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Biomedical subjects

K Iwata

Publications and source records attributed to K Iwata.

At least 361 records · Page 20Linked to original sources
PubMed1986

Immunological properties of monoclonal antibodies to human and rat prolyl 4-hydroxylase.

Monoclonal antibodies to human (8 clones) and rat (12 clones) prolyl 4-hydroxylase [EC 1.14.11.2] were prepared and characterized as regards subclass, subunit specificity, inhibition and crossreactivity. Among the antibodies to the human enzyme, four clones showed the IgG1 subclass, two IgA, one IgG2b, and one IgM. Four clones reacted with the alpha subunit of the enzyme, while the others reacted with the beta subunit. The enzymatic activity was inhibited by four clones. Five clones crossreacted with the rat enzyme. One clone inhibited the rat enzyme. Among the antibodies to the rat enzyme, seven clones showed the IgG1 subclass, four IgG2a and one IgG2b. Seven clones reacted with the alpha subunit, and four with the beta subunit. One reacted with neither subunit. The enzymatic activity was inhibited by seven clones. Seven clones crossreacted with the human enzyme. Three clones inhibited the human enzyme.

Animals↗
PubMed1986

Active substance of Histoplasma capsulatum that inhibits blastogenic response of lymphocytes.

A substance inhibiting blast transformation of murine spleen lymphocytes stimulated with various mitogens, such as LPS, PHA, and PWM, was obtained from yeast-form cells of Histoplasma capsulatum. This active substance was partially purified from the cell-free extract by DEAE-Sepharose CL-6B column chromatography. As a result of this partial purification, the inhibitory activity was 1.26 micrograms/ml in terms of ID50. Materials from H. capsulatum also inhibited blast transformation of murine spleen lymphocytes stimulated with the antigen PPD as well as mitogens LPS, PHA, and PWM. However, the con A-induced proliferative response was only slightly affected. A similar result was observed for the MLR. These inhibitory activities were abolished by heating at 70 C for 30 min. These results suggest that the heat-labile active substance produced by H. capsulatum might directly affect the lymphocytes, leading to inhibition of their blast transformation.

Animals↗
PubMed1986

Increased sensitivity to phagocytosis of Staphylococcus E-46 after growth in artificial media.

Staphylococcus E-46, which exhibits high virulence in mice mainly due to resistance to phagocytosis, gradually lost its virulence during growth in artificial media [Heart-Infusion (HI) slants]. Staphylococcus E-46 is coagulase-negative and DNase-positive, and has a capsule-like structure, and the less-virulent derivative (LVD) strain seemed not to be changed in this respect. The bacteria which had been exposed to HI slants for more than one year (= LVD strain) became more sensitive to phagocytosis by mouse peritoneal macrophages than bacteria which were kept in a lyophilized state. The chemiluminescent response of macrophages to the LVD strain was remarkably higher than that to the original Staphylococcus E-46. When the LVD or the sera for opsonization were heated, the chemiluminescence to the LVD was as low as that to the original Staphylococcus E-46. Polyacrylamide gel electrophoresis of sonication-released membrane protein from the LVD strain showed a unique band with a molecular weight of about 40,000. The factor concerned with the virulence of Staphylococcus E-46 is discussed based on these results.

Animals↗
PubMed1986

Regional cerebral blood flow changes in aging.

Regional cerebral blood flow (rCBF) changes during the aging process were studied, using 131Xe inhalation and emission computed tomography in 38 healthy, non-hypertensive, alert and active volunteers (23-65 years of age). The rCBF showed a slight but statistically non-significant negative correlation. As regards cerebrovascular resistance (CVR), significant correlation to aging was observed, and there was an increase of CVR after the forties compared with the twenties. This appeared to be due to the positive correlation of blood pressure to aging.

Adult↗
PubMed1986

Magnetic resonance imaging in the diagnosis of the posterior fossa and the spinal column.

Magnetic resonance imaging (MRI) is more advantageous for evaluation of the posterior fossa and spinal column because it can delineate the brain stem and the spinal cord in multidimensional planes without intrathecal contrast and ionizing radiation. In 18 cases with posterior fossa tumors, MRI was definitely superior to computed tomography (CT) in 11 cases (61%) and was equally diagnostic in 5 cases (28%). In investigations in 58 cases of spinal disorders examined by MRI, MRI was useful in diagnosing intramedullary cord tumors, syringomyelias, herniated discs, and infections, but CT was still more diagnostic in spondylosis, ossification of the posterior longitudinal ligament, and canal stenosis.

