Search PubMed⌕ Search

Biomedical subjects

K Higashi

Publications and source records attributed to K Higashi.

At least 217 records · Page 12Linked to original sources
PubMed1991

Down modulation of N-myc, heat-shock protein 70, and nucleolin during the differentiation of human neuroblastoma cells.

Cultured human neuroblastoma (GOTO) cells were induced to differentiate by dibutyryl cyclic AMP (Bt2cAMP) and/or retinoic acid (RA). A combination of Bt2cAMP (1 mM) and RA (1 microM) yielded the most significant networks of neurites after 3 to 4 days, this being associated with the reduction of N-myc mRNA levels. Next, we examined several cellular genes that were possibly linked with changes in N-myc gene expression under these conditions. Among the genes examined, both nucleolin and a major heat-shock protein (hsp70) mRNAs showed changes concomitant with those in N-myc mRNA levels when induced by Bt2cAMP and RA. Dibutyryl cAMP alone induced several short cellular processes and caused a marked decrease in N-myc mRNA within 2 days. RA alone induced a few long and straight neurites along the longitudinal axis of individual cells and a significant decrease in growth rate but showed neither network formation nor a decrease in N-myc gene expression. These results indicate differential effects of Bt2cAMP and RA on the regulatory mechanisms of both cell proliferation and differentiation and also indicate a possible association of expression of N-myc gene with those of hsp70 and nucleolin genes.

Bucladesine↗
PubMed1991

Detection of varicella-zoster virus (VZV) DNA in clinical samples from patients with VZV by the polymerase chain reaction.

A polymerase chain reaction system for the detection of varicella-zoster virus was established. Of 25 nucleotides, 4 oligonucleotide pairs (regions of thymidine kinase, thymidylate synthetase, glycoprotein I, and immediate early gene) were synthesized. The first three oligonucleotide pairs could be used as primers on the basis of specific DNA amplification. Varicella-zoster virus DNA was amplified by this polymerase chain reaction system in 20 of 20 vesicle samples, 5 of 6 crusts, and 12 of 13 throat swabs collected from patients with clinical varicella.

Base Sequence↗
PubMed1991

Electron-microscopic observations of the alveolar brush cell of the rat.

The alveolar brush cells in the rat lung were observed by transmission electron microscopy. The general structural features of the brush cells in this report were basically in agreement with earlier descriptions. However, this report is the first to detect long, thick microvilli with a unique form protruding into the alveolar lumen in parallel with the basement membrane, not vertically to the basement membrane. Moreover, intranuclear inclusions in the nucleus were observed for the first time in the alveolar brush cells in this study.

Animals↗
PubMed1991

Cloning and sequencing of viral integration site in human fibroblasts immortalized by simian virus 40.

We have analyzed cellular DNA sequences at the viral genome integration site in a human fibroblast cell line VA13 immortalized by simian virus 40 (SV40). The computer analysis of the junctional cellular DNA sequences did not show any homology to the DNA sequences previously reported. This suggests that immortalization by SV40 was not induced by the destruction of any known oncogene or anti-oncogene at the integration site. We did not find the precise substantial sequence homology at the junctional site between the cellular DNA and SV40 DNA, indicating that the recombination mechanism involved does not require precise sequence homology and therefore, SV40 genome was probably not integrated by homologous recombination. Short direct and inverted repeats of 5 to 29 nucleotides were found in the junctional cellular and SV40 DNA. Cellular DNA abutting SV40 DNA was found by the Northern blot analysis to be expressed in diploid human fibroblasts and SV40-transformed cells. The nature of this RNA is now under study.

Base Sequence↗
PubMed1991

Local drug delivery systems for the treatment of periodontal disease.

