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Biomedical subjects

T Shiga

Publications and source records attributed to T Shiga.

At least 199 records · Page 11Linked to original sources
PubMed1987

Erythrocyte deformation in shear flow: influences of internal viscosity, membrane stiffness, and hematocrit.

The effect of shear force (depending on shear rate and viscosity of extracellular medium) and hematocrit of RBC suspension on RBC deformation was studied quantitatively using a cone-plate rheoscope with various kinds of cells, ie, partially hemolyzed (PH) cells, density-fractionated intact cells, and diamide-treated cells. The deformation index (DI) of ellipsoidally deformed cells was shown to be a function of beta gamma eta ex(eta ex/eta in)alpha, where gamma eta ex is applied shear stress, eta ex and eta in are external and internal viscosities, respectively, and alpha and beta are adjustable parameters related to the membrane viscoelastic properties. The increase of suspension viscosity at higher hematocrits (Hts) generally enhanced the ellipsoidal deformation of cells, in the same manner as increasing the suspending medium viscosity of a diluted cell suspension. The suppressing effect on cell deformation appeared above a certain Ht. When intact cells were mixed with glutaraldehyde-treated, hardened cells, the ellipsoidal deformation of intact cells was disturbed. The suppression of deformation probably occurred through disturbance of laminar flow-lines around intact cells.

Blood Viscosity↗
PubMed1987

[The possibility of surgery for aged patients with gastric cancer].

The possibility of surgery for aged patients with gastric cancer has been studied. Of 484 cases who underwent a gastrectomy, patients 70 years of age or over amounted to 86 (20%). The postoperative mortality rate for these aged patients was 3% and the postoperative mortality rate with hospital deaths added from other causes than operative deaths was 7%. The postoperative mortality rate of aged patients who underwent total or proximal subtotal gastrectomy improved during the period between 1975-1983 compared with the period between 1967-1974. In the second period, there were no deaths among aged patients who underwent an R3-operation and/or a combine operation. This fact shows that operative procedures have become safer for aged patients.

Adult↗
PubMed1987

[Detection and prognosis of alimentary tract cancers--mass screening].

The limitation of detectability and curability in terms of current techniques (screening and details) were sought in otherwise healthy examinees. Not a few cancers were present in the alimentary tract, except for the stomach, in these otherwise healthy examinees who voluntarily underwent gastric cancer mass screening. The prognosis of alimentary tract cancers deteriorates in the descending, following order: colon cancer, stomach cancer, and esophageal cancer. The survival rate of primary liver cancer, cholecyst cancer, and pancreas cancer is extremely low. Unless new techniques are developed in these diagnoses, no improvement in the survival rate can be anticipated.

Digestive System Neoplasms↗
PubMed1986

A contribution of calmodulin to cellular deformability of calcium-loaded human erythrocytes.

The effect of intracellular calcium on the deformability of human erythrocytes was studied with a rheoscope, especially in relation to the dynamic structure of membrane cytoskeleton. The appropriate calcium-loading and calcium-depletion were performed to intact erythrocytes with A23187 in potassium buffer. The total calcium content was varied in the range of 0.25 to 3 times as much as normal content, without complete ATP depletion and shape change (the reduction of mean cell volume and the condensation of hemoglobin due to dehydration were avoided). Increasing the intracellular calcium content by about 1.5 times of normal, the deformability was distinctly decreased, while calcium depletion did not affect the deformability. Reduced deformability of the calcium-loaded erythrocytes was restored by the treatment with calmodulin inhibitors, W-7 or trifluoperazine. However, such an effect by calmodulin inhibitors was not detected on normal or calcium-depleted erythrocytes. In conclusion, the interaction between calcium-calmodulin complex and cytoskeletal proteins may affect the membrane stiffness which is regulated through the change of the cytoskeletal structure, and contributes to the deformability of erythrocytes.

Calcium↗
PubMed1986

Drift of an erythrocyte flow line due to the magnetic field.

Drifts of erythrocyte-flow lines due to inhomogeneous magnetic field in a laminar flow in a buffer solution are shown for the first time, and are interpreted as being due to the paramagnetism of hemoglobins included in the erythrocytes. The drifts were dependent on the hematocrit of the flowing erythrocyte suspension.

Buffers↗
PubMed1986

Increase of ATP level in human erythrocytes induced by S-adenosyl-L-methionine.