Brain Neoplasms↗
PubMed1986

[Postoperative spinal cord herniation diagnosed by metrizamide CT: a case report].

A 55-year-old man came to our hospital, complaining of progressive deterioration of gait disturbance 13 years following C4-7 laminectomy. Neurological examination showed marked spastic gait, hyperreflexia in the lower limbs, ankle clonus, hypesthesia below C5, and loss of position and vibratory sensations in great toes. Preoperative metrizamide CT clearly demonstrated pseudomeningocele and cervical cord herniation through the dural defect at C6-7 and narrow canal at C3. Moreover, sagittal and coronal reconstructions reveal a clear-cut posterior displacement of the cervical cord with posterior protrusion of the cord through the possible dural defect and the obvious extent of pseudomeningocele. At the operation, herniation of the posterior aspect of the cord through the dural defect at C6-7 was encountered as well as pseudomeningocele from the leakage at the C5 level. The cause of spinal cord herniation is classified into i) congenital, ii) traumatic, iii) iatrogenic. An iatrogenic spinal cord herniation is rare and its preoperative diagnosis used to be hard. Discussion was made on the points of preoperative diagnosis of a postoperative spinal cord herniation by metrizamide CT.

Hernia↗
PubMed1985

Movements of the jaw and orofacial regions evoked by stimulation of two different cortical areas in cats.

Functional properties of the jaw and orofacial motor areas in the cerebral cortex of the lightly anesthetized cat were studied on the basis of the motor effects produced by intracortical microstimulation (ICMS). Jaw and orofacial motor effects were evoked by ICMS (less than 30 microA) delivered to the anterior parts of the coronal and lateral sigmoid gyri (C, coronal area), and the anterior part of the orbital gyrus (O, orbital area). Different patterns of movements in the jaw and orofacial regions were evoked from these two areas. In C one or, at most, two types of simple movement were produced by ICMS to one location, while in O more coordinated movements than those in C were produced. Cytoarchitectonically the jaw and orofacial motor areas were restricted to areas 3a, 4 gamma, and 6a beta in C, and to area 43 in O.

Animals↗
PubMed1985

Distribution and response characteristics of masseteric nerve-driven neurons in two separate cortical projection areas of cats.

Cortical projection areas and distribution and response characteristics of masseteric nerve-driven neurons (MDN) were studied by recording surface-evoked potentials and single neuronal activities elicited by stimulation of the contralateral masseteric nerve in cats. Neuronal activities of MDNs could be recorded in two separate cortical areas. One was located in laminae II-III of area 3b of the posterior part of the coronal gyrus (P), and the other in laminae IV-V of areas 3a and 6a beta of the anterior parts of the coronal and lateral sigmoid gyri (A). The majority of MDNs were driven by low-threshold muscle afferents (Group I and II). Peak latencies of MDNs in P were shorter than those in A. Intracortical microstimulation (less than 30 microA) in A produced oro-facial movements while stimulation in P did not produce any motor effects.

Animals↗
PubMed1985

Growth factor- and dexamethasone-induced proteins in Swiss 3T3 cells. Relationship to DNA synthesis.

Dexamethasone synergistically enhances the stimulation of DNA synthesis in quiescent Swiss 3T3 cells by cartilage-derived growth factor (CDGF) while having no consistent effect when added with platelet-derived growth factor (PDGF) or serum. We examined the hypothesis that this difference might be attributed to selective synthesis of individual proteins early in the G1 phase of the cell cycle. Swiss 3T3 cells were treated with CDGF, PDGF, and fetal bovine serum for 3 h, with or without dexamethasone, and [35S]methionine-labeled proteins were separated by two-dimensional electrophoresis on giant gels. Over 3300 proteins could be distinguished; 34 of these were consistently induced more than 3-fold by all three factors, while an additional 30 inductions were variably present. Dexamethasone by itself induced 8 other proteins, and at least 9 growth factor inductions were synergistically enhanced by addition of the hormone. To identify proteins intimately associated with growth control, we looked for inductions that reflected the dexamethasone synergy with CDGF on DNA synthesis and lack of such an effect with PDGF. The induction of only one group of proteins, the Band 1 isoforms (44-46 kDa, pI 6.1-5.9) displayed such selective synergy. The majority of the other growth factor inductions were inhibited by dexamethasone, even in the context of maximal DNA synthesis, implying that their increased synthesis is not required for growth. When 3T3 cells were treated with increasing doses of CDGF with and without dexamethasone, autoradiographic densities of induced proteins varied in a dose-responsive fashion. However, only levels of the Band 1 proteins bore a constant linear relationship to DNA synthesis, suggesting that they play an important role in early control of the cell cycle.

