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A Rose

Publications and source records attributed to A Rose.

At least 55 records · Page 3Linked to original sources
PubMed1998

The bis(naphthalimide) DMP-840 causes cytotoxicity by its action against eukaryotic topoisomerase II.

DMP 840 ((R,R)-2,2'-[1,2-ethanediylbis[imino(1-methyl-2, 1-ethanediyl)]-bis(5-nitro-1H-benz[de]isoquinoline-1,3(2H)-dione] dimethanesulfonate) is a novel bis(naphthalimide) that has shown promising antitumor activity in a variety of preclinical model systems. The compound binds to DNA with high affinity and intercalates, but the mechanism of cell killing has not been elucidated. We have used yeast strains to test whether DMP-840 is active against either topoisomerase I or II. We found that temperature-sensitive top2 mutants resistant to etoposide or amsacrine also confer resistance to DMP-840. In addition, cells overexpressing yeast topoisomerase II were hypersensitive to the drug. By contrast, top1 deletions rendered cells hypersensitive to the drug. These results strongly suggest that DMP-840 acts against eukaryotic topoisomerase II and kills cells by converting the enzyme into a cellular poison. We verified that DMP-840 is active against eukaryotic topoisomerase II by demonstrating that the drug stimulates formation of a cleavage complex with purified yeast topoisomerase II in vitro. We also demonstrated that the drug is active against human topoisomerase II by showing that expression of human topoisomerase II restored sensitivity of resistant yeast cells to DMP-840. We have also directly demonstrated that DMP-840 acts as a poison against purified human topoisomerase II alpha. Taken together, these results indicate that DMP-840 acts like other intercalating topoisomerase II poisons; it kills eukaryotic cells by stabilizing the cleavage complex of topoisomerase II with DNA.

Adenine↗
PubMed1998

Regulation of enzymes involved in anthocyanin biosynthesis in carrot cell cultures in response to treatment with ultraviolet light and fungal elicitors.

The accumulation of anthocyanins in cell cultures of Daucus carota L. and the enzymes involved in their biosynthesis were investigated under growth in the dark, continuous irradiation with UV light, incubation with elicitors from Pythium aphanidermatum, and elicitor treatment of UV-irradiated cells. Upon UV irradiation, anthocyanin accumulation was strongly enhanced, and the enzymes of the phenylpropanoid and flavonoid pathways, including the "late" enzymes cyanidin galactosyltransferase, cyanidin galactoside xylosyltransferase, cyanidin triglycoside sinapoyltransferase and sinapic acid glucosyltransferase, all showed transient increases in their activities. The time courses of the enzyme activities exhibited successive maxima with an ordered sequence corresponding to their position in the biosynthetic pathway, suggesting a coordinated induction of the entire set of enzymes. The key enzymes phenylalanine ammonia-lyase and chalcone synthase are regulated on a transcriptional level. Incubation of dark-grown carrot cells with fungal elicitors led to a rapid and transient induction of phenylalanine ammonia-lyase corresponding to the formation of 4-hydroxybenzoic acid, but the amount of anthocyanin did not increase and there was no enhancement of any of the enzyme activities which are part of the anthocyanin pathway, including the enzymes catalyzing glycosylation and acylation reactions. Treatment with UV light and elicitors resulted in a rapid induction of the phenylpropanoid pathway, whereas the inducing effect of UV light on the anthocyanin content, on chalcone synthase and on the enzymes catalyzing the final steps of anthocyanin biosynthesis was suppressed. These results indicate a coordinated regulation of the enzymes involved in anthocyanin biosynthesis, an independent inducibility of the phenylpropanoid pathway, and a hierarchy of the different effectors, as shown by the dominating role of the elicitor-signal over the UV stimulus.

Anthocyanins↗
PubMed1997

Alignment of the genetic and physical maps in the dpy-5 bli-4 (I) region of C. elegans by the serial cosmid rescue of lethal mutations.

