Cell-based screen for identification of inhibitors of tubulin polymerization.

This assay is based on morphological changes of rat glioma cells treated with db-cAMP. The db-cAMP treatment induces a tubulin-dependent change causing the cells to acquire a spherical shape. Pretreatment with tubulin inhibitors brings about the disintegration of tubulin polymer and/or prevents its polymerization.

Time to talk: counselling for people with dysphasia.

In this small-scale qualitative study, 20 dysphasic people, including some with severe language impairments, were offered up to 20 sessions of individual counselling. The trained counsellors were a speech and language therapist and a teacher who had personal experience of dysphasia. The paper describes how the service was set up, and how it was evaluated through the use of interviews before, during and after the process of counselling.

Tubercidin analogs from the ascidian Didemnum voeltzkowi.

Two new 5'-deoxypyrrolo[2,3-d]pyrimidine (7-deazapurine) nucleosides, 5'-deoxytubercidin and 5'-deoxy-3-bromotubercidin, were identified from the ascidian Didemnum voeltzkowi. Two known anomers of 5'-deoxy-3-iodotubercidin were also purified from the extract. Assignments were made on the basis of 1H and 13C chemical shifts as well as HPLC-MS experiments.

Differences in the topoisomerase I cleavage complexes formed by camptothecin and wakayin, a DNA-intercalating marine natural product.

Wakayin is bispyrroloiminoquinone isolated from a Clavelina sp. ascidian by cytotoxicity directed fractionation. Like camptothecin, it has been found to inhibit the topoisomerase I catalyzed relaxation of supercoiled DNA.

Endo-exonuclease of human leukaemic cells: evidence for a role in apoptosis.

Inactive forms of endo-exonuclease, activated in vitro by treatment with trypsin, have been identified in human leukaemic CEM and MOLT-4 cells. They comprise over 95% of the total single-strand DNase activity in nuclei and are mainly bound to chromatin and the nuclear matrix. The activated enzyme had Mg2+(Mn2+)-dependent, Ca(2+)-stimulated activities with single- and double-strand DNAs and RNA (polyriboadenylic acid) and other properties characteristic of endo-exonucleases previously described.

Increased tubulin acetylation accompanies reversion to stable ploidy in vincristine-resistant CCRF-CEM cells.

The T-cell leukemia line CCRF-CEM is unstable with respect to ploidy, whereas a vincristine-resistant subline, CEM/VCR R, maintains a stable pseudodiploid karyotype. Ploidy change in the parental cells requires the involvement of two cell cycle lesions. The first, in mitosis, prevents cell division after S-phase.

Resistance to apoptotic cell death in a drug resistant T cell leukaemia cell line.

In this study, we investigated the responses of the T cell leukaemia cell line, CCRF-CEM, and a vincristine-resistant subline, CEM/VCR R, to the induction of cell death by serum withdrawal. This treatment was used to overcome any contribution of P-glycoprotein-mediated drug resistance to the responses of the CEM/VCR R cells. Following serum withdrawal both cell lines exhibited typical apoptotic responses including morphological changes and nucleosomal cleavage of the DNA.

Topoisomerase II-mediated DNA cleavage by adocia- and xestoquinones from the Philippine sponge Xestospongia sp.

Investigation of an orange Xestospongia sp. sponge collected at Cape Bolinao in northern Luzon, Philippines, yielded the known compounds adociaquinones A and B (1, 2) and six new metabolites, secoadociaquinones A and B (3, 4), 14-methoxyxestoquinone (5), 15-methoxyxestoquinone (6), 15-chloro-14-hydroxyxestoquinone (7), and 14-chloro-15-hydroxyxestoquinone (8). All compounds showed inhibition of topoisomerase II in catalytic DNA unwinding and/or decatenation assays.

Tubulin alterations in taxol-induced apoptosis parallel those observed with other drugs.

We have described previously that during apoptosis cellular tubulin is reorganized into visible tubulin structures that correlate with apoptotic morphology. Such changes have been observed in human leukaemic cells treated with a variety of cytotoxic agents. These structures are unlike those seen in untreated non-mitotic or mitotic cells.

Polymerization of tubulin in apoptotic cells is not cell cycle dependent.

Prominent, specific tubulin structures were identified in human leukemic cells undergoing apoptosis following treatment with cytotoxic drugs. In order to determine whether tubulin reorganization was dependent upon the stage of the cell cycle at which apoptosis was induced, the human leukemic T-cell line CCRF-CEM was treated with cytotoxic doses of drugs known to arrest cells at different stages of the cell cycle. Apoptosis was confirmed by the detection of characteristic single and multiple nucleosome-sized fragments by agarose gel electrophoresis of isolated DNA.

Establishment of an in vitro model for cisplatin resistance in human neuroblastoma cell lines.

Two unique cisplatin-resistant neuroblastoma (NB) cell lines have been derived from the established lines IMR-32 and SK-N-SH by treatment with escalating doses of cisplatin. IMR/CP.20 was 6.

Inhibition of topoisomerase II catalytic activity by pyridoacridine alkaloids from a Cystodytes sp. ascidian: a mechanism for the apparent intercalator-induced inhibition of topoisomerase II.

Several new pyridoacridine alkaloids, dehydrokuanoniamine B (1), shermilamine C (2), and cystodytin J (3), in addition to the known compounds cystodytin A (4), kuanoniamine D (5), shermilamine B (6), and eilatin (7), were isolated from a Fijian Cystodytes sp. ascidian. Their structures were determined by analyses of spectroscopic data.

