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D de Vos

Publications and source records attributed to D de Vos.

At least 19 recordsLinked to original sources
PubMed2002

Identification of mebeverine acid as the main circulating metabolite of mebeverine in man.

The intestinal spasmolytic drug mebeverine is known to undergo fast in vivo enzymatic hydrolysis into mebeverine alcohol and veratric acid. A reversed-phase HPLC method with coulometric detection was developed in order to assay the hitherto unidentified secondary metabolite mebeverine acid. After intake of a single oral dose of 405 mg mebeverine hydrochloride in four healthy human volunteers, peak plasma concentrations of mebeverine acid were found to be 1000-fold higher than those of mebeverine alcohol, i.e. approximately 3 microg/ml versus 3 ng/ml. The appearance of mebeverine acid in plasma (median T(max)=1.25 h) as well as its disappearance (median apparent t(1/2)=1.1 h) were rapid. The urinary excretion of mebeverine acid within the first 4 h after dosing amounted to 67% of the mebeverine dose (median range: 23-107%). Mebeverine acid appears to be a valuable marker of oral exposure to mebeverine.

Administration, Oral↗
PubMed2000

Synthesis, characterization and in vitro antitumor activity of di- and triorganotin derivatives of polyoxa- and biologically relevant carboxylic acids.

An overview of the development of anti-tumor organotin derivatives, sometimes as active in vitro as doxorubicin, is presented and discussed. Solubility in water is an important issue, dominating the in vivo testing of compounds with promising in vitro properties. Several water-soluble organotin compounds gave the best in vitro activities. Novel, useful organotin anti-tumor compounds should be designed toward improved water solubility.

Antineoplastic Agents↗
PubMed2000

Paclitaxel esters of malic acid as prodrugs with improved water solubility.

The synthesis of paclitaxel esters of malic acid is described. These compounds were found to have improved water solubility and are stable in solution at neutral pH. The C2' modified compounds behave as prodrugs, that is, paclitaxel is generated upon exposure to human plasma, whereas the C7 modified derivatives do not. 2'-Malyl paclitaxel sodium salt demonstrated enhanced antitumour activity and less toxicity in a P388 murine leukaemia in vivo model when compared to paclitaxel.

Animals↗
PubMed1998

Serum and urine levels of tamoxifen and its metabolites in patients with advanced breast cancer after a loading dose and at steady-state levels.

PURPOSE: To compare serum and urine levels of tamoxifen and metabolites after a loading dose and at the steady state. METHODS: A loading dose of 160 mg of tamoxifen was given to 14 patients with advanced breast cancer. Thereafter a regular daily dose of 30 mg of tamoxifen was given. Serum and urine levels of tamoxifen and metabolites were measured by high-performance liquid chromatography and compared with levels determined in 31 patients with advanced breast cancer at the steady state at a daily dose of 30 mg of tamoxifen. RESULTS: Serum and urine levels (24-h values) of tamoxifen and metabolites were lower (P < 0.05) after a loading dose than at the steady state. The difference was most pronounced for the metabolites, whereas the tamoxifen loading-dose level was near the steady state. CONCLUSION: Tamoxifen steady state can be reached in 1-2 days by the administration of a loading dose of 160 mg of tamoxifen for 2 days. Tamoxifen metabolite steady-state levels are reached regularly after 4 or more weeks during application of a loading dose. Very little tamoxifen or metabolites are excreted into the urine.

Adult↗
PubMed1998

Clinical efficacy and safety of beclomethasone dipropionate inhalation capsules inhaled by Cyclohaler compared with Becotide Rotacaps inhaled by Rotahaler.

The study was undertaken to compare the efficacy and safety of beclomethasone dipropionate inhalation powder inhaled by Rotahaler (Becotide Rotacaps, Glaxo Wellcome) and by Cyclohaler (Beclomethasone Cyclocaps, Pharmachemie). Both the Cyclohaler and the Rotahaler are single-dose dry powder inhalation devices for inhalation capsules. 182 asthma patients stabilized on inhaled beclomethasone dipropionate 800 micrograms daily, were randomly assigned to treatment with 800 micrograms beclomethasone dipropionate inhaled by Rotahaler (91 patients) or Cyclohaler (91 patients) in a double-blind manner, using the double-dummy method. It was shown that the asthma remained stable during the 16-week study period with both preparations. There were no statistically significant differences in the pulmonary parameters (morning PEF, evening PEF, FEV1). The test/reference ratio of the morning PEF (99.5%, CI 93.0% - 106.5%) was well within the equivalence interval, which had been set a priori from 85% to 117.6%. There were no marked differences between the Cyclocaps and Rotacaps group in symptom scores and adverse events. A total of 12 patients had an asthma exacerbation: 8 exacerbations occurred in the Rotahaler group and 4 in the Cyclohaler group. The difference was not statistically significant. The use of rescue medication was somewhat higher in the Rotahaler group, but the difference did not reach statistical significance. Significantly more patients (17 patients) withdrew from the study in the Rotahaler group than in the Cyclohaler group (5 patients). In conclusion, there was no difference in asthma control of patients treated with Beclomethasone Cyclocaps inhaled by Cyclohaler and Becotide Rotacaps inhaled by Rotahaler. Both preparations are therapeutically equivalent.

