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Biomedical subjects

T Ohtsuka

Publications and source records attributed to T Ohtsuka.

At least 307 records · Page 17Linked to original sources
PubMed1985

Synaptic contacts between red-sensitive cones and triphasic chromaticity horizontal cells in the turtle retina.

Using combined physiological and anatomical methods, we have shown that triphasic chromaticity horizontal cells (THC) in the turtle retina make ribbon synaptic contacts with about 20 cones, two-thirds were red-sensitive, while the rest were blue-sensitive. The response of THC to red flashes appeared to be generated via synapses from red-sensitive cones; this interpretation differs from those of the previous studies where only blue-sensitive cones were thought to make synaptic contacts with the THC.

Animals↗
PubMed1985

Quantitative morphological study of the outer nuclear layer in the turtle retina.

Types and densities of retinal cells with somata located in the outer nuclear layer of the turtle retina were studied with combined light and electron microscopic observations of serial sections. One third of the somata in the outer nuclear layer were found to be those of displaced bipolar cells, while the rest were of those of photoreceptors. Somata were 8-10 micrometers in horizontal diameter for both types of retinal cells.

Animals↗
PubMed1985

Relation of spectral types to oil droplets in cones of turtle retina.

The spectral sensitivities and color of oil droplets of cone photoreceptors in the retina of the red-eared turtle (Pseudemys scripta elegans) were investigated by intracellular recording and injections of Lucifer yellow dye. Six morphological types of cones could be distinguished by the color of the oil droplets located in the outermost inner segments. Single cones containing either red or pale green oil droplets were sensitive to red light, cones with yellow oil droplets to green, and cones with clear oil droplets to blue. Contrary to previous reports, both principal and accessory members of double cones were sensitive to red, and no diffusion of dye was detected between the two apposed members. Thus, the oil droplets provide a reliable morphological basis for further investigation of the neuroanatomical networks underlying the processing of color information in the vertebrate retina.

Animals↗
PubMed1985

Diverse involvements of Ni protein in superoxide anion production in polymorphonuclear leukocytes depending on the type of membrane stimulants.

Effects of islet-activating protein (IAP) were examined to assess the involvement of the guanine nucleotide-binding regulatory protein responsible for inhibition of adenylate cyclase system (Ni protein) in the superoxide anion (O-2) production in polymorphonuclear leukocytes (PMNL) stimulated with various agents. N-Formyl-methionyl-leucyl-phenylalanine (FMLP)-stimulated O-2 production was inhibited by the pretreatment with IAP. O-2 production induced by each of phorbol myristate acetate, concanavalin A, and A23187, however, was rather resistant to the pretreatment with IAP. This observation indicates that the Ni protein does not involve in the common pathway for the O-2 production. in PMNL, and the involvement is rather specific for the FMLP-induced production. O-2 production in PMNL stimulated with various membrane perturbing agents was also diverse in the requirement of extracellular Ca2+.

Adenylate Cyclase Toxin↗
PubMed1985

Characterization of interaction between Tb3+ and porcine intestinal brush-border membranes.

Effects of ionic strength and temperature on the interaction between Tb3+ and porcine intestinal brush-border membrane vesicles were studied. When Tb3+ was added to the vesicle suspension, Tb3+ fluorescence increased with increasing concentration of Tb3+, showing a saturation. The apparent dissociation constant of one of at least two components of this binding reaction was estimated to be about 12.5 microM at 25 degrees C, pH 7.4. But the affinity of Tb3+ for the membrane vesicles was variable with changes of ionic strength and temperature. The affinity was lowered by addition of KCl to medium and by increase of temperature above 30 degrees C. In addition, temperature-induced change in the affinity of Tb3+ for the membranes was reversible over a temperature range from 13 to 46 degrees C. Temperature-dependence profiles of the excimer formation efficiency of pyrene-labeled membranes and of the harmonic mean of the rotational relaxation times of pyrene molecules in the membranes revealed that the phase transition of the membrane lipids occurs at about 30 degrees C. Based on these results, characteristics of Tb3+ binding to the membranes are discussed in relation to the nature of lipid phase and surface charges of the membranes.

Animals↗
PubMed1985

Spectral sensitivities of seven morphological types of photoreceptors in the retina of the turtle, Geoclemys reevesii.

