Search PubMed⌕ Search

Biomedical subjects

T Hamanaka

Publications and source records attributed to T Hamanaka.

At least 73 records · Page 4Linked to original sources
PubMed1987

Morphological and functional effects of Na2EDTA on the outflow routes for aqueous humor in monkeys.

The chelating agent Na2EDTA was perfused through the anterior chambers of monkeys eyes in an attempt to find a concentration that would cause a rise in outflow facility without harming the cornea or anterior uvea. Na2EDTA (0.5 mM) proved effective in increasing the facility within 60 min. There were marked effects on the tissue at the iridocorneal chamber angle with loss of cell processes from the trabecular cells, ballooning of the juxtacanalicular region and the inner wall of Schlemm's canal into the canal and ruptures of the inner wall of Schlemm's canal. After 60 min of perfusion there were mild vascular changes in the ciliary muscle and the iris and more pronounced stasis and leukocyte extravasation at the base of the ciliary processes and in the pars plana region. The corneal endothelium tended to swell but only after prolonged perfusion. After interruption of the perfusion there was rapid reduction in outflow facility, that seemed to be due to occlusion of the ruptures in Schlemm's canal by thrombocytes.

Animals↗
PubMed1987

A novel antitumor cyclic hexapeptide (RA-700) obtained from Rubiae radix.

The antitumor activity of a newly obtained cyclic hexapeptide, RA-700, from Rubiae Radix was studied using several murine experimental tumor systems. In P388 leukemia (inoculated intraperitoneally (i.p.), administered i.p.: i.p.-i.p.) the maximal increase in life span (ILSmax) resulting from an administration of RA-700 (4 mg/kg/d for 9 d) was 134% and the therapeutic ratio was 400. These values indicate that RA-700 has higher anti-tumor activity and broader active dose range than that of mitomycin C (MMC, 1 mg/kg/d for 9 d) which was used as a positive control. In the study of the treatment schedules on P388, RA-700 had the highest activity by consecutive injections. In MOPC-104E mouse plasmacytoma system (i.p.-i.p.), ILSmax of RA-700 (2.5 mg/kg/d for 9 d) was 84%. In a solid tumor, colon adenocarcinoma 38 (subcutaneously (s.c.)-intravenously (i.v.], RA-700 (4 mg/kg/d for 11 d) showed complete cures (8/8) compared to MMC (0.5 mg/kg/d for 11 d) which showed one cure out of 8 animals. In the study of a model of the inhibition of lymph node metastasis using P388 leukemia, the administration of RA-700 at more than 2.5 mg/kg/d i.v. for 7 d resulted in the survival of all animals (5/5) for over 60 d. In the amputation system of the same metastasis model at a dose of 4 mg/kg/d i.v. for 7 d, 3 animals out of 5 survived over 60 d.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Wavelength modulation by molecular environment in visual pigments.

The absorption and regenerability characteristics are compared for rhodopsin contained in rod outer segment membranes and purified in a series of alkyl sucrose esters. It is found that membrane-bound rhodopsin has maximum absorbance from 504 to 500 nm between 1.5 and 40 degrees C. After purification, rhodopsin absorbance can be blue-shifted by up to 6 nm, depending on the detergent species used. Only the longest chain sucrose esters give purified rhodopsin with maximum absorbance comparable to that of the native pigment. In the same manner, detergent-purified rhodopsin will be easily regenerated as long as its native spectral characteristics are maintained. Sucrose esters thus prove to be mild enough to maintain rhodopsin functionality with respect to these two properties and could probably be used successfully to maintain other membrane proteins' integrity.

Animals↗
PubMed1986

Kinetic study of transfer of 11-cis-retinal between rod outer segment membranes using regeneration of rhodopsin.

The present study demonstrates some important facts on the regeneration of rhodopsin in rod outer segment membranes. 11-cis-Retinal added to a rod outer segment membrane suspension did not react directly with opsin but was rapidly solubilized into membranes and then recombined with opsin in the membrane. It was also revealed that the regeneration of rhodopsin was perturbed by the formation of retinylidene Schiff base with phosphatidylethanolamine in rod outer segment membranes, which decreased with increasing temperature. The activation energy of rhodopsin regeneration in rod outer segment membranes was 18.7 kcal/mol, being smaller than the value of 22 kcal/mol in 1% digitonin solution. 11-cis-Retinal could be found to transfer relatively fast (tau-1/k(1) R 10(3) s) between rod outer segment membranes by using the regeneration of rhodopsin. It was demonstrated that the kinetic measurement for the transport of membrane-soluble molecules such as retinal between membranes could be perform ed with ease and precisely by the method described in this paper.