The effect of S-adenosyl-L-methionine (SAM) on the ATP level, the morphology and the deformability of human erythrocytes was investigated and compared with that of adenosine. (i) Upon incubation with SAM, the ATP level increased considerably in fresh cells (in both young and old cells in similar extent) and in stored (partially ATP-depleted) cells. But the incubation with adenosine increased ATP level to a lesser extent. (ii) The incubation of stored cells with SAM hardly affected (or rather decreased) the IMP level, while that with adenosine remarkably increased IMP (and ITP). (iii) The morphology and the deformability of stored erythrocytes were well conserved in spite of the treatment with SAM, as compared with the treatment with adenosine. The echinocytic transformation was induced in old cells to some extent by SAM, while did not in young cells.

Adenosine↗
PubMed1986

Opposite effect of albumin on the erythrocyte aggregation induced by immunoglobulin G and fibrinogen.

The effect of albumin on the immunoglobulin G (IgG)-induced and fibrinogen-induced aggregation of human erythrocytes was quantitatively examined by using a rheoscope combined with a television image analyzer and a computer. As albumin concentration in the medium was increased, the IgG-induced erythrocyte aggregation was inhibited, while the fibrinogen-induced erythrocyte aggregation was accelerated (albumin itself was not able to aggregate erythrocytes). These relations were empirically expressed by the equations, v = aG1.8/A and v = a'F1.5 (A + b'), respectively (v, the velocity of erythrocyte aggregation; A, G and F, the concentrations of albumin, IgG and fibrinogen, respectively; a, a' and b', constant). The IgG-induced erythrocyte aggregation was remarkably inhibited by the addition of poly(glutamic acid), but the fibrinogen-induced erythrocyte aggregation was not. A mechanism for the interaction of immunoglobulin G and fibrinogen with the surface of erythrocytes was proposed.

Adult↗
PubMed1986

Effect of immunoglobulin preparations on the aggregation of human erythrocytes.

The aggregation of human erythrocytes induced by four kinds of immunoglobulin preparations was examined by a low shear rheoscope. After removing anti-A+ and anti-B+ activities contaminated in all preparations by incubating with erythrocytes of different blood groups, the facilitating effect on the rouleau formation of erythrocytes was compared: (i) The effect of polyethyleneglycol-treated preparation was the same in A+-, B+-, AB+- and O+-erythrocytes. (ii) Sulfonation did not affect the velocity of rouleau formation. (iii) Some of pepsin-treated preparations showed the strongest facilitation for A+-, B+- and AB+-erythrocytes, but the facilitation was much weaker for O+-erythrocytes. The others showed the weak facilitation for all types of erythrocytes (especially O+-erythrocytes). (iv) Plasmin treatment markedly decreased the velocity of rouleau formation of AB+- and O+-erythrocytes, but was not of A+- and B+-erythrocytes.

Adult↗
PubMed1986

[Diagnosis of malignant thyroid tumor using high-frequency ultrasonography with piezoelectric transducer, soft X-rays and aspiration biopsy cytology].

Diagnosis of thyroid cancer has been based mainly on palpation and also soft X-rays because of its calcification. As the gland itself is very small and Aspiration Biopsy Cytology (ABC) has had a high level of diagnostic accuracy the clinical significance of ultrasonography did not become apparent for a long time. However, recently it has become possible to carry out detailed study and to detect suspect histological structures, following the remarkable progress which has been made in ultrasonography, using a high-frequency piezoelectric transducer. A single mechanical arch scanner, with a piezoelectric 7.5-MHz transducer (SAL-25A Toshiba Corp.) was employed for examination using the water bath method. The rates of correct diagnosis for each of the above methods among 847 nodular goiters including 184 malignant tumors which were microscopically examined were shown to be: ultrasonography 89.7%, soft X-rays 66.9% and ABC 86.4%. Ultrasonography was capable to revealing a few cases which could not be shown by ABC or soft X-rays. Using these three methods jointly, there was 1 false positive and no false negative cases. This study revealed that combined diagnosis with ultrasonography using a high-frequency piezoelectric transducer improved the accuracy of examination of malignant thyroid tumors.

Biopsy, Needle↗
PubMed1985

An HRP study of afferent connections of the supracommissural ventral telencephalon and the medial preoptic area in himé salmon (landlocked red salmon, Oncorhynchus nerka).