Adult↗
PubMed1997

Results of decitabine therapy in the accelerated and blastic phases of chronic myelogenous leukemia.

The aim of the study was to evaluate the activity of decitabine, a hypomethylating agent, in the treatment of patients with chronic myelogenous leukemia (CML) in transformation. Thirty-seven patients with CML in blastic (20 patients) or accelerated phases (17 patients) were treated. Their median age was 52 years; 36 had Philadelphia chromosome-positive disease. Decitabine was given at 100 mg/m2 over 6 h every 12 h x 10 doses (1000 mg/m2) to 13 patients, and at 75 mg/m2 over 6 h every 12 h x 10 doses (750 mg/m2) to 24 patients. In blastic phase, two patients (10%) achieved a complete hematologic response (one with Ph suppression), and three (15%) had a hematologic improvement (marrow CR, platelets <100 x 10[3]/microl), for an overall response rate of 25%. In accelerated phase, six patients (35%) returned to a second chronic phase (two with Ph suppression), one (6%) had a hematologic improvement, and two (12%) had a partial hematologic response, for an overall response rate of 53%. Prolonged myelosuppression was the most significant side-effect. The median time to recovery of granulocytes above 500/microl was 48 days, and to recovery of platelets above 30 x 10(3)/microl, 31 days. Febrile episodes occurred in 25 patients (68%) including documented infections in 17 patients (46%). Decitabine has promising activity in CML. The most significant side-effect is prolonged myelosuppression. Decitabine may show activity in other myeloid disorders such as acute myeloid leukemia and myelodysplastic syndrome, as well as in other hematologic malignancies, alone or with other drug combinations. Its value in the context of stem cell support should also be investigated.

Adult↗
PubMed1997

Studies of decitabine with allogeneic progenitor cell transplantation.

The aim was to determine the efficacy and safety of decitabine in the settings of relapse post-allogeneic progenitor cell transplantation or as part of the conditioning regimen. Three patients (two AML, one ALL) received single agent decitabine 1000 mg/m2 total dose) for treatment of relapse post-transplant (group 1). Median age was 32 years. Median time to relapse was 7 months. In another study four patients (three CML in an accelerated phase, one AMML) received decitabine 400 mg/m2, with busulfan 12 mg/kg and cyclophosphamide 100 mg/kg as conditioning for allogeneic stem cell transplantation (group 2). Median age was 42 years; median time to transplant was 5 months. All patients received at least 4 x 10(6) CD34+ cells from their HLA compatible donors. All patients in group 1 achieved complete remissions after decitabine therapy. The median time to neutrophil and platelet recovery were 24 and 23 days, respectively. Two patients required reinfusion of donor cells because of delayed engraftment. One patient remains alive and in remission 160 days post-decitabine therapy. Two patients in group 2 engrafted on days 23 and 25. Two patients required reinfusion of stem cells because of lack of neutrophil recovery by day 21. Two patients achieved complete cytogenetic and hematologic remission. Three patients are alive at 167,129, and 109 days post-transplant. One patient died of progressive Pseudomonas cellulitis 54 days post-initial infusion. Decitabine therapy is well tolerated in the setting of allogeneic stem cell transplantation, initial results in patients relapsing after transplant are encouraging and warrant further studies. The causes of delayed engraftment after single agent or combination therapy need to be better explored. The existence of active metabolites of decitabine which may still be present in the blood at the time of stem cell infusions, and/or insufficient immunosuppression of the preparative regimen are being explored as possible explanations for this phenomenon.

Adult↗
PubMed1995

Schedule-dependent enhancement of antitumor activity of ethyldeshydroxy-sparsomycin in combination with classical antineoplastic agents.

The efficacy of the protein synthesis inhibitor ethyldeshydroxy-sparsomycin (EDSM) as a biochemical response modifier of several antitumor agents against L1210 leukemia and B16 melanoma is described. Seven drugs with different intracellular targets were selected for this combination study. Tumor implantation and drug treatment were both i.p., and the time interval between the administration of EDSM and the cytostatic agent was varied. Our results show that in the B16 tumor model EDSM is not able to potentiate any of these drugs, whereas antagonism is seen in combination with doxo-rubicin (DX). In the L1210 tumor model, however, no loss of activity is seen for this specific combination. The effect of the combination of cytosar (Ara-C), 5-fluorouracil (5-FU) or vincristine (VCR) with EDSM in the L1210 model is strongly time interval dependent. Loss of 5-FU antitumor activity is seen when EDSM is given 3 or 24 h after 5-FU; however, no effect is observed when EDSM is given 6 h after 5-FU. Enhancement of the 5-FU activity is not noticed. The VCR activity is potentiated when EDSM is given at least 6 h after VCR administration, which increases the antitumor response from 32 to > 60 days and the percentage survivors from 33 to 83% (p = 0.04). In combination with Ara-C, potentiation of antitumor activity is seen only when EDSM is given 24 h after Ara-C, which increases the antitumor response from 32 to > 55 days and the percentage survivors from 11 to 50% (p = 0.008). No modulatory effects are found when EDSM is combined with carmustine or DX.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Tetrasomy 15q: two marker chromosomes with no detectable alpha-satellite DNA.

