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Biomedical subjects

Y Obara

Publications and source records attributed to Y Obara.

At least 19 recordsLinked to original sources
PubMed1991

Effects of long-term medication for essential hypertension on cardiac hypertrophy and function.

The effects of long-term treatment of hypertensive patients with alacepril (angiotensin-converting enzyme inhibitor) on cardiac mass and function were investigated. A total of 12 patients was examined. Both systolic and diastolic blood pressure were significantly reduced by treatment with alacepril for 1 year. Left ventricular mass, as estimated by echocardiography, was significantly decreased by alacepril treatment, although electrocardiographic and chest x-ray findings were not significantly altered. Cardiac pump function, which was also assessed by echocardiography, was not changed. These results indicate that long-term treatment of hypertension with alacepril induces regression of cardiac hypertrophy without any change in cardiac contractile function.

Adult↗
PubMed1991

[A study on auditory disturbances after microvascular decompression for hemifacial spasm].

After establishing an operation of microvascular decompression by Jannetta in 1975, an improvement rate of hemifacial spasm have increased. However, postoperative hearing deficits, equilibrium disturbances and facial paresis have been described in some publications. Fifty-seven of 119 patients with hemifacial spasm operated from 1982 to 1989, were examined by audiometry before and after operation. In patients with tinnitus at the time of facial spasm and closing eyelids, tinnitus improved almost in many cases. Of 57 patients, 8 (5 with sensorineural hearing loss, 3 with conductive hearing loss) had postoperative hearing impairments in operated ears, and 7 (7 with sensorineural hearing loss) had in the other ears, too. Of 7 patients having sensorineural hearing loss observed for several months, 4 having slight sensorineural hearing loss recovered at the same hearing level before operation. In 2 patients having profound sensorineural hearing loss, however, hearing improvement did not observed in each case.

Adult↗
PubMed1991

[The biochemical study in the nucleus opacification of the senile cataractous lens].

The lens nucleus has various colors, sizes and hardness. It is of significance to investigate the components of the nucleus and the factors participating in the mechanism of development of cataract. Recently, the author demonstrated that free lipid in cataract does not undergo quantitative change, compared with that in the normal lens but that the cholesterol and phospholipid in the nucleus and cortex increase in the urea-soluble protein fraction. An assay of lipid-protein complex (lipoprotein) was made and also quantitative changes were studied using nucleus with different colors in senile cataract. The study was made by the technique developed by the author because no other experimental procedure has been established for lipoprotein in the tissue. Chylomicron, VLDL, LDL and HDL were identified in lipoprotein. The amount of lipoprotein decreased as the color of the nucleus became dense, but only HDL among these increased. The catabolism of lipoprotein advanced when the color of nucleus changed from light yellow to brown, suggesting that disorder in mass transfer is caused.

Aged↗
PubMed1990

Chromosome banding analysis of a new stemline of hypodiploid Hirosaki sarcoma established by single cell transplantation.

A new hypodiploid stemline of the long-lasting ascites sarcoma, Hirosaki sarcoma (HS), was established by means of single-cell transplantation, and its G-, C- and NOR-banding patterns were compared with those of the predecessor stemline, with special notice taken of the structural alteration of marker chromosomes. Their chromosomal relationship was well explained by the rearrangement, t(M7pM8q): Translocation of the short arm of marker M7 to the NOR of marker M8 produced a new marker M8t, and the translocation-carrying variant cells grew into a subline. A new translocation-carrying stemline was formed from this subline by single-cell transplantation. Judging from the size and number of silver-positive NORs, the NOR activity was significantly higher in this stemline than in its predecessor. The increased NOR activity might have been partly responsible for the growth of a translocation-carrying variant cell into a new subline. Single-cell-mass transplantation may be one of the most effective systems for studying the proliferative ability of subline cells and for understanding the mechanism of stemline formation in transplantable rat ascites sarcomas.

Animals↗
PubMed1990

Effects of ultraviolet B irradiation on lenticular riboflavin metabolism and high-molecular-weight-protein aggregation.

We investigated the effects of ultraviolet B (UVB) irradiation on the formation of ester forms of riboflavin and of high-molecular-weight (HMW) protein aggregates and on lenticular riboflavin-binding capacity (LRBC). Esterification of riboflavin decreased as the duration of UV irradiation increased, suggesting the irradiation-induced denaturation of the apoenzyme of synthetases of ester forms of riboflavin. UVB irradiation of lens homogenate supplemented with riboflavin increased LRBC and the formation of HMW protein aggregates, while gamma-crystallin was decreased. These results are consistent with those of our earlier studies in which we obtained data suggesting that, upon exposure of rat lens homogenate to fluorescent light, photosensitized riboflavin may bring about cross-linking of lens protein. Our data demonstrate that the photosensitivity of lenticular riboflavin is increased by longer periods of UV irradiation.