Animals↗
PubMed1985

Wedge-shaped retinal nerve fiber layer defects in experimental glaucoma preliminary report.

Many investigators have reported that abnormalities in the retinal nerve fiber layer may be the earliest sign of primary open-angle glaucoma. We attempted to create defects in the retinal nerve fiber layer in experimentally induced glaucoma and to examine their histology. By repeated circumferential argon laser photocoagulation of the trabecular meshwork of normal cynomolgus monkeys, we succeeded in causing a continuous increase in intraocular pressure (IOP). During the course of this experiment, cupping of the optic nerve head, wedge-shaped retinal nerve fiber layer defects, and halo glaucomatosus developed, all of which are defects that are similar to those seen clinically in primary open-angle glaucoma. The IOP required for this fundus change was 25, 35, and 43 mmHg, indicating great individual variation. Histological examination revealed localized degeneration, loss of axon bundles, and diffuse thinning of the nerve fiber layer in the area of these wedge-shaped defects in the retinal nerve fiber layer. These results may indicate that the optic-nerve-damaging mechanism, both localized and generalized, is the same in the cynomolgus monkey and in man.

Animals↗
PubMed1985

Inhibition of 12-O-tetradecanoylphorbol-13-acetate-induced nitroblue tetrazolium reduction in mouse peritoneal macrophages by various tumor promotion inhibitors.

The effects of various inhibitors on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced reduction of nitroblue tetrazolium (NBT) in mouse peritoneal macrophages were investigated. The reduction was inhibited by phospholipase A2 inhibitors, such as dibromoacetophenone, the lipoxygenase inhibitor nordihydroguaiaretic acid, an NADH-dehydrogenase inhibitor, the microfilament inhibitor cytochalasin B, oxygen radical scavengers such as superoxide dismutase, antioxidants such as butyl hydroxyanisole and non-specific inhibitors such as retinoic acid. The reduction was not affected by the cyclooxygenase inhibitor indomethacin or the H2O2 scavenger catalase.

Animals↗
PubMed1985

Induction of nitroblue tetrazolium reduction in mouse peritoneal macrophages by tumour promoters and inhibition of the induced nitroblue tetrazolium reduction by some inhibitors.

Two polyacetates, aplysiatoxin and debromoaplysiatoxin, as well as 12-O-tetradecanoylphorbol-13-acetate (TPA), mezerein and teleocidin enhance nitroblue tetrazolium (NBT) reduction in mouse peritoneal macrophages in vitro. The ED50 values for NBT reduction of these 5 TPA-type tumor promoters were 4.2 ng/ml for TPA, 36 ng/ml for mezerein, 0.53 ng/ml for teleocidin, 1.5 ng/ml for aplysiatoxin and 108 ng/ml for debromoaplysiatoxin. The NBT reduction induced by the 5 tumor promoters is inhibited by 2 inhibitors of tumor promotion, retinoic acid and dibromoacetophenone. The possibility that tumor promotion by TPA-type tumor promoters involves similar mechanisms such as superoxide anion radicals release in cell membranes is discussed.

Acetophenones↗
PubMed1985

Histidine increases the frequency of chromosomal aberrations induced by the xanthine oxidase-hypoxanthine system in V79 cells.

The combined effects of the xanthine oxidase (XO)-hypoxanthine (HX) system and the various kinds of amino acids in Eagle's minimum essential medium on chromosomal aberrations were studied in Chinese hamster V79 cells. Among 13 amino acids tested, only histidine significantly increased the number of aberrant chromosomes and cytotoxicity in combination with the XO-HX system. This enhancing effect of histidine on chromosomal aberrations was dose-dependent at 0.063% - 0.25%; it was not affected by superoxide dismutase, but was strongly inhibited by catalase.

Animals↗