronic hydrocephalus allowing drainage of free water in the periventricular white matter, which in turn permits bound water to return to relatively normal levels.

Animals↗
PubMed1990

Characterization of periventricular edema in normal-pressure hydrocephalus by measurement of water proton relaxation times.

The magnetic resonance longitudinal relaxation time (T1) and transverse relaxation time (T2) of the water proton of the periventricular white and cortical gray matter were measured for 17 control patients and 21 patients with suspected normal-pressure hydrocephalus (NPH). Of the latter group, 14 showed good response to shunting (true-NPH group) and seven showed no response (false-NPH group). In the true-NPH group, both the T1 and the T2 of the periventricular white matter were significantly prolonged compared to the control values, and slowly shortened after cerebrospinal fluid (CSF) shunting. The true-NPH group showed significantly longer T1 and T2 of the white matter than did the false-NPH group. The T1 and T2 of the white matter were longer than those of the gray matter in this group, which was the reverse of the relationship observed in the control patients. In the white matter of the false-NPH group, there was a significant prolongation of T1 only; no difference was seen in the T2 compared to control values. There was no change in either T1 or T2 of this region after CSF shunting. The false-NPH group showed no significant difference in either T1 or T2 between the white and the gray matter. There was no difference in either T1 or T2 of the gray matter between the false-NPH and control groups or between preshunt and postshunt measurements in each patient group. It is suggested that a distinction between true- and false-NPH, which cannot be made from the radiographic appearance alone, may be possible from measurement of relaxation times. The mechanism of varied relaxation behavior between two entities may be explained by a difference in properties of the biological water and its environment.

Adult↗
PubMed1989

The "thousand-hands Kannon" universal headframe. Technical note.

The authors describe a new headframe system, by which a variety of instruments, such as brain retractors, suction tubes, mirrors, forks, armrests, and cotton-sheet trays, can be simultaneously supported. This frame enables neurosurgeons to perform operations with greater ease and fewer problems.

Brain↗
PubMed1988

[Intramedullary invasion by a cervical cystic neurinoma--a case report].

This report examines a case involving a huge cystic cervical neurinoma existing extra- and intramedullary. The histogenesis of intramedullary neurinoma, pathohistogenesis of large intratumoral cyst are discussed. The role of Magnetic Resonance Imaging (MRI) in the diagnosis of spinal tumors is also discussed. A 23-year-old male was admitted to our ward or having tetraparesis. On admission, spastic tetraparesis and sensory disturbance below level C 2 were noticed. Electrophysiological examinations suggested a left-dominant intraspinal lesion. Conventional radiological examinations revealed widened cervical spinal canal, swelling of the spinal cord at level C 6-7, left extramedullary mass at level C 5, and a complete block at level C 4. MRI disclosed intramedullary tumor existing from the medulla oblongata to the lower cervical including macrocysts, and an extramedullary tumor on the left at level C 3-5. Surgical exploration was made and both of intra- and extramedullary tumors were confirmed to be neurinoma. The postoperative course was favourable. The patient was able to walk with aids, and was referred to the rehabilitation center 6 months after the operation. In histological investigations, the major components of the tumors were typically Antoni-A type neurinoma, and an abundant hemosiderin deposits. There were many hyalinized whorling portions around the cysts. Though spinal neurinoma is the most common spinal tumor, the intramedullary neurinoma is extremely rare. Only 31 cases have been reported as far as we could investigated. The histogenesis of this type of lesion is still unsettled.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

[The effects of ticlopidine and nicardipine on the prevention of symptomatic vasospasm after aneurysmal rupture].

From the previous reports that the pathogenesis of cerebral vasospasm is most likely multifactorial process and that early removal of the clot may decrease the incidence or severity of the ischemic deficits and also that antifibrinolytic therapy increases the incidence and the severity of the symptomatic vasospasm, we attempted at prevention of the symptomatic vasospasm in aneurysmal patients with our own protocol. One hundred twenty-one consecutive patients with a ruptured aneurysm were operated upon within 48 hours after subarachnoid hemorrhage. Seventy-seven patients in group (A) were treated with a regimen of postoperative Ticlopidine and Nicardipine without antifibrinolytic therapy. Fifty-four patients in group (B) were not treated with the above regimen. Symptomatic vasospasm occurred only in four patients (5%) in group (A), but in 18 patients (33%) in group (B). In total series, 82% in group (A) and 63% in group (B) had an excellent to good outcome. Nine % in group (A) and 20% in group (B) had a poor outcome. The results indicate that our protocol with Ticlopidine and Nicardipine can reduce the incidence of symptomatic vasospasm following the aneurysmal rupture.

Adult↗
PubMed1984

Measurement of cerebral blood flow in the rat with intravenous injection of [11C]butanol by external coincidence counting: a repeatable and noninvasive method in the brain.

No method has been reported for measuring CBF, repeatedly and noninvasively, in the rat brain. A new method is described, which is noninvasive to the brain, skull, or cervical large vessels. Two pairs of coincidence detectors were positioned, one over the rat brain and the other at the loop of a catheter inserted into the femoral artery. The coincidence head curve and arterial curve were recorded after intravenous injection of 1-[11C]butanol in 15 rats. CBF was calculated by one-compartment curve fitting ( CBFo ) from 1-min data and with the recirculation corrected height/area method from 3-min data ( CBFh X 3 min) and 5-min data ( CBFh X 5 min). CBFo agreed well with CBFh X 5 min, although a slight overestimation was observed in CBFh X 3 min. The normal CBFo in the normocapnic group (n = 6, paCO2 36.7 +/- 2.3 mm Hg) was 1.76 +/- 0.49 ml/g min (mean +/- SD). A good correlation was observed between CBFo (y) and PaCO2 (x), and the regression line was y = 0. 0629x -0.715 (r = 0.88, p less than 0.0001). We concluded that this method gives the stable blood flow values noninvasively and with a minimum loss of blood (less than 0.28 ml per measurement). Applications of this method include activation studies, studies on the effect of drugs and treatments, and water and oxygen extraction fraction studies using different tracers in the same rat.

Animals↗
PubMedDate not supplied

Water extraction fraction and permeability-surface product after intravenous injection in rats.

A quantitative method has been developed to measure the water extraction fraction of rat brain after successive intravenous bolus injections of [15O]water and [11C]butanol based on a mathematical equation developed by the authors. This new method is noninvasive to the brain or craniocervical large vessels and does not require sacrifice of the rats. Arterial concentration curves and total head counts were measured in 8 rats by means of external coincidence detectors. Water extraction fraction in rat brain was 0.67 +/- 0.13 (mean +/- SD) and permeability-surface product was 1.75 ml/g min, where cerebral blood flow and arterial carbon dioxide tension were 1.71 +/- 0.86 ml/g min and 44.8 +/- 14.0 mm Hg, respectively. Water extraction fraction was stable with different measurement times from 20 to 80 seconds.

Animals↗