PubMed Health⌕ Search

Biomedical subjects

K Tasaki

Publications and source records attributed to K Tasaki.

At least 55 records · Page 3Linked to original sources
PubMed1992

[CD3-negative natural killer cell leukemia with aggressive clinical course].

The authors report an autopsy case of CD3- large granular cell leukemia with an aggressive clinical course. A 15-year-old male was admitted to our hospital with complaint of high fever. Clinical examination revealed cervical lymphadenopathy and hepatosplenomegaly. His white blood cell count was 7,000/microliters with 45% large granular lymphocytes. A biopsy specimen of the cervical lymph node showed diffuse lymphoma, mixed small and large cells (DM). Surface marker analysis by immunohistochemical technique revealed that neoplastic cells expressed CD2, CD38, CD56 and HLA-DR but lacked CD3, CD4 and CD8. Southern blot analysis of immunoglobulin (Ig) and T cell receptor (TCR) genes showed germ line of Ig and TCR. These findings indicate that this case was a large granular cell leukemia with the natural killer cell phenotype. Despite anti-leukemic therapy, he died of hyperkalemia and acidosis. Autopsy showed a marked swelling of the liver (3,122 g) and spleen (2,434 g) with leukemic cell infiltration.

Adolescent↗
PubMed1991

[Development of image processing system for fundus video-angiography with non-stroboscopic illumination].

A new recording system for fluorescein video-angiography using a highly sensitive color charge coupled device (CCD) camera was developed. An image processing unit installed in a personal computer made it possible to process video signals from the camera and/or a video tape recorder. Functions of the unit are on-line and/or off-line operations on image data such as smoothing, digital subtraction, differentiation etc. Application of the unit improved the quality of images observed on a monitor screen. This system enabled observation of the ocular fundus with illumination of low intensity, which reduced physical and psychological suffering of patients. In addition continuous and whole sequences of fundus fluorographs were recorded, without using strong stroboscopic lights. Extraction of a clear image from ambiguous records at any moment was possible through off-line processing on the stored data. Furthermore quantification of the blood flow in any blood vessels was possible by subtracting two successive images. With this system, quantitative expression of a slight difference in the color of the fundus could be made through calculation of the ratios among R-, G-, and B-components of signals at any place. Finally, comparative study of images of the fundus with natural color could be made with those of fluorography. These features may provide further information on the physiology and pathology of the fundus.

Animals↗
PubMed1990

Bimodality in the nocturnal behavior of the giant land snail, Achatina fulica.

Entrainment and phase advance of the circadian locomotor rhythms in the giant land snail, Achatina fulica, were examined by a running wheel method. The mean activity patterns in three light-dark (LD) cycles (LD 14: 10, LD12: 12, LD 10: 14) were characterized by bimodal peaks, namely an initial major peak 1-2 hr after the onset of darkness and a later peak after nearly 6 hr. The activity rhythms were able to follow a 6 hr phase advance shift of the LD 14: 10 cycle with transients, accompanied by shortening or splitting of the activity time. When splitting occurred, the initial component showed phase advancement in the dark and phased to lights-off whereas the later one phased to lights-on, with post-dawn activity being suppressed by light. These results suggest the presence of multioscillator circadian organization which shows monophasic or biphasic entrainment under the LD cycles.

Animals↗
PubMed1990

[Fundus video fluorescein angiography with low steady light].

To decrease both the intensity of the exciting light and the amount of sodium fluorescein, we attached a compact image intensifier incorporating a microchannel plate with a fundus photoscope and tried to record video-fluorescein angiography with low steady light. We preliminarily examined the relationships of exciting and emitted light intensity with various concentrations of sodium fluorescein. The strongest fluorescence was obtained with a concentration of 0.01 mg/ml solution of sodium fluorescein. When the compact image intensifier was attached to the equipment, the exciting light intensity could be decreased to 1/300 with an exciting filter of lambda max of 486 nm. When sodium fluorescein of 0.01 mg/ml solution was injected directly into the heart of Rana catesbeiana, complete video-fluorescein angiography with sufficient brightness and resolution was possible. With the same machine, we recorded video-fluorescein angiography in a normal human subject with injection of 5 ml of 10% sodium fluorescein. The ordinary observing light of the machine was strong enough for video-recording. This exciting light intensity caused no trouble and elicited no complaint from the examinee. These results showed that the use of a compact image intensifier incorporated microchannel plate with a fundus photoscope made it possible to record video-fluorescein angiography and to decrease exciting light intensity and the amount of fluorescein dye. This means that light damage to photoreceptors by exciting light and problems induced by allergic reaction with fluorescein dye might be decreased. These aspects might be very important to obtain information about both retinal circulation and disruption of the blood-retinal barrier and also to perform safe fluorescein angiography examination.

Animals↗
PubMed1990

[A case of subdural effusion secondary to dural metastasis of prostatic cancer: case report].