The supracommissural ventral telencephalon and the medial preoptic area have been shown to play important roles in the sexual behavior of himé salmon (landlocked red salmon, Oncorhynchus nerka). In the present study, the sites of neurons projecting to these regions were examined by means of the retrograde horseradish peroxidase (HRP) tracing method. The morphology of neurons in these sites of origin was also studied by means of the Golgi method. The nucleus preopticus periventricularis and the rostral part of nucleus preopticus (NPP-rNPO) received bilateral projections from the middle parts of the area ventralis telencephali pars ventralis (Vv) and the area ventralis telencephali pars dorsalis (Vd), NPP and lateral part of the preoptic area (LPOA), ipsilateral projections from the caudal part of Vv, nucleus anterioris periventricularis (NAPv), nucleus ventromedialis thalami (NVM) at the level of the posterior commissure, nucleus lateralis tuberis pars medialis (NLTm), nucleus anterior tuberis (NAT), nucleus saccus vasculosus (NSV), nucleus recessus posterioris (NRP) and midbrain tegmentum (TG), and a projection from the nucleus posterior tuberis (NPT), which is situated on the midline of the brain. The area ventralis telencephali pars supracommissuralis and neighboring caudal ventral telencephalon (Vs-cV) received ipsilateral projections from almost all parts of the Vv, the middle and caudal parts of Vd, almost all parts of the NNP, the NPO at the level between the habenula and the posterior commissure, and the rostral part of the nucleus dorsomedialis thalami (NDM). The Vs-cV also received a projection from NPT. These findings seem to give anatomical bases for understanding the neural mechanisms involved in sexual behavior as well as neuroendocrine functions.

Afferent Pathways↗
PubMed1985

Inhibition and acceleration of erythrocyte aggregation induced by small macromolecules.

The aggregation (especially the 'rouleau' formation) of human erythrocytes induced by polysaccharide and polyglutamic acid was quantitatively examined by using a low-shear rheoscope combined with a television image analyzer and a computer. (1) The morphological characteristics of rouleaux induced by these macromolecules are presented. (2) Polysaccharides with high molecular weights of 70 400 and 494 000 and poly(glutamic acids) with weights of 50 000 and 66 000 formed the rouleaux (then the three-dimensional aggregates). But polysaccharides with the low molecular weights of 10 300 and 42 500 and poly(glutamic acids) with weights of 8000 and 20 000 did not. The dependences of the velocity of rouleau formation on the macromolecule concentration and on the shear rate are shown. (3) The erythrocyte aggregation induced by high-molecular-weight polysaccharides was inhibited by low-molecular-weight polysaccharides and glucose, but was not affected by low-molecular-weight poly(glutamic acids). (4) The aggregation induced by high-molecular-weight poly(glutamic acids) was inhibited by poly(glutamic acid) with a molecular weight of 8000, but was accelerated by that of 20 000. The poly(glutamic acid)-induced aggregation was not affected by low-molecular-weight polysaccharides. (5) The stereochemical structure-dependent interaction (or the mode of bridging) of macromolecules with erythrocytes was stressed for the mechanism of erythrocyte aggregation.

Adult↗
PubMed1985

Cell age-dependent changes in deformability and calcium accumulation of human erythrocytes.

The deformability of human erythrocytes was measured in a rheoscope, as a function of intracellular calcium content (varied with ionophore (A23187) and CaCl2) without complete ATP depletion and echinocytic transformation. Loading calcium into intact erythrocytes (calcium content: 16.8 mumol/1 packed cells = 1.48 amol per cell), the cell volume and energy charge gradually decreased. Further, the membrane fluidity of the lipid portion decreased without crosslinking of membrane proteins. A distinct transition from deformable to undeformable cells was observed by the rheoscope technique: i.e., 50% transition occurred at 40-50 mumol calcium/1 packed cells (= 3.5-4.0 amol per cell) and more than 90% above 100 mumol/1 packed cells (= 6.5 amol per cell) at a shear stress of 140 dyn/cm2. The deformable cells maintained their deformability to ellipsoidal disks independent of the average calcium content. The underformable cells, separated as high-density cells by density gradient centrifugation after calcium-loading, showed lower glucose-6-phosphate dehydrogenase activity than low-density-deformable cells; thus, the calcium-loaded, undeformable cells were presumably in vivo aged cells. The younger cells, fractionated as low-density cells from intact erythrocytes, were more deformable than aged cells. Upon calcium-loading, the younger cells restored their cell volume and deformability, while the aged cells, containing originally more calcium and less ATP, decreased their volume and became undeformable. Therefore, calcium accumulation by ionophore-CaCl2 takes place in preference to aged cells of lower energy metabolism, and leads to cellular dehydration and loss of deformability, due to condensed hemoglobin and altered membrane organization.