Spectral sensitivities of photoreceptors in the turtle (Geoclemys) retina were studied by intracellular recording, and each cell was filled with Lucifer yellow (LY). Photoreceptors were classified into seven morphological types: rod, four types of single cones, and two members of a double cone. Single cones contained one of four different oil droplets: red, pale-green, orange, and clear. Double cones consisted of two apposed cones; principal members contained yellow oil droplets, while accessory members contained no oil droplet. Spectral sensitivities recorded from these seven types of photoreceptors were classified into one type of rod and three chromatic types of cones. Rods (n = 19) showed peak sensitivity at 520 nm. Single cones containing either a red (n = 51) or a pale-green (n = 9) oil droplet were red-sensitive (lambda max at 620 nm). Single cones containing an orange oil droplet (n = 14) were green-sensitive (lambda max at 540 nm). Single cones containing a clear oil droplet (n = 3) were blue-sensitive (lambda max at 460 nm). Both members of the double cone, principal (n = 22) and accessory (n = 15), were red-sensitive (lambda max at 620 nm). No diffusion of LY was detected between the apposed members of double cones. Red-sensitive cones, therefore, consisted of four different morphological types of cones, and they occupy about 70% of the photoreceptor mosaic in the turtle retina.

Animals↗
PubMed1985

[Treatment of meningeal carcinomatosis--neocarzinostatin perfusion therapy in the CSF pathway].

The authors presented the results of perfusion chemotherapy in the CSF pathway with neocarzinostatin (NCS) for the treatment of meningeal carcinomatosis. In three cases of stomach cancer and one case of malignant lymphoma, cranial polyneuropathy, progressive hydrocephalus and positive cytology of the CSF were found during treatment of malignant tumors. NCS therapy was performed by means of perfusion from the spinal subarachnoid space to the ventricle utilizing Ommaya's reservoir, or simply by repeated lumbar punctures. In all of four cases the number of malignant cells in the CSF was significantly diminished, and temporary neurological improvement was observed until the patient's death due to advanced primary lesions. These results indicated that in cases of meningeal carcinomatosis, NCS perfusion therapy using the CSF pathway was a much more favorable method than treatment with other chemotherapeutic agents with less noticeable side effects.

Adult↗
PubMed1984

Fluorescence from colorless oil droplets: a new criterion for identification of cone photoreceptors.

Vertebrate retinal photoreceptors containing colorless oil droplets have often been described as blue-sensitive. This identification is reexamined by intracellular recording and Lucifer yellow dye injections in turtle retina. Contrary to previous reports, the majority of the cones with colorless oil droplets were found to be red-sensitive; only one-third of the cones sampled were blue-sensitive. In addition, colorless oil droplets contained in the red-sensitive cones displayed a bright green fluorescence upon near-ultraviolet irradiation, while those of the blue-sensitive cones did not fluoresce.

Animals↗
PubMed1984

A new EPR signal associated with photosystem 1 of algal and plant photosynthesis.

A new low temperature electron paramagnetic resonance (EPR) signal with a g-value of 1.97 was found in Photosystem-1 particles from a blue-green alga, Anacystis nidulans, illuminated at room temperature. A similar signal was also found in spinach Photosystem-1 particles treated with thiophenol to decrease interference from a signal due to Center A. In the dark, the signal appeared only when the Anacystis particles were at redox potentials lower than -0.5 volts where Centers A and B were also reduced. The signal is most likely due to another iron-sulfur cluster, tentatively designated as Center C. Center C could be photoreduced at low temperatures like Center A when Centers A and B were partially reduced prior to illumination, indicating possible close association of these centers in Photosystem 1 of green plant and algal photosynthesis.

Cyanobacteria↗
PubMed1984

[Correlation between EEG and auditory brainstem response (ABR) in comatose patients--diagnosis of brain death by ABR].

ABRs and EEGs were recorded from fifty comatose patients. Among them 21 patients were in deep coma and remaining 29 were in brain death that was diagnosed from clinical criteria. All the patients who showed some activity in EEG had ABR which showed waves I through V. However, there was no correlation between grade of EEG classification, dominant alpha, theta, or delta rhythm, and the inter wave latencies between waves I through V in the ABRs. Eleven of the twenty-nine patients who were diagnosed as brain death from clinical criteria and isoelectric EEG showed waves I through V potentials in ABR. Eight of these eleven patients even exhibited normal or nearly normal ABRs which had I to V latencies less than 4.4 ms. However, all the patients who showed isoelectric EEG and no response ABR died. Thus it is concluded that the ABR should be included for identification of brain death in addition to the clinical examination and EEG recordings.

