Biomedical subjects

H Sakagami

Publications and source records attributed to H Sakagami.

At least 199 records · Page 11Linked to original sources

PubMedDate not supplied

Induction of non-apoptotic cell death by sodium 5,6-benzylidene-L-ascorbate in a human salivary gland tumor cell line.

We investigated whether sodium 5,6-benzylidene-L-ascorbate (SBA) induces apoptotic cell death in a human salivary gland tumor cell line HSG, using two different cytochemical methods. Millimolar concentrations of SBA dose-dependently reduced the viable cell number of HSG cells, accompanied by the detachment of dying cells from the culture plates. The nuclei of the dying cells were not stained with TUNEL reagent, indicating the lack of DNA nicks or fragments. On the other hand, the nuclei of epigallocatechin gallate (EGCG)-treated cells (positive control) were TUNEL-positive, demonstrating the production of DNA nicks or fragments. Furthermore, the cytoplasms of SBA-treated cells were not stained with M30 monoclonal antibody, which reacts with the degradation products of cytokeratin 18 by the activated caspases, in contrast to those of EGCG-treated cells. These results suggest that SBA induces non-apoptotic cell death, possibly necrosis, in HSG cells.

Antibodies, Monoclonal↗

PubMedDate not supplied

Relationship between cytotoxic activity and dipole moment for phthalimido- and chloroethyl-phenothiazines.

Among twelve phenothiazine-related compounds, the cytotoxic activity of six "half-mustard type" phenothiazines [7-12] was significantly higher than that of six phthalimido compounds [1-6]. 1-(2-Chloroethyl)-3-(2-chloro-10H-phenothiazin-10-yl)propylurea [9], 1-(2-chloroethyl)-3-(2-chloro-10H-phenothiazin-10-yl)butylurea+ ++ [10] and 1-(2-chloroethyl)-3-(2-trifluoromethyl-10H-phenothiazin-10-yl)b utylurea [12] showed the highest cytotoxic activity, in parallel with high delta mu (difference between two dipole moments, mu g and mu e). There was also positive relationship between cytotoxic activity and molecular orbital energy such as pi-LUMO, pi-HOMO, and lone pair orbitals originated from O, N1, and N3 atoms. The present study demonstrated that cytotoxic activity of "half-mustard type" phenothiazines can be predicted by their dipole moments and molecular orbital energies.

Cell Division↗

PubMedDate not supplied

Interaction between sodium ascorbate and polyphenols.

The interaction between sodium ascorbate and polyphenols was investigated by two different parameters: radical intensity and cytotoxicity induction. ESR spectroscopy shows that sodium ascorbate, lignins (alkali-lignin, lignin sulfonate, pine cone-derived lignin) and tannins (gallic acid, epigallocatechin gallate (EGCg), tannic acid) all produced radicals with different intensities under alkaline conditions. All lignin samples significantly enhanced the radical intensity and cytotoxic activity of sodium ascorbate, whereas all tannin samples slightly reduced the radical intensity of sodium ascorbate. Sodium ascorbate efficiently scavenged the radical and cytotoxic activity of gallic acid, as expected by the ionization potential and heat of reaction by the PM3 semiempirical method. EGCg and tannic acid slightly reduced the cytotoxic activity of sodium ascorbate. The present study demonstrates that lignins and tannins modify the radical intensity and cytotoxic activity of sodium ascorbate in different manners, and suggests the applicability of ESR spectroscopy for the screening of drug to drug interaction.

Ascorbic Acid↗

PubMedDate not supplied

Effect of anticancer drugs, metals and antioxidants on cytotoxic activity of epigallocatechin gallate.

Various modulation factors for the cytotoxic action of epigallocatechin gallate (EGCG) against two human oral tumor cell lines (HSC-2, HSG) were investigated. Three anticancer drugs (tamoxifen, sulindac, doxorubicin), two metals (CuCl2, FeCl3) and two antioxidants (sodium ascorbate, tiopronin) did not significantly affect the cytotoxic activity of EGCG, Catalase and N-acetyl-L-cysteine only marginally reduced the cytotoxic activity of EGCG. On the other hand, CoCl2 significantly protected the cell injury induced by EGCG. This suggests that the site of EGCG action might be intracellular rather than extracellular. Possible involvement of the expression of transcription factor (s) for EGCG-induced cytotoxicity is discussed.

Acetylcysteine↗

PubMedDate not supplied

Induction of cell death by ascorbic acid derivatives in human renal carcinoma and glioblastoma cell lines.

