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Biomedical subjects

Y Ohtani

Publications and source records attributed to Y Ohtani.

At least 109 records · Page 6Linked to original sources
PubMed1992

Inhibitory interaction in a split/fusion apparent motion: lack of spatial-frequency selectivity.

Spatial-frequency selectivity of apparent motion (AM) between isolated Gabor patches was examined under two- and three-patch conditions. In the two-patch condition, the likelihood of seeing AM between two Gabor patches was measured with varying frequency difference between the patches. In the three-patch (split/fusion) condition, the likelihood of AM between target patches of the same frequency was measured as a function of the frequency of the inhibiting patch. AM perception in the two-patch condition deteriorated with increasing frequency difference, showing symmetrical spatial-frequency selectivity. On the other hand, the inhibition of AM in the three-patch condition was frequency asymmetric; when the frequency of the inhibiting patch was higher than that of the target patches, the magnitude of inhibition decreased with increasing the frequency of the inhibiting patch. When the frequency of the inhibiting patch was lower, the magnitude of inhibition remained almost constant regardless of the frequency difference between the inhibiting and target patches.

Contrast Sensitivity↗
PubMed1992

Ultrastructure of Warthin-Starry stain-positive bacteria in abscess-forming reticular lymphadenitis.

This study describes the ultrastructure of Warthin-Starry (WS) stain-positive bacteria in abscess-forming reticular lymphadenitis (ARL) compatible with cat scratch disease (CSD). Sections containing WS-positive bacteria were re-embedded in Epon, and semithin sections were examined by electron microscopy. Silver particles were aggregated on the outer surfaces of the bacteria. Stereoscopic observations clearly showed that the bacteria were pleomorphic, rod-shaped, arranged in a row or at an angle, and frequently showed septal formation. Electron microscopy of ultrathin sections revealed that the cell wall possessed an outer membrane characteristic of gram-negative bacteria. The results indicate that rod-shaped bacteria with the WS-positive, gram-negative staining cause ARL histopathologically consistent with CSD.

Abscess↗
PubMed1992

Postnatal growth curves of very low birthweight Japanese infants.

To construct standard growth curves for Japanese infants of very low birthweight, longitudinal data provided by 47 neonatal centers in Japan were reviewed. Data were collected on the growth of infants admitted to those units during 1986 and 1987 and who survived beyond 3 years of age. A total of 379 singleton infants, who were free of neurological sequelae and appropriate for gestational age, were enrolled. Those whose birthweights were more than 600 g and less than 1,500 g were grouped into nine weight categories separated by increments of 100 g. Data on the increase in weight and head circumference were compiled and analyzed until more than half the infants in each weight category had been discharged from each site. Growth curves of bodyweight and head circumference in the nine groups were constructed using polynomial regression analysis to define the curve of best fit. With increasing prematurity, significant trends of greater weight loss (P < 0.05), longer time to reach the lowest weight (P < 0.01) and a longer time to regain birthweight (P < 0.01) were observed. In addition, there was a significantly higher incidence of chronic lung disease in such groups (P < 0.0001). Growth curves were characterized by the average clinical profiles in each of the nine groups. We believe that these data will be useful in evaluating the growth of very low birthweight infants being cared for in modern neonatal intensive care units in Japan.

Birth Weight↗
PubMed1992

Cardiac adaptation and its limitation in an experimental model of congestive heart failure.

To elucidate mechanisms of adaptation and maladaptation in heart failure, abnormalities of left ventricular function and their relationships to myocardial contractile protein were studied in the Syrian hamster Bio 14.6. Left ventricular and heart weights were both increased in 20-week-old cardiomyopathic hamsters, indicating cardiac hypertrophy as a compensatory mechanism to the disease process of cardiomyopathy. However further increase in the left ventricular weight was not observed in older (40-week-old) cardiomyopathic hamsters. On the other hand left ventricular volume and volume/mass ratio were increased progressively. Correspondingly, V3 type myosin was increased and myosin sliding velocity was decreased. Left ventricular function of cardiomyopathic hamsters evaluated using an isovolumically beating perfused heart preparation was depressed, and this functional impairment was also progressive. Chronic administration of metoprolol, a beta-blocking agent, induced further increase in left ventricular volume and mass without changing left ventricular function and myosin isozyme pattern. Thus in cardiomyopathic hamsters, left ventricular function progressively deteriorates in spite of a variety of adaptive mechanisms, and remodeling occurs.

Adaptation, Physiological↗
PubMed1992

[Bicuspid aortic valve with sudden onset of aortic insufficiency due to rare causes: report of two cases].

This report describes two cases of aortic valve replacement which was warranted by the suddenly developed aortic regurgitation due to a congenitally bicuspid aortic valve. Aortic insufficiency was caused by the rupture of the strand which lifted a larger cusp to the aortic wall in one, and by the perforation of valvular aneurysm in another. Reviewing the literature these types of aortic insufficiency are rarely reported.

Acute Disease↗
PubMed1991

Contribution of transient and sustained responses to the perception of apparent motion.

The likelihood of seeing apparent motion (AM) was measured as a function of inter-stimulus-interval (ISI) between two isolated Gabor patches separated by 4 deg with spatial frequency (0.75, 2.0 and 4.5 c/deg) and exposure duration (33 and 1000 msec) as parameters. For the short stimuli, the likelihood of AM for the low-spatial-frequency of 0.75 c/deg was higher than that for the high-spatial-frequency of 4.5 c/deg, but for the long stimuli, the former was similar to, or lower than the latter. Decreasing the mean luminance from 190 to 0.8 cd/m2 impaired AM for the short stimuli of 2.0 c/deg, but improved AM for the long stimuli. The dependencies of AM on spatial frequency, exposure duration and adaptation level may be ascribed to the changing contribution of the transient and the sustained responses.

Adaptation, Ocular↗
PubMed1991

Progressive myoclonus epilepsy: dentato-rubro-pallido-luysian atrophy (DRPLA) in childhood.

A 22-year-old female with progressive myoclonus epilepsy (PME) considered to be due to hereditary dentato-rubro-pallido-luysian atrophy (DRPLA) was reported. Some of her family members showed progressive myoclonus, seizures, dementia, ataxia and choreoathetosis, with variation of onset from childhood to adult life, which suggested that they had been suffering from DRPLA. CT scan and MRI studies, including some on family members, revealed cerebral and cerebellar atrophy accompanied by dilatation of the fourth ventricle, compatible with the findings in DRPLA reported previously. We emphasize that a detailed family history may be essential in dealing with a PME patient and that DRPLA should be considered in the differential diagnosis of the PME syndrome with onset in childhood, in Japan.

Adolescent↗
PubMed1991

Vascular alterations in Fukuyama type congenital muscular dystrophy.

Blood vessels in muscle biopsy specimens from 6 Fukuyama type congenital muscular dystrophy (FCMD) patients were examined by electron microscopy and compared with ones in non-diagnostic biopsy specimens from age-matched controls and patients with childhood neuromuscular disorders. The most striking feature was the blister-like swelling of vascular endothelial cells in the biopsied muscle specimens from 5 of the 6 patients with FCMD. Morphometric analysis of capillaries in biopsied muscles showed the extremely greater capillary, endothelial and pericyte areas in the FCMD patients than in controls. These phenomena are quite similar to those found in Duchenne muscular dystrophy (DMD) at the preclinical stage and suggest an as yet undetermined process in blood vessels in FCMD as well as DMD. An immunohistochemical study involving dystrophin antibodies showed positive staining in FCMD.

Capillaries↗
PubMed1991

A nationwide survey on transient hyperammonemia in newborn infants in Japan: prognosis of life and neurological outcome.

A nationwide survey of transient hyperammonemia in newborns was carried out in Japan. A total of 18 patients, consisting of 12 male and 6 female infants, were reported from 11 facilities. These neonates exhibited hyperammonemia with plasma ammonia levels in the range from 124 to 6256 micrograms/dl. Four newborn infants of the 18 died in the neonatal period, and an additional one died in the early infancy. Among the 13 infants who were alive at the time of this survey, 6 had neurological sequelae, including mental retardation, spastic quadriplegia and epilepsy. The multivariate analysis revealed that the Apgar score at 1 minute, peak plasma ammonia concentration, birth weight and sex were significant factors affecting the prognosis of life.

Ammonia↗
PubMed1991

[An outbreak of gastroenteritis possibly caused by Escherichia coli O167:H9].

An outbreak of gastroenteritis involving a total of 256 patients (49.7%) among 515 persons occurred at a primary and secondary school in Agatsuma Town, Gunma Prefecture between the 23rd and 28th of June 1988. The majority of the cases occurred within the first 4 days. The main symptoms were abdominal pain (81.6%), diarrhea (57.0%) and headache (40.2%). In most cases, the stools were watery and occasionally mucous. Although food-borne infection was strongly suggested epidemiological evidence did not incriminate any foods as the cause of the outbreak. In the bacteriological study on stool specimens from 25 patients, Escherichia coli O167:H9 was isolated from 20 of these specimens, virtually in pure culture. The isolates of the E. coli serovar were negative for recognized diarrheagenic virulence properties: production of heat-labile and heat-stable enterotoxins, enteroinvasion, and production of Shiga-like toxin. When the HEp-2 cell-adherence test was used, however, they exhibited localized adherence. All the strains were demonstrated to carry 56 Md plasmids that presumably mediate the production of the adherence factor.

Adolescent↗
PubMed1991

Coenzyme Q10 attenuates the progression of cardiomyopathy in hamsters.

Coenzyme Q10 (10 mg/kg/day) or digoxin (2 micrograms/kg/day) was given orally to cardiomyopathic hamsters (BIO 14.6) for 8 weeks from 12 weeks of age. The left ventricular weight per gram of body weight (mg/g) was lower (p less than 0.01) in the coenzyme Q10 group (3.09 +/- 0.13) than in the digoxin (3.32 +/- 0.20) and control (3.44 +/- 0.14) groups. Left ventricular function was evaluated in isovolumically beating hearts. Left ventricular developed pressure (63 +/- 5 vs. 54 +/- 10 mmHg, p less than 0.05), -dP/dt (1385 +/- 100 vs. 1211 +/- 136 mmHg/sec, p less than 0.05), and -dP/dt (1068 +/- 126 vs. 896 +/- 141 mmHg/sec, p less than 0.05) were greater in the coenzyme Q10 than in the control group. The time constant of left ventricular relaxation was shorter in the coenzyme Q10 group than in the control group (25 +/- 3 vs. 28 +/- 3 msec, p less than 0.05). By contrast, in the digoxin group, the indices of left ventricular function did not differ from the control group. These results suggest that coenzyme Q10, but not digoxin, attenuated disease progression and preserved left ventricular function in cardiomyopathic hamsters.

Animals↗
PubMed1991

Oxygen dependence of lipid peroxidation in mice.

Peroxidation of lipids in serum and tissues of mice placed in low or high levels of oxygen was examined. After exposure to 100% oxygen for 3 h, no significant differences were observed between control and exposed mice. However, exposure to 100% oxygen for 6 h resulted in a decrease in oxygen consumption, an increase in lipid peroxides in tissues and serum, and the formation of hydroxyl radicals in tissues and serum. At low concentrations of oxygen (14% or 16%), a decrease in oxygen consumption, peroxidation of lipids and formation of hydroxyl radicals also were observed. Damage to mice was great with the lower oxygen concentrations of oxygen. There was a close correlation between the consumption of oxygen lipid peroxidation, formation of hydroxyl radicals.

Animals↗
PubMed1990

Stromelysin synthesizing cells in the synovial tissues of rheumatoid arthritis demonstrated by in situ hybridization and immunohistochemical methods.

We identified the cells synthesizing stromelysin to be synovial cells in the synovial tissue from four biopsy cases with rheumatoid arthritis (RA) by in situ hybridization and immunohistochemical studies. In the cases which showed severe inflammation of synovia such as well developed lymphoid follicle and diffuse inflammatory infiltration, synovial cells located only in the superficial layer of synovial tissues showed abundant mRNA and enzymic protein of stromelysin.

Arthritis, Rheumatoid↗
PubMed1990

[Hepatic arterial infusion chemotherapy using implantable reservoir in colorectal liver metastasis].

Hepatic arterial infusion chemotherapy was performed in 47 cases with colorectal liver metastasis. Methods of hepatic arterial cannulation were as follows: operative insertion of polyvinyl chloride catheter in 12 cases, angiographic insertion of polyethylene catheter via the left high brachial artery in 20 cases and operative implantation of reservoir in 15 cases. Mean durations of chemotherapy were 31 days, 25 days and 115 days, respectively. Chemotherapies were discontinued because of complications and catheter troubles in 7 cases (58%), 8 cases (40%) and 6 cases (40%), respectively. Regression of tumor size was observed only in the group with reservoir. Prolonged therapy is achievable by use of the reservoir. But catheter troubles, including obstruction, infection, extravasation and pseudoaneurysm, are still observed in the course of chemotherapy. Radionuclide study using 99m Tc macroaggregated albumin is useful to detect catheter troubles. We stressed that the proper management of reservoirs is important.

Antineoplastic Combined Chemotherapy Protocols↗