Lethal mutations in the 0.5 map unit region between dpy-5 and bli-4 on chromosome I in Caenorhabditis elegans were serially rescued using cosmid-containing transgenic strains. All the lethal mutations analyzed came from a set of 495 EMS-induced, sDp2-rescued lethals described previously. Germline transformation with cosmid DNA was used to create 25 transgenic strains bearing heritable extrachromosomal arrays. These arrays were used as small duplications for the fine-scale mapping of essential genes, via the rescue of lethal mutations. Lethal mutations in 13 essential genes have been phenotypically rescued, allowing the alignment of the genetic and physical maps in this region. Extrachromosomal arrays were found to be transmitted 2- to 7-fold less frequently in oocytes than in hermaphrodite sperm for 12 of the 16 arrays that were examined. Three of these strains showed a subsequent 4- to 13-fold increase in array stability in oocytes. This phenomenon may be influenced by cosmid sequences. Early mitotic loss of the arrays was observed in all 17 transgenic strains examined, suggesting that loss of the array can occur at any time during development when cell divisions are occurring. As a result of this work, 13 of the essential loci positioned between dpy-5 and bli-4 are anchored to the physical map, thereby providing links between the physical and genetic maps on average every 85 kb.

Animals↗
PubMed1997

Transforming growth factor-beta 3 mediated modulation of cell cycling and attenuation of 5-fluorouracil induced oral mucositis.

Mucositis is a common, dose-limiting complication in patients receiving cancer chemotherapy, which derives from damage to the epithelial cell layer. We have shown that transforming growth factor-beta 3 (TGF-beta 3) negatively regulates epithelial cell proliferation and reduces the incidence of oral mucositis. Here, we report the findings of a large study examining the effects of TGF-beta 3 administration in a hamster model on oral epithelial cell cycling in vivo, on oral mucositis, on weight retention and on survival. Topical application of TGF-beta 3 to the buccal mucosa significantly reduced basal cell proliferation, as measured by proliferating cell nuclear antigen (PCNA) immunohistochemistry and DNA ploidy. Administration of topical TGF-beta 3 prior to chemotherapy with 5-fluorouracil (5-FU) significantly reduced the severity of mucositis with respect to time, reduced chemotherapy-associated weight loss and increased survival.

Administration, Topical↗
PubMed1996

Functional expression of human topoisomerase II alpha in yeast: mutations at amino acids 450 or 803 of topoisomerase II alpha result in enzymes that can confer resistance to anti-topoisomerase II agents.

DNA topoisomerase II is the target of a variety of important antitumor agents, including etoposide, adriamycin, and amsacrine. We have constructed a system for analyzing the action of anti-topoisomerase II agents using the yeast Saccharomyces cerevisiae and have constructed vectors for expressing human topoisomerase II functionally in yeast. We have demonstrated that temperature-conditional yeast TOP2 mutants can be complemented by expression of wild-type human topoisomerase II alpha. Furthermore, expression of human topoisomerase II in yeast results in a quantitatively unique pattern of sensitivity to amsacrine. We also have constructed mutations in human TOP2 based on previously identified mutations from a human cell line selected for resistance to teniposide. Our experiments demonstrate that mutation of either arginine 450 or proline 803 of human topoisomerase II can result in an enzyme that has altered sensitivity to anti-topoisomerase II agents, and that a human enzyme carrying both mutations confers a higher level of drug resistance than enzymes carrying either single mutation.

Alleles↗
PubMed1996

Purification and characterization of glycosyltransferases involved in anthocyanin biosynthesis in cell-suspension cultures of Daucus carota L.

The major anthocyanins accumulated by an Afghan cultivar of Daucus carota L. are cyanidin 3-(xylosylglucosylgalactosides) acylated with sinapic or ferulic acid. The formation of the branched triglycoside present as a common structural element requires an ordered sequence of glycosylation events. Two of these enzymic glycosylation reactions have been detected in protein preparations from carrot cell-suspension cultures. The first step is a galactosyl transfer catalyzed by UDP-galactose: cyanidin galactosyltransferase (CGT) resulting in cyanidin 3-galactoside. The putative second step is the formation of cyanidin 3-(xylosylgalactoside) catalyzed by UDP-xylose: cyanidin 3-galactoside xylosyltransferase (CGXT). Both enzyme activities were characterized from crude protein preparations. The CGT was purified 526-fold from the cytosolic fraction of UV-irradiated cell cultures by ion-exchange chromatography on diethylaminoethyl (DEAE)-Sephacel, affinity chromatography on Blue Sepharose CL-6B, gel permeation chromatography on Sephadex G-75 and elution from the gel matrix after non-dissociating PAGE. Its molecular mass was estimated by SDS-PAGE and by calibrated gel permeation chromatography on Sephadex G-75. In both cases a molecular mass of 52 kDa was determined, indicating that the native protein is a monomer of 52 kDa. The galactosyl transfer and the xylosyl transfer are presumed to be catalyzed by separate enzymes.