Journal Article↗
PubMed1986

Time-resolved x-ray study of effect of sinusoidal length change on tetanized frog muscle.

Time-resolved x-ray diffraction studies were done on frog skeletal muscles with synchrotron radiation by applying sinusoidal length changes of frequency 10 Hz and amplitude approximately 1% to isometrically contracting muscles at approximately 17 degrees C. Distinct periodic intensity changes were observed in the 14.3-nm myosin meridional reflection and the equatorial 1,0 and 1,1 reflections. Response of the 14.3-nm reflection to the sinusoidal length change was nonlinear, as evidenced by a large second harmonic in its oscillatory intensity change, whereas the response of the equatorial 1,1 reflection was closely linear, as evidenced by almost sinusoidal intensity change. Intensity change of the 1,0 reflection was nearly antiphase to that of the 1,1 reflection. Integral widths of the 14.3-nm meridional reflection measured along the meridian and of the equatorial 1,1 reflection remained almost constant during tension development, while that of the 1,0 reflection tended to decrease. The widths of the 14.3-nm meridional reflection perpendicular to the meridian and of the equatorial 1,0 reflection appeared to undergo oscillatory changes in response to the sinusoidal length changes.

Animals↗
PubMed1986

[A case of jargon aphasia--a clinicopathological study].

An autopsied case of jargon aphasia by multiple cerebral infarction was reported. A 75-year-old right-handed woman developed a Wernicke's aphasia with the first attack of cerebral infarction in the left hemisphere in July 1980. With the second attack of infarction in October 1980, she developed a neologistic and semantic jargon aphasia, in which her speech consisted of neologisms, literal paraphasias, empty phrases and so-called "misused words". CT-findings showed two low density areas; one was in the left hemisphere and the other in the posterior region of the right hemisphere. Her jargon aphasia persisted for about one year. In November 1981, she suffered a third attack of infarction and developed an apallic syndrome. Neuropathological examination confirmed that the lesion of the right hemisphere played a decisive role in the outbreak of jargon aphasia in this case.

Aged↗
PubMed1986

Structural changes during contraction in vertebrate skeletal muscle as studied by time-resolved X-ray diffraction technique.

To obtain information about the structural changes in vertebrate skeletal muscle during contraction, time-resolved X-ray diffraction studies were performed on the intensity changes of the 59 A and 51 A actin layer lines from bullfrog sartorius muscle during the isometric force development, and the intensity changes of the 143 A and 215 A myosin meridional reflections and of the 1.0 and 1.1 equatorial reflections when isometrically contracting muscle was subjected to sinusoidal length changes (1%, 5-10 Hz) with the following results. The integrated intensities of the 59 A and 51 A actin layer lines increased during the force development by 30-50% for the 59 A reflection, and by about 70% for the 51 A reflection compared to their respective resting values. These intensity changes were greater than those taking place during the transition from rest to rigor state, and observed to precede the intensity changes of the 429 A myosin off-meridional reflection and of equatorial reflections. When sinusoidal length changes were applied to the muscle generating steady isometric force, the resulting periodic intensity changes in the 1.0 and 1.1 equatorial reflections were in phase and in antiphase with the length changes respectively. On the other hand, the 143 A myosin reflection exhibited a characteristic periodic changes; its intensity reached a maximum at each boundary between the stretch and release phases of the length changes. These results are discussed in connection with the behaviour of the cross-bridges during contraction.

Actin Cytoskeleton↗
PubMed1985

Volatile anesthetics cause conformational changes of bacteriorhodopsin in purple membrane.

We examined the effects of volatile anesthetics on the structure of the bacteriorhodopsin in the purple membrane by measurements of the absorption spectrum and the visible circular dichroism (CD) spectrum and assay of the retinal composition. As the concentrations of halothane, enflurane and methoxyflurane were increased, the absorption at 560 nm decreased but that at 480 nm increased with an isosbestic point around 510 nm. These anesthetic-induced spectroscopic changes were reversible. The CD spectrum showed the biphasic pattern with a positive and a negative band. As the concentration of halothane was increased from 4 mM to 8mM, the negative band reversibly diminished more drastically than the positive band, and at 8 mM of halothane the positive band shifted to around 480 nm. These results show that halothane disturbed the exciton coupling among bacteriorhodopsin molecules. The retinal isomer composition was analyzed using high performance liquid chromatography. The ratio of 13-cis- to all-trans-retinal was 47:53, 34:66 and 19:81 at control, 7.4 mM and 14.9 mM enflurane, respectively. After elimination of enflurane, the ratio returned to the control value. These findings indicate that volatile anesthetic directly affect a bacteriorhodopsin in the purple membrane and induce conformational changes in it.

