Biomedical subjects

K Oyama

Publications and source records attributed to K Oyama.

At least 109 records · Page 6Linked to original sources

PubMed1992

Effects of fetal growth retardation on the development of central and peripheral catecholaminergic pathways in the sheep.

Regional norepinephrine and dopamine content and cerebral alpha 1- and beta-adrenergic receptor mechanisms were studied in the brain of sham operated control and single umbilical artery ligation (SUAL) induced growth retarded newborn sheep. Brain sparing was evidenced by relative preservation of brain weight compared to other organ systems. Norepinephrine and dopamine content of the brain were not affected by SUAL. This is in contrast to decreased norepinephrine levels in the brown fat, a normally densely innervated peripheral tissue. Alpha 1- and beta-adrenergic receptor numbers and affinity states were similar between the two groups. Coupling between beta-receptor and guanine nucleotide stimulatory protein and agonist stimulated adenylyl cyclase activity were unaffected by SUAL. Brain regional DNA content and protein/DNA ratios were not different between the two groups. These data suggest that single umbilical artery ligation induced fetal growth retardation modifies peripheral but not central catecholaminergic pathways in the sheep. Both growth and expression of specific catecholaminergic signal transduction system are protected in the brain.

Adipose Tissue, Brown↗

PubMed1992

[A dissociation of thresholds between Goldmann kinetic perimetry and high-pass resolution perimetry in retinitis pigmentosa].

The authors studied the differences between the automated static perimetry of high-pass resolution perimeter (HRP) and the kinetic perimetry of the Goldmann perimeter in 12 patients with retinitis pigmentosa. In a total of 10 eyes of 6 patients, we found 19 quadrants in which the patients were not able to recognize the largest ring target even when the target was within the isopter of the Goldmann perimetry. Also, there were 10 quadrants in which the largest target was not recognized in a total of 6 eyes of 4 patients even though their visual field showed symmetrical isopter in upper and lower or right and left quadrants in the Goldmann perimetry. As a result, it was suggested that the causes of the dissocation were a greater decrease in sensitivity for the low spatial frequency target than the high spatial frequency target and/or a greater decrease in resolution sensitivity than light sensitivity in retinitis pigmentosa.

Adolescent↗

PubMed1992

[CT rim effects in various head and neck lesions].

The authors evaluated various head and neck lesions seen from April 1988 through March 1990 both by plain and enhanced CT, examined the incidence of rim effect (or rim enhancement), classified these effects, and discussed underlying mechanisms. Materials consisted of 177 cases including primary tumors (28 benign and 49 malignant cases) and lymphadenopathy associated with malignancy (9 cases, metastatic nodes and malignant lymphomas), inflammatory lesions (20 cases), cystic lesions (12 cases), other lesions (7 cases, jugular thrombosis, carotid atheroma and aural lesions), and 22 cases without abnormal findings. Among the 177 cases, rim effects were observed in 22 cases (12%). These effects were analyzed and classified. The incidences of rim effect according lesion type are as follows; cervical lymphadenopathy associated with malignancy 5/9 (56%), primary tumors 8/77 (10%), inflammatory lesions none, cystic lesions 7/12 (58%), and others 3/7 (43%). The highest incidence was seen with cystic lesions including mucoceles of the paranasal sinuses and cervical cysts. Rim effects were classified as follows; Type 1: cystic pattern, Type 2: parenchymatous pattern, Type 3: vascular pattern and Type 4: others. Type 1 was seen in 15 cases (68%), Type 2 in 3 cases (14%), Type 3 in 3 cases (14%), and Type 4 in 1 case (5%). Type 1 included 6 cystic lesions, 3 malignant lymphadenopathies, 3 benign tumors and others. Type 2 included 2 malignant lymphadenopathies and 1 benign tumor, and Type 3, 2 jugular thromboses and 1 carotid atheroma. There was only one Type 4, a cystic lesion. Of interest is the mode of incidences among cervical lymphadenopathies associated with malignancy.(ABSTRACT TRUNCATED AT 250 WORDS)

Cysts↗

PubMed1991

Inhibition of monoamine oxidase by two substrate-analogues, with different preferences for 5-hydroxytryptamine neurons.