Adenosine Triphosphate↗
PubMed1985

Electron spin relaxation of synthetic melanin and melanin-containing human tissues as studied by electron spin echo and electron spin resonance.

Electron spin lattice relaxation times (T1) and the phase memory times (Tm) were obtained for the synthetic melanin system from 3-hydroxytyrosine (dopa) by means of electron spin echo spectroscopy at 77 degrees K. Saturation behavior of the ESR spectra of melanins in melanin-containing tissue and of the synthetic melanin was also determined at the same temperature. The spin lattice relaxation time and the spectral diffusion time of the synthetic melanin are very long (4.3 ms and 101 microseconds, respectively, in the solid state), and the ESR signal saturates readily at low microwave powers. On the other hand, ESR spectra of natural melanins from the tissues chosen for this study, as well as those of synthetic melanins which contain Fe3+ of g = 4.3 and Mn2+ of g = 2, are relatively difficult to saturate compared with samples without such metal ions. These results show clearly that a large part of those two metal ions in sites responsible for the ESR spectral components with these particular g values are coordinated to melanin in melanin-containing tissue, and modify the magnetic relaxation behavior of the melanin. Accumulations of these metal ions in melanins are different from system to system, and they increase in the order: hair (black), retina and choroid (brown), malignant melanoma of eye and skin, and lentigo and nevus of skin.

Copper↗
PubMed1985

Efferents from the supracommissural ventral telencephalon in the hime salmon (landlocked red salmon, Oncorhynchus nerka): an anterograde degeneration study.

Efferents from the area ventralis telencephali pars supracommissuralis (Vs) of hime salmon (landlocked red salmon, Oncorhynchus nerka) were studied using anterograde degeneration methods. It was found that Vs sends intratelencephalic fibers bilaterally to the internal cell layer of the olfactory bulb and wide areas of telencephalon, while it sends extratelencephalic fibers bilaterally to habenulae, inferior lobes and midbrain tegmenti through medial and lateral forebrain bundles and lateral preoptic area. A possibility was pointed out that some of these extratelencephalic projections are involved in the pathway controlling the sexual behavior which are suggested from behavioral experiments.

Animals↗
PubMed1984

Rheological characteristics of desialylated erythrocytes in relation to fibrinogen-induced aggregation.

The effect of fibrinogen and sialic acid content of erythrocytes on the aggregation of erythrocytes was quantitatively examined by using a rheoscope combined with a television image analyzer and a computer. (1) The electrophoretic mobility of erythrocytes was proportional to the sialic acid content of erythrocytes (the surface potential of erythrocytes could be expressed by the sialic acid content). (2) The aggregation of erythrocytes was accelerated by increasing fibrinogen concentration in the medium (due to the increased bridging force among erythrocytes) or by decreasing the sialic acid content (due to the reduction of the electrostatic repulsive force among erythrocytes). (3) An empirical equation expressing the velocity of aggregate formation (v, in micron2/min) by the concentration of fibrinogen (F, in g/dl) and the sialic acid content (S, in mumol/ml red blood cells), log v = -0.065 F-1.2S + 2.2 F0.35, was deduced. (4) The contribution of the bridging force of fibrinogen to the erythrocyte aggregation was much greater than that of the electrostatic repulsive force produced by sialic acid on the surface of erythrocytes.

Adult↗
PubMed1984

Increased erythrocyte aggregation in diabetes mellitus and its relationship to glycosylated haemoglobin and retinopathy.

The velocity of erythrocyte aggregation in vitro was determined in 15 non-diabetic and 28 Type 1 (insulin-dependent) diabetic subjects, in autologous plasma under uniform shear flow using a rheoscope combined with a television image analyzer and a computer. In the diabetic subjects, the velocity of aggregation showed a significant correlation with the haemoglobin A1 level, and was significantly increased in the proliferative retinopathy group. An alteration of plasma protein composition in the diabetic subjects (increase of phi- and alpha 2-fractions) also influenced erythrocyte aggregation, being related to the haemoglobin A1 level. The percentage of the phi-fraction and a parameter, (alpha 2 + phi)/albumin, defined by plasma electrophoresis, showed a strong correlation with the velocity of aggregation.

Aged↗