Anesthetics↗
PubMed1985

Time-resolved x-ray diffraction studies on the intensity changes of the 5.9 and 5.1 nm actin layer lines from frog skeletal muscle during an isometric tetanus using synchrotron radiation.

Time-resolved x-ray diffraction studies have been made on the 5.9- and 5.1-nm actin layer lines from frog skeletal muscles during an isometric tetanus at 6 degrees C, using synchrotron radiation. The integrated intensities of these actin layer lines were found to increase during a tetanus by 30-50% for the 5.9-nm reflection and approximately 70% for the 5.1-nm reflection of the resting values. The intensity increase of both reflections was greater than that taking place in the transition from rest to rigor state. The intensity change of the 5.9-nm reflection preceded those of the myosin 42.9-nm off-meridional reflection and of the equatorial reflections, as well as the isometric tension development. The intensity profile of the 5.9-nm layer line during contraction was found to be different from that observed in the rigor state.

Actins↗
PubMed1985

Effect of phospholipids and detergents on transitions and equilibrium between the bleaching intermediates of rhodopsin.

The thermal stability of bleaching intermediates and the metarhodopsins I in equilibrium II equilibrium have been examined for purified rhodopsin in cholic acid and a series of alkyl sucrose esters. The results are compared with rhodopsin contained in its natural phospholipid environment. It is found that detergents modify the transition temperatures of the photointermediates in a complex manner. The equilibrium between metarhodopsins I and II is also strongly dependent on the detergent species. It is shifted according to the micellar rigidity. This effect is reversible and allows direct observation of a back reaction from metarhodopsin II to I.

Animals↗
PubMed1985

Kinetic assay of gamma-glutamyltransferase with use of bilirubin oxidase as a coupled enzyme.

We studied the kinetic measurement of gamma-glutamyltransferase (EC.2.3.2.2), coupling the reaction with that catalyzed by bilirubin oxidase (EC 1.3.3.5), which oxidizes and combines a phenylenediamine derivative with an aniline derivative to produce a green pigment. We measured the formation of the pigment kinetically (at lambda max745 nm, epsilon = 75 000 L mol-1 cm-1), with L-gamma-glutamyl-N-hydroxyethylaminoanilide as substrate and N-ethyl-N-hydroxy-3-sulfopropyl)-m-toluidine as a the coupling derivative. The within-run CV for measuring this reaction in samples of normal sera was 2.4%. A calibration plot of the change in absorbance per minute vs enzyme activity concentration showed good proportionality in the range of 0-1300 U/L. The results of this assay correlated well (r = 0.995) with those of the Boehringer method, in which L-gamma-glutamyl-3-carboxy-4-nitroanilide is the substrate. This new, highly sensitive procedure may be adapted to other assays involving phenylenediamine derivates as synthetic substrates.

Glycylglycine↗
PubMed1984

Kinetics of human pancreatic and salivary alpha-amylases with carboxymethylamyloses as substrates.

The enzymatic measurement of alpha-amylase in human serum with chemically modified amylose as substrate was studied. Several substitutions of carboxymethylamylose were prepared from amylose, suitable amounts of monochloroacetic acid, and sodium hydroxide. The relationship between the degree of substitution of the carboxymethylamylose and the kinetic parameters of human pancreatic, salivary and porcine pancreatic alpha-amylases was determined. The action of alpha-amylases on such modified amyloses in the presence of glucoamylase was measured by a specific enzymatic assay having glucose as the product. The kinetic parameters of human pancreatic alpha-amylase were similar to those of human salivary alpha-amylase. It was possible to determine suitable sensitivities for the alpha-amylase assay using this substrate. These results suggested a subsite model.

Amylose↗
PubMed1984

Application of fibrin glue to burns. Its haemostatic and skin transplant fixation effects in the excised wound.

Fibrin glue was clinically applied to the excised wound in 10 extensively burned patients, and its haemostatic and fixation effects on the isolated skin transplants were investigated. The following advantages resulted from the application of the fibrin glue: The haemostatic procedures and fixation of the isolated skin transplants were simplified. The quick and efficient haemostatic procedures considerably reduced the blood transfusion volume during and after the surgical procedures, by achieving a notable reduction in blood loss. Based on the above merits, the operation time was reduced and, eventually, the surgical stress might be alleviated. Satisfactory haemostatic effects were attained particularly in the limbs without supplemental haemostatic aids, leading us to conclude that the application of fibrin glue to the excised wound in burns is very useful.

Adolescent↗