Various intraperitoneal doses of 5-fluoro-alpha-methyltryptamine (5-FMT), given to mice, dose-dependently inhibited only MAOA activity, with similar degrees of inhibition in the striatum, hypothalamus and the rest of the forebrain. The activity inhibited in these regions, completely recovered to control levels within 24 hr after the injection. In contrast, p-chloro-beta-methylphenethylamine (p-CMP), selectively inhibited MAOB activity, with complete recovery within 45 min after the injection. Regardless of the differences in time interval and degree of inhibition of MAOA by 5-FMT or MAOB by p-CMP, both kinds of inhibition were competitive, with respect to oxidation of the respective substrate. 5-Fluoro-alpha-methyltryptamine markedly protected only MAOA against inhibition by phenelzine, without protecting MAOB. Also, 5-FMT greatly increased one kind of animal behaviour, the head-twitch and this behaviour was greatly reduced by treatment with fluoxetine, but increased by reserpine. The results indicate that p-CMP is a short-acting, probably reversible, MAOB-selective inhibitor and 5-FMT has the same characteristics of selectivity for MAOA in central serotonergic neurons.

Animals↗

PubMed1991

Inhibition of rat brain monoamine oxidase activity by cerebral anti-ischemic agent, ifenprodil.

Ifenprodil, which is clinically used as a cerebral vasodilator, inhibited rat brain type A (MAO-A) and type B (MAO-B) monoamine oxidase activity. It did not, however, affect rat lung semicarbazide-sensitive amine oxidase. The degree of inhibition of either form of MAO was not changed by 30 min preincubation of the enzyme preparations at 37 degrees C with ifenprodil. Modes of inhibition of MAO-A and MAO-B by ifenprodil were competitive towards oxidation of their respective substrates, 5-hydroxytryptamine and benzylamine, with Ki values of 75 microM for inhibition of MAO-A and 110 microM for inhibition of MAO-B.

Amine Oxidase (Copper-Containing)↗

PubMed1991

Inhibition of brain MAO-A and animal behaviour induced by p-hydroxyamphetamine.

Intra- and extra-synaptosomal activity of monoamine oxidase-A (MAO-A) and -B (MAO-B), dopamine (DA) and its main metabolites were examined to clarify the mechanism of action(s) of p-hydroxyamphetamine (p-OHA) in animal behaviour mediated by central dopaminergic systems. Intrasynaptosomal DA was oxidized by MAO-A and MAO-B and this oxidation is inhibited by p-OHA. The inhibition is due to two effects: 1) uptake of DA is inhibited by p-OHA, and 2) p-OHA also inhibits intrasynaptosomal oxidation of DA by MAO-A and MAO-B. The inhibition of oxidation by MAO-A is predominant. Administration (ICV) of 80 and 160 micrograms p-OHA to mice, doses that cause various behavioural, significantly reduced striatal DA and 3,4-dihydroxyphenylacetic acid (DOPAC) levels, but greatly increased 3-methoxytyramine, without significantly changing homovanillic acid (HVA). The release of DA and blockade of DA uptake into dopaminergic neurons by p-OHA, together with preferential inhibition of the DA metabolizing enzyme, MAO-A, may contribute to p-OHA-induced behaviour mediated by the central dopaminergic systems.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1991

Cardiovascular effects of SKF 104078 in lambs.

We studied the effects of SKF 104078 in anesthetized, newborn lambs and compared it to nonspecific alpha-receptor blockade by tolazoline. SKF 104078 infusion decreased pulmonary and systemic arterial pressures in newborn lambs when infused during normoxic ventilation. When infused during hypoxia, SKF 104078 decreased cardiac output and systemic blood pressure without affecting pulmonary pressure. Due to the predominance of systemic effects, the usefulness of SKF 104078 in states of hypoxic pulmonary vasoconstriction is limited.

