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Biomedical subjects

I Nagata

Publications and source records attributed to I Nagata.

At least 253 records · Page 14Linked to original sources
PubMed1989

[The development of spinal endoscope using a flexible optic fiber].

The development of spinal endoscope using a thin (0.75 mm in diameter) flexible fiber catheter AS-001, Fukuda-densi Co Ltd., Japan) is described in this study. This fiber catheter contains 3,000 optic fibers as imaging and illuminating fibers within its diameter. The effective length and the visual angle is 1.10 m and 53 degree, respectively. Video processor system was connected to this fiber catheter. With a patient in the lateral decubitus position under local anesthesia, this fiber catheter was introduced into the lumbar subarachnoid space in a similar manner as lumbar spinal drainage. Eight patients with myelopathy were evaluated by this spinal endoscopic study. With other radiological diagnostic modalities such as myelography, selective spinal angiography using intraarterial digital subtraction angiography (DSA), or magnetic resonance imaging (MRI), it was difficult to make definitive diagnosis in these 8 patients. In 4 patients among them, vascular tangle, or tortuous course of the dilated vessels were visualized on the dorsal surface of the spinal cord by the spinal endoscopic study, which strongly suggested the spinal arteriovenous malformation. In 3 of them, operative findings verified these preoperative endoscopic diagnoses to be correct. In the remaining case, surgical intervention was not attempted because of the personal affair of the patient. In every case, several structures around the thoracolumbar cord such as spinal dura mater, arachnoid membrane, or conus medullaris were observed under the pulsation of the cerebrospinal fluid. No complication was associated with this spinal endoscopic study. About 10 minutes were required for the whole procedure.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

[The effect of glycerol on regional cerebral blood flow, blood volume and oxygen metabolism].

Using positron emission tomography with 15O-labelled CO2 O2 and CO gases, the effects of glycerol on regional cerebral blood flow (CBF), blood volume (CBV) and oxygen metabolism (CMRO2) were investigated in 6 patients with meningioma accompanying peritumoral brain edema. The same study was done in 5 normal volunteers. The changes of blood gases, hematocrit and hemoglobin were also examined. After a drip infusion of glycerol, the regional CBF increased not only in the peritumoral cortex and white matter but also in the intact cortex and white matter on the contralateral side. The increase of CBF was extensive and substantially there were no regional differences. In contrast, the changes of CMRO2 were not significant. This was derived from the increase in oxygen extraction fraction throughout extensive areas including the peritumoral area. There were no changes in CBV. Hematocrit and hemoglobin decreased to a small degree. In the normal volunteers, the same findings were noted. Thus, glycerol increases the functional reserve for cerebral oxygen metabolism, not only in the peritumoral regions but also in the intact regions. The effects of glycerol on hemodynamics and metabolism were discussed with reference to some differences from mannitol.

Adult↗
PubMed1988

Changes in plasma cyclic AMP and cyclic GMP during spontaneous labor and labor induced by oxytocin, prostaglandin F2 alpha and prostaglandin E2.

To investigate the response of cyclic nucleotides to the oxytocic agents administered for induction of labor, plasma concentrations of cyclic AMP (cAMP) and cyclic GMP (cGMP) were determined by radioimmunoassay during spontaneous labor and labor induced by oxytocin (OT), prostaglandin F2 alpha (PGF2 alpha), or PGE2 (PGE2). Subjects were 7 Japanese women in each labor group. Plasma cAMP levels significantly rose at the time of crowning of the fetal head in all 4 groups. They did not increase until that time in the 3 labor groups (spontaneous, OT-induced, and PGF2 alpha-induced labor groups). In the PGE2-induced labor group, plasma cAMP levels were significantly higher at labor onset (mean +/- SEM = 16.5 +/- 1.3 pg/ml) when compared to the pretreatment values (13.7 +/- 1.0 pg/ml), and increased thereafter gradually toward the time of crowning of the head (26.3 +/- 2.0 pg/ml). Plasma cGMP levels in the OT-induced group significantly rose after the onset of labor and remained at a high level until expulsion of the fetus. Plasma cGMP levels in the other groups did not change significantly throughout labor. These results suggest that cAMP may be involved in the labor process induced by PGE2, and that cGMP may be in that induced by OT.

