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Biomedical subjects

S Yamagata

Publications and source records attributed to S Yamagata.

At least 127 records · Page 7Linked 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

[Ultrasonographic evaluation of the endometrium in postmenopausal women to select the high risk group of endometrial carcinoma of the uterus].

We examined the usefulness of ultrasonography (USG) for endometrial cancer screening in postmenopausal women. 207 postmenopausal women were ultrasonographically examined. The endometrial echo was classified into 4 types: 1, anechoic; 2, hair-line; 3, linear; and 4, navicular, and was compared with histological findings. No abnormal histological findings were observed in the cases showing type 1 and 2. On the other hand, abnormal histological findings including endometrial hyperplasia, atypical hyperplasia, and endometrial cancer, were seen in 57.7% (15/26) of type 3 cases, and 65.6% (21/32) of type 4 cases. Furthermore, type 3 and 4 women had enlargement of the uterus, and an increased incidence of postmenopausal bleeding. Positive rates in the progesterone challenge test (PCT) and karyopicnotic index (KPI) were higher in type 3 and 4 cases than in type 1 and 2. It was concluded that USG is able to accurately determine the endometrial condition and is useful for identifying high-risk patients in endometrial cancer screening.

Aged↗
PubMed1989

[Estrogen production in epithelial tumors of the ovary--localization of estrogen-synthesizing cells].

The origin of the elevated serum estrogen in postmenopausal patients with common epithelial tumors of the ovary was investigated by means of endocrinological, histochemical, immune histochemical and autoradiographic techniques. Estrone and estradiol and their precursors were quantitatively extracted from the tumor tissue homogenate, and the results indicated that the estrogen-producing pathway was not uniform among the tumors. On the tissue section Sudan-IV staining showed positive in the stromal area in the form of fine granules or droplets. The immune peroxidase method revealed that the Sudan staining-positive substance included estrogen and its precursors. Estrogen was also detected in the epithelium, but it seemed to be present in the epithelial (tumor) cells as an estrogen-estrogen receptor complex. Cholesterol staining was focally positive in the subepithelial stromal area and incorporation of 3H-cholesterol into the stromal cells was observed by microautoradiography. These findings indicated that steroid synthesis from cholesterol to estrogen appeared in the stroma of the tumor and high serum concentrations of estrogen in the patient were the result of accelerated estrogen-synthesis in the ovarian tumor.

Autoradiography↗
PubMed1989

[Delayed neuronal dysfunction after recirculation of cerebral ischemia].

Delayed neuronal deterioration of recovered neuronal function from cerebral ischemia was investigated in experiments using 25 cats. The neuronal function was evaluated by direct cortical response (DCR) and EEG. To induce cerebral ischemia clamps were applied to both the innominate and left subclavian arteries and were removed 15 minutes after complete loss of DCR. Following recovery of circulation, DCR and EEG were studied for at least 48 hours, along with the changes of cerebral blood flow (CBF) and intracranial pressure (ICP). In 7 of 25 cats CBF gradually or rapidly decreased after it was regained through recirculation due to the increase of ICP, resulting in no recovery of neuronal function. In the other 18 cats normal values of CBF and ICP were observed soon after the recirculation although temporary increase of ICP was found. The recovery of DCR and EEG was observed in 12 of these 18 cats, and these functions were maintained up to the end of the experiment in 9 of these 12 cats. In the other 3 cats and another 5 cats in which only DCR was recovered, these neuronal functions deteriorated 8 to 30 hours after recirculation. In one cat neither DCR nor EEE was recovered at all. Moreover, in the 9 cats mentioned ICP gradually increased before or after the deterioration of neuronal functions, and it finally reached the level of systemic blood pressure. These results indicate that the recovery of neuronal function from ischemic insults must be judged at least 48 hours after recirculation because of delayed neuronal deterioration, and pathogenesis of delayed neuronal dysfunction and delayed increase of ICP must be fully investigated thereafter.

Animals↗
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

Gelatinases of metastatic cell lines of murine colonic carcinoma as detected by substrate-gel electrophoresis.

Gelatinases were detected in the conditioned medium of murine colonic carcinoma cells by SDS-polyacrylamide gel electrophoresis using gels copolymerized with gelatin. Several gelatinase activities differing in molecular weight were detected but the major activities migrated with molecular weights of 60,000 and 95,000. The enzymes did not hydrolyze bovine serum albumin or casein, and required calcium for activity. All of the gelatinase activities were inhibited by EDTA, 1,10-phenanthroline and dithiothreitol but not by N-ethylmaleimide and phenylmethylsulfonyl fluoride. The 95,000 dalton gelatinase was separated from the 60,000 dalton gelatinase by affinity chromatography on Ricinus communis agglutinin-agarose, and the former activity was markedly increased in highly metastatic cell lines as compared with its activity in poorly metastatic cell lines.

Animals↗
PubMed1988

[Reversibility of cerebral cortical function after recirculation in experimental cerebral ischemia].

