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J Alder

Publications and source records attributed to J Alder.

5 recordsLinked to original sources
PubMed1992

Calcium-dependent transmitter secretion reconstituted in Xenopus oocytes: requirement for synaptophysin.

Calcium-dependent glutamate secretion was reconstituted in Xenopus oocytes by injecting the oocyte with total rat cerebellar messenger RNA (mRNA). Co-injection of total mRNA with antisense oligonucleotides to synaptophysin message decreased the expression of synaptophysin in the oocyte and reduced the calcium-dependent secretion. A similar effect on secretion was observed for oocytes injected with total mRNA together with an antibody to rat synaptophysin. These results indicate that synaptophysin is necessary for transmitter secretion and that the oocyte expression system may be useful for dissecting the molecular events associated with the secretory process.

Animals↗
PubMed1992

Antibodies to synaptophysin interfere with transmitter secretion at neuromuscular synapses.

The involvement of synaptophysin, a synaptic vesicle-specific protein, in transmitter release at neuromuscular synapses was studied by intracellular application of synaptophysin antibodies into presynaptic neurons. Polyclonal antibodies or their Fab fragments were loaded into spinal neurons by injection into one of the early blastomeres of Xenopus embryos 1 day prior to culturing or, alternatively, directly through a whole-cell recording pipette at the soma of cultured neurons. At synapses made by antibody-loaded neurons in culture, the spontaneous synaptic currents showed marked reduction in frequency without significant change in their mean amplitude. The impulse-evoked synaptic currents showed reduced amplitude and increased failure rate. These results suggest that interference with synaptophysin function by antibody binding inhibits transmitter secretion.

Animals↗
PubMed1992

Synthesis and antitumour activities of quinolone antineoplastic agents.

DNA topoisomerases, found in all prokaryotic and eukaryotic cells, play a key role in controlling the topological state of DNA. Quinolone antibacterial agents have been shown to be inhibitors of DNA gyrase, a bacterial topoisomerase II enzyme. The eukaryotic topoisomerase II is the target of various cytotoxic agents such as adriamycin and etoposide. Recently, several quinolones having C-8 fluoro and C-8 chloro substituents have been found to have cytotoxic activities and to interact with mammalian topoisomerase II. In searching for an antitumour agent of the quinolone class, we identified several quinolones having excellent in vitro cytotoxic activity. A-74932 also possesses good activity in vivo against both systemic tumour and subcutaneously implanted murine solid tumours as well as human tumour xenografts. The chemical synthesis as well as biological properties of A-74932 are described.

Animals↗
PubMed1986

Prognostic importance of DNA flow cytometry in non-Hodgkin's lymphomas.

Eighty one cases of non-Hodgkin's lymphoma were examined by DNA flow cytometry, using fixed embedded histological tissue. The frequency of detection of DNA aneuploidy and the values for S phase fractions depended on the histological subtype and grade of lymphoma. Twenty two of the patients with low grade centroblastic/centrocytic non-Hodgkin's lymphoma had repeat biopsies. Eleven of these patients remained histologically and cytometrically stable, but the remaining eleven transformed into high grade non-Hodgkin's lymphoma. The mean value for the S phase fraction in the initial biopsy specimens from patients which transformed was higher than that for patients whose lymphomas remained stable (p less than 0.001). It is proposed that estimates of S phase fraction prospectively identify patients with low grade non-Hodgkin's lymphoma at risk from transformation.

Aneuploidy↗