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Biomedical subjects

T Nishimura

Publications and source records attributed to T Nishimura.

At least 1,045 records · Page 58Linked to original sources
PubMed1988

5'-Nucleotide phosphodiesterase and alkaline phosphatase in tumor cells: evidence for existence of novel species in the cytosol.

Characteristics of 5'-nucleotide phosphodiesterase (phosphodiesterase I, EC 3.1.4.1) and alkaline phosphatase (EC 3.1.3.1) activities in tumor cell lines of human and murine origin were examined. Of the 15 cell lines tested, 5'-nucleotide phosphodiesterase activity in 13 cell lines and alkaline phosphatase activity in 10 cell lines were inhibited by N-ethylmaleimide and activated by dithiothreitol (N-ethylmaleimide-sensitive), and suggested to be SH-enzymes. In contrast, the two phosphohydrolases from normal tissues were inactivated by dithiothreitol, but not by N-ethylmaleimide (dithiothreitol-sensitive). There was only one tumor cell line in which both activities were dithiothreitol-sensitive. Human hepatoma PLC/PRF/5 cells appear to possess both types of 5'-nucleotide phosphodiesterase and alkaline phosphatase, and the subcellular distribution of these enzymes in this cell line was investigated. Dithiothreitol-sensitive 5'-nucleotide phosphodiesterase and alkaline phosphatase of PLC/PRF/5 cells were localized in the plasma membrane as in normal tissues, but N-ethylmaleimide-sensitive phosphohydrolases were soluble cytosolic proteins. N-Ethylmaleimide-sensitive 5'-nucleotide phosphodiesterase and alkaline phosphatase activities from other cell lines were also recovered in the cytosol. Molecular masses of cytosolic N-ethylmaleimide-sensitive phosphohydrolases were apparently smaller than their membrane-bound dithiothreitol-sensitive counterparts, as judged from gel filtration. It was concluded that many tumor cell lines lack plasma membrane 5'-nucleotide phosphodiesterase and alkaline phosphatase, but express enzymes with similar activities in the cytosol, with properties clearly distinguishable from enzymes so far characterized.

Alkaline Phosphatase↗
PubMed1988

Activities of lysosomal enzymes in rabbit brain with experimental neurofibrillary changes.

Rabbits were injected intracerebrally with aluminum salt leading to experimental neurofibrillary change formation as a model of Alzheimer neurofibrillary change. Eleven days after the injection, the brain tissues were excised from the cortex, hippocampus, and cervical region of spinal cord. Five lysosomal enzymes (cathepsin D, beta-glucuronidase, acid phosphatase, acid DNase, alkaline DNase) were assayed and compared with the control. Cathepsin D, acid DNase and beta-glucuronidase activities increased significantly in all 3 areas of aluminum-injected brain. On the other hand, acid phosphatase and alkaline DNase activities remained at the same level. The results showed the lysosomal enzymes did not change in parallel after aluminum administration, suggesting a role of the increased enzymes in the brain with neurofibrillary changes.

Acid Phosphatase↗
PubMed1988

Neurofilament degradation by bovine brain cathepsin D.

The effect of cathepsin D on bovine neurofilament protein was studied biochemically, immunologically, and morphologically. Degradation products of each neurofilament triplet by bovine brain cathepsin D at neutral pH were identified by electrophoresis and immunoblotting with anti-neurofilament antibodies. The 68-kDa subunit was the most susceptive to cathepsin D proteolysis among the triplet proteins. All of the triplet gave rise to partial degradates of the 50-kDa size. The reconstituted fiber from neurofilament triplet proteins and the 68-kDa subunit protein were attacked by cathepsin D and the mode of disruption of the fiber structure was studied by electronmicroscopy.

Animals↗
PubMed1988

Exclusion chromatography with controlled-pore glass beads to isolate Chlorella chromatin and its applications.

A simple and rapid method was developed to isolate chromatin from the unicellular alga, Chlorella, by exclusion chromatography utilizing controlled-pore glass beads. This method takes advantage of the giant size of the chromatin supramolecules and does not require the preliminary isolation of cell nuclei. In order to raise the histone yield, commercially available materials were silanized with dimethyldichlorosilane. The isolated algal chromatin had properties similar to those of other organisms, and the histones contained all five components found in calf thymus. A hierarchy of the higher order structures was also observed in the algal chromatin. This method can be used for the study of chromatin in various cell types, especially in microbial cells, from the viewpoints of not only mere preparation but also cell dynamics and fractionation in relation to the specific components or activities. Some application examples are presented.

Cell Cycle↗
PubMed1988

Propranolol blocks recurrent synaptic activation in paravertebral sympathetic ganglia of bullfrogs.

Intracellular recordings were made from neurons in bullfrog sympathetic ganglia. Orthodromic, intracellular and antidromic stimulations evoked recurrent depolarizing responses accompanied by a spontaneous firing of the action potential in type 2 neurons. The depolarizing response elicited by intracellular and antidromic stimulations was selectively blocked by propranolol (1 microM), but not by yohimbine and phenoxybenzamine. Propranolol did not block the 'nicotinic' fast excitatory postsynaptic potential evoked by orthodromic stimulation. These results suggest that excitatory beta-adrenoceptors mediate the recurrent synaptic facilitation of nicotinic transmission in type 2 neurons of bullfrog sympathetic ganglia.

