Biomedical subjects

S Furuya

Publications and source records attributed to S Furuya.

185 records · Page 11Linked to original sources

PubMedDate not supplied

Effect of epidermal growth factor on mouse sperm acrosome reaction induced by zona pellucida.

PROBLEM: The effect of epidermal growth factor (EGF) on the acid-solubilized zona pellucida (ZP)-induced acrosome reaction was investigated in mouse sperm. METHOD: Mouse epididymal sperm were capacitated in modified Krebs-Ringer bicarbonate buffer (m-KRB) for 120 min and further treated with acid-solubilized ZP(4 zona/microliters) for an additional 60 min to induce the acrosome reaction. The chlortetracycline fluorescence assay was used to monitor the acrosome reaction. The acrosome reacted sperm featured the acrosome reacted (AR) pattern, which demonstrates the lack of fluorescence on the head and bright midpiece. RESULTS: EGF caused an early increase in the AR pattern in response to the acid-solubilized ZP in a dose-dependent manner. The EGF-dependent stimulation of the ZP-induced acrosome reaction was inhibited by an inhibitor of protein tyrosine kinases, genistein or activators of Ca++ and phospholipid-dependent protein kinase (protein kinase C). Furthermore, the stimulatory effect of EGF was not attenuated when sperm were capacitated in the presence of islet-activating protein, an inactivator of inhibitory guanine nucleotide-binding regulatory protein (Gi protein). CONCLUSION: EGF stimulates the ZP-induced acrosome reaction in a manner that is independent of the Gi protein. The EGF action is regulated by protein tyrosine kinase and protein kinase C.

Acrosome↗

PubMedDate not supplied

Does aggressive surgical resection improve the outcome in advanced gallbladder carcinoma?

BACKGROUND/AIMS: Patients with advanced gallbladder carcinoma have usually been considered nonresectable, leading to a very poor outcome. This study was aimed to evaluate the results of our aggressive surgical approaches in certain cases of advanced gallbladder carcinoma. METHODOLOGY: Ninety-one patients with advanced gallbladder carcinoma of stages pT3 and pT4 who underwent surgery at our institution were the subjects of this study. Fifty-eight of 91 patients had surgical excision; 44 by hepatic resection and 14 by hilar resection. Post-operative outcome was evaluated. Advanced gallbladder carcinomas were classified according to our previously reported classification: type I hepatic; type II biliary; type III hepatobiliary; type IV others. RESULTS: Curative resection was obtained at a more increased rate in type I tumor patients than in types II and III (91% vs. 29%, p < 0.01). The surgical mortality rate was 17%. Survival rates of resected patients were significantly higher that those of nonresected patients: 45%, 31%, 22%, 17%, 13% at 1, 2, 3, 4, 5 years vs. 9%, 9%, 0% at 1, 2, 3 years (p < 0.01). Survival rates of type I tumor patients after curative resection were remarkably higher than those of type II and III tumor patients, (69%, 64%, 56%, 48%, 39% at 1, 2, 3, 4, 5 years vs. 17%, 17%, 0% at 1, 2, 3 years). CONCLUSIONS: Aggressive surgical approaches might bring about improved prognosis in advanced gallbladder carcinoma, especially for patients with type I tumors.

Adult↗

PubMedDate not supplied

Cytotoxic activity of steroidal saponins against human oral tumor cell lines.

Three steroidal saponins showed higher cytotoxicity against human oral squamous cell carcinoma cell lines (HSC-2), as compared with normal human gingival fibroblasts HGF. Tumor specificity of saponins exceeded that of tannins and flavonoids. Agarose gel electrophoresis showed that saponins failed to induce internucleosomal DNA fragmentation, but produced large DNA fragments in both HSC-2 cells and human promyelocytic leukemic HL-60 cells. In contrast to epigallocatechin gallate or gallic acid, cytotoxic activity of saponins was not significantly affected by metals (Co2+, Cu2+, Fe3+) nor by antioxidants (sodium ascorbate, N-acetyl-L-cysteine, catalase). Furthermore, saponins did not produce radicals (detected by ESR spectroscopy) nor oxidation potential (measured by NO monitor). These data suggest that an oxidation-mediated mechanism is not involved in the cytotoxicity induced by steroidal saponins.

Antineoplastic Agents↗

PubMedDate not supplied

Cytotoxic activity of saponins from Camassia leichtlinii against human oral tumor cell lines.

Five steroidal saponins from Camassia leichtlinii showed higher cytotoxicity against human oral squamous cell carcinoma cells HSC-2, as compared to normal human gingival fibroblasts HGF. The tumor specificity of saponins varied considerably from sample to sample, but was generally higher than that of tannins, flavonoids and prenylated compounds such as geranylgeraniol and vitamin K2 (MK-2). Agarose gel electrophoresis showed that the saponins failed to induce internucleosomal DNA fragmentation, but produced large DNA fragments in HSC-2 cells, whereas two saponin samples (compounds 1 and 5) induced internucleosomal DNA fragmentation in human promyelocytic leukemic HL-60 cells. In contrast to epigallocatechin gallate or gallic acid, the cytotoxic activity of saponins was not significantly affected by metals (Co2+, Cu2+, Fe3+) or by antioxidants (sodium ascorbate, N-acetyl-L-cysteine, catalase). Furthermore, the saponins did not produce radicals (detected by ESR spectroscopy) nor oxidation potential (measured by NO monitor). These data suggest that an oxidation-mediated mechanism is not involved in the cytotoxicity induced by the steroidal saponins.

Antineoplastic Agents, Phytogenic↗

PubMedDate not supplied

Interaction of amino acid-substituted partial extension peptides of adrenodoxin precursor with artificial membranes and isolated mitochondria.

The N-terminal fragment Met-Ala-Ala-Arg-Leu-Leu-Arg-Val-Ala-Ser-Ala-Ala-Leu-Gly (PA1-14) of the adrenodoxin precursor was previously found to inhibit the import of the precursor into mitochondria. In order to obtain further information on the structure-function relationship, five analogs of PA1-14 ([Leu1]PA1-14 (1), [Leu1,Ala10]PA1-14 (2), [Leu1,Ser4]PA1-14 (3), [Leu1,Arg11]PA1-14 (4) and [Leu1,Ser7,Arg10]PA1-14 (5) were synthesized. The CD study showed that PA1-14 and all analogs were random in an aqueous solution and formed an alpha-helical structure in the solution containing acidic liposomes. Peptides 1 and 2 were found to cause dye leakage from lipid vesicles more strongly than other analogs and PA1-14. All analogs completely inhibited the import of the precursor into mitochondria at a concentration of 30 microM. However, 1 and 2 destroyed the mitochondrial membrane potential. These results indicate that an increase in hydrophobicity by replacement of the Met and Ser residues by Leu and Ala, respectively, participates in the perturbation of the membranes. Furthermore, the requirement for the number and position of the Arg residue was found to be not very strict, although its presence in the extension peptide is essential for the precursor to import into mitochondria.

1,2-Dipalmitoylphosphatidylcholine↗