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Biomedical subjects

B Desoize

Publications and source records attributed to B Desoize.

At least 19 recordsLinked to original sources
PubMed1998

Cofactors in in vitro induction of apoptosis in HL60 cells by all-trans retinoic acid (ATRA).

The aim of this study was to determine the culture conditions that could modulate the induction of apoptosis by all-trans retinoic acid (ATRA). Cell viability was evaluated by trypan blue test, differentiation by nitro blue tetrazolium test, and apoptosis by morphological analysis. ATRA induced apoptosis in HL60 cells only when more than 100,000 cells/mL were seeded, while differentiation was induced regardless of the seeded cell concentration. Reduction in the concentration of foetal calf serum or glutamine in the medium led to a weak increase in apoptosis. In contrast, a dramatic enhancement of apoptosis occurred when the culture medium was supplemented with glucose or when the culture pH was decreased. These characteristics were independent of the mechanism of action of ATRA, but the action of glucose could be of significance in diabetic patients. An exchange of supernatants after 3 days of culture showed that supernatants from control cultures seeded at high cell density were better apoptosis inducers than supernatants from cultures treated with ATRA, but seeded at low cell density. Factor(s) in this supernatant which induced apoptosis was (were) removed by ultrafiltration. In conclusion, our results showed that ATRA alone cannot induce apoptosis, but can do so in conjunction with cofactors. The depletion of some components of the medium and the appearance of secreted macromolecule(s) could be cofactor(s) in the induction of apoptosis.

Apoptosis↗
PubMed1998

HL60 cells exhibit particular ultrastructural features during all-trans retinoic acid-induced apoptosis.

Ultrastructural features induced by 1 micromol/l all-trans retinoic acid (ATRA) treatment of HL60 cells were observed with transmission electron microscopy. Whilst some cells were unaffected, most of the others underwent granulocytic differentiation, starting point for apoptosis and then, possibly, secondary necrosis. First steps of apoptosis led to nuclear fragmentation into dense bodies. Then three different ways were observed: i) cells shrank and dense bodies were expelled, mostly associated with a fine lamellae of cytoplasm, ii) a secondary necrosis involved the release of apoptotic bodies without cytoplasm or iii) cells showed a dual or bipolar structure, not previously described.

Apoptosis↗
PubMed1998

Multicellular resistance: another mechanism for multidrug resistance?

Cells cultured as spheroids present an heterogeneity similar to that of tumours in vivo. In the spheroid peripheral layers, cells are proliferating, deeper cells are non-cycling, when in the aggregate centre, cells form often a necrotic core. A multicellular resistance appears in spheroids, it is a result of the cell contact to other cells (homogeneous or heterogeneous cells) and/or to the extracellular matrix. The mechanism of this resistance is not known, nevertheless, it can be hypothesised to be linked to the spheroid centre hypoxia, to the quiescence of a large fraction of the cell population and to the apoptose inhibition due to the cell contact. The classical or unicellular mechanisms of resistance, as mdr1, MRP, can coexist with the multicellular resistance, but are not responsible for this resistance. The spheroid model of culture is a good opportunity to study a resistance type which looks close to the tumour resistance found in vivo in mice and in patients. A new class of therapeutic molecules appears that can reverse this multicellular resistance, inhibit tumours growth and preclude metastases. The principal mechanism of action of this new pharmacological class appears to be the disruption of the intercellular adhesion forces. Preliminary results obtained with these compounds in patients are promising.

Journal Article↗
PubMed1996

Evaluation of a prediction model of cisplatin dose based on total platinum plasma concentration.

The aim of this study was to validate prospectively a model of cisplatin dose adjustment. 27 patients (63 courses) with lung cancer were treated by a 5 day continuous infusion of cisplatin and etoposide. The dose of cisplatin was adjusted in order to reach a target plasma concentration of total platinum (TP) of 2000 mu/l at the end of the infusion. The target concentration was reached with a mean bias of 2.7% and a precision of 7.8%. The results were compared with those of a population of 38 patients (97 courses) with lung cancer and treated with the same protocol of chemotherapy, but without dose adjustment. The average dose adjustment was an increase of cisplatin dose of 20.2%. This augmentation was most important during the first course, decreasing during the following courses. There was also an increase in the etoposide AUC, although its dose was not modified. Toxicity to polymorphonuclear cells was significantly increased and was linked to etoposide AUC.