Cyclic AMP↗
PubMed1988

Pitfalls in the surgical treatment of moyamoya disease. Operative techniques for refractory cases.

Eleven cases of moyamoya disease refractory to indirect non-anastomotic revascularization, including encephalomyosynangiosis in two, encephaloduroarteriosynangiosis in seven, and encephalomyoarteriosynangiosis in two, are described. The patients suffered from recurrent cerebral ischemic symptoms, and further operative intervention, including superficial temporal artery-middle cerebral artery anastomosis and intracranial omental transplantation, was performed. The choice of operative maneuver depended on the availability of scalp arteries and on the nature of the ischemic symptoms. Although indirect non-anastomotic revascularization procedures have the advantage of technical ease and most patients respond to these procedures alone, there are some patients like the 11 presented here who are not cured by such procedures. In such cases, direct anastomotic revascularization is necessary for the prevention of stroke.

Activities of Daily Living↗
PubMed1988

Changes in the concentrations of prostaglandins E and F in the utero-placental tissues of late pregnant rabbit after the administration of oxytocin or prostaglandin F2 alpha.

We have investigated the effects of exogenous oxytocin and prostaglandin F2 alpha (PGF2 alpha) on the concentrations of prostaglandins E and F (PGE and PGF) in the utero-placental tissues in late pregnant rabbit. The subjects were 5 rabbits each on days 26, 27 and 30 of pregnancy. After one side of the uterine horn was excised as the control, 3,000 micrograms of PGF2 alpha, 10 microU of oxytocin or 1 ml of saline was administered to 2,2 and 1 rabbits as an iv bolus dose. After 10 minutes, the remaining side of the uterine horn was excised. The myometrium, fetal and maternal cotyledon, decidua and amnion were separated. The concentrations of PGE and PGE in each tissue were measured by radioimmunoassay after extraction. The highest concentration of PGE was observed in the fetal cotyledon and that of PGF in the decidua. The amniotic PGE concentration significantly decreased after the administration of both oxytocin and PGF2 alpha. The myometrial PGF concentration increased significantly after the administration of PGF2 alpha, and the degree of the increase in PGF became greater as pregnancy advanced. However, the myometrial PGF concentration did not increase after the administration of oxytocin.

Animals↗
PubMed1988

[Problems in the embolization therapy of spinal arteriovenous malformation].

Six cases with spinal arteriovenous malformation refractory to repetitive embolization therapy were reported. In these, de novo feeding arteries appeared after the emboli obliterated the proximal portion of the blood feeding system. Though the malformation disappeared after the embolization therapy in the angiograms of the original feeding arteries, the lesion was visualized in the follow-up angiogram from different segmental arteries via various collaterals. Through angiographic evaluation and magnetic resonance imaging were necessary to point out the "false angiographic disappearance" of the spinal arteriovenous malformation after the embolization therapy.

Adolescent↗
PubMed1988

[Criteria for elective irradiation of postoperative patients with stage 1b cervical cancer and radical hysterectomy without pelvic peritonealization].

One hundred and sixty cases of cervical carcinoma have been treated surgically for the last 8 years. The numbers of cases of stage 0, 1a, 1b, 2a, 2b, 3 and 4 were 55, 14, 45, 15, 16, 10 and 1, respectively. Simple or extended hysterectomy without lymphadenectomy was performed for stage 0 and 1a cases, radical hysterectomy for stage 1b, 2a and 2b cases, and staging laparotomy for stage 3 and 4 cases. Before July, 1976, postoperative irradiation had been applied only for stage 1b, 2a, 2b cases with evidence of histological lymph node metastasis. Since two cases of vaginal stump recurrence were encountered during this period, irradiation was performed for all cases with a tumor size greater than 1cm in diameter, or with infiltration reaching half of the cervical wall thereafter. Three year comulative survival rates (3YCSR) for stage 0, 1a, 1b, 2a, 2b, 3a and 3b groups were 100%, 90%, 90.6%, 84.6%, 79.5%, 60% and 55.5%, respectively. In stage 1b group, there was a significant difference (p less than 0.05) in the 3YCSR between the cases with lymph node involvement (65.6%) and without it (96.2%). There was no significant difference in the factors indicating postoperative outcomes (the period for recovery of urinary functions, the incidence of ileus and the fever index) between the cases with and without pelvic peritonealization at the time of radical hysterectomy.