Anthocyanins↗
PubMed1996

Multicentre dosimetry study of mantle treatment in Australia and New Zealand.

PURPOSE: To determine the difference between expected and measured dose for patients prescribed a mantle treatment for Hodgkin's disease and estimate the range of dose at critical sites and between different treatment centres. METHODS AND MATERIALS: Twenty three radiotherapy centres were surveyed with regard to the accuracy of dose delivery to a custom-built upper-torso phantom. Thermoluminescent dosimeters were used to monitor the delivered dose at sites such as mid-plane, spinal cord, neck, axilla and lung. RESULTS: The intended dose to the phantom at each centre was 1 Gy to central axis mid-plane. Of the centres surveyed, the median measured dose to this region was 0.96 Gy with a minimum of 0.92 and a maximum of 1.00 Gy. Median dose to the axilla region was low (0.90 Gy) whereas median dose to the blocked lung and neck region were higher than expected, 0.18 Gy and 1.25 Gy, respectively. The 95% confidence interval on the reported relative dose using the 4000 thermoluminescence dosimetry readings in this study was +/- 1.5% CONCLUSION: In this controlled experiment, using conventional methods to calculate dose, there was a surprising variability in the dose delivered at the central axis mid-plane position. This was traced to lack of uniformity in the use of equivalent squares to calculate the output factor. The measured doses to axilla and lung are explained by photon and electron scattering effects. Centres, where dose compensation was included, had a superior dose homogeneity in the neck. The off-axis dose calculations depend on computer planning software but the magnitude of these differences is secondary to that of central axis mid-point dose differences. Improved consistency of dose calculation techniques between centres would enable more reliable dose response evaluation from multicentre clinical studies of Hodgkin's disease.

Australia↗
PubMed1996

Dietary fiber in weaning cereals: a study of the effect on stool characteristics and absorption of energy, nitrogen, and minerals in healthy infants.

We evaluated the effect of increased dietary fiber (DF) content in weaning cereals based on wheat/soy (8.0 and 1.8% DF) and wheat/milk (5.3 and 2.0% DF) in healthy, formula-fed infants 7-17 weeks old. The study had a cross-over design, each infant acting as his or her own control. Stool characteristics and anthropometry were monitored over 4-week periods in groups of 34 (wheat/soy) and 23 (wheat/milk) infants. Absorption of zinc (Zn) and calcium (Ca) was studied by measuring the fecal excretion of stable isotopes during 72 h (70Zn and 42Ca) in a subgroup of the infants consuming wheat/soy cereals. Iron (Fe) bioavailability was evaluated by analysis of the incorporation of 58Fe into erythrocytes 14 days after administration. Fractional absorption (X +/- SD: 8.0 versus 1.8% DF) was 45.3 +/- 27.5 versus 41.2 +/- 19.4% of 70Zn and 63.4 +/- 15.8 versus 64.4 +/- 10.6% of 42Ca. Bioavailability of 58Fe varied between 1.0% and 5.4% (8.0% DF) and from <0.9% to 9.1% (1.8% DF). No significant difference in energy (95.3 +/- 2.0% versus 95.7 +/- 1.2%) or nitrogen (92.6 +/- 2.3% versus 93.0 +/- 1.6%) apparent absorption from the total diet was found during consumption of cereal with 8.0 and 1.8% DF. The intake of cereal decreased with higher DF content in the wheat/soy product: 34 +/- 23 g/d (8.0% DF) versus 42 +/- 23 g/d (1.8% DF), p < 0.01. While consuming the 8.0% DF product, 11 infants were reported to have "gritty stools"; no other differences were observed between different groups in stool characteristics or anthropometry. These results demonstrate no negative effect on the absorption of energy and nutrients with higher dietary fiber intake in primarily formula-fed infants. The impact of increased dietary fiber levels remains unknown in less well-nourished infants.