Two patients with specific and similar phenotypes were both found to have an unusual marker chromosome present in 70%-80% of their lymphocytes at routine cytogenetic examination. The marker chromosomes were isolated by flow sorting and were amplified by degenerate oligonucleotide-primed PCR. These libraries and a cosmid probe located at 15q26 were used to characterize the marker chromosomes by FISH. Both marker chromosomes were found to consist of duplicated chromosome material from the distal part of chromosome 15q and were identified as inv dup(15) (qter-->q23::q23-->qter) and inv dup(15) (qter-->q24::q24-->qter), respectively. Hence, the markers did not include any known centromere region, and no alpha-satellite DNA could be detected at the site of the primary constriction. Tetrasomy 15q may be a new syndrome, associated with a specific type of marker chromosome. In addition, further analyses of this type of marker chromosome might give new insight into the structure and function of the mammalian centromere.

Abnormalities, Multiple↗
PubMed1993

Coincidence painting: a rapid method for cloning region specific DNA sequences.

We have developed a novel coincidence cloning strategy, termed Coincidence Painting, which enables the rapid generation of large numbers of region specific sequences. Coincidence Painting utilises Degenerate Oligonucleotide Primed PCR (DOP-PCR) amplification of flow sorted derivative translocation chromosomes. The PCR products are hybridised in situ onto specific flow sorted chromosomes for coincident sequence selection. Eluted and reamplified material is then cloned using a novel insert end revelation and ligation technique. Cloned inserts range in size from 150-1300 bps of which approximately 54% appear to be single copy sequences. The cloning method permits the excision of vector free probe for library hybridisation screening and the small insert size facilitates analysis for the generation of sequence tagged sites (STSs). We have used such clones successfully for YAC screening by PCR and for cosmid screening by filter hybridisation. This new methodology should allow the rapid saturation with probes of regions defined by specific translocation breakpoints.

Base Sequence↗
PubMed1993

Chromatid contamination can impair the purity of flow-sorted metaphase chromosomes.

We describe a phenomenon where a second flow karyotype is superimposed on the normal metaphase flow karyotype of human lymphoblastoid chromosomes. The events of this second flow karyotype contain half the DNA content of corresponding events in the normal flow karyotype and, when sorted, show the morphology of single chromatids. DNA amplified by degenerate oligonucleotide-primed PCR of 300 chromatids sorted from a single peak and hybridized onto normal metaphase spreads painted the entire length of the corresponding chromosome type. In retrospect, we could observe this phenomenon at a low level in 37% of randomly selected, previously analyzed flow karyotypes and in several published flow karyotypes from other laboratories. Experimentally, chromatid frequency was shown to vary with the colcemid blocking conditions as well as with the cell line used. At the extreme, we obtained a 4:10 ratio of chromatids to metaphase chromosomes, whereas this could be reduced tenfold by altering the colcemid blocking conditions in the same cell line. The presence of chromatids in chromosome preparations has important implications for the purity of isolated fractions used for generating libraries and in PCR analysis.

Cell Line↗
PubMed1992

Complete characterization of a large marker chromosome by reverse and forward chromosome painting.

Marker chromosome are small supernumerary chromosomes that are sometimes associated with developmental abnormalities. Hence, the genes involved in such cases provide an interesting approach to understanding developmental abnormalities in man. As a first step towards isolating such sequences, marker chromosomes need complete characterization. By combining chromosome isolation by flow sorting and the "degenerate oligonucleotide primed - polymerase chain reaction", we have constructed a DNA library specific for a marker chromosome found in a child with severe developmental abnormalities. We used fluorescent in situ hybridization of the library onto normal metaphase spreads ("reverse chromosome painting") and were thus able to determine that the marker consists of the centromeric part of chromosome 7, the telomeric region of the long arm of chromosome 5 and the telomeric region of the short arm of the X-chromosome. Subsequently, we hybridized normal chromosome-specific libraries of the relevant chromosomes onto metaphases containing the marker chromosome ("forward chromosome painting") and could in this manner establish the precise location of the different chromosome regions on the marker chromosome itself. This is a general approach suitable for outlining marker chromosomes in detail, and will aid the identification of the genes involved.

Adult↗
PubMed1989

The bioavailability of three altretamine formulations.

The bioavailability of two altretamine preparations was studied in a randomized cross-over design. The two preparations were compared with a third in a parallel design. Dissolution differences between the preparations were observed, which could give rise to differences in bioavailability caused by the extensive first-pass effect of altretamine. The in vivo data showed a trend to differences in bioavailability.

Adult↗