Adrenergic alpha-Antagonists↗

PubMed1991

[Isolated medial orbital wall fracture and late fronto-ethmoidal mucocele].

Twenty-one cases of isolated medial orbital wall fractures were reported and CT findings by coronal planes were evaluated as to the effects of fractures upon the ethmoidal cells and nasal meati. Three coronal planes, which respectively contain such structures as Agger nasi, Pars membranacea and superior meatus, were selected for the study. The extent of fracture was evaluated by dividing the medial wall into three equal portions, i.e., superior, middle and inferior. The prolapsed volume was evaluated in three classes of occupying 1/3, 2/3 and 3/3 of the ethmoid. The presence of soft tissue density was recorded at the three surfaces, upper, medial and lower, around the prolapsed orbital content. The extent of the fracture was most often seen in such cases as involving all the three divisions in 41.3%. The prolapsed volume occupying 1/3 was seen in 28, 6%, and 2/3 in 23.8%. The presence of soft tissue density was seen in 38.1% of upper surface, in 36.5% of medial, and 11.1% of lower. Summarizing the total effects of the fractures, the coronal plane containing Pars membranacea was most severely damaged followed by the plane of the superior meatus. Two rare cases of fronto-ethmoidal mucoceles, caused by the traumas of 23 and 14 years before respectively, were also included and reported. The ophthalmological prognosis was favorable in 90.5% of cases by observations extending more than 6 months. Five cases were surgically treated including two cases of mucoceles.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

[Bone scan "flare" in patients irradiated to formerly false negative bone metastasis].

We discuss three cases irradiated to their bone metastases. 99mTc-MDP bone scan before irradiation showed normal uptake in the lesions. In all the cases, the irradiation therapy was effective, but focal increased uptake area corresponding to the site of bone metastasis was revealed by the follow-up bone scan one to three months after irradiation. We concluded that the change of tracer uptake was so-called flare in formerly false negative lesion. The cause of this phenomenon was considered either elevation of osteoblastic activity with control of tumor or progression of osteolysis until tumor got well-controlled.

Aged↗

PubMed1990

[Thin-section computed tomography of the normal minor fissure].

The minor fissure was studied with thin computed tomographic (CT) sections (2 mm thickness, 3 mm interval) in 50 patients. It showed high density line or area in all patients. In nine patients CT sections were not obtained through the all region of the minor fissure. Of other 41 patients the fissure was complete in 12 (29%), slightly incomplete in 18 (44%), half incomplete in 7 (17%), and considerably incomplete in 4 (10%). The upper surface of the middle lobe appeared to be upwardly convex in all 50 patients. The location of the highest portion of the minor fissure was hilar in 12 (24%) of 50 patients, medial 1 (2%), anterior 0 (0%), lateral 8 (16%), posterior 3 (6%), dorsal 10 (20%), central 12 (24%), others 2 (4%), and indeterminate 2 (4%). The minor fissure was higher medially than laterally in 22 (44%) patients, and higher posteriorly than anteriorly in 40 (80%) patients. The lowest portion of the minor fissure was anterior in 20 (40%) patients, lateral in 4 (8%), and posterior 3 (6%). The anterior vein of the anterior segment of the right upper lobe (V3b) came in contact with the minor fissure in 20 (40%) patients. In 18 (90%) of these 20 patients minor fissure medial to V3b was incomplete partially. Three dimensional reconstruction image of the minor fissure improved understanding of the anatomy. Familiarity with the anatomic detail of the minor fissure and with variations in the relationships of the upper and middle lobes is useful in localization or extension of a lesion.

Adult↗

PubMed1990

Screening for bacteriuria in Japanese school children.