Aging↗
PubMed1996

Immunohistochemical localization of nitric oxide synthase activity in upper respiratory epithelium.

Nitric oxide (NO) production in the respiratory epithelium of the upper airways has recently been described. To better delineate the role of epithelial NO, the authors of this study attempted to identify the cell type responsible for the production of NO in rat tracheal epithelium and human nasal epithelium. They localized the activity of NO through immunohistochemical analysis with an antibody to L-citrulline, a marker for activity of the L-arginine-dependent nitric oxide synthase (NOS) pathway. Using anti-inducible NOS (iNOS) and anti-constitutive NOS (cNOS) antibodies, they also attempted to identify the specific NO isotypes that were present. The tracheal and nasal epithelium demonstrated strong immunoreactivity to citrulline in ciliated cells. The ciliated cells of the nasal turbinates demonstrated strong iNOS positivity, but no significant cNOS immunoreactivity. The study findings that iNOS activity is present in ciliated epithelial cells of rat and human upper respiratory epithelium suggest that NO may play a role in epithelial homeostasis and could potentially play a role in the pathogenesis of mucociliary dysfunction.

Animals↗
PubMed1996

Medical students in general practice: how do patients feel?

BACKGROUND: The General Medical Council has recommended that medical students should gain more experience in general practice. AIM: The study set out to determine patients' reactions to the presence of medical students in general practice consultations. METHOD: Patients attending a random sample of general practice surgeries completed a questionnaire following consultation with and without a medical student present in six general practices in the Oxford area. RESULTS: The questionnaires were completed by 278 patients. Only eight (3%) of all respondents had negative responses to the presence of a medical student. Of those completing questionnaires following a teaching consultation, 107 (56%) felt positively about the presence of students, compared with 36 (41%) who had attended a nonteaching surgery. Only three patients (1%) felt the quality of the consultation to be impaired by the presence of a student, while 48 patients (17%) felt there to be some improvement. The majority felt that the sex of the student was unimportant, but significantly more female than male patients (17% versus 5%) felt that it made a difference. CONCLUSION: Only a small proportion of patients object to the presence of a medical student in general practice consultations. A significant minority said that the presence of a student improves the consultation.

Attitude to Health↗
PubMed1995

Testicular doses in definitive radiation therapy for localized prostate cancer.

PURPOSE: To measure the dose received by the unshielded testes during a conventional course of 18 MV photon radiotherapy for localized prostate cancer and to identify the factors influencing it. METHODS AND MATERIALS: For each of four patients, a wax block containing thermoluminescent chips was attached to the posterior aspect of the scrotum in close proximity to the testes on each day of treatment during a full course of radical radiotherapy, and dose measurements were obtained. The distances between the thermoluminescent chips and the beam edge were verified by measurement from port films. The accuracy of the in vivo measurements and the factors influencing the testis dose were studied using a phantom arrangement. Six factors were considered: (a) the relative contributions from primary and scattered radiation, (b) the amount of buildup required for the thermoluminescent chips that monitored testis dose, (c) the position of the testes within the scrotum, (d) field size, (e) distance from the field lower border, and (f) the effect of port films. RESULTS: Median daily doses to the testes in four patients ranged from 5 to 7 cGy. Daily doses for the four patients ranged from 4 to 14 cGy. The total dose to the testes over the full course of therapy ranged from 1.8 to 2.4 Gy. The daily dose depended primarily on the distance from the field lower border. This was increased by approximately 2.5 cGy when a 6 MV port film was taken. The relative contributions from primary and scattered radiation were found to be similar. Dose measurements at the posterior aspect of the scrotum overestimated the testis dose by approximately 15%. CONCLUSION: The most important factors influencing the dose received by the testis are the distance from the testes to the field lower border and the occasion of a port film. A knowledge of the number of port films and the average distance from the field lower border to the testes allows a reasonable prediction of testes dose without daily measurement.

Humans↗