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Biomedical subjects

Y Shimoda

Publications and source records attributed to Y Shimoda.

At least 55 records · Page 3Linked to original sources
PubMed1989

[Diagnosis of colon cancer (depth of invasion) by barium enema examination; present condition].

Accuracy of the barium enema examinations in diagnosis of the depth of invasion of the small carcinomas of the colon was reviewed. The materials included 101 sessile carcinomas and 12 small advanced carcinomas that were 20 mm or less in diameter. The carcinomas with stalks and the depressed type early carcinomas (Type IIc) were excluded from the study, because the former were impossible to the nature by X-ray examinations and the latter were extremely rare. Presence of the depressed portions on the surface of the elevated lesions observed in the frontal views and the degree of the deformity observed in the profile views of the lesions were correlated with the pathological specimen and the accuracy of the radiological diagnosis of the depth of invasion was estimated. The cases with gross malignant cell invasion into the submucosal or the deeper layers were diagnosed correctly with present radiological diagnostic criteria. But, those with a small amount of malignant cell invasion into the submucosal layer or the cases with malignant cell invasion limited to the mucosal layer (intramural cancer) were not always correctly diagnosed and there was a variety in diagnosis of the depth of invasion in this group. With the current radiological techniques, proper profile views of the lesions were not obtained in quite a few cases, nor the surface characteristics of the small elevated lesions were well documented. It would probably be possible to improve these techniques and to improve diagnostic accuracy to some extent, but with certain limitations.

Barium Sulfate↗
PubMed1989

[The change of colloid osmotic pressure (COP) during simple deep hypothermia].

The change of colloid osmotic pressure (COP) was measured during simple deep hypothermia in patients and in dogs. The following results were obtained; 1) There was no change in COP in dogs without occlusion of blood flow. This suggests that simple deep hypothermia has no effect on COP. 2) In the cases of open heart surgery with occluding blood flow for 40 minutes at 20 degrees C, COP remained almost constant during the cooling period. COP decreased from 23.0 +/- 0.8 mmHg to 19.1 +/- 0.8 mmHg after occluding blood flow and it did not recover with rewarming. 3) COP recovered during rewarming period with using methylprednisolone. 4) These observations suggest that the change of COP is caused by the change of microcirculation due to hypoxia during occlusion, and methylprednisolone is useful to prevent it.

Animals↗
PubMed1986

Electron-microscopic cytochemistry of the catecholaminergic innervation of TRH neurons in the rat hypothalamus.

The catecholaminergic innervation of thyrotropin-releasing hormone (TRH) neurons was examined by use of a combined method of 5-hydroxydopamine (5-OHDA) uptake or autoradiography after intraventricular injection of 3H-noradrenaline (3H-NA) and immunocytochemistry for TRH in the same tissue sections at the electron-microscopic level. TRH-like immunoreactive nerve cell bodies were distributed abundantly in the parvocellular part of the paraventricular nucleus (PVN), in the suprachiasmatic preoptic nucleus and in the dorsomedial nucleus of the rat hypothalamus. In the PVN, a large number of immunonegative axon terminals were found to make synaptic contact with TRH-like immunoreactive cell bodies and fibers. In the combined autoradiography or 5-OHDA labeling with immunocytochemistry, axon terminals labeled with 3H-NA or 5-OHDA were found to form synaptic contacts with the TRH immunoreactive nerve cell bodies and fibers. These findings suggest that catecholamine-containing neurons, probably noradrenergic, may innervate TRH neurons to regulate TRH secretion via synapses with other unknown neurons in the rat PVN.

Animals↗
PubMed1986

[Analytical study of Xenopus hindlimb regenerate with special reference to muscle regeneration].

Amputated hindlimbs of Xenopus laevis, develop various types of regenerates in relation with amputation level as well as stage development. The present experiments is an attempt to study the histological characteristics of Xenopus regenerations, i.e., rational changes of tissue components along the length of the regenerated part with special emphasis on the degree of muscle regeneration. Four types of regenerates were studied viz; a 4th toe obtained from a completely restored regenerated limb at 126 days after amputation of limb at base level in stage 51. An amputated limb with no external sign of regeneration of limb at thigh level in stage 60. A spike-shaped regenerate at 96 days after amputation of limb at shank level in stage 63. A spike-shaped regenerate at about 2 years after amputation of limb at shank level in stage 60. Cross sectional areas of muscle, skin gland, epidermis and cartilage in each of the four types of regenerates were measured with Image Analyzing Apparatus (VIP 121 CH, Olympus Co.). The relative area of each tissue was expressed as a percentage of the cross sectional area of the limb. The obtained values were plotted along the length of the regenerate. Digitiform regenerates were found to be more or less similar to the control limbs, i.e., provided joints and muscle, while the heteromorphic spike or rod shaped regenerates were simply provided with cartilaginous axial core without joint formation. Muscle area were reduced rapidly near the amputation area of these heteromorphic regenerates with no more continuation in the regenerated tissue. It is interesting to mention that percentage cartilage area of about 2 years old spike regenerate was higher than that of similar 96 days regenerate. In addition muscle regeneration was completely absent even in such an aged regenerate. The area showed fairly similar ratio irrespective of the external appearance of the regenerate. In 32 regenerates of which limbs were amputated at various developmental stages ranging between stage 51 and adult stage, the histological condition of muscle at the amputation site, were well observed. In all digitated types of regenerates even in those with reduced number of toes, muscles were found grown well in the regenerates. In heteromorphic regenerates without toe formation muscle did not usually regenerate. In few cases, however, a small mass of myoblastic like cells or small aggregation of differentiated muscle cells without any structural continuation with the stump muscles, were seen to develop in the midst of the regenerate.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1984

Rod light response augmented by active phosphodiesterase.

