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P P Brons

Publications and source records attributed to P P Brons.

9 recordsLinked to original sources
PubMed1996

Cell cycle kinetics in normal human skin by in vivo administration of iododeoxyuridine and application of a differentiation marker--implications for cell cycle kinetics in psoriatic skin.

Renewal of epidermal cells is a highly coordinated process in which terminal differentiation balances the proliferative rate in the germinative compartment. Exact quantitative data on cell cycle parameters of normal human epidermis are fragmentary, and do not allow firm conclusions on issues such as cell cycle time, duration of the various cell cycle phases, and the pool sizes of the different cellular populations. As part of a study on bone marrow cell cycle kinetics, 14 lymphoma patients were infused with the thymidine analogue iododeoxyuridine (IdUrd). This provided us with the unique opportunity to study the cell cycle kinetics in normal epidermis obtained from these patients. Single epidermal cell suspensions were prepared from skin, stained with propidium iodide (PI) for relative DNA content, and simultaneously labeled with an anti-IdUrd antibody to detect DNA-synthesizing cells. In parallel samples suprabasal cells were analyzed by labeling with an anti-cytokeratin 10 antibody. Analysis was performed using bivariate flow cytometry. The results showed that 3.5% of the total epidermal cell population was in S-phase. An S-phase duration of 9.7 +/- 0.6 h and a cytokeratin 10-positive pool size of 59.6 +/- 4.6% were obtained. The duration of the G1-phase and the G2M-phase were calculated to be 7.6 +/- 2.0 h and 11.1 +/- 2.0 h, respectively. From these data a total cell cycle time can be calculated of 28.4 h. Combining this data with previous findings we were able to determine a similar cell cycle time of 27.8 h, and pool sizes of the epidermal cells: 30% quiescent (resting, G0) and 10% cycling cells. The implications of these findings for the interpretation of deviations in growth control as found in hyperproliferative skin diseases (e.g. psoriasis) are discussed.

Antibodies, Monoclonal↗
PubMed1994

Cell cycle kinetics of hematopoiesis before and after in vivo administration of GM-CSF in refractory anemia: evidence for a shortening of the granulocyte release time.

GM-CSF administration to patients with refractory anemia (RA) induces an increase in neutrophils and eosinophils. We studied cell kinetic mechanisms underlying this observation using clonogenic assays and in vivo iododeoxyuridine labeling of bone marrow cells. Cell cycle kinetics were studied in three patients before and during GM-CSF administration (two daily subcutaneous injections of 54 or 108 micrograms). No consistent effect on the relative number of bone marrow CFU-GM was noticed. The DNA synthesis time and potential doubling time of low-density bone marrow cells remained essentially the same. A slight decrease (1.5-3.7%) in labeling index was found, originating from the myelo(-mono)cytic lineage. In all three patients the release time of labeled granulocytes from the bone marrow into the peripheral blood was shortened (before GM-CSF treatment 5-7 days and during GM-CSF 3-4 days). Cell cycle kinetics of CD34+ cells were studied in order to obtain kinetic information on immature precursor and progenitor cells. The DNA synthesis time of the CD34+ cells was shortened during GM-CSF therapy, resulting in a shorter potential doubling time. GM-CSF administration to patients with RA results in a rise in granulocytes that might be due partly to an accelerated release of granulocytes from the bone marrow compartment into the circulating blood and partly to an increased proliferative activity of the immature precursor and progenitor cells.

Anemia, Refractory↗
PubMed1993

Proliferation patterns in acute myeloid leukemia: leukemic clonogenic growth and in vivo cell cycle kinetics.