Filmy local drug delivery systems (LDDSs) were administered to periodontal pockets in beagles with induced periodontitis, and the in vivo-in vitro correlation of drug release from the LDDS and changes in the clindamycin (CLDM) concentration in the periodontal pocket fluid were studied. The in vitro drug release rate from the LDDS was determined by the dissolution study, without agitation, using phosphate buffer as the dissolution medium at 37 degrees C, and the in vivo drug release rate was determined according to the decrease in the drug load remaining in the LDDS after administration in periodontal pockets. The in vivo drug release rate from LDDSs was lower than the in vitro rate determined by the dissolution study, but the two rates showed a correlation in LDDSs that released drugs by diffusion. Therefore, the in vivo drug release rate was considered to be estimated from the results of the in vitro dissolution study. Changes in the drug concentration in the periodontal pocket fluid after administration of LDDS were dependent on the drug release properties of the LDDS. Also, when CLDM was administered as an aqueous solution in periodontal pockets, its concentration in the periodontal pocket fluid decreased according to a pseudo first-order equation. Therefore, the concentration in the periodontal pocket fluid after administration of a LDDS is considered to be simulated by the one compartment model based on a pseudo first-order elimination process.

Administration, Topical↗
PubMed1991

Change of ras-transformed NRK-cells back to normal morphology by mycalamides A and B, antitumor agents from a marine sponge.

Mycalamide A and mycalamide B, isolated as antiviral and antitumor agents from a New Zealand sponge of the genus Mycale, converted the morphology of ras-transformed NRK-cells to normal morphology at 10 and 1 ng/ml, respectively. The effect on protein synthesis suggests that these agents converted the morphology by preferentially inhibiting the biosynthesis of p21 protein.

Animals↗
PubMed1991

Effects of ubenimex on erythroid progenitors (CFU-E and BFU-E) in human bone marrow.

Ubenimex (UBX, bestatin) is known to be an immunomodulator and host-mediated antineoplastic agent. Effects of UBX on human bone marrow erythroid progenitors (erythroid colony-forming units, CFU-E; and erythroid burst-forming units, BFU-E) were investigated in vitro. UBX enhanced CFU-E and BFU-E growth in the nonseparated bone marrow mononuclear cell fraction at concentrations from 0.005 to 5 micrograms/ml. The enhancements of CFU-E and BFU-E were independent of the concentration of erythropoietin added to culture system. In the T-cell-depleted bone marrow fraction, UBX also increased CFU-E and BFU-E growth, but it failed to stimulate these cells in the nonphagocytic and nonadherent bone marrow fraction. These findings indicate that UBX may stimulate erythroid progenitors mediated through monocytes and macrophages.

Bone Marrow Cells↗
PubMed1991

Otologic findings of DIDMOAD syndrome.

Two brothers with DIDMOAD (Wolfram) syndrome are described. The elder brother is 12 years old and was diagnosed as having diabetes mellitus at five. He later developed optic atrophy. The younger brother is 10 years old. He also has suffered from diabetes mellitus and optic atrophy. Their audiograms showed moderate hearing loss only at 8000 Hz. Auditory brainstem response (ABR) was normal. No vestibular abnormalities were found. In 151 reported cases, including present cases, 17.4 percent have moderate to severe or at least subjective deafness, 45.0 percent have deafness only at high frequency, 6 percent have deafness for which the severity was not described, 13.4 percent have normal hearing, and in 18.1 percent the status of hearing was not mentioned.

Child↗
PubMed1990

Evaluation of international normalized ratios by a controlled field survey with 4 different thromboplastin reagents.

A nationwide survey has been performed in Japan involving 75 laboratories to assess the relative reliability of different methods of reporting prothrombin time results in anticoagulant control. The interchangeability of results using prothrombin time, prothrombin activity percentage, prothrombin ratio and international normalized ratios (INR) were compared with four different thromboplastin reagents and a range of coagulometers. A secondary batch of reference thromboplastin of human brain origin (BCT/454) was used to calibrate the local thromboplastins and for comparison of methods of reporting. The study revealed the closest agreement of the results between BCT and the other reagents, and the regression lines of these reagents were almost identical, when the results were reported as INR. Box-Whisker plot analysis showed that the distribution of the results was large with the more deficient plasmas with all methods of reporting. It was found by this analysis that the interchangeability of the results was greatest when the results were expressed by INR, because the mean values obtained of each plasma using different thromboplastin reagents gave the lowest CV and the frequency of the far-out data was least, compared with the other methods of expression. On the other hand, the type of coagulometer had almost as much effect as the thromboplastin reagent on the prothrombin time, even if INR was used. Interchangeability of INR would be further improved by providing ISI values for each reagent/instrument combination.