Adenocarcinoma↗
PubMed1988

[Fundamental studies on the measurement of plasma concentration of oxytocin during perinatal period].

This is an attempt to establish an easy but reliable method for the measurement of the plasma concentration of oxytocin (OT) during the perinatal period. Samples of blood from pregnant and puerperal women were taken by venipuncture and collected in prechilled vacutainers containing EDTA and ophenanthroline. Acidified plasmas were loaded into a ODS-silica column (SEP-PAK). Rinsing of the column and elution of OT were performed with 5ml of 0.1M acetic acid and 3ml of methanol, respectively. The optimal incubation condition for RIA was 25 degrees C for 24 hours. Dextran charcoal was preferable to second antibody (DASP) for bound/free separation of 125I-OT. The recovery rate for plasma OT levels was 95%. Changes in the OT levels in maternal plasma during labor induced with OT infusion and neonatal suckling in postpartum were well demonstrated by the extracts. Radioimmunoactivity of OT in the plasma extract was observed in exactly the same fraction as that of standard OT on high performance liquid chromatography (HPLC).

Chromatography, High Pressure Liquid↗
PubMed1988

[A case of tentorial cavernous angioma].

A case of tentorial cavernous angioma is reported. A 61-year-old woman was admitted because of left auditory disturbance and left hemifacial spasm. CT scan and angiography, MRI revealed a dumb-bell typed tumor extended above and below the left tentorium cerebelli. Under the preoperative diagnosis of tentorial meningioma, a craniotomy was performed and the tumor was removed totally with minimal bleeding by left subtemporal approach. The tumor was well capsulated and spongy, attached to the tentorium cerebelli. Histologically, the tumor had many various vascular cavities with the wall lined with a single layer of endothelial cell, had neither glial cell nor meningeal cells. Some of cavities were thrombosed. Pathological diagnosis was a cavernous angioma. We discussed the characters of this rare tumor with a review of 4 cases.

Cerebellar Neoplasms↗
PubMed1987

Inhibitory effect of TI-31 on autoimmune nephritis in NZB/NZW F1 mice through regulation of the immune response.

TI-31 (TEI-3096; 6-p-chlorobenzyl-5H-2,3,6,7-tetrahydro-5,7-dioxothiazolo[3,2-a]pyr imidine) is a novel immunomodulator. Various nephritic changes observed in female NZB/NZW F1 (B/W) mice with aging were suppressed by TI-31 when administered orally 5 times per week for 16 weeks at doses of 2, 10, or 50 mg/kg. It suppressed proteinuria, oliguria, the decrease of erythrocyte count, and increase of serum urea nitrogen, immune complex and anti-double-stranded DNA antibody levels. The anti-nephritic effect of TI-31 was confirmed by histopathological evaluation. TI-31 (10 mg/kg) could improve both the elevated polyclonal B cell activation and the depressed antibody response to sheep red blood cells in B/W mice, in comparison with age- and sex-matched BALB/c mice, without any effect on the antibody response in these normal mice. These findings indicate that TI-31 may inhibit B/W nephritis by regulating the antibody production through a mechanism different from that of anti-inflammatory drugs or immunosuppressants.

Animals↗
PubMed1987

Anti-arthritic and immunoregulatory effects of TI-31 on collagen-induced arthritis.

TI-31 (TEI-3096, 6-p-chlorobenzyl-5H-2,3,6,7-tetrahydro-5,7-dioxothiazolo[3,2-a]pyr imidine) reduced bovine type II collagen-induced arthritis (CIA) in rats in a time- and dose-dependent manner. Oral TI-31 treatment in doses of 10 and 50 mg/kg daily for 7 days prior to collagen immunization depressed the development of arthritis. However, it had no obvious effect on CIA when administered daily for a 7-day or 28-day period after the immunization. This compound was also ineffective against the established arthritis. On the contrary, cyclophosphamide, dexamethasone, or ibuprofen strongly protected the animals from the development of arthritis and/or cured the established arthritis by these dose regimens. Both humoral and delayed-type hypersensitivity skin responses to bovine type II collagen were decreased in rats treated with TI-31 daily for 7 days before the induction of arthritis. These results suggest that TI-31 depresses CIA by regulating the immune response to collagen through a mechanism different from that of anti-inflammatory drugs or immunosuppressants.