Several kinds of monitoring systems to evaluate cerebral function have been introduced such as somatosensory evoked potential, visual evoked potential and auditory brain stem response. Although these monitoring systems are employed in practice in neurosurgical operations, the reversibility of these cerebral functions after ischemia insult is little known. In this study the reversibility of direct cortical response (DCR) as well as EEG from global ischemia was investigated using total 60 cats. Cortical cerebral blood flow was also measured continuously by the thermal diffusion flow probe with a peltier stack calibrated by hydrogen clearance. Global ischemia was made by the occlusion of innominate and left subclavian arteries. Although the EEG was abolished soon after occlusion of these arteries, DCR was preserved and it started to decay at the cortical CBF of about 21 ml/100 g/min. It had completely disappeared at the CBF of about 8 ml/100 g/min. Recovery of DCR was not correlated with the occlusion time, but it was well correlated with the interval of loss of DCR. When the DCR was not completely lost, DCR amplitude was completely recovered about 3 hours after ischemia insult with the CBF below 20 ml/100 g/min. Moreover, in all 8 cats which were recirculated within 5 minutes after loss of DCR, complete recovery of DCR amplitude was obtained. However, it was observed in 10 of 12 cats (83%) with 10 minutes loss of DCR, 5 of 12 cats (42%) with 15 minutes loss of DCR, 4 of 14 cats (29%) with 20 minutes loss of DCR, and only one of 11 cats (10%) with 30 minutes loss of DCR.(ABSTRACT TRUNCATED AT 250 WORDS)

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

[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↗
PubMed1988

[The effect of Gd-DTPA on magnetic resonance imaging: a potential blood-brain barrier indicator].

Magnetic resonance image (MRI) has been applied on central nervous system to evaluate the anatomical and functional aspects. On the other hand, gadolinium-diethylenetriamine-pentaacetic acid (Gd-DTPA) is considered to be a valuable contrast agent on MRI. This paramagnetic compound shortens the magnetic relaxation times of surrounding hydrogen nuclei by altering local magnetic environments. A molecular weight of this compound was 590, therefore this does not pass through the normal blood-brain barrier (BBB), and it may possible to detect a breakdown of BBB in vivo. In order to investigate the effect of Gd-DTPA as an indicator of BBB disruption on MRI, we measured T1 value of hemisphere of rat in osmotic BBB disruption model and experimental global cerebral ischemic model with and without Gd-DTPA. The MRI system employed was JNM-SMR 270 (JEOL) and the superconducting magnet was operated at a field strength of 6.34 tesla. Gd-DTPA was injected intra-venously through femoral vein and its dose was 0.5 mmol/kg. Osmotic BBB disruption model was made by intra-arterial injection of 25% mannitol through an internal carotid artery. Calculated T1 value of the ipsilateral hemisphere decreased with Gd-DTPA to 43.3 +/- 10.2% (n = 4) of control value immediately after BBB disruption with mannitol administration but no change of T1 value was recognized with Gd-DTPA in rats which Gd-DTPA was injected 4 hours after BBB disruption. Global ischemic insult was made by 3 vessel occlusion permanently and temporarily (30 or 120 minutes).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

[Measurement of cerebral blood volume by reflections spectrophotometry: methodological improvement and quantitative evaluation].

The authors described methodological improvement and quantitative evaluation in measurement of cerebral blood volume (CBV) by reflectance spectrophotometry. The measurement of blood volume by this method has not been applied to the brain tissue because of the methodological difficulties. In order to obtain the accurate CBV values with this method, it is necessary to keep the proper contact between the sensor for the measurement and the brain tissue to be measured. For this purpose we developed a balance arm. A sensor for CBV measurement was fixed with the one side of the arm and a weight was installed to the other side. The pressure of the sensor to the brain can be adjusted by moving the weight, and the sensor was placed on the brain tissue with the proper pressure. Moreover, the sensor was attached with an acryl-made cap to make the pressure adjustment easier by enlarging the contact surface and to enable to observe the vasculature on the surface of the brain. With this improved method the reasonable changes of CBV could be obtained when the CO2 gas was inhalated and cerebral ischemia was produced in cats. The possibility of the quantitative evaluation was investigated using the homogenized brain tissue of cats. After the elimination of the blood from the brain by the perfusion with the saline, the brain was removed and homogenized. Then, the definite volume of blood, of which hemoglobin volume was already known, was added and measured by this method.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Amino acid analysis by high-performance liquid chromatography of a single stained protein band from a polyacrylamide gel.

A single stained band containing approximately 5 micrograms of protein was cut out of a polyacrylamide gel and subjected to hydrolysis together with the gel. The hydrolysate was subsequently analyzed for its amino acid content by high-performance liquid chromatography and postlabeling with o-phthalaldehyde. Bovine serum albumin, ribonuclease B, ovalbumin, pepsin, and chymotrypsinogen A were analyzed by this method, and their amino acid compositions were found to be in good agreement with the reported values. By this method, it is possible to quantitate 16 amino acids: Asx, Thr, Ser, Glx, Pro, Cys, Gly, Ala, Val, Ile, Leu, Tyr, Phe, His, Lys, and Arg. Thioglycolic acid is effective protection against the decomposition of Tyr, Cys, and Met; however, the recovery of Met is inconsistent. This method might be very helpful for the amino acid analysis of proteins of multicomponent systems, especially, those which can be resolved only by polyacrylamide gel electrophoresis.

Amino Acids↗