Light activates rod outer segment (ROS) phosphodiesterase (PDEase), as shown by previous biochemical and physiological studies. We have further investigated the role of PDEase in this system by injecting trypsin-activated PDEase, purified from bovine ROS, into single ROS of the isolated retina of the toad Bufo marinus. Injection of about 300 molecules of activated PDEase in darkness is without immediate detectable effect, as measured by intracellular membrane-voltage recording. The effect of the activated PDEase injections only becomes evident after illumination. The light response is augmented; kinetics of repolarization are slowed. We conclude that this augmentation of the light-dependent hyperpolarization results from the hydrolysis of endogenous cyclic GMP caused by injected PDEase. These results provide evidence that PDEase affects light-dependent channels of the vertebrate scotopic photoreceptors but do not specify whether the effects are exercised for the initial hyperpolarizing phase of the receptor potential and for the recovery phase or only for the recovery phase.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1983

Response to light of various retinal cell types during spreading depression.

The retina in low Cl-media gives rise to spreading depression (SD) accompanied by a large, receptor side negative potential change (SDP). Changes during SD in the membrane potential and the responsiveness to light of various retinal cell types are studied, using a pair of intra- and extracellular electrodes and applying dim white light flashes to the retina at 5 sec intervals throughout the experiment. The study shows that the amacrine and ganglion cells depolarize strongly during SD to complete loss of response to light, and that the start of depolarization in these cell types precedes a little that of SDP. The other cell types continue to respond to light flashes during SD, though their response amplitude decreases as the cells depolarize due probably to an increase in [K+]0 accompanying SD. The results suggest that the amacrine and ganglion cells take an initiative role in the SD generation, and that the changes in the other cell types are mostly of passive nature.

Animals↗
PubMed1982

67Ga scanning and upper gastrointestinal series for gastric lymphomas.

67Ga scanning and upper gastrointestinal (UGI) series were performed in 13 patients with gastric lymphomas before any treatment was initiated. Seven of these patients also underwent both examinations after completing chemotherapy and/or radiation therapy. Prior to treatment, all 13 patients had abnormalities on the UGI examination, and 12 of them had abnormalities on the 67Ga scans. In 6 patients, more extensive gastric abnormalities were demonstrated by 67Ga scanning than by UGI examination. Although persistent 67Ga uptake after treatment was indicative of relatively poor therapeutic response, lack of uptake did not always indicate a good response to treatment.

Aged↗
PubMed1982

GABA-mediated negative feedback from horizontal cells to cones in carp retina.

In the isolated, perfused retina of the carp, properties of the feedback pathway from horizontal cells to cones were investigated by means of electrophysiological and neuropharmacological methods. When horizontal cells were hyperpolarized by illumination with an annulus, a depolarizing synaptic potential was produced in cones at the center of the annulus, suggesting that horizontal cells receive inputs from cones and exert a negative feedback to cones. On the other hand, a hyperpolarization (EPSP) was induced in horizontal cells by application of a transretinal current pulse, which activated the release of transmitter from the photoreceptor terminals. The IPSP was abolished when the retina was perfused with a GABA-containing Ringer solution, because of desensitization of the feedback synapse. GABA also hyperpolarized the cone membrane, indicating the presence of a GABA-sensitive site in the cone. These results suggest that the GABA-mediated negative feedback operates from horizontal cells to cones in the dark, and ceases its function in the light.

Animals↗
PubMed1982

GABA-mediated negative feedback and color opponency in carp retina.

In the isolated, perfused retina of the carp, the effects of GABA and its antagonists, picrotoxin and bicuculline, were investigated on spectral responses of horizontal cells. When the GABA-mediated feedback from horizontal cells to cones was desensitized or blocked by these chemicals, remarkable changes were observed in spectral responses, due to selective suppression of responses to long wavelengths. In particular, the depolarizing responses in the biphasic C-type (H2) cell were abolished, while the hyperpolarizing responses to short wavelengths were retained, resulting in a monophasic spectral response curve. From these results, it was concluded that the GABA-mediated negative feedback plays an essential role in neural mechanisms which convert the trichromatic process at the level of cones into the opponent color process in horizontal cells.

Animals↗
PubMed1981

Preservation and transportation of bacteria by a simple gelatin disk method.

A wide range of bacterial species, e.g., Enterobacteriaceae and Neisseria, Streptococcus, Branhamella, Haemophilus, Gemella, Pseudomonas, Flavobacterium, and Bacteroides species, were successfully preserved for 1 to 5 years by our gelatin disk drying method. The beta-lactamase activity of penicillinase-producing Neisseria gonorrhoeae was retained for more than 3 years with this method. Good results were also obtained upon airmailing many strains of N. gonorrhoeae embedded in gelatin disks from Japan to the United States. Neisseria, Branhamella, Gemella, and Haemophilus organisms suspended in the reagent used in the preparation of the gelatin disks could be preserved for 6 to 12 months after freezing the cell suspensions at -20 degrees C. Furthermore, modification of our gelatin disk preservation method made possible the safe long- and short-distance transportation of clinical isolates. Our methods can be used by any small laboratory, since they require only conventional instruments and reagents.

Bacterial Infections↗