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Biomedical subjects

L L Vindeløv

Publications and source records attributed to L L Vindeløv.

At least 19 recordsLinked to original sources
PubMed2003

A comparison of T-, B- and NK-cell reconstitution following conventional or nonmyeloablative conditioning and transplantation with bone marrow or peripheral blood stem cells from human leucocyte antigen identical sibling donors.

This retrospective study compares the reconstitution of T, B and NK cells in three groups of patients transplanted for haematological malignancies with grafts from their HLA-identical sibling donors. In all, 15 patients received PBSC after a nonmyeloablative conditioning regimen consisting of fludarabine and 200 cGy TBI, 13 patients received PBSC after myeloablative conditioning and 37 patients received BM after myeloablative conditioning. In the nonmyeloablative group, the NK cells normalised after 1 month, the CD8+ T cells normalised after 3 months, the CD4+ T cells reached near normal values after 9 months and the B cell values were reduced until 12 months after transplant. In the two myeloablative groups, recipients of PBSC had a significantly higher number of CD4+ T cells after 4 months (P=0.004) and after 12 months (P=0.001), than recipients of BM. We found no differences in the T cell reconstitution between the two PBSC groups. This was of interest as the recipients of nonmyeloablative conditioning were older (P<0.001) and had a higher occurrence of chronic GVHD (P<0.05) than the recipients of myeloablative conditioning. In contrast, the recipients of nonmyeloablative conditioning had a delayed B cell recovery when compared to the patients who received myeloablative conditioning (P=0.04).

Adolescent↗
PubMed2001

Autoreactivity, backstimulation and reproducibility in a helper T lymphocyte precursor assay.

Helper T lymphocyte precursor (HTLp) frequencies determined by limiting dilution analysis (LDA) have a predictive value for alloreactivity in allogeneic bone marrow transplantation. Methodological problems in LDA include autoreactivity in the responder or stimulator cell populations and interleukin 2 (IL-2) production by the stimulator cells as a response to the responder cells (backstimulation). The extent and impact of these aspects for IL-2 production and HTLp frequency determination were studied by autologous and allogeneic mixed lymphocyte reactions with healthy volunteers and HTLp determinations from bone marrow transplantation donor/recipient pairs. We found that autoreactivity occurred in the unirradiated cells with a reproducible inter-individual variation. The immunogenicity of the stimulator cells was preserved after gamma irradiation with 50 Gy and the risks of autoreactivity and backstimulation were limited. Higher doses of irradiation decreased the immunogenicity. Immune reactions to antigens present in the serum supplement of the culture medium were seen with foetal calf serum and to a lesser extent with pooled human sera. This could be avoided by the use of autologous serum. We were unable to ensure satisfactory culture conditions in serum-free medium. The reproducibility of the HTLp frequency determinations was tested for intra- and inter-assay variation. The coefficients of variation were estimated as 24% and 35%, respectively. This was acceptable considering the range of the HTLp frequencies (1:10(2) to 1:10(7)). The influence of the extent of autoreactivity of the bone marrow donors was investigated in 28 HLA-identical sibling transplantations. We found no correlation between the autoreactivity of the donors and the HTLp frequencies. The extent of autoreactivity of the donor did not correlate with the clinical outcome in terms of acute graft-versus-host disease, treatment-related mortality, risk of relapse and overall survival. In spite of methodological difficulties and interference from autoreactivity and backstimulation, reproducible quantification of clinically significant alloreactivity can be attained.

Autoimmunity↗
PubMed2001

The predictive value of