Animals↗
PubMed1990

Classification system for cataracts. Application by the Japanese Cooperative Cataract Epidemiology Study Group.

A cataract classification and grading system for the main purpose of cataract epidemiological studies is proposed by the Japanese Cooperative Cataract Epidemiology Study Group. Cataractous types are classified principally into cortical, nuclear and subcapsular opacities. Stages of cataract advancement are classified into grade I (early stage), grade II (moderate stage) and grade III (advanced stage). Regarding cortical opacities an opacified area obtained from red-reflex images is utilized for grading judgment. Nuclear opacity grading is based on the intensity of scattering at the nucleus. Grading of subcapsular opacities is judged from their extension in the three different pupillary areas. To help grading judgments, standard pictures of cortical and nuclear cataracts are provided. Gradings of lens coloration are divided into pale yellow (grade I), yellow (II), brownish yellow (III) and brown including reddish and black brown (IV). A recording chart is also provided.

Adult↗
PubMed1989

[A cataract classification and grading system].

A cataract classification and grading system developed for cataract epidemiological survey was introduced. Cataractous opacities were classified into cortical, nuclear and subcapsular types. Gradings of cataract progression were divided into early (Grade I), moderate (II) and advanced (III) stages. The grading of cortical opacity was judged by the opaque area in a maximally dilated pupillary zone of which findings were obtained from a red-reflex image. The grading of nuclear opacity was judged from the intensity of scattering light at the nucleus. Three grading steps were based on the densitometrical analysis of photographed images. Subcapsular opacities were classified into three gradings by extensions up to the normal, moderately dilated and maximally dilated pupil size. Regarding cortical and unclear cataracts, standard images indicating border findings between Grades I and II and Grades II and III were provided to help with classification. Nuclear coloration was classified into pale yellow, yellow, brownish yellow and brown including reddish brown and black brown. To document cataractous findings, a recording chart was made.

Cataract↗
PubMed1987

Amino acid synthesis from ornithine: enzymes and quantitative comparison in brain slices and detached retinas from rats and chicks.

The regional distribution of proline biosynthetic enzymes, ornithine-delta-aminotransferase and delta 1-pyrroline-5-carboxylate reductase, in the rat brain, and basic conditions for proline synthesis from ornithine in rat and chicken brain slices and chicken retinas were investigated. The cerebral regions relating to memory formation and imprinting (cortex, hypothalamus and hippocampus) exhibited a high activity of ornithine-delta-aminotransferase, while delta 1-pyrroline-5-carboxylate reductase activity was ubiquitously high. Amino acids were determined fluorometrically after separation and reaction with o-phthaldialdehyde by high-performance liquid chromatography. Proline formation was both ornithine- and 2-oxoglutarate-dependent, and the proline level was suppressed by a high-potassium medium in the brain slices but not in the detached retinas. Its main precursor in vitro seemed to be ornithine but not arginine. The retinas from formoguanamine (2,4-diamino-S-triazine)-treated chicks showed a 10-fold higher level of proline and a marked decrease in gamma-aminobutyric acid, presumably due to an impairment of the blood-retina barrier. The different response in proline level to the high-potassium medium in the brain slices and detached neuroretinas suggests that cellular distribution of the enzymes relating to ornithine and proline metabolism is different in the brain and the neuroretina.

Amino Acids↗
PubMed1987

Sectional classification of cataract.

It is of importance to epidemiologically explore the risk factors which will induce cataract. Both the sections of lenses and their grades of opacity were classified only on the basis of the findings by the slitlamp microscope in order to examine the cases with cataract. There are split ways for classification of the cases with cataract, but it would be of no meaning if the classification for this purpose is not generally utilized, no matter how detailed it may be. Therefore, a simplified method for classification was discussed in the present study. There were variations in the grades of opacity with the sections of the lens, and the variations give different effects upon the visual disturbances. Especially, it was conceived that the visual power would be affected by the opacity of the posterior cortex. Also, it was conceived that the opacity of the posterior cortex tends to advance faster.

Cataract↗
PubMed1986

Immunohistochemical distribution of ferritin, lactoferrin, and transferrin in granulomas of bovine paratuberculosis.

Granulomatous lesions of bovine paratuberculosis contained ferritin, lactoferrin, and a small amount of transferrin, as demonstrated by the immunohistochemical method. Macrophages in the normal bovine ileum did not contain lactoferrin and transferrin; however, ferritin was found in individual macrophages of Peyer's patches. These results may help elucidate the relationship between intracellular growth of Mycobacterium paratuberculosis and the presence of iron-binding proteins in the granulomas.

