Biomedical subjects

A Hara

Publications and source records attributed to A Hara.

At least 343 records · Page 19Linked to original sources

PubMed1993

Metabolism and neurite promoting effect of exogenous sphingosylphosphocholine in cultured murine neuroblastoma cells.

Exogenous sphingosylphosphocholine analogues and naturally occurring sphingomyelin stimulated the neurite outgrowth in cultured murine neuroblastoma cell lines, NS-20Y, Neuro2a, and N1E-115, whereas exogenous sphinganine at a non-cytotoxic concentration inhibited the neurite outgrowth in NS-20Y and Neuro2a cells. The effect of sphingosylphosphocholine on the neurite outgrowth was reversible, indicating that the extended neurites needed to be maintained by continuous stimulation. The uptake and metabolism of the exogenous [3-3H]sphingosylphosphocholine in pulse and chase experiments suggested that the radioactive ceramide and sphingomyelin, which were detected as major metabolic products, were in a precursor/product relationship. It is thus assumed that the exogenous sphingosylphosphocholine taken up by the cells is first degraded into phosphocholine and sphingosine, of which the latter is rapidly acylated to ceramide then converted to sphingomyelin by phosphocholine transfer. Metabolism of sphingosylphosphocholine through sphingomyelin synthesis in the cells may be associated with neurite outgrowth.

Animals↗

PubMed1993

Anticoagulant activity of sulfatide and its anti-thrombotic effect in rabbit.

The mechanism of anticoagulant activity of sulfatide (galactosylceramide I3-sulfate), which exists in serum lipoproteins of various mammals except rodents, was investigated, together with the pharmacological effects of the glycolipid on the blood coagulation system in rabbits. The sulfatide was shown to be an effective anticoagulant when it was added in vitro in the form of pure micelle without auxiliary lipids such as phosphatidylcholine and/or cholesterol. The anticoagulant activity of synthetic galactosylceramide I6-sulfate, a positional isomer with respect to the sulfate group, was stronger than that of the sulfatide. The anticoagulant activity was specifically inhibited by anti-sulfatide antibody. The study on the pharmacological effects of sulfatide showed that the fibrin-precipitation time after single injection of the lipid (10 mg/kg body weight) into rabbits increased 2.5-fold compared with the normal level, and the maximum effect was observed 1 h after the injection. The half-life of anticoagulant activity was 5 h. These results suggest that sulfatide may be effective for the prevention of thrombosis. Sulfatide may be safer than other anticoagulant drugs, because it is a natural component of serum lipoproteins. Further, it may well play an essential role as an endogenous anticoagulant in mammals. Unlike heparin, sulfatide failed to inhibit thrombin and coagulation factor Xa activities in the presence of antithrombin III, indicating that the anticoagulant mechanism of sulfatide is independent of antithrombin III. These results indicate that the anticoagulant activity of sulfatide is potent and specific, and the lipid may be available as a useful and safe antithrombotic drug.

Animals↗

PubMed1993

Inhibition of neurite outgrowth in neuroblastoma cells by sphingosine.

Mouse neuroblastoma NS-20Y cells were induced to grow neurites by removal of serum from the medium. The percentage of cells with neurites reached about 50-60% after 24 h, whereas in medium containing 10% serum only a few cells (1-3%) were bearing neurites. Sphingosine inhibited the neuritogenesis in serum-free medium in a dose-dependent manner; a maximal effect was observed at 1-2 microM. Sphingosine also caused retraction of neurites which had been induced to extend in serum-free medium. N,N-Dimethylsphingosine was 10 times more potent in preventing neurite outgrowth, and N-acetylsphingosine was 10 times less effective compared to sphingosine. However, 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7) did not inhibit the extension of neurites. Neurite outgrowth in serum-free medium and its inhibition by sphingosine were still observed in the cells made protein kinase C-deficient by prolonged treatment with phorbol ester. These results suggest that the effect of sphingosine is not mediated by inhibition of protein kinase C.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed1993

Changes of proliferative activity and phenotypes in spontaneous differentiation of a colon cancer cell line.

We examined the alterations of proliferative activity and c-myc expression of a colon cancer cell line (Caco-2) during its spontaneous differentiation. Caco-2 cells were cultured in various types of media and the degree of differentiation was monitored in terms of dome formation in cell monolayers and expression of alkaline phosphatase (ALP) activity. In Caco-2 cells cultured with Eagle's minimum essential medium (EMEM) containing 10% fetal calf serum (FCS), dome formation was demonstrated and ALP activity was markedly increased after the cells reached confluence. Five-fold reduction of c-myc mRNA and a marked decrease in S-phase cells were observed in the differentiated cells. These changes were not induced in FCS-free EMEM. The addition of insulin and transferrin to FCS-free EMEM did not induce cell differentiation or reduction of c-myc mRNA expression. When Caco-2 cells were cultured with three different serum-free media, the induction of dome formation and the increase of ALP activity were observed to varying degrees. Expression of c-myc mRNA in the cells cultured with one serum-free medium decreased to a level similar to that in fully differentiated cells cultured with EMEM containing 10% FCS. These results suggest that a spontaneous switch from a proliferative state with high c-myc expression to differentiated phenotype occurs after cells reach confluence and depends on the culture conditions.

Cell Differentiation↗

PubMed1993

Lidocaine attenuates both mechanical and metabolic changes induced by hydrogen peroxide in the rat heart.

The effect of lidocaine on the hydrogen peroxide (H2O2)-induced mechanical and metabolic changes was studied in the Langendorff rat heart, which was perfused aerobically at a constant flow rate and paced electrically. H2O2 (600 microM) increased the left ventricular end-diastolic pressure (i.e., mechanical dysfunction), decreased the tissue levels of ATP and creatine phosphate (i.e., metabolic change), and increased the tissue level of malondialdehyde (MDA). The mechanical and metabolic alterations induced by H2O2 were attenuated by lidocaine (50 or 200 microM). Lidocaine also attenuated the H2O2-induced increase in MDA. Nevertheless, lidocaine modified neither the myocardial ferrylmyoglobin level that was increased by H2O2 nor the H2O2 concentration in vitro and did not affect the mechanical function and energy metabolism of the normal heart. These results suggest that lidocaine attenuates both mechanical and metabolic changes induced by exogenous H2O2. The protective action of lidocaine on the H2O2-induced changes is due to neither energy-sparing nor H2O2-scavenging effect, but probably due to its effect to reduce the H2O2-induced lipid peroxidation.

Adenosine Triphosphate↗

PubMed1993

Radiosensitization and inhibition of deoxyribonucleic acid repair in rat glioma cells by long-term treatment with 12-O-tetradecanoylphorbol 13-acetate.

Patients with brain tumors often undergo radiotherapy, and the cellular resistance is a major obstacle. It has been suggested that protein kinase C (PKC) may be one of a number of important regulatory enzymes in cell response to ionizing radiation. We therefore investigated the effect of PKC depletion on deoxyribonucleic acid (DNA) damage and repair after radiation in C6 cells using a microgel electrophoresis method to explore the role of PKC in glioma radioresistance. When cells are embedded in agarose on slides, lysed, and subjected to an electric field, broken DNA is able to migrate toward the anode. A significant increase in the length of DNA migration was observed in the cells exposed to irradiation. Inhibition of PKC activity by prolonged treatment with 12-O-tetradecanoylphorbol 13-acetate (TPA) or staurosporine, a potent PKC inhibitor, before irradiation enhanced radiation-induced DNA damage and attenuated the repair of damaged DNA. The half-times of DNA repair in parent C6 cells and PKC-depleted C6 cells were about 30 and 60 min, respectively, and the extent of DNA migration was still seen in the PKC-depleted cells even at 120 min after irradiation. In addition, the C6 cell clonogenicity after irradiation was also attenuated by long-term exposure of the cells to 12-O-tetradecanoylphorbol 13-acetate. These data suggest that PKC may play an important role in regulating the cell response to irradiation. The inhibitors of PKC might represent a new class of pharmacological agents to manipulate the radiosensitivity of gliomas.

Animals↗

PubMed1993

Localization of the placental form of glutathione S-transferase messenger ribonucleic acid in human glioma cell lines.

Localization of the placental form of glutathione S-transferase (GST-pi) messenger ribonucleic acid (mRNA) in three human glioma cell lines (A172, T98G, and Tc77) was studied by in situ hybridization with digoxigenin-labeled GST-pi complementary DNA followed by immunocytochemistry with antidigoxigenin antibody. A172 glioma cells showed hardly any GST-pi mRNA. GST-pi mRNA was recognized in the cytoplasm of T98G and Tc77 glioma cells. Tc77 cells especially had a strong expression of GST-pi mRNA. GST activity and the expression of GST-pi protein were also investigated for these cell lines. Cytosolic GST activity was determined with 1-chloro-2,4-dinitrobenzene as substrate, and the results were as follows: A172, 24.3 +/- 2.0; T98G, 60.8 +/- 4.9; Tc77, 84.0 +/- 1.7 (mean +/- standard deviation, in nanomoles per minute per milligram of protein). The expression level of GST-pi protein analyzed by Western blotting with anti-GST-pi antibody as a primary antibody was compatible with the results of both in situ hybridization of GST-pi mRNA and GST activity. A172 cells possessing the lowest GST activity showed a weak expression of both GST-pi mRNA and protein. Tc77 cells with the highest GST activity had the strongest expression of GST-pi mRNA and protein in three cell lines. The GST-pi expression of T98G cells was moderate. These findings indicate that some human glioma cells have GST-pi expression and that GST-pi in glioma cells is the major isozyme of GSTs for the significant activity of glutathione conjugation.

Blotting, Western↗

PubMed1993

Efficacy of denopamine, a beta 1 adrenoceptor agonist, in preventing coronary artery spasm.

The selective beta 1 adrenoceptor agonist denopamine was studied for its effectiveness in abolishing active vasospastic angina in 10 patients without obstructive coronary artery stenosis. All patients had anginal attacks at least once a day during the 3-day placebo period. Denopamine, 40 mg/day, completely abolished the attacks in 7 patients (efficacy 70%). Denopamine reduced the mean daily number of anginal attacks and nitroglycerin consumption in comparison with placebo (0.56 +/- 1.23 vs 2.20 +/- 1.27; p < 0.005 and 0.10 +/- 0.24 vs 1.60 +/- 1.93; p < 0.05, respectively). Aggravation of anginal attacks was not seen in any patient. During placebo period, anginal attacks were provoked in 6 of the 10 patients who received exercise stress test, and in 6 of the 7 patients who received the cold pressor test in combination with hyperventilation. Denopamine prevented anginal attacks induced by exercise stress tests in 4 of the 6 patients (67%) and that induced by the cold pressor test in 4 of the 6 patients (67%). There were no severe adverse effects during denopamine therapy. These results suggest that 1) denopamine is a safe and effective medication for vasospastic angina; 2) beta 1 adrenoceptors may play an important role in the prevention of coronary artery spasm.

Adrenergic beta-Agonists↗

PubMed1993

Effect of interferon-gamma on ACNU-induced DNA damage and cytotoxicity in human glioblastoma cells.

Interferons (IFNs) are a natural body defense with powerful effects on tumor growth, including gliomas. The direct effects of IFN-gamma on (1-4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-3-nitrosourea hydrochloride (ACNU)-induced deoxyribonucleic acid (DNA) damage and cytotoxicity were investigated in two human glioblastoma cell lines, A-172 and T98G, using a single cell microgel electrophoresis technique and a microculture tetrazolium assay. The results demonstrated a synergistic effect of IFN-gamma with ACNU on intracellular damage in both cell lines. 10 micrograms/ml ACNU induced a cell inhibition rate of 23.9% in A-172 cells, and almost no effect on T98G cells. 1000 U/ml IFN-gamma and 10 micrograms/ml ACNU caused a significant increase in cell inhibition, 51.2% for A-172 and 72.3% for T98G cells. DNA damage in individual A-172 and T98G cells exposed to ACNU was enhanced significantly by IFN-gamma (p < 0.001). The findings suggest a direct effect of IFN-gamma on ACNU-induced cell damage in human glioma, in addition to its effect on immunomodulation.

Brain Neoplasms↗

PubMed1993

Relationship between Ricinus communis agglutinin-1 binding and nucleolar organizer regions in human gliomas.

Histochemical staining using lectins from Ricinus communis (RCA-1), Arachis hypogaea, and Canavalia ensiformis was investigated in 40 human gliomas, three central neurocytomas, one human neuroblastoma cell line (IMR-32), and two normal brain tissues. Staining was uniform in low-grade gliomas, but heterogeneous in high-grade gliomas, particularly with RCA-1. The correlation between RCA-1 reactivity and cellular proliferative potential was investigated in 10 high-grade gliomas using a combined staining technique: the silver colloid method for nucleolar organizer regions (Ag-NORs) and histochemistry with RCA-1. The mean number of Ag-NORs counted on a simple preparation was significantly greater in the nuclei of RCA-1-negative cells than in those of RCA-1-positive cells (p < 0.001). The staining intensity of inflammatory cells was obviously higher than that of neoplastic cells, and therefore inflammatory cells were easily discriminated from neoplastic cells. Combined RCA-1 histochemical and Ag-NOR silver colloid staining revealed heterogeneous expression of RCA-1 receptor in high-grade gliomas with changes in Ag-NOR number. This result seems to show that high-grade gliomas express heterogeneous cellular carbohydrate structure and proliferative potential even within the same tumor.

Agglutinins↗

PubMed1993

The effect of endocochlear potential suppression upon susceptibility to acoustic trauma.

In the present study we investigated the influence of decreased endocochlear potential (EP) on acoustic trauma. Guinea pigs with decreased EP following i.v. administration of furosemide (FUR) and normal EP given physiological saline solution (PSS) i.v. instead of FUR were exposed to 2 kHz pure tone ranging from 110 to 130 dB SPL for 5 min. The input-output curves of the compound action potential (CAP) before acoustic overstimulation were compared with those at 2 h after the exposure. In 125 and 130 dB SPL exposure there was no difference in threshold shift between the FUR and PSS groups. In 115 and 120 dB SPL exposure, however, the threshold shift of the FUR group was significantly smaller than that of the PSS group. There was no significant difference between the two groups in 110 dB SPL exposure. These results indicate that the threshold shift of the CAP is mainly due to excessive vibration of the basilar membrane in the greater stimulus groups (125-130 dB SPL) but that the energy exhaustion of the hair cells to a certain extent participates in the threshold shift when the stimulus is milder (115-120 dB SPL). It is concluded that susceptibility to acoustic trauma of a milder intensity (115-120 dB SPL) is reduced when the energy consumption rate of the organ of Corti is decreased by EP suppression.

Acoustic Stimulation↗

PubMed1993

[Effects of acoustic overstimulation and perilymph perfusion--with Joro spider toxin on the concentrations of amino acids in the perilymph].

Glutamate (Glu) is considered one of the most probable neurotransmitter candidates in primary afferent nerves of the cochlea. In the present study, the amino acid profile in the perilymph was determined in order to investigate the effects of acoustic overstimulation and perilymph perfusion with Joro Spider Toxin (JSTX), a specific antagonist of the quisqualate sensitive Glu receptor, on the stimulus-induced release of Glu. In the first series of experiments (control group; n = 10), samples of the scala tympani perilymph (PST) were collected from albino guinea pigs at 60 and 75 min after initiating cochlear perfusion with an artificial perilymph. In the second series of experiments (acoustic overstimulation group; n = 7), the PST samples were collected before (at 60 min after the initiation of perilymph perfusion) and after (at 75 min after the initiation of perilymph perfusion) exposure to a pure tone (2000 Hz, 110 dBSPL for 15 min). In the third series of experiments (JSTX group; n = 8), the PST samples were collected as described above under condition of cochlear perfusion with an artificial perilymph containing of 3.54 x 10(-8) M and 3.54 x 10(-6) M of JSTX. The concentrations of Glu, aspartate, glycine, alanine and leucine were measured by high-performance liquid chromatography (HPLC) using phenylisothiocyanate derivatization. There was no significant effect of acoustic overstimulation or perilymph perfusion with JSTX on the levels of amino acids.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Stimulation↗

PubMed1993

[Biochemical profile of proteoglycans and glucosaminoglycans of the mammalian tectorial membrane].

The tectorial membrane is an acellular connective tissue which plays an essential role in cochlear function. While a comparatively large amount of information is available on the collagen network of the tectorial membrane, studies on the biochemical nature of this highly hydrated matrix, which is composed of proteoglycans (PGs) and glycosaminoglycans (GAGs), have been quite limited. Previous reports on the biochemical analysis of the tectorial membrane have failed to detect uronic acid, which is present in large amounts in all mammalian GAGs except keratan sulfate. Applying a colorimetric assay based on the binding of GAGs to cationic dye Safranin-0 in combination with enzymatic techniques, we were able to measure GAGs in the murine tectorial membrane. Approximately 0.3% uronic acid-containing GAGs (mainly in the form of chondroitin/dermatan sulfate) and 0.17% keratan sulfate were detected in the tectorial membrane (both on a wet weight basis). In addition, various types of electrophoresis revealed one large PG with a molecular mass similar to that of the large type cartilage PGs and three small PGs, containing chondroitin sulfate and keratan sulfate side chains, respectively. Judging by coelution of standards, one of the small PGs seemed to correspond to fibromodulin, which has at least one keratan sulfate side chain, and binds to type I and type II collagen to regulate collagen organization in tissues. Our results suggest: (1) Donnan equilibrium is established in the tectorial membrane because sulfated GAGs are highly negatively charged and consequently bring about an influx of large amounts of water and cations into the matrix.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

[Treatment with ACVP-16 for relapsed and refractory non-Hodgkin's lymphoma].

ACVP-16 chemotherapy combined with recombinant granulocyte-colony stimulating factor (rG-CSF) was carried out on patients with malignant lymphoma which were recurrent or resistant to chemotherapy including adriamycin. Twenty patients with non-Hodgkin's lymphoma, 11 men and 9 women, with a median age of 54 years, were entered in this study. Fourteen patients had diffuse large cell lymphoma, 4 diffuse medium, and 2 diffuse mixed. The previous treatments for these patients were COP-BLAM, IMV-triple P and COP-BLAM III. The ACVP-16 regimen included ara-C at 100 mg/m2 i.v. on day 1 to 5, CBDCA at 250 mg/m2 i.v. on day 1, and VP-16 at 70 mg/m2 i.v. on day 1 to 3. Subcutaneous administration of rG-CSF at 2 micrograms/kg was started on day 7. Since complete remission was achieved in 7 patients (35%) and partial remission in 8 (40%), the total response rate was 75%. The median survival duration after the initiation of this therapy was 11 months for those who achieved CR and 4 months for those who achieved PR and those who had no response. Leukopenia (< or = 1,000/microliters) and thrombocytopenia (< or = 50,000/microliters) were observed in 15 (75%) and 12 (60%), respectively. We conclude that the ACVP-16 regimen is useful for the treatment of refractory or relapsed non-Hodgkin's lymphoma. However, the patients who are treated with this regimen should be carefully managed in order to avoid severe infection, because leukopenia was observed even when rG-CSF was administered.

Adult↗

PubMed1993

Sulphatide as a major glycosphingolipid in WHHL rabbit serum lipoproteins and its anticoagulant activity.

Sulphatide is found to be a major glycosphingolipid in serum lipoproteins of rabbit and its content is markedly elevated in serum of WHHL rabbit, an animal model for human familial hypercholesterolemia. On analysis of tissue sulphatide contents, serum appears to derive its sulphatide from liver (90%) and small intestine (10%) and passes on to aorta of WHHL rabbit which is found to have a large amount of sulphatide while none is found in normal aorta. Thus it seems that sulphatide finally accumulates in arterial walls along with the progression of atherosclerosis in WHHL rabbit. Since sulphatide at median concentration (8 nmole/ml serum) in various mammals is found to increase activated partial thromboplastin time by 25%, it is suggested that anticoagulant activity may be one of the physiological functions of sulphatide in serum. The observation of an increase in activated partial thromboplastin time by 2.5-fold on injection of sulphatide (10 mg/kg body wt) into rabbit suggests that sulphatide may be an effective and safe antithrombotic agent.

Animals↗

PubMed1993

[Nucleolar organizer regions in meningiomas with reference to histopathological findings and recurrence].

A silver staining technique was used in the study of nucleolar organizer regions (Ag-NORs) in paraffin sections of 40 meningiomas. The specimens were divided into three groups as follows: typical (n = 24), atypical (n = 8) and recurrent (n = 8) groups, and the mean number of Ag-NORs was evaluated in three groups. The mean Ag-NORs number (mean +/- S.D.) of typical, atypical and recurrent group was 1.48 +/- 0.14, 1.82 +/- 0.16 and 2.05 +/- 0.23 respectively. The mean Ag-NORs number of atypical and recurrent groups was significantly greater than that of typical group. These results suggest that the proliferative potential of meningiomas and the risk of recurrence could be evaluated by quantification of Ag-NORs.

Adult↗

PubMed1992

Chemical modification of cysteinyl, lysyl and histidyl residues of mouse liver 17 beta-hydroxysteroid dehydrogenase.

Monomeric 17 beta-hydroxysteroid dehydrogenase from mouse liver was rapidly inactivated by 5,5'-dithiobis(2-nitrobenzoic acid) and 2,4,6-trinitrobenzene-1-sulfonate, and the absorption spectra of the inactivated enzymes indicated that cysteine and lysine residues were modified. The kinetics of inactivation and spectrophotometric quantification of the modified residues suggested that complete inactivation was caused by modification of two cysteine residues or one lysine residue per active site. The inactivation by the two reagents was protected by NADP+ and some coenzyme analogs, but not by a steroid substrate, testosterone. Moreover, chemical modification by diethyl pyrocarbonate also produced inactivation of the enzyme, and showed a difference spectrum with a peak at 242 nm characteristic of N-carbethoxyhistidine residues, which decreased with the addition of hydroxylamine. The inactivation by this reagent, following pseudo-first-order kinetics, was protected partially by either NADP+ or testosterone and completely in the presence of both the coenzyme and substrate. The results suggest the presence of essential cysteine and lysine residues at or near the coenzyme-binding site and that of essential histidine residue(s) in the catalytic region of the active site of mouse liver 17 beta-hydroxysteroid dehydrogenase.

17-Hydroxysteroid Dehydrogenases↗

PubMed1992

Structural and functional comparison of two human liver dihydrodiol dehydrogenases associated with 3 alpha-hydroxysteroid dehydrogenase activity.

Two monomeric dihydrodiol dehydrogenases with pI values of 5.4 and 7.6 were co-purified with androsterone dehydrogenase activity to homogeneity from human liver. The two enzymes differed from each other on peptide mapping and in their heat-stabilities; with respect to the latter the dihydrodiol dehydrogenase and 3 alpha-hydroxysteroid dehydrogenase activities of the respective enzymes were similarly inactivated. The pI 5.4 enzyme was equally active towards trans- and cis-benzene dihydrodiols, and towards (S)- and (R)-forms of indan-1-ol and 1,2,3,4-tetrahydronaphth-1-ol and oxidized the 3 alpha-hydroxy group of C19-, C21- and C24-steroids, whereas the pI 7.6 enzyme showed high specificity for trans-benzene dihydrodiol, (S)-forms of the alicyclic alcohols and C19- and C21-steroids. Although the two enzymes reduced various xenobiotic carbonyl compounds and the 3-oxo group of C19- and C21-steroids, and were A-specific in the hydrogen transfer from NADPH, only the pI 5.4 enzyme showed reductase activity towards 7 alpha-hydroxy-5 beta-cholestan-3-one and dehydrolithocholic acid. The affinity of the two enzymes for the steroidal substrates was higher than that for the xenobiotic substrates. The two enzymes also showed different susceptibilities to the inhibition by anti-inflammatory drugs and bile acids. Whereas the pI-5.4 enzyme was highly sensitive to anti-inflammatory steroids, showing mixed-type inhibitions with respect to indan-1-ol and androsterone, the pI 7.6 enzyme was inhibited more potently by non-steroidal anti-inflammatory drugs and bile acids than by the steroidal drugs, and the inhibitions were all competitive. These structural and functional differences suggest that the two enzymes are 3 alpha-hydroxysteroid dehydrogenase isoenzymes.

3-Hydroxysteroid Dehydrogenases↗