In a prospective study of 33 newly diagnosed patients with acute myeloid leukemia (AML), we analyzed the relationship of proliferation parameters with clinical parameters, response to induction therapy, and survival. The median follow-up was 26 months. The proliferative capacity of the leukemic progenitor cells was studied using colony-forming assays (number of colony-forming units, growth pattern, and spontaneous clonogenic growth capacity). The cell kinetic parameters of the bone marrow blasts were determined by in vivo labeling with iododeoxyuridine and subsequent flow cytometry: labeling index (LI), DNA synthesis time (Ts), potential doubling time. No or only weak relationships were observed between the experimental and clinical parameters such as age, sex, % blasts, white blood cell count, FAB subtype, cytogenetics, and % CD 34+ cells. This suggests that clonogenic growth and cell cycle kinetics of bone marrow blasts are independent cell biologic properties of AML. No association between the proliferation parameters and induction response rate was noticed. Analysis of the overall survival and event-free survival revealed trends to longer survival rates in patients with a below-median LI (< or = 7.6%) and below-median Ts value (< or = 14.3 h). These trends were more pronounced in the group of de novo AML (n = 23), where the prolonged event-free survival in patients with below-median Ts reached statistical significance (p = 0.02). None of the other parameters appeared significantly correlated with survival, although there was a trend to longer survival rates in patients who had no spontaneous clonogenic growth capacity (p = 0.13). In conclusion, proliferation parameters in leukemic cells provide additional information on the cell biologic characteristics of AML, and these parameters may have prognostic value for response and duration of survival in AML.

Adult↗
PubMed1992

Cell cycle kinetics in malignant lymphoma studied with in vivo iododeoxyuridine administration, nuclear Ki-67 staining, and flow cytometry.

Cell cycle kinetics of malignant lymphoma were investigated using in vivo labeling with iododeoxyuridine (IdUrd) and subsequent flow cytometry (FCM) of IdUrd/DNA and Ki-67/DNA. This approach provides an extensive cell kinetic profile from only one single tumor biopsy, including data upon the percentage of S-phase cells, the IdUrd labeling index (LI), Ki-67-derived growth fraction, duration of the S-phase, duration of the G1-phase, potential doubling time, cell production rate, and total cell cycle time. Tissue samples from 33 patients were studied: non-Hodgkin's lymphoma (NHL; n = 22), Hodgkin's disease (HD; n = 7), and reactive hyperplasia (n = 4). In NHL, the percentage of S-phase cells, LI, growth fraction, duration of the S-phase, and cell production rate were significantly correlated with the histologic malignancy grade according to the Working Formulation (P < or = .02). Data found in HD were not essentially different from those in low-grade NHL and reactive hyperplasia. Remarkably, the duration of the S-phase, the duration of the G1-phase, and the total cell cycle time appeared to be rather independent of histologic malignancy grade within the NHL category. A significant correlation was observed between the IdUrd LI and the percentage of S-phase cells, the growth fraction, the potential doubling time, and the cell production rate (P < .001), but not with the duration of the separate cell cycle phases (P > .05). Our data show (1) that it is feasible to obtain detailed information on the in vivo growth characteristics of malignant lymphoma; and (2) that the transition time through the different cell cycle phases widely varies, even within distinct histologic subgroups.

Adult↗
PubMed1991

Effect of doxorubicin exposure on cell-cycle kinetics of human leukemia cells studied by bivariate flow cytometric measurement of 5-iodo-2-deoxyuridine incorporation and DNA content.

Cell kinetics of two human leukemic cell lines, Molt-4 and K562, following a 2-h exposure to doxorubicin, were studied. DNA flow cytometry provided static information that for both cell lines a dose-dependent accumulation occurred at the G2 + M compartment that disappeared in time. Kinetic information was provided by time-monitoring cells labeled with 5-iodo-2-deoxyuridine (IdUrd) by two-parameter flow cytometry, analyzing the IdUrd label and the DNA content. The cell-cycle time (Tc) of exponentially growing Molt-4 cells was determined to be 20 h. Twenty-four hours after a 2-h exposure to 0.25 micrograms/ml doxorubicin, the Tc had increased to 23 h; following exposure to 1.0 micrograms/ml, it increased to 33 h. Cell kinetics of K562 cells following doxorubicin exposure were monitored in time up to 4 days. The average Tc of exponentially growing K562 cells was determined to be 24.7 h. Twenty-four hours following 2-h exposure to 0.25 or 0.5 micrograms/ml doxorubicin, the Tc were determined to be 28 and 32 h, respectively. After an additional 2 days, the Tc were both determined to be 24 h. The dose-dependent, reversible cell-cycle delay that persisted at least 48 h should be taken into account as an additional mode for decrease of a (tumor) cell population doubling time after exposure to doxorubicin.