Sodium-L-ascorbate, L-ascorbic acid, D-isoascorbic acid, sodium 5,6-benzylidene-L-ascorbate and sodium-6-beta-O-galactosyl-L-ascorbate, which produce ascorbyl radicals during the oxidative degradation, also induced cytotoxicity against cultured human renal carcinoma (TC-1) and glioblastoma multiform tumor (T98G) cell lines. On the other hand, L-ascorbic acid 2-phosphate magnesium and L-ascorbic acid 2-sulfate dipotassium salt, which do not produce the ascorbyl radical, were inactive. This suggests the possible role of the ascorbyl radical for cell death induction. T98G cells were more resistant to ascorbate analogs than TC-1 and HL-60 cells, possibly due to higher intracellular glutathione concentrations. Ascorbate treatment induced rapid elevation of both intracellular concentration of cAMP and Ca2+ in HL-60 cells, but not in TC-1 and T98G cells. However, the elevation of cAMP by theophyline and N,2-dibutyryl adenosine 3,5 cyclic monophosphate (dibutyryl cAMP) resulted in a decrease in the viable cell number. This suggests the possible role of cAMP for ascorbate-induced cell death.

Apoptosis↗

PubMedDate not supplied

Inhibition of epigallocatechin gallate-induced apoptosis by CoCl2 in human oral tumor cell lines.

Epigallocatechin gallate (EGCG) induced apoptotic cell death in two human oral tumor cell lines (HSC-2, HSG), as judged by TUNEL method which detects DNA nick. Furthermore, the cytoplasm of EGCG-treated HSG cells was stained by M30 monoclonal antibody, which detects the degradation product of cytokeratin by activated caspase. The apoptosis-inducing activity of EGCG was significantly reduced by millimolar concentrations of CoCl2. CoCl2 also inhibited the cytotoxic activity of sodium ascorbate, gallic acid and curcumin, but not that of sodium-5, 6-benzylidene-L-ascorbate (SBA). This suggests that SBA, an antitumor agent, induces cell death by a different mechanism from that of other antioxidants used in this study. The possible role of CoCl2 for cell survival was discussed.

Antioxidants↗

PubMedDate not supplied

Effect of glutathione-modulating compounds on platinum compounds-induced cytotoxicity in human glioma cell lines.

The relation between the effect of glutathione(GSH)-modulating compounds and platinum compounds (Cisplatin, Nedaplatin)-induced cytotoxicity was investigated. Pretreatment of human glioblastoma (T98G, U87MG) and glioma (KG1C) cell lines with L-buthionine-[S,R]-sulfoximine, which decrease the intracellular GSH concentration, remarkably increased their sensitivity against platinum compounds, whereas pretreatment with N-acetyl-L-cysteine, which increase the intracellular GSH concentration, only marginally protected the cells from the cytotoxic effect of platinum compounds. The results suggest that platinum compounds-induced cytotoxicity can be modified by GSH-modulating compounds in glioblastoma and glioma cell lines.

Acetylcysteine↗

PubMedDate not supplied

Interaction between antioxidants and hydroquinone/bisphenol.

We have investigated the stability of semiquinone radical (SQ .) produced from the mixture of hydroquinone (HQ) and bisphenol A (BPA) in the presence of various antioxidants, some of which induce apoptosis in tumor cell lines. BPA produced no detectable amount of ESR signal. The acceleration of HQ oxidation by BPA results in the production of SQ .. The BPA-enhanced SQ . production may occur through either SQ. regeneration by electron transfer from BPA working as an antioxidant or the O2- scavenging activity of BPA. SQ . intensity of HQ/BPA was reduced by lower concentrations of sodium ascorbate, epigallocatechin, gallate and quercetin, but significantly enhanced by gallic acid. The initial SQ . was replaced by the radicals of antioxidants except lignin and salicylic acid, at higher concentrations, due to their radical-radical coupling or dismutation process. Among these compounds, gallic acid enhanced the radical intensity of SQ . to the greatest extent. The results suggest that antioxidants from foods suppress the activity of xenobiotics such as HQ, however, they produce their own radical at higher concentrations, suggesting their bimodal actions. The present study demonstrates the usefulness of ESR spectroscopy for the interaction between HQ/BPA and antioxidants.

Antioxidants↗

PubMedDate not supplied

Systemic effects of the occlusal destruction in guinea pigs.

Although there is an increasing amount of information pertaining to the systemic effects of malocclusion, its mechanisms still remain unclear in many ways. This study was conducted to find out the systemic effects of the occlusal destruction in guinea pigs. The animals showed an abnormality in posture and a reversal of the T wave in electrocardiogram (ECG) about 6 days after the grinding of all molar teeth. All the animals died about 7 days after the occlusal destruction. We established the optimal condition of occlusal destruction for the induction of the above symptoms in guinea pigs: at least 6 molars, both side premolar, 1st and 2nd molar of upper jaw, because of the ease for repair. The following results were obtained: 1. The experimental group died about 5 days earlier than the fasting group. 2. The animals could not hold their head positions and dropped the head to the earth. 3. The animals died about 12 hours after the onset of postural abnormality. 4. Ninety percent of the animals with postural abnormalities showed T wave inversion on ECG. 5. None of the above symptoms occurred with bite rising. These results indicate that occlusal destruction affects head position, preventing the animals to hold their head positions and causing the head to drop to the ground. Occlusal destruction may also cause abnormality of the masticatory muscles, which control posture and modulate cardiac function via the trigeminal system. This experimental model is suitable for the analysis of the systemic effects of occlusal destruction.