Aged↗
PubMed1996

[In vivo evaluation of potential doubling time (Tpot) of tumors by flow cytometry: practical difficulties and possible solutions].

Kinetic parameters of tumor growth yield predictive values and allow an optimisation of the treatment schedule, especially for fractionation in radiotherapy. Among those parameters, the labelling index (LI) and the potential doubling time (Tpot) may be measured by flow cytometry, a semi-quantitative analysis, after in vivo administration of iododeoxyuridine (IdUrd) to humans. This Begg's recommended methodology needs the selection of thresholds and gates whose boundaries are arbitrary. They can be positioned on a more objective basis using a negative control (aspecific fixation). Moreover a previous identification of the different cell populations of the tumour samples according to the method of Vindelov allows a better determination of these cell populations processing IdUrd-DNA staining. This procedure was used with 11 tumour biopsies including mainly head and neck cancers. This method displayed results similar to the literature concerning LI and Tpot determinations as well as shortened Tpot when the patients recurred. One sample has no labelling at all. A small fraction, likewise up to 10% of cells exhibiting on S DNA content were not labelled by IdUrd. These cells leave the S phase or progress too slowly in order to display IdUrd uptake. Intra-tumoral hypoxia is a possible explanation of these findings. DNA ploidy and the percentage of cells in S phase could be worth while to precise the relationship between DNA index and tumour kinetic. The measurement of Tpot could also be used in other cancers and for optimisation of dose of chemotherapy.

Antibodies, Monoclonal↗
PubMed1994

Individual dose adaptation of anticancer drugs.

The dose of anticancer drugs is currently adjusted to the patient body surface area, although patients have different abilities to clear anticancer drugs. The dose adjustment to physiological functions permits major toxic accidents to be avoided. The adjustment to tumour drug content is considered, but for ethical or technical reasons, it cannot be used routinely The best criterion for the dose adjustment seems to be drug plasma concentration. The relationship between plasma concentration and efficacy may not be excellent, since it depends on the presence of resistant cells and on the blood flow through the tumour. A relationship between plasma concentration and/or the area under the curve (AUC) with toxicity has been reported with all major anticancer drugs. Different methods of dose adjustment to the drug plasma concentration are reported. In conclusion, dose adjustment to the drug plasma concentration or to the AUC can improve the chemotherapy efficacy, while reducing toxicity.

Antineoplastic Agents↗
PubMed1994

[Effects of aclarubicin on growth, differentiation and apoptosis of tumor cells in vitro].

Aclarubicine induces various effects after several days of incubation with human leukemic cells HL60: cell growth inhibition, inductions of differentiation, necrosis and apoptosis. Several methods of detection of differentiated and apoptotic cells were studied. The methods utilizing optical microscopy were used as references. Flow cytometry (FCM) appeared to have a higher sensitivity, but it yielded somewhat different results. Aclarubicine and doxorubicin have dose-dependent effects, except for the differentiation induction by aclarubicine, which had a maximum effect and then decreased; this probably means that the inductions of differentiation and apoptosis could be independent. Different kinetic studies indicated that differentiation increased quickly after 24 to 48 hours and reached a plateau toward 72 hours, where approximately 80% of the cells were differentiated. Necrosis increased at the same time, but less, with a 1 hour incubation with 75 nmol/l of aclarubicine. Apoptosis appeared in an irregular and non-reproducible manner. The kinetic study also indicated a certain independence between the differentiation and apoptosis inductions.

Aclarubicin↗
PubMed1993

The antileukemic alkaloid fagaronine is an inhibitor of DNA topoisomerases I and II.