Animals↗
PubMed1986

Effects of aging on the formation of ester forms of riboflavin in the rat lens.

We studied the effects of aging on the formation of ester forms of riboflavin in the lens of rats. The formation was highest in newborn and 2-week-old rats; a sharp decrease was noted at one month, thereafter it continued to decrease gradually reaching a plateau at 3 months. In general, esterification of riboflavin was higher in female than male rats. We found that a decrease in the esterification of riboflavin with increasing age is a characteristic change in the rat lens. This finding may help to clarify the pathogenesis of senescent change in the lens.

Aging↗
PubMed1985

Clinical application of NMR-CT for idiopathic cardiomyopathy.

The accuracy of a newly developed nuclear magnetic resonance-computed tomography (NMR-CT) technique in diagnosing idiopathic cardiomyopathy was assessed and compared with other procedures such as echocardiography, coronary angiography, left ventriculography, myocardial biopsy, and electrocardiography. In case 1, the NMR-CT clearly revealed thickening of the lateral ventricular free wall and ventricular septum, which strongly suggested hypertrophic cardiomyopathy. Catheterization showed a pressure gradient of 54 mm Hg and this patient was diagnosed as having hypertrophic obstructive cardiomyopathy. In case 2, the NMR-CT showed dilatation of the ventricular cavity indicative of dilated cardiomyopathy. This was confirmed by echocardiography, which revealed the enlarged cavity of the ventricle and poor movement. In case 3, the patient had marked hypertension; the cardiac silhouette was enlarged, but the NMR-CT revealed that the ventricular free wall and septum were of normal thickness. This study shows that NMR-CT is of value in the differential diagnosis of idiopathic cardiomyopathy.

Adult↗
PubMed1985

Retinal damage in hatched chicks induced by formoguanamine. Decrease in ornithine aminotransferase activity and vitamin B6 content.

Subcutaneous injection of formoguanamine (2,4-diamino-s-triazine) induced sightlessness in newly hatched chicks within 28-32 hr. The specific activity of retinal ornithine aminotransferase, localized exclusively in the mitochondria of retinal pigment epithelium, and the retinal vitamin B6 content decreased rapidly after formoguanamine administration. An absorption spectrum of retinal extract showed reduced absorbance at 400 nm in the formoguanamine-treated chicks, but delta 1-pyrroline-5-carboxylate reductase, an enzyme in the retinal cytosol, did not change significantly. A drug-metabolizing enzyme, glutathione transferase, showed an increase in specific activity during a later phase. Histological examination of the formoguanamine-treated chicks revealed characteristic degeneration of pigment epithelium and photoreceptors, acute retinal detachment and a secondary gliosis in the outer nuclear layer. From these findings it may be concluded that formoguanamine primarily damages the physiological functions of retinal pigment epithelium and photoreceptors and results in irreversible retinal detachment in newly hatched chicks.

Animals↗
PubMed1979

Intraruminal injection of urea and changes in secretion of parotid saliva in sheep.

1. Sheep were injected with varying doses of urea into the rumen and changes in the amount of saliva secreted from one parotid gland were studied. When the dose of urea was 0.1-0.2 g/kg, the secretion underwent no change. When the dose was 0.3 g/kg, the secretion was inhibited. When the dose was 0.4 or 0.5 g/kg, there was a marked inhibition in the secretion. 2. There was a close relationship between the ammonia level of the jugular blood and the inhibition of salivary secretion. When the ammonia level exceeded approximately 0.28 mmol/l, the secretion was inhibited abruptly. 3. Salivary secretion and rumen movement were inhibited when the blood ammonia level exceeded 0.28 mmol/l, after injection of ammonium acetate into the jugular vein. 4. Based on the results mentioned previously, the mechanism of inhibition on the secretion of parotid saliva is discussed in relation to the domestic ruminant in which urea had been injected into the rumen.

Ammonia↗
PubMed1979

Preservation of Neisseria gonorrhoeae by the gelatin-disc method.

Studies of Neisseria gonorrhoeae are difficult to perform because of the organism's poor survival in vitro. To solve this problem we tried to preserve the organism by a gelatin-disc method. The rate of survival and changes of variations in some biochemical properties of eight strains of N. gonorrhoeae were followed for three years. These studies proved that preservation was satisfactory with only a 1/10 reduction of the living cells. Another trial showed that the organism survived for over six months after being frozen at -20 degrees C. The colonial types, agglutination against red cells from rabbit and guinea pig, and antibiotic susceptibility to penicillin, chloramphenicol, tetracycline, kanamycin, and streptomycin did not change after three years' preservation.

Anti-Bacterial Agents↗