Bacteriuria was screened among 28,202 healthy school children, 14,575 boys and 13,627 girls, by dipstick and dipslide methods and also by pour plate culture. The prevalence of bacteriuria was 0.06% in boys and 0.52% in girls after the third screening. A high rate of false negative results with the dipstick test and a high rate of false positive results with the dipslide culture method using Microstix-3 were observed. About 60% of screened children continued to have bacteriuria persistently for 9 months after the third screening, which was followed by monthly urine cultures. Anomalies of the urinary tract were detected in 9 of 26 children with persistent bacteriuria.

Adolescent↗

PubMed1990

[The influence of maxillary sinusitis upon the posterior fatty layer--a CT investigation].

CT values were estimated at the fatty layer in contact with the posterior wall of the maxillary sinus in various condition, i.e., normal, sinusitis, postop. sinus, and mucocele. By the unilateral sinusitis (40 cases), CT values obtained by the affected sides were significantly higher than those of the non-affected normal sides. A single maxillary bone was used for experiments to show that the dense++ materials filing the sinus do not affect the CT values of the fatty layer, thus confirming the above clinical data was real and not artifact. In addition, by the mucocele of the maxillary sinus (9 cases) with negligible inflammatory change in the sinus, the CT values of the fatty layer did not show any remarkable increase such as seen by sinusitis. These data lead us to the impression that the increased density is due to the transmitted effects of maxillary sinusitis through the posterior wall. In postop, sinuses (11 cases) with various postop. periods, CT values were slightly higher than those in normal sinuses, suggesting that the sinus infection was under improvement. The enhancement performed by 14 cases (28 sides) showed increased density of the fatty layer, but the increase was similar in both affected and non-affected sinuses. This suggests that the increased rate of circulation at the fatty layer is not the contributory factor to higher CT values. The results described above, combined with the previous reports concerning the bony changes in sinusitis, will lead to the conclusion that the increased CT values at the fatty layer is caused by the direct engagement of the inflammatory conditions in the sinus cavities.

Adipose Tissue↗

PubMed1990

[A case report of the reinforcing technique with collared prosthesis for the prosthetic valve endocarditis in mitral position].

A 58-year-old female was admitted to our hospital because of the prosthetic valve endocarditis in mitral position. In the past, this patient was undertaken double valve replacement in mitral and aortic position. Nevertheless, postoperative course was not in stable condition, showing persistent sign of the infection. The appearance of mitral regurgitant murmur and regurgitant signal by colour Doppler cardiography could make sure of the diagnosis for prosthetic valve endocarditis (PVE) in mitral position. The operation for PVE in mitral prosthesis was undertaken as follows. As there was extensive annular infection around the mitral valve, the new mitral prosthesis (Duromedics valve) with the Gore-tex flange, so called collared prosthesis, was revised. The collared prosthesis was implanted in the mitral annulus by using the suture ring of the Duromedics valve as well as possible, furthermore, the Gore-tex flange were sutured in the left atrial wall 2 cm above the mitral ring. Postoperatively, the infection sign and congestive heart failure were completely subsided. This patient has been in very healthy condition these days and restored to the daily life.

Endocarditis, Bacterial↗

PubMed1990

[Thin-section computed tomography of the bronchi; 2. Right upper lobe and left upper division].

Thin (2mm) section contiguous computed tomographic (CT) scans were obtained through the bronchi of the right upper lobe and the left upper division in 30 patients. All segmental bronchi were identified. The right subsegmental bronchi were identified in 100%, and the left subsegmental bronchi in 97%. The type of the orifice of the right bronchus was trifurcated (53%), the extension of B1 was apicoanterior (50%), and the size of B2b was equal to B3a (63%). The extension of the left B3 was subapicoanterior (38%), and the size of B1+2c was equal to B3a (62%).

Adult↗

PubMed1990

[Renal lymphoma; six cases].