Animals↗
PubMed1987

Changes in the plasma prostaglandin F2 alpha metabolite before and during spontaneous labor and labor induced by amniotomy, oxytocin and prostaglandin E2.

To elucidate the role of endogenous prostaglandin F2 alpha in spontaneous and induced labor, plasma concentrations of 13, 14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) were determined before the onset of labor, at onset of labor, during active labor, at the crowning of the fetal head, and 1 and 2 hours after delivery. Patients in spontaneous labor and labor induced by amniotomy, oxytocin, and prostaglandin E2 were studied. The levels of plasma PGFM in patients who entered spontaneous labor fell 2 to 3 weeks before delivery, whereas those in the induced labor group did not change until the time of induction. Although the levels of PGFM rose gradually with the progress of labor in all cases, the levels in the spontaneous labor were significantly lower in each stage than in the corresponding stage of induced labor. These results suggest that endogenous prostaglandin F2 alpha (PGF2 alpha) production decreases 2-3 weeks prior to the spontaneous onset of labor and is increased again as labor progresses, that the patterns of PGF2 alpha production are similar to each other during spontaneous labor and labor induced by various methods. Therefore, it is felt that endogenous PGF2 alpha may participate in the progress of all kinds of labor.

Adult↗
PubMed1987

[Cerebral blood flow in subarachnoid hemorrhage: analysis in patients with poor outcomes].

Cerebral blood flow (CBF) of 6 patients with poor outcome after subarachnoid hemorrhage is analyzed. Neurological grades of these patients were grade III in 2 and grade IV in 4 patients, and subarachnoid hemorrhage on CT was diffuse and thick in all patients. Cerebral blood flow was continuously measured for 7 to 19 days by the thermal diffusion flow probe with a peltier stack which was left on the cerebral cortex at the surgery for ruptured aneurysm. Moreover, CBF studies by cold xenon CT and 133Xe inhalation methods were also performed in discussing cases. At the same time intracranial pressure was monitored. Cerebral angiography was carried out in all except for 2 patients who died due to severe cerebral vasospasm. The initial CBF value of all patients was 20 to 40 ml/100 g/min (mean value: 27 ml/100 g/min), and these were significantly low compared to normal value (50 ml/100 g/min). Moreover, these CBF was substantially decreased several days after surgery in all patients, and it was marked in 3 patients who died. From these results it was clear that the degree of vasospasm is important to determine the prognosis. One of 3 patients who died had ruptured left posterior cerebral artery aneurysm with occlusion of bilateral internal carotid arteries. In this case further decrease of CBF due to vasospasm was observed in addition to low initial CBF resulting diffuse low flow in both hemispheres although extracranial to intracranial bypass was performed. On the other hand, it was also shown that the intracranial pressure was an important factor to influence the outcomes.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1987

Changes in plasma oxytocin, prostaglandin E1, and 13,14-dihydro-15-keto-prostaglandin F2 alpha during labor induced by prostaglandin E2 or F2 alpha and spontaneous labor.

To observe the changes in endogenous oxytocics during spontaneous and induced labor, the plasma concentrations of oxytocin, prostaglandin E1 (PGE1) and 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) were measured during labor in 9 cases of spontaneous labor (group 1), 10 of PGE2-induced labor (group 2), and 7 of PGF2 alpha-induced labor (group 3). Unextracted samples were used for radioimmunoassay of oxytocin. PGE and PGF were extracted and separated for radioimmunoassays of PGE1 and PGFM. Although oxytocin levels in groups 1 and 3 did not change during labor or slightly increased toward delivery, those in group 2 decreased as labor progressed. The mean oxytocin in group 2 was significantly lower at the times of established labor (15.3 +/- 3.2 microU/ml, mean +/- SE) and crowing of the fetal head (10.8 +/- 2.0 microU/ml) than before labor (52.7 +/- 14.8 microU/ml). Plasma PGE1 levels in groups 1 and 3 were low and did not change during labor. Plasma PGFM levels in groups 1 and 2 gradually rose toward delivery. These results suggest that exogenous PGE2 suppresses oxytocin secretion during labor and stimulates endogenous PGF2 alpha production, that endogenous PGE1 may not play an important role in the progress of spontaneous and PGF2 alpha-induced labor, and that endogenous PGF2 alpha may participate in the promotion of all kinds of labor.

Alprostadil↗