The antileukemic alkaloid, fagaronine, is a potent differentiation inducer of various hematopoietic cell lines. We show here that fagaronine is a DNA base-pair intercalator with a K(app) of 2.1 x 10(5) M-1 for calf thymus DNA. Fagaronine inhibits the catalytic activity of purified calf thymus topoisomerase I as shown by relaxation of supercoiled plasmid DNA followed by electrophoresis in neutral as well as in chloroquine-containing gels. The catalytic activity of topoisomerase I is inhibited at concentrations above 30 microM. Fagaronine also inhibits the catalytic activity of purified calf thymus topoisomerase II at concentrations above 25 microM as shown by decatenation of kinetoplast DNA. Fagaronine stabilizes the covalent DNA-enzyme reaction intermediate (the cleavable complex) between topoisomerase I and linear pBR322 DNA at concentrations up to 1 microM. Further increase of the fagaronine concentration leads to a progressive decrease in the cleavable complex formation, which is totally inhibited at 100 microM. In contrast, up to 1 microM fagaronine has no effect on cleavable complex formation between purified calf thymus topoisomerase II and linear pBR322 DNA, whereas cleavable complex formation is inhibited at higher concentrations. Exposure to fagaronine results in an increase in DNA-protein complex formation in intact P388 murine leukemia cells. P388CPT5 cells, which have an altered topoisomerase I activity, are 4-fold resistant to the growth inhibitory effects of fagaronine compared to the parental cell line. Similarly, DC-3F/9-OH-E Chinese hamster fibrosarcoma cells, which have an altered topoisomerase II activity, are about 5-fold resistant to the growth inhibitory effects of fagaronine. We conclude that fagaronine is an inhibitor of both DNA topoisomerase I and II and propose that this might play a role in the cytotoxic activity.

Alkaloids↗
PubMed1993

[To which criterion should the dosage of anticancer drug be adapted?].

The dose of anticancer drugs is currently adjusted to the body surface area of the patient, although for a given body surface, patients have different distribution and metabolism for a given drug. The dose adjustment to the tumour drug content was studied, we noted that it is not always possible to obtain a tumour sample; the sample and its drug content may not be representative of the whole tumour content, this measured drug content is neither indicative for the evaluation of the dose to be administered, nor indicative of the chemotherapy efficacy. The best criterion for the dose adjustment seems to be the plasma concentration of the drug. Correlations between drug plasma concentration and clinical data are examined. The relationship between plasma concentration and efficacy cannot be excellent, since it depends on the presence of resistant cells and on the blood flow through the tumour. A relationship between plasma concentration and toxicity has been reported with many anticancer drugs. The drug plasma concentration and the area under the curve (AUC) give better correlations than the administered dose with efficacy and toxicity. Different methods of dose adjustment are reported. They use mathematical models which allow to decrease the number of blood samples, without losing precision in the pharmacokinetic parameter evaluation. In conclusion, the dose adjustment to the drug plasma concentration or to the AUC can play an important role in improving the chemotherapy efficacy, while toxicity is reduced.

Antineoplastic Agents↗
PubMed1993

[Correlations between clinical pharmacodynamics and pharmacokinetics of cisplatin and etoposide].

Currently, the dose of anticancer drugs is adjusted according to patient body surface area, although the best criterion for dose adjustment seems to be the plasma concentration of the drug, since a correlation has been established between plasma concentration and efficacy for several drugs. We report here similar results with etoposide and cisplatinum. The plasma concentration and the area under the curve (AUC) of etoposide and platinum (Pt) were higher in responders compared to non-responders, and etoposide clearance was higher in responders. The etoposide toxicity (assessed by the polymorphonuclear blood count) was higher in responders. There was a good correlation between the Pt concentration and creatininaemia. The AUC for Pt was significantly higher in patients with nausea and vomiting. There was no correlation between the infected dose of either drug and efficacy or toxicity. It is not possible to assign efficacy to either compound since they were injected simultaneously. We conclude that when the plasma etoposide or platinum concentrations are low, tumour response is unlikely.