The authors reported a case of subdural effusion secondary to dural metastasis of prostatic cancer. A 61-year-old man was referred for headache, vomiting and gait disturbance. He had undergone hormonal therapy for prostatic cancer. He showed a mild left hemiparesis and anemia without bleeding. CT-scan disclosed a multilobular crescent shaped low density area in the right hemisphere. Under the diagnosis of chronic subdural hematoma, burr hole irrigation therapy was performed. Xanthochromic fluid was evacuated from the subdural space, in which no tumor cells were shown to exist. CT-scan on the 21st day disclosed a low density area, which was diagnosed as recurrent chronic subdural effusion. Therefore, craniotomy was performed to evacuate the subdural fluid and to explore the dura mater. Removal of the red hemorrhagic tumor at the dura mater and the fluid was performed. The patient died of heart failure in the 16th month despite complete recovery after the second operation. Histopathological examination of the tumor revealed adenocarcinoma at the outer part of the dura mater and the adjacent skull bone, where capillaries were embolized with tumor cells. However, no tumor cells were found in the subdural fluid. The authors could find in the literature 30 cases of subdural hematoma or effusion secondary to dural metastasis of carcinoma. The pathogenesis of the subdural hematoma in this case might be due to circulatory disturbance at the dura mater brought about by the invasion of the tumor or tumor cells emboli in the capillaries.

Adenocarcinoma↗
PubMed1989

Dorsal dislocation of the D.I.P. joint with fracture of the volar base of the distal phalanx.

Between 1978 and 1985, we treated 12 cases of dorsally displaced fracture-dislocation of the I.P. joint of the thumb or of the D.I.P. joint of the finger, with a volar bony fragment. All were treated surgically, active exercise being started three to five weeks later. At the last follow-up, averaging 6.4 years (range 4.3-10 years) after operation, none of the joints was painful but the range of motion was somewhat limited.

Adolescent↗
PubMed1989

Human rods are acting in the light and cones are inhibited in the dark.

The light- and color detection thresholds were measured at three different states of retinal adaptation, i.e., light- and dark adapted states and the intermediate state which was obtained just before the Kohlrausch kink in the course of dark adaptation. At 20 degrees from fixation in the nasal visual field, the wavelength function was examined. The color threshold was higher in the dark adapted state than in the state just before the kink, and the amount of increase was more prominent when the wavelength of the stimulus light was closer to the peak wavelength of rod sensitivity. It was concluded that the rod activation interferes with the cone sensitivity, and that the interference effect becomes stronger as a function of the responsiveness of rods. On the other hand, the spectral sensitivity curve determined in the light adapted state could be divided into two parts. The curve for shorter wavelength than 500 nm was well fitted by the scotopic luminosity curve, suggesting that the light threshold for shorter wavelength is determined by the rod system even in the light adapted state.

Adaptation, Physiological↗
PubMed1988

Influences of 7-alkyl substitution on the reversible binding of the proximate carcinogen trans-3,4-dihydroxy-3,4-dihydrobenz[a]anthracene to DNA.

The effects of 7-alkyl substitution on the reversible intercalation of the proximate carcinogen trans-3,4-dihydroxy-3,4-dihydrobenz[a]anthracene (BAD) to calf thymus DNA have been examined using time-resolved fluorescence spectroscopy. The results indicate that in 10(-3) M sodium cacodylate the binding constant of BAD is 1.8 x 10(3) M-1. 7-Ethyl substitution decreases the binding constant 1.6 times, while 7-methyl substitution increases the binding constant 1.7 times. UV Photoelectron data and results from ab initio molecular orbital calculations suggest that an increase in polarizability contributes to the increased binding accompanying methyl substitution. The decreased binding accompanying ethyl substitution arises from steric inhibition. The physical binding data correlates with the decrease in carcinogenic activity which occurs with 7-ethyl substitution of benz[a]anthracene metabolites.

Alkylation↗
PubMed1988

UV photoelectron spectroscopy and ab initio characterization of valence orbital structures and conformations of neutral phosphate esters.

The HeI UV photoelectron spectrum of trimethyl phosphate (TMP) has been measured and interpreted with the aid of SCF molecular orbital calculations carried out with STO-3G, STO-3G* and 4-31G basis functions. The photoelectron spectrum of TMP is more accurately reproduced by results from 4-31G calculations than by results from STO-3G or STO-3G* calculations. However, all three basis sets yield results which predict the same assignment of the photoelectron spectrum. Results at the 4-31G level indicate that whether calculations are based on crystallographic bond angles and bond lengths or on STO-3G optimized geometries has little effect on the energetic ordering of the upper occupied orbitals. The energetic ordering of orbitals is also found to be only weakly dependent upon the torsional angle phi, describing rotation of ester groups about P-O bonds and upon the torsional angle psi, describing rotation of methyl groups about C-O bonds. For trimethyl phosphate, with C3 symmetry, the vertical ionization potentials of the upper occupied orbitals are 10.81 eV (8e), 11.4 eV (9a), 11.93 eV (7e), 12.6-12.9 eV (8a and 6e), 14.4 eV (7a) and 15.0-16.0 eV (5e and 6a). Calculations at the 4-31G level indicate that many of the highest occupied orbitals in neutral dimethyl phosphate and methyl phosphate have energies and electron distributions similar to orbitals in TMP. For TMP, a search for optimized values of phi and psi has been carried out at the STO-3G*level. In agreement with previous NMR studies and with classical potential calculations, the STO-3G* results indicate that both the gauche (phi = 53.1 degrees) and anticlinal (phi = 141.9 degrees) conformations are thermally accessible. Also in agreement with the classical potential calculations, the STO-3G* results predict that in the all gauche conformation energy is minimized when the methyl groups assume a staggered geometry (psi = 60 degrees to 80 degrees) and that an energy maximum occurs for an eclipsed geometry (phi = 0 degrees to 20 degrees). A study of the dependence of optimized values of O-P-O ester bond angles on the torsional angles, phi, was carried out at the STO-3G, STO-3G* and 4-31G levels. The results demonstrate that for C3 symmetry, the coupling of O-P-O angles to phi is influence by repulsive steric interactions.

Chemical Phenomena↗
PubMed1988

Rods also participate in human color vision.

In the retinal periphery, rod and cone thresholds to the same green light were measured. After the rod-cone break in the course of dark adaptation, cone sensitivity decreases gradually as rod sensitivity progressively increases. Cone sensitivity, however, increases when rod sensitivity is decreased by blue light. The emergence of the facilitatory effect of rod activation requires at least a few hundred msec after rod stimulation. It is concluded that rod activation plays a major role in sensitivity regulation of the cone system, i.e., in human color vision.

Color Perception↗
PubMed1988

Cone activation delaying recovery time of rod sensitivity after flash exposure.

The recovery time of rods to the fully dark adapted state after flash exposure was psychophysically and electrophysiologically measured. The recovery time increased abruptly once cones were activated. This abrupt increment was not found for the receptor component (P III) of the frog electroretinogram. It was suggested that the cone activation results in inhibitory influence upon the recovery process of the rod sensitivity.

Amplifiers, Electronic↗
PubMed1988

The activation of cones in scotopic and rods in photopic vision.

Over the whole course of dark adaptation, light- and color detection thresholds were measured. At 6 degrees in the nasal visual field, the effect of wavelength was examined. After the rod-cone break (Kohlrausch kink), the color threshold began to rise while the light threshold was progressively decreasing. The rise of the color threshold was more remarkable as the test wavelength was more close to the peak wavelength for rod sensitivity. With green test light, the sensitivity difference of retinal position was investigated. The rise of the color threshold was more prominent at the retinal position where rods were more densely packed. Finally, the Stiles-Crawford effect was examined with a green test light at 12 degrees in the nasal visual field. This effect appeared for the color threshold over the whole course of dark adaptation but not for the light threshold even before the rod-cone break. It was concluded that the rod activation interferes with cone sensitivity and the interference effect becomes stronger as rods become progressively more dark adapted, and that the rod system is also acting even before the rod-cone break.

Color Perception Tests↗
PubMed1983

Inhibitory retinal efferents from dopaminergic cells in the optic lobe of the octopus.

The effect of dopamine (DA) and its related compounds upon retinal activities of the octopus was compared with that of repetitive stimulation of the optic nerve, while recording ERGs and light-elicited spike discharges. Retinal perfusion with DA or its agonist, apomorphine, markedly enhanced ERGs. The effect appeared at about 10(-8) M and saturated at 10(-6) M. Norepinephrine and L-DOPA had very little effect. Intraretinal injections of DA at different depths revealed that the site of DA action was in the plexiform layer. ERGs were also enhanced by optic nerve stimulation, which inhibited spike discharges. This inhibitory effect was particularly evident when discharges were weak. Consequently the inhibitory effect of optic nerve stimulation was exerted predominantly to the peripheral areas of the receptive field of a nerve bundle, thus resulting in a considerable reduction in the size of the receptive field. These observations suggest that the spatial resolution of this animal may be improved by the efferent activity.

Animals↗
PubMed1983

Improvement of oral bioavailability of prednisolone by beta-cyclodextrin complexation in humans.

Inclusion complex of prednisolone with beta-cyclodextrin (beta-CyD) in 1:2 molar ratio was prepared and its dissolution, membrane permeation and oral absorption behaviors were examined. The rates of dissolution and permeation through a cellophane membrane in water were significantly increased by beta-CyD complexation. A crossover bioavailability study was performed using human subjects with lower doses of prednisolone tablets, where the plasma levels of the drug were determined by radioimmunoassay. The enhanced bioavailability of prednisolone by beta-CyD complexation suggested the possibility of smaller doses and fewer side effects in prednisolone therapy.

Adult↗
PubMed1982

A circadian locomotor rhythm in the giant land snail, Achatina fulica.

A circadian rhythm in the locomotor behavior of the giant land snail, Achatina fulica, was studied by a running wheel method in a 24 hr light-dark cycle (LD 12:12) and also in constant dim light. The locomotor rhythm could be entrained to the LD cycle, and the entrained rhythm was characterized by the bulk of activity in the dark period, the major activity appeared in the first half of the dark period. In constant dim light the locomotor rhythm free-ran with a period of about 24 hr.

Animals↗