Brain Death↗
PubMed1983

Axons connecting somata and axon terminals of luminosity-type horizontal cells in the turtle retina: receptive field studies and intracellular injections of HRP.

Luminosity (L)-type horizontal cell responses to small and large spots of light in the turtle (Geoclemys) retina were recorded intracellularly, and each cell so studied was filled with horseradish peroxidase (HRP) by ionophoretic injection. Following histochemical reaction of the HRP with diaminobenzidine (DAB), light microscopic inspection demonstrated that this type of horizontal cell has a cell body connected to a tuberous axon terminal by a fine axon. By examining the location of the cell in relation to the linear array of electrode penetrations in each preparation, it was possible to determine whether a given recording was made in the cell body or in the axon terminal. The size of the receptive field of the cell body was significantly smaller than that of the axon terminals. Although the center-to-center distances between the cell body and the axon terminal of some L-type horizontal cells were as short as 50 micron, the length of the intervening axon was invariably longer and was at least 250 micron. Unless signals are amplified by some active mechanisms during their propagation along the axon, it is unlikely that current generated in the cell body spreads to the axon terminal through the thin axon, or in the opposite direction. The difference in receptive field sizes of cell body and of axon terminal may therefore indicate that these two structural subunits are electrically isolated.

Animals↗
PubMed1983

[Fundamental and clinical studies of T-1982 (cefbuperazone) in the field of obstetrics and gynecology].

Fundamental and clinical studies on T-1982 (cefbuperazone), a new cephamycin antibiotic, in the field of obstetrics and gynecology were carried out, and the following results were obtained. The levels of T-1982 transferred to uterine artery, elbow vein and uterus were determined after intravenous drip infusion of 1.0 g for 1 or 2 hours. No difference of concentration between uterine artery and elbow vein was observed from 45 minutes to 5 hours after the end of administration. The concentration of T-1982 in uterine artery ranged from 9.8 to 48 micrograms/ml after drug administration, and decreased slowly, but remained at about 10 micrograms/ml even 5 hours after the end of administration. Endometrium exhibited comparatively higher concentration of T-1982, but the difference of concentration was not observed among the other uterine tissues. T-1982 concentration ratios of various uterine tissues to elbow vein blood ranged from 172 to 10.2%, and mean ratio was 34.7%. Also, T-1982 concentration of more than 3 micrograms/g in each tissue was maintained for 2 hours after the end of administration. Clinical results on abscess of Bartholin's gland (1) and adnexitis (1) were good, although bacteria were not detected. No side effects caused by the drug were observed. These results indicate the usefulness of T-1982 in the treatment of infections in obstetrics and gynecology.

Adult↗
PubMed1982

[Fundamental and clinical studies of piperacillin in the field of obstetrics and gynecology].

We conducted experimental and clinical tests on piperacillin (PIPC), a drug with a broad antibacterial spectrum, and achieved the following results. PIPC exhibited the following rather high therapeutic blood concentrations: 30--60 micrograms/ml at 1 hour after intravenous injection of 1 g of PIPC, 10 micrograms/ml at 2 hours after intravenous injection of 2 g of PIPC, 7.2 micrograms/ml at 1 1/2 hours after the completion of 1 hour dripping infusion of 1 g of PIPC, and 5.6 micrograms/ml up to 4 hours after the completion of 2 hours dripping infusion of 2 g of PIPC. The yield to the various uterine tissues is presented in decreasing order: the highest yield to ovary was about 40--50% of the blood level, followed by the uterine cervical region, portio vaginalis, myometrium and oviduct, the lowest yield, about 25--30% of the blood level was found in endometrium. We conducted a clinical test on 7 patients with infections of the sexual organs and it proved to be excellent in 3, good in 3, and ineffective in 1 case so that the overall efficacy rate was 85.7%. The patient in whom PIPC proved ineffective suffered from an underlying disease, namely the end stage of cervical cancer. One patient suffered from a slight headache but whether this side effect was due to administration of the drug is not clear. Absolutely no abnormal findings during laboratory tests which could be attributed to drug administration were made. Based on the above results, PIPC was judged to be an extremely useful drug in the treatment of infections in the obstetric and gynecological fields.

Adult↗