Cell Cycle↗
PubMed1990

Simultaneous measurement of DNA content and cell-surface immunofluorescence of human bone marrow cells using a single laser flow cytometer.

This paper describes the measurement of S phase DNA content in human bone marrow subpopulations using a single laser method for bivariate analysis of DNA content and cell-surface immunofluorescence (s-IF). Low density (less than 1.077 g/ml) bone marrow cells were labeled with a panel of unconjugated monoclonal antibodies (MoAb) for the lymphoid (CD2 + CD19), T-lymphoid (CD2), B-lymphoid (CD19), erythroid (anti-glycophorin-A), myelomonocytic (CD13, CD33; single and as cocktail) and monocytic (CD14) lineages. A fluorescein isothiocyanate (FITC)-conjugated goat anti-mouse label was used as second step. Unfixed, MoAb-labeled cells were incubated for 24 h with a hypotonic propidium iodide solution for DNA staining. Cells were analysed on a single-laser flow cytometer, operating at 488 nm. The effect of the combined staining protocol upon both s-IF and DNA stainability was evaluated. Only a slight decrease (mean: 29.0%) in s-IF intensity was observed after DNA staining. The percentages of immunofluorescent cells in the bone marrow samples of 10 normal individuals before and after DNA staining were essentially unchanged for all the MoAbs used. The DNA histograms of the immunophenotypically defined subpopulations were of excellent quality with a mean coefficient or variation of 1.8%. This procedure allows the assessment of very low levels of S-phase DNA content, as measured in normal low density blood cells of 8 healthy volunteers (mean 0.07%).(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗
PubMed1988

A rapid flow cytometric method for bivariate bromodeoxyuridine/DNA analysis using simultaneous proteolytic enzyme digestion and acid denaturation.

This report describes an immunocytochemical procedure for the simultaneous quantification of bromodeoxyuridine (BrdUrd) incorporated into cellular DNA and total DNA content in individual cells in suspension. Improvement of existing methods was achieved by combining acid denaturation and proteolytic enzyme digestion (0.2 mg/ml pepsin in 2N HCl for 30 min at room temperature). Acid denaturation preceded by enzyme digestion resulted in a large amount of debris and the occurrence of naked nuclei. In contrast, the simultaneous denaturation/protein digestion procedure did not damage the cellular structure, is rapid and reproducible, and has cell recoveries of more than 85%. Although experimental conditions were tested on human cultured keratinocytes, this method also appeared applicable to bone marrow cells and cells obtained from solid tissues.

Bone Marrow↗
PubMed1987

Determination of amsacrine in human nucleated hematopoietic cells.

A new method has been developed for the determination of amsacrine (AMSA) in human nucleated hematopoietic cells. In order to prevent efflux during the cell separation procedure, white blood cells (WBCs) were separated from red blood cells by dextran sedimentation, leaving the WBCs in their natural environment. After cell counting, pelletting the cell suspension and correcting for the admixture of supernatant, AMSA was extracted from the WBCs and determined by high-performance liquid chromatography. Linearity of extraction was observed up to 40.10(6) cells. The inter-assay variation was 4.7%. Plasma and cellular concentrations were measured in five patients at the end of a 3-h infusion of 100 mg/m2 AMSA. A pharmacokinetic study of plasma and cellular AMSA concentrations up to 19 h after infusion was carried out. AMSA concentrations in WBCs correlated well with the plasma levels (n = 20, r = 0.967) with an accumulation factor compared to the plasma concentration of 2.6-9.8 in the patients studied. The method described is useful for studying cellular pharmacokinetics of AMSA in man.

Amsacrine↗