Action Potentials↗
PubMed1988

A peplomycin-supersensitive cell line lacking activation of poly(adenosine diphosphate ribose) synthetase by peplomycin.

In peplomycin-supersensitive Chinese hamster lung cells, the increase in poly(ADP-ribose) synthesizing activity following peplomycin treatment was significantly reduced as compared with the parental lung cells, suggesting that peplomycin-supersensitive lung cells may have some deficiency in DNA repair. On the contrary, peplomycin-supersensitive ovary cells, which undergo increased DNA damage induced by peplomycin, showed normally increased poly(ADP-ribose) polymerizing activity compared with the parental ovary cells. Relationship between poly(ADP-ribose) polymerase and peplomycin sensitivity was discussed.

Animals↗
PubMed1988

5-hydroxytryptamine inhibits cholinergic transmission through 5-HT1A receptor subtypes in rabbit vesical parasympathetic ganglia.

Intracellular recordings were made from parasympathetic neurons of the rabbit vesical pelvic ganglia (VPG) maintained in vitro. 5-Hydroxytryptamine (5-HT) inhibited cholinergic transmission in the VPG by reducing the fast excitatory postsynaptic potential (EPSP) evoked by stimulations of pelvic nerves. 8-Hydroxy-2-(di-n-propyl-amino) tetralin hydrochloride mimicked the inhibitory effect of 5-HT on the ganglionic transmission. 5-HT-induced inhibition of the fast EPSP was antagonized by spiperone. The results suggest that 5-HT1A receptor subtypes mediate the inhibition of cholinergic transmission in the rabbit VPG.

Animals↗
PubMed1988

Establishment of mouse thymic nurse cell clones from a spontaneous BALB/c thymic tumor.

This is the first report on the establishment of the readily identifiable and functioning thymic nurse cell (TNC) clones from the mouse thymus. In the course of the culture of an epithelial cell line using a medium with a low concentration of Ca2+ from the spontaneous BALB/c thymic tumor, lymphocytes as well as thymic stromal cells which were not apparently typical epithelial cells by light microscopy seemed to grow relatively well in one flask. The culture medium was exchanged with regular Dulbecco's modified Eagle's medium in the third week, and from that flask TNC clones were established together with lymphoblast cell clones. The established cells (IT-79MTNC3) were easily identified as TNC. They formed complexes with simultaneously established lymphoblast cells and were remarkably similar to those of fresh TNC and thymocytes. Cloned TNC could express Ia antigens. In co-culture experiments, cloned TNC together with recombinant interleukin 2 (rIL 2) appeared to support the growth of fetal thymocytes which with rIL 2 alone failed to proliferate. The supernatant of IT-79MTNC3 was previously found to contain the growth factor for some T cell clones. It remains to be solved whether the TNC affects fetal thymocytes through direct contact or secretes an active growth-promoting factor. Experiments along this line are now in progress.

Animals↗
PubMed1988

Higher level expression of lymphocyte function-associated antigen-1 (LFA-1) on in vivo natural killer cells.

Normal mouse spleen cells express low levels of lymphocyte function-associated antigen-1 (LFA-1) as well as other lymphoid cells. However, fractionation of spleen cells with Percoll discontinuous gradients resulted in the appearance of lymphocytes expressing high levels of LFA-1 molecule (LFA-1 high lymphocytes) in parallel with the enrichment of natural killer (NK) activity. Lower density spleen cells (fractions 1 and 2) expressed higher level of LFA-1 antigen than unfractionated spleen cells and showed a higher NK activity. In contrast, higher density spleen cells (fractions 3 and 4) expressed lower levels of LFA-1 antigen and revealed lower NK activity. LFA-1 high lymphocytes possessed a high level of asialo GM1, which was the cell surface marker for NK cells. Moreover, sorting of LFA-1 high lymphocytes from spleen cells caused a great enrichment of NK cells. These results demonstrated that in vivo NK cells expressed higher levels of LFA-1 molecule, which was an important adhesion molecule for NK cell-mediated cytotoxicity.

Animals↗
PubMed1988

Brainstem auditory evoked potentials in Chiari-II malformation.

Brainstem function in patients with Chiari-II malformation was evaluated by brainstem auditory-evoked potentials (BAEPs). All cases had associated hydrocephalus, some of which were shunted. The effect of the shunting operation on the wave forms was examined as well as the age-wave relationships. Although the shunting operation resulted in shortened brainstem conduction time, the overall postshunt responses were still far from normal. Another significant finding was that whereas there were remarkable abnormalities in recorded waveforms in cases younger than 8 years, normal or almost normal responses were obtained in all cases older than 8. BAEP abnormalities could not be correlated with the severity of meningomyelocele, nor was the predictive value of response in assessing potential risk of symptomatic Chiari malformation established.

Adolescent↗
PubMed1988

Two patients with meningioma visualized as high uptake by SPECT with N-isopropyl-p-iodo-amphetamine (I-123).

It has been reported that brain tumors show decreased IMP uptake, however, we encountered two cases of meningioma which had initially increased IMP uptake. SPECT was performed at 30 min, 2 hr and 6 hr after intravenous administration of IMP (3 mCi). The delayed images (2 and 6 h) showed decreased IMP uptake. These were convexity and parasagittal meningiomas which had tumor stains at angiography. Although the mechanism of IMP uptake in brain tumor is still unclear, this finding should be considered in the interpretation of IMP-SPECT.

Adult↗
PubMed1988

Magnetic resonance imaging of cerebral infarction: time course of Gd-DTPA enhancement and CT comparison.

Thirty-five patients (7 females and 28 males) with cerebral infarction and suspicion of cerebral infarction of 4 h to 27 months duration were studied 45 times with magnetic resonance (MR) imaging using Gd-DTPA. Spin echo (SE) images were obtained before and after the administration of Gd-DTPA (0.1 or 0.15 mmol/kg) and compared with the enhanced CT. MR imaging using Gd-DTPA was more sensitive than enhanced CT and very useful for detecting a new focus of cerebral infarction, especially in the cases with multiple infarcted areas and for showing the extent of cortical and subcortical infarction. In most cases the MR enhancement was obvious in the subacute stage, especially after cerebral embolism, and the signal intensity of the lesion tended to show a gradual increase. The diagnosis of embolism was accepted on the basis of acute onset without prior TIA, coupled with angiography showing the embolus itself and/or a capillary blush and a wide area of infarction.

Adult↗
PubMed1988

Induction of anomalous killing activity from antigen-specific CTL clones by adding high doses of human recombinant interleukin 2.

Four out of six long-term murine cytotoxic T lymphocyte (CTL) clones specific for trinitrophenyl (TNP)-modified spleen cells could develop an anomalous cytotoxicity against syngeneic and allogeneic tumor cells upon stimulation with TNP-modified spleen cells and high doses of human recombinant interleukin 2 (rIL-2). On FACS analysis, hyperactivated CTLs were positive for Thy-1, Ly 2 and LFA-1, but negative for L3T4 and asialo GM1. The staining profile of the cells with each antibody indicated that the CTL clones consisted of just one cell type. Monoclonal anti-Ly 2.2 and anti-LAA (lymphokine-activated cell-associated antigen) antibodies inhibited cytolysis of CTL and hyperactivated CTL clones against TNP-modified spleen cells, but failed to inhibit the anomalous killing of the hyperactivated CTL. The cold target competition test suggested the degeneracy of antigen specificity. The present study demonstrated that the CTL clone acquired a new specificity for tumor target cells upon stimulation with a high dose of rIL-2.

Animals↗
PubMed1988

In vivo generation of lymphokine-activated killer cells by sensitization with interleukin 2-producing syngeneic T-lymphoma cells.

Culture of C57BL/6 mouse spleen cells with syngeneic EL4 lymphoma cells resulted in no induction of killer cells reactive against EL4 cells. However, in vitro sensitization of C57BL/6 mouse spleen cells with interleukin 2 (IL-2)-producing EL4 lymphoma cells caused the generation of lymphokine-activated killer (LAK) cells, which lyse a variety of tumor cells. Consistent with an in vitro system, we demonstrate that Thy 1.2+, Ly2+, asialo GM1+ LAK cells were successfully induced by in vivo immunization with syngeneic IL-2-producing EL4 lymphoma cells.

Animals↗
PubMed1988

Calcium-activated chloride conductance in parasympathetic neurons of the rabbit urinary bladder.

Intracellular recordings were made from vesical pelvic ganglion cells of the rabbit in a Krebs solution containing tetrodotoxin (1 microM). Experiments were carried out during complete suppression of the calcium-dependent potassium conductance by tetraethylammonium (greater than or equal to 20 mM) and/or intracellular injection of cesium ions. The action potential was followed by a depolarizing afterpotential which lasted for 0.3-10 s and had a peak amplitude of 5-20 mV at about -50 mV. The afterdepolarization (ADP) could not be observed when the preceding calcium-dependent action potential was blocked in a nominally calcium-free solution. Intracellular injection of ethyleneglycol-bis(beta-aminoethyl ether)N,N'-tetraacetic acid (EGTA) or total substitution of extracellular calcium ions with barium ions selectively blocked the ADP. The ADP, associated with an increased membrane conductance, reversed its polarity at -17 mV, when ganglion cells were impaled with microelectrodes filled with potassium chloride or cesium chloride. This reversal level was similar to that of the depolarization induced by gamma-aminobutyric acid. The reversal potential shifted to about -50 mV when acetate or sulphate were injected as counter anions. The peak amplitude and the total duration of the ADP was increased by substitution of external sodium chloride with sucrose or sodium isethionate. These results suggest that the ADP results from calcium entry during the spike and subsequent opening of chloride channels in parasympathetic neurons of the rabbit.

Action Potentials↗