Six patients had nine kidneys with lymphoma. Five patients (83%) had non-Hodgkin lymphoma, and three (50%) bilaterally. There were multiple nodules in four kidneys (44%). The lesions were changeful in the course. Gallium scintigraphy showed abnormal uptakes. Magnetic resonance imaging was examined in one case. The lesions were hypovascular in the angiographies. Inflammation is one of the different diagnosis.

Adult↗

PubMed1990

[Arterial thrombosis associated with Crohn's disease: a case report].

In the English literature, only 27 cases of arterial thrombosis associated with Crohn's disease have been described. The present case appears to be the first reported case in the Japanese literature. A 43-year-old man was treated for intestinal obstruction caused by Crohn's disease and complicated by superior mesenteric vein thrombosis by surgical resection of 150cm of small bowel in June 1981. In March 1983, the right external iliac artery had become occluded and part of the left external iliac artery had assumed an irregular shape and the right ilio-femoral bypass surgery using PTFE was carried out. Three months later occlusive ileus reoccurred and angiograms showed that the superior mesenteric and right hepatic arteries had 30% and 20% stenosis respectively. Small bowel in 50cm in length was resected with subsequent administration of salicylazosulfapyridine at a dose of 3g per day. There was no reappearance of bowel symptoms. The patient again complained of numbness in the right leg in February 1988 and a left external iliac-right common femoral crossover bypass operation was carried out using a ringed 8mm Dacron graft. Intraoperatively, it was found that the left external iliac and the right common femoral arteries had intimal thickening but no atherosclerosis.

Adult↗

PubMed1989

[The role of high-resolution CT in evaluating disease of the posterior tympanum].

The posterior tympanum consists of several irregular eminences, ridges, and sinuses. These sinuses do not communicate with the mastoid air cell system, and cholesteatoma and/or granulation tissue prefer to fill them. This area cannot be visualized with ease by the usual surgical approach, and is thus quite important for surgeons. Recent developments in high-resolution computed tomography (HRCT) allow more than ever precise identification of subtle changes in the posterior tympanum. Axial HRCT sections provide essential information for the preoperative evaluation of the posterior tympanum. The performance of surgeons has been promoted both in evaluation and treatment planning of patient with suspected posterior tympanic lesions. HRCT findings were compared with the operative findings in 52 patients (54 ears) who had the operation for chronic otitis media. Important findings by HRCT diagnosis of posterior tympanum are as follows: (1) Bone destruction in the posterosuperior part of the tympanic anulus and in the lateral wall of the facial sinus are the important findings for the diagnosis of invasion of cholesteatoma in the posterior tympanum. (2) Similarly important finding is the bone destruction of the pyramidal eminence. This was found in 6 of 9 cases with cholesteatomas extending into the sinus tympani. (3) The soft tissue density in the posterior tympanum does not necessarily indicate pathological processes. Effusion in the posterior tympanum is imaged as soft tissue density, and can not be differentiated from cholesteatoma or granulation by present HRCT.

Adolescent↗

PubMed1989

[Superstructure of stapes: an analysis by high-resolution computed tomography].

High-resolution Computed Tomography (HRCT) of the temporal bone has now become a routine test for the diagnosis of various temporal bone lesions. Correct assessment of such minute structures as ossicles, especially stapes, is important in the pre-operative HRCT evaluation. On the other hand, analysis for the reliability of HRCT findings has not been done, including the superstructure of the stapes. A retrospectively study was done in order to assess the availability of HRCT findings in axial overlapping scans in 226 ears, with respect to the superstructures of stapes. The study was concerned with the analysis of HRCTs of 148 normal ears, 71 ears of chronic otitis media and 7 ears of ossicular abnormalities. HRCT findings were compared to those of surgeries in pathological cases. The present study revealed that the superstructures of stapes are noted in 70% when the stapes surrounded by air. The major limitations in the proper analysis of stapes by HRCT are partial volume averaging and effects of soft tissue silhouetting, this is especially so when the stapes is surrounded by soft tissue density.

Chronic Disease↗