Animals↗

PubMedDate not supplied

Use of the monoclonal antibody M30 for detecting HSG cell apoptosis.

An immunocytochemical method using a monoclonal antibody (MoAb), M30, which reacts with the product resulting from the cleavage of cytokeratin 18 by activated caspase, was applied to detect the apoptosis of human salivary gland tumor (HSG) cells induced by epigallocatechin gallate (EGCG), gallic acid (GA) and sodium ascorbate (SA). EGCG, GA and SA dose-dependently induced HSG cell death. Immunoreactive products were significantly observed in the cytoplasm of HSG cells after treatment with all these compounds. The reactions occurred with lower concentrations of these agents and after shorter treatment times, in comparison with DNA fragmentation detected by the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) method. These results suggest that immunocytochemical staining with the MoAb M30 may be useful for detecting the apoptosis-inducing activities of various chemical compounds.

Antibodies, Monoclonal↗

PubMedDate not supplied

Induction of apoptosis by dopamine in human oral tumor cell lines.

Dopamine dose-dependently reduced the viable cell number of both human salivary gland tumor HSG and oral squamous cell carcinoma HSC-2, HSC-4, and NA cells. CoCl2 significantly reduced both the cytotoxic activity and radical intensity of dopamine (determined by ESR spectroscopy). Dopamine produced DNA fragments (demonstrated by TUNEL method) and induced degradation of cytokeratin by activated caspase in HSG cells (detected by an immunocytochemical method, using a specific M30 monoclonal antibody). FACS analysis demonstrated that dopamine induced DNA fragmentation, a biochemical hallmark of apoptosis, in human promyelocytic leukemia HL-60 cells. The addition of catalase did not prevent the apoptosis-inducing activity of dopamine, reducing the possibility of the involvement of H2O2 for dopamine-induced apoptosis. Dopamine transiently induced p38 mitogen-activated protein kinase (MAP kinase) phosphorylation. However, an inhibitor of p38 MAP kinase phosphorylation, SB203680, failed to inhibit the dopamine-induced apoptosis. These data suggest that p38 phosphorylation at an early stage may not be a causative event for apoptosis.

Apoptosis↗

PubMedDate not supplied

Changes in intracellular concentrations of amino acids and polyamines during the apoptosis of HL-60 cells.

Possible changes in the intracellular concentrations of amino acids and polyamines were investigated during the apoptosis of human promyelocytic leukemic HL-60 cells. Treatment of HL-60 cells with sodium 5,6-benzylidene-L-ascorbate (SBA) or sodium ascorbate induced apoptotic cell death characterized by chromatin condensation, nuclear fragmentation, loss of microvilli, and production of numerous vacuoles and apoptotic bodies. The apoptosis was accompanied by a significant increase in the intracellular concentration of almost all neutral and basic amino acids (regardless of their polarity). On the other hand, the concentration of glutamic acid, the most abundant amino acid in the cells, was significantly reduced. These data suggest the reduced amino acid utilization and possible membrane impairment, especially in SBA-treated cells. Among three major polyamines, the intracellular concentration of putrescine rapidly declined, whereas that of spermidine and spermine was almost unchanged during apoptosis. Conversely, the concentration of putrescine, but not that of spermidine and spermine, was significantly increased during the chemically-induced carcinogenesis of mouse liver tissue. The present study demonstrates that the putrescine level is the most sensitive to the proliferation capability of the cells, among three polyamines, and provides an early marker for apoptosis and proliferation.

Amino Acids↗

PubMedDate not supplied

Induction of apoptosis by flavones, flavonols (3-hydroxyflavones) and isoprenoid-substituted flavonoids in human oral tumor cell lines.

Various flavones, flavonols (3-hydroxyflavones) and isoprenoid-substituted flavones (flavonols) were investigated for their cytotoxic activity. Most of these compounds were more cytotoxic against human oral squamous cell carcinoma and salivary gland tumor cell lines than human gingival fibroblasts. The cytotoxic activity of flavonoids was generally higher than that of tannin-related compounds. Flavonoids induced apoptotic cell death characterized by DNA fragmentation (as identified by TUNEL method) and activation of caspase(s) (as identified by degradation products of cytokeratin 18 with M30 monoclonal antibody). ESR spectroscopy revealed that higher concentrations of flavonoids produced radicals under alkaline conditions. However, not all of them enhanced the radical intensity of sodium ascorbate, suggesting that the redox potential of flavonoids differs considerably from samples to samples. Catalase failed to eliminate the cytotoxic activity of flavonoids, reducing the possibility of the involvement of hydrogen peroxide for the cytotoxicity induction by them.

Apoptosis↗

PubMedDate not supplied

3,5-diacetyl-1,4-dihydropyridines: synthesis and MDR reversal in tumor cells.

Eleven 4-phenyl-3,5-diacetyl-1,4-dihydropyridines (AcDHPs) [G1-11] substituted at the phenyl ring were synthesized and compared for their cytotoxic activity and multidrug resistance (MDR)-reversing activity in in vitro assay systems. Among them, compound [G7] showed the highest cytotoxic activity against human promyelocytic leukemia HL-60 and human squamous cell carcinoma HSC-2 cells. However, no compounds tested produced radicals at pH 7.4-12.5. The activity of P-glycoprotein (Pgp) responsible for MDR in tumor cells was reduced by compounds [G2, 3, 6, 5, 8, 1, 11], verapamil [VP] and nifedipine [NP]. However, compounds [G4, 7, 10] were hardly active while G9 did not show a MDR reversing effect at 2.0-20.0 micrograms/mL. These data show a relationship between chemical structures and MDR-reversing effect on tumor cells.

Antineoplastic Agents↗

PubMedDate not supplied

Selective cytotoxic activity of grape peel and seed extracts against oral tumor cell lines.

Grape seed extracts were more cytotoxic than grape peel extracts. Methanol and 70% methanol extracts of grape seed selectively killed two human oral tumor cell lines, more efficiently than human gingival fibroblasts. ESR spectroscopy revealed that these extracts produced radicals under alkaline conditions and enhanced the radical intensity of sodium ascorbate at higher concentrations. On the other hand, lower concentration of these extracts slightly reduced the radical intensity of sodium ascorbate, and scavenged superoxide anion, generated by hypoxanthine and xanthine oxidase reaction. These properties of grape seed extracts suggest their possible application for cancer prevention.

Anticarcinogenic Agents↗

PubMedDate not supplied

Antimicrobial and radical modulation activity of AV-07, a poly-herbal formula.

An extract of AV-07 was investigated for various biological activities. Pretreatment of mice with the AV-07 extract significantly protected them from lethal infection with E. coli. ESR spectroscopy showed that the extract produced radicals under alkaline conditions and enhanced the radical intensity of sodium ascorbate, suggesting its pro-oxidant action at higher concentrations. The extract effectively scavenged superoxide anion, produced by hypoxanthine-xanthine oxidase reaction and hydroxyl radical, produced by Fenton reaction. These data demonstrate that AV-07 extract contains various bioactive substances, suggesting its medicinal efficacy.

Animals↗

PubMedDate not supplied

Interaction between hydroquinone and ascorbic acid derivatives: quenching effect of organic solvents.

The interaction between hydroquinone (HQ) and ascorbic acid analogs was investigated. Semiquinone radicals (SQ.) generated by HQ were comparably scavenged by ascorbic acid, sodium ascorbate and ascorbate 6-palmitate, but much less efficiently by ascorbate 2,6-dipalmitate. Organic solvents, such as dimethysulfoxide (DMSO) or ethanol, which are utilized for solubilization of water-insoluble analogs, ascorbate 6-palmitate and ascorbate 2,6-dipalmitate, also scavenged SQ.. DMSO scavenged the SQ. more efficiently than ethanol. This suggests the importance of considering such a quenching effect of organic solvent in the study of the interaction between HQ and antioxidants. The involvement of the ascorbate radical for cytotoxicity induction is discussed.

Ascorbic Acid↗

PubMedDate not supplied

Role of carbohydrate moiety in granulocyte colony stimulating factor.

Biological activities of two granulocyte-colony stimulating factor (G-CSF) preparations with (Lenograstim) or without (Filgrastim) sugar moiety were compared. Both G-CSF preparations similarly enhanced the N-Formyl-Met-Leu-Phe-induced-migration of human peripheral blood polymorphonuclear cells, but did not significantly affect the proliferation of human oral tumor cell lines (HSC-2, HSG). However, Lenograstim induced cytotoxicity (accompanied by the production of cytoplasmic vacuoles and large DNA fragments) in human promyelocytic leukemic cells HL-60, more potently than Filgrastim. Lenograstim, but not Filgrastim, enhanced the cytotoxic activity of sodium ascorbate. In contrast to Lenograstim, Filgrastim was degraded gradually, but too slowly to explain its lower biological activity. These data suggest that the carbohydrate moiety in G-CSF might confer unique biological activities.

Ascorbic Acid↗