Bistramides A, B, C, D, and K: a new class of bioactive cyclic polyethers from Lissoclinum bistratum.

The isolation and characterization is described of four novel cyclic polyethers, bistramides B [2], C [3], D [4], and K [5], which are closely related to the previously reported bistramide A [1] from the New Caledonian urochordata Lissoclinum bistratum. The structures of these metabolites were defined by spectroscopic methods. The four compounds exhibited in vitro cytotoxicity toward six tumor cell lines, including the human non-small cell lung carcinoma (NSCLC-N6) line.

Eusynstyelamide, a highly modified dimer peptide from the ascidian Eusynstyela misakiensis.

Eusynstyelamide, a novel peptide derivative from the ascidian Eusynstyela misakiensis, was isolated and characterized by spectroscopic methods.

A rapid mechanism-based screen to detect potential anti-cancer agents.

Several mutant Chinese hamster ovary (CHO) cell lines have been adapted to the microtiter tetrazolium assay in order to obtain useful mechanistic information relevant to the cytotoxic activity of marine natural products. The sensitivity of a DNA double-strand break repair deficient CHO line, xrs-6, was compared with that of a DNA repair competent CHO line, BR1, to several known drugs. The deficiency of the xrs-6 cells makes them overly sensitive to compounds [e.

Presence of serotonin in the venom of Conus imperialis.

The bioactive components in the venoms of cone snails are largely small peptides which target to a diverse set of ion channels and neuronal receptors. We report here the presence of substantial levels of serotonin in the venom of the imperial cone snail, Conus imperialis. This venom also contains many small bioactive peptides.

A study on the mechanism of action of sceptrin, an antimicrobial agent isolated from the South Pacific sponge Agelas mauritiana.

The mechanism of action of sceptrin, an antimicrobial agent isolated from the sponge Agelas mauritiana, was investigated. Sceptrin has been reported to exhibit antibacterial and antifungal activities. In our studies, sceptrin demonstrated a bacteriostatic rather than bactericidal effect on exponentially growing Escherichia coli cells at the MIC.

Makaluvamines, marine natural products, are active anti-cancer agents and DNA topo II inhibitors.

The makaluvamines were isolated from a sponge of the genus Zyzzya by following bioactivity against the human colon carcinoma cell line, HCT 116. These compounds have considerable cytotoxic activity. The makaluvamines appear to be acting through inhibition of DNA topoisomerase II.

The crime cocktail: licensed premises, alcohol and street offences.

There is widespread acknowledgment for a connection between alcohol consumption and crime, but the extent of the connection and its implications continue to promote debate. Previous research has concentrated on assessment of alcohol involvement of offenders following arrest. Not all incidents coming to the notice of police result in an arrest.

Applications of the improved computerized analysis of 2D INADEQUATE spectra.

This paper illustrates the use of the program CCBond to determine the carbon skeletons of bioorganic molecules in low concentration samples. Discussed is the structure elucidation of bistramide A, a compound extracted from a Fijian Lissoclinum sp. and cholesterol in 71- and 20-mumol samples, respectively.

Psammaplysin C: a new cytotoxic dibromotyrosine-derived metabolite from the marine sponge Druinella (= Psammaplysilla) purpurea.

The new, cytotoxic dibromotyrosine-derived metabolite psammaplysin C [3], in addition to the two known psammaplysins A [1] and B [2], was isolated from the marine sponge Druinella purpurea. All three compounds were found to possess moderate in vitro cytotoxicity towards the human colon tumor cell-line HCT116.

Patellamide E: a new cyclic peptide from the ascidian Lissoclinum patella.

A new cyclic peptide, patellamide E [1], was isolated from the ascidian Lissoclinum patella collected at Pulau Salu, Singapore. Its structure was determined by nmr spectroscopy, and its absolute configuration by acid hydrolysis and analysis of the derivatized constituent amino acids by hplc. Patellamide E was mildly cytotoxic against human colon tumor cells in vitro.

Analysis of N-ras gene mutations in acute myeloid leukemia by allele specific restriction analysis.

N-ras gene activation occurs via single base substitutions in codons 12, 13, and 61. We have developed a rapid screening method, termed allele specific restriction analysis (ASRA), for detection of N-ras mutations at these three critical codons in acute myeloid leukemia (AML). Patient DNA samples are amplified by the polymerase chain reaction (PCR) by using primers that induce restriction sites in normal but not mutant N-ras alleles.

Allele-specific enrichment: a method for the detection of low level N-ras gene mutations in acute myeloid leukemia.

Point mutations involving codons 12, 13, and 61 of the N-ras gene are found in patients with acute myeloid leukemia (AML). We have developed a sensitive assay for the analysis of these mutations which we have called allele-specific enrichment. In this protocol the polymerase chain reaction (PCR) amplifies DNA with primers that introduce new restriction sites into the normal N-ras allele only.

Lissoclinolide, the first non-nitrogenous metabolite from a Lissoclinum tunicate.

The isolation and characterization of a new metabolite from the tunicate Lissoclinum patella is described. The structure of lissoclinolide [1] was solved using spectral and chemical methods, and it is shown to be the first non-nitrogenous, non-sulfur-containing compound to be isolated from the genus Lissoclinum.