Humans↗
PubMed1990

Some properties of fibroblasts from a patient with debrancher deficiency.

Glycogenosis Type III is characterized by a deficiency of debranching enzyme (amylo-1,6-glucosidase, E.C. 3. 2. 1. 33) in most tissues. Low activity of liberating glucose from limited dextrin in the biopsied muscle can be demonstrated in a patient with this disease. We cultured fibroblasts from a skin biopsy from a patient with debrancher deficiency and examined the metabolism of glycogen in these cultured fibroblasts. Debrancher activity in the post-mitochondrial supernatant obtained from these fibroblasts showed a good concentration dependent manner but had approximately half of that from normal human fibroblasts (YH-1). Although the enzymatic activity of debrancher in the cultured fibroblasts from the skin was reduced essentially to the same levels as observed in muscle biopsy, little glycogen granules were accumulated in the cytoplasm of these fibroblasts as revealed by either light- or electron-microscopic observation. The fibroblasts obtained in the present study may be useful for the analysis of molecular mechanism of the debrancher deficiency disease, glycogenosis Type III.

Adolescent↗
PubMed1990

Phospholipase C activation by ethanol in rat hepatocytes is unaffected by chronic ethanol feeding.

The activation of phosphoinositide-specific phospholipase C by ethanol was compared in hepatocytes isolated from ethanol-fed rats and from pair-fed control animals. Ethanol (100-300 mM) caused a dose-dependent transient increase in cytosolic free Ca2+ levels in indo-1-loaded hepatocytes from both groups of animals. The rate of Ca2+ increase was similar in hepatocytes from control and ethanol-fed rats, but the decay of the Ca2+ increase was somewhat slower in the latter preparation. The ethanol-induced Ca2+ increase caused activation of glycogen phosphorylase, with 50% response at 50 mM-ethanol and a maximal response at 150-200 mM-ethanol, not significantly different in hepatocytes from control and ethanol-fed animals. Ins(1,4,5)P3 formation in response to ethanol (300 mM) or vasopressin (2 nM or 40 nM) was also similar in the two preparations. It is concluded that long-term ethanol feeding does not lead to an adaptive response with respect to the ethanol-induced phospholipase C activation in rat hepatocytes. The ability of ethanol in vitro to decrease membrane molecular order in liver plasma membranes from ethanol-fed and control rats was measured by e.s.r. Membranes from ethanol-fed animals had a significantly lower baseline order parameter compared with control preparations (0.313 and 0.327 respectively), indicative of decreased membrane molecular order. Addition of 100 mM-ethanol significantly decreased the order parameter in control preparations by 2.1%, but had no effect on the order parameter of plasma membranes from ethanol-fed rats, indicating that the plasma membranes had developed tolerance to ethanol, similar to other membranes in the liver. Thus the membrane structural changes associated with this membrane tolerance do not modify the ethanol-induced activation of phospholipase C. The transient activation of phospholipase C by ethanol in hepatocytes may play a role in maintaining an adaptive phenotype in rat liver.

Alcoholism↗
PubMed1990

A possible role of the beta-subunit of (Na,K)-ATPase in facilitating correct assembly of the alpha-subunit into the membrane.

mRNAs from the alpha- and beta-subunits (mRNA alpha and mRNA beta, respectively) of Torpedo californica (Na,K)-ATPase were injected into Xenopus laevis oocytes either separately or in combination, and the properties of the two subunits synthesized were studied. The alpha-subunit synthesized in oocytes injected with mRNA alpha alone was recovered in both the membrane and cytosol fractions and was susceptible to tryptic attack. When mRNA beta was coinjected with mRNA alpha, almost all the alpha-subunit was found in the membrane fraction and was resistant to trypsin. In all cases, essentially all of the beta-subunit was recovered in the membrane fraction and was resistant to trypsin. As the amount of mRNA beta coinjected increased, the amounts of both the alpha- and beta-subunits as well as (Na,K)-ATPase activity of the membrane fraction increased. These results suggest that the beta-subunit facilitates the correct assembly of the alpha-subunit into the membrane probably by forming a stable complex with the nascent alpha-subunit.