Carcinoma, Bronchogenic↗
PubMed1992

Evaluation of a method for detection of cells with reduced drug retention in solid tumours.

A method for detection of cells with reduced drug retention was evaluated in solid tumours. After a 1 h incubation with daunorubicin (DNR), the right angle scatter (RAS), forward angle scatter (FAS), and specific fluorescence (Fluo) were measured in sensitive and resistant cells; only Fluo was related qualitatively, but not quantitatively, to resistance. Various incubation conditions were examined. When the pH of the incubation medium increased, the DNR retention increased in sensitive and resistant cells. In contrast, when the cell concentration increased, the DNR retention decreased. Using sensitive and resistant cell lines, a proportion of resistant cells lower than 10% can be detected in a mixture. To analyse cells from solid tumours, the cells were dissociated by repeated fine needle aspirations. Tumours from 22 patients have been processed with this technique; 8 samples were classified as S (sensitive); 2 as R (resistant); and 12 as I (intermediate). Further experiments were run to study and improve the method. Another method of detection of dead cells was tested. The intra-assay variability of the technique was found to be less than 10%. When the study was performed with different fragments of the same tumour, the variation, corresponding to the tumour heterogeneity, rose to 21 to 36%. The inter-assay reproducibility was too bad, so a variant of this technique has been adapted, using verapamil or cyclosporin A, which is able to block DNR efflux; this new method allows tumour cells to be used as their own controls.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1992

[Apoptosis or programmed cell death: concepts, mechanisms and contribution in oncology].

Programmed cell death, or apoptosis, corresponds to a sequence of intracellular events that lead to cell death. It has been shown that apoptosis is necessary in some physiological conditions such as embryogenesis, homeostasis of the immune system, erythropoiesis, etc. Some xenobiotics can induce apoptosis at lower doses and necrosis at higher doses. When a cell dies, it is either by apoptosis or by necrosis, and there are many differences between these two deaths. Apoptosis begins by a pre-commitment phase, which is reversible; during this phase the cell has a high level of second messengers. The commitment phase then follows and is irreversible, even when the xenobiotic that triggered the induction is removed. Most often, apoptotic cell death requires synthesis of macromolecules, the inhibition of their synthesis can prevent it. The cell undergoes important morphological changes during apoptosis, its volume decreases when its density increases. Then chromatin becomes granular, intensively osmiophilic, it condenses along the nuclear membrane. Later, chromatin disintegrates into small granules which will be phagocytized. One of the most important characteristics of the programmed cell death is the activation of an endonuclease, that gives rise to DNA fragments of 180-200 base pairs or multiples of these numbers; then after electrophoresis, the DNA gives the appearance of a ladder. Apoptotic cells can be characterized after classic staining, and flow cytometry; they can be separated from other cells by centrifugation on a gradient of density. It has been hypothesized that cell transformation could be due to a sudden resistance to apoptosis. However, the most interesting aspect in oncology recently demonstrated is that well-known anticancer drugs are able to induce apoptosis. One can hope that the discovery of new targets for anticancer drugs could lead to discovering new drugs that could be more active.

Animals↗
PubMed1991

Correlation of clinical pharmacokinetic parameters of cisplatin with efficacy and toxicity.

Twenty-two pharmacokinetic studies were carried out in 11 patients receiving cisplatin (20 mg/m2 per d) associated with etoposide (50 mg/m2 per d), as 5-day continuous infusions, every 4 weeks. Blood was withdrawn at 8:30 am from day 1-5. Within 15 min after taking the blood, an aliquot of plasma was filtered for the ultrafilterable platinum (UP) assay. Total platinum (TP) and UP were assayed by flameless atomic absorption. The plasma concentrations and AUC0-120 h of TP were correlated with those of UP (P less than 0.05 to P less than 0.001). TP concentrations increased significantly during the infusion and with each successive course, whereas the increase of plasma concentration of UP during and between courses was not statistically significant. The responders had significantly higher levels of TP (AUC, concentrations) in the first and second courses than the non-responders. No renal toxicity was observed, nevertheless, the AUC0-120 h of TP and UP were positively correlated with the serum creatinine (P less than 0.05). The digestive intolerance (grade 1-3) was significantly correlated with TP concentrations and AUC0-120 h. There was no statistical difference in UP concentrations either between responders and non-responders in any course, nor between toxic and non-toxic courses. Since etoposide was concomitantly administered, we can formulate the conclusion as follows: no "objective" response was observed in the patients with low TP plasma concentrations and AUC0-120 h.