Animals↗
PubMed1990

ATP-dependent regulation of phospholipase C in permeabilized 3T3 cells.

Regulation of phospholipase C (PLC) coupled with a G-protein was studied with Swiss 3T3 cells permeabilized by digitonin. In permeabilized cells, activation of phospholipase C required millimolar concentrations of ATP in addition to a G-protein activator, AlF4- or nonhydrolysable GTP analogues. To determine the mechanism of the action of ATP, we examined the effects of ATP analogues. ATP gamma S directly activated phospholipase C in the presence or absence of AlF4-. On the other hand, neither beta,gamma-methylene ATP nor adenyl-5'-yl imidodiphosphate nor ADP beta S could support the AlF4(-)-dependent activation of phospholipase C. The action of ATP gamma S was not through the substrate supply for phospholipase C, because ATP gamma S did not augment the levels of PIP2 or PIP in permeabilized cells. These results suggested the significance of the gamma-phosphate group of ATP and/or phosphorylation by ATP in the activation of phospholipase C by a putative G-protein.

Adenosine Triphosphate↗
PubMed1990

Translocation of protein kinase C to membranes induced by TNF does not cause the inhibition of EGF binding to human wish cells.

Tumor necrosis factor (TNF) caused an inhibition of 125I-labeled epidermal growth factor [( 125I]EGF) binding to its receptors of human amniotic (WISH) cells at 5 min after addition of TNF, which reached a maximal level (60-70% reduction) after 15-30 min and declined thereafter. TNF also induced a translocation of protein kinase C activity from the cytosol to the membrane, which peaked at 45-60 min after addition of TNF and almost returned to basal level at 120 min. Furthermore, prolonged incubation of WISH cells with 12-O-tetradecanoylphorbol 13 acetate (TPA) diminished the TPA effect on the inhibition of EGF binding to the cells due to the desensitization of protein kinase C; however, TNF still reduced the EGF binding to the cells pretreated with TPA for a long time. These results indicate that although TNF causes the translocation of protein kinase C to the membrane, activation of protein kinase C is not required for TNF to induce a decrease in EGF binding to the cells.

Amnion↗
PubMed1990

Assembly of the alpha-subunit of Torpedo californica Na+/K(+)-ATPase with its pre-existing beta-subunit in Xenopus oocytes.

The alpha- and beta-subunits of Torpedo californica Na+/K(+)-ATPase were expressed in turn in single oocytes by alternately microinjecting the specific mRNAs for the alpha- and beta-subunits. The mRNA first injected was degraded prior to the injection of the second mRNA by injecting the antisense oligonucleotide specific for the first mRNA. The pre-existing beta-subunit, which had been synthesized by injecting mRNA for the beta-subunit, could assemble with the alpha-subunit expressed later in the single oocytes and the resulting alpha beta complex acquired both ouabain-binding and Na+/K(+)-ATPase activities. On the other hand, formation of the alpha beta complex was not detected when the alpha-subunit was expressed first, followed by the beta-subunit. These data suggest that the beta-subunit acts as a receptor or a stabilizer for the alpha-subunit upon the biogenesis of Na+/K(+)-ATPase.

Animals↗
PubMed1990

[A possible role of the beta subunit of (Na, K)ATPase on the biogenesis of the enzyme].

(Na, K)ATPase is composed of two heterologus subunits; a catalytic alpha subunit and a glycosylated beta subunit whose role remains unclear. To elucidate a possible role of the beta subunit, the alpha and beta subunits of Torpedo californica (Na, K)ATPase were expressed in the Xenopus oocytes system which allows the specific programmed synthesis of different subunits in a cell by alternately injecting individual mRNA. When oocytes were injected with mRNA alpha alone, no significant increase in (Na, K)ATPase activity was observed, whereas a slight increase was detected in oocytes injected with mRNA beta alone. The pre-existing beta subunit, which had been synthesized by injecting mRNA beta, could assemble with the alpha subunit, expressed later in the single oocytes and the resulting alpha beta acquired both ouabain-binding and (Na, K)ATPase activities. The results reported in this paper strongly indicate that the beta subunit plays an essential role, at least in the biogenesis of the enzyme.

Animals↗