Cisplatin↗
PubMed1991

Phosphatase isoenzymes as bone metastasis markers in prostatic carcinoma.

Bone alkaline phosphatase (b-ALP) and tartrate resistant acid phosphatase (tr-ACP) are markers of the activity of osteoblasts and osteoclasts, respectively. We have already shown that the serum activity of these isoenzymes was elevated in breast cancer patients with bone metastasis (BM); we show here that the serum activity of b-ALP and tr-ACP were also elevated in prostate cancer patients with BM. Specificity and sensitivity of b-ALP for BM were 0.90 and 0.75, respectively; and for tr-ACP, 0.60 and 0.60, respectively. The accuracy of b-ALP as a BM marker was higher than the accuracy of usual markers of prostatic carcinoma (tartrate labile ACP [tl-ACP], prostatic acid phosphatase [PAP] and prostate specific antigen [PSA]). The highest value predictive of a positive bone scan was obtained with b-ALP (0.88); this increased to 0.97 when b-ALP was coupled with PAP.

Acid Phosphatase↗
PubMed1991

Comparison of phosphatase isoenzymes PAP and PSA with bone scan in patients with prostate carcinoma.

The aim of this study was to assess the diagnostic value of five biological markers--prostate acid phosphatase (PAP), prostate specific antigen (PSA), tartrate resistant (Tr-ACP), and tartrate labile (TI-ACP) acid phosphatases, and alkaline phosphatase bone isoenzyme (B-ALP)--for the detection of bone metastases in patients with prostate carcinoma. Using the Tc-99m HMDP bone scans of 80 patients scored from 0 (normal) to 2 (diffuse bone involvement) as the "gold standard," a receiver operating characteristic (ROC) analysis was performed. This method allows the determination of different threshold values (corresponding to different couples of sensitivity and specificity) for the assays. An ROC curve comparison was also performed. Results show that B-ALP is the best test for such detection (area under the ROC curve = 0.93; Spearman Rank correlation with bone scan r' = 0.81). Among the other markers, PSA was found to be the best (area under the ROC curve = 0.81; Spearman Rank correlation with bone scan r' = 0.58). In addition to the prostatic tumor markers (PSA and PAP), we suggest the use of the low-cost B-ALP assay in the follow-up of prostate carcinoma patients to determine the optimum moment to perform a bone scan. A normal result of this assay indicates a very low probability of bone metastasis; conversely, raising of B-ALP concentration must lead to a bone scan.

Acid Phosphatase↗
PubMed1990

Alterations of growth fraction and DNA content in K562 cells by differentiating agents.

The growth fraction, estimated by the monoclonal antibody Ki-67 labeling, and DNA content, assessed by ethidium bromide staining, were determined simultaneously in K562 leukemic cells by flow cytometry. A multiparametric analysis enabled the fraction of the cell population with G1, S, and G2 + M contents in Ki-67-positive and Ki-67-negative cells to be evaluated. Butyric acid (BUT) was used as positive control. The fraction of Ki-positive cells decreased with the BUT concentration, while the proportion of cells with G1 DNA content increased only in the Ki-negative cells. Adriamycin, aclacinomycin A, and fagaronine induced differentiation, as assessed by benzidine staining and glycophorin A expression. These drugs decreased the fraction of Ki-positive cells by more than 50% for both anthracyclines and by 25% for fagaronine. Following treatment, Ki-negative cells displayed a G1, but also a G2 and a S DNA content in different proportions, indicating that induction of quiescent cells by differentiating agents is not a uniform process and is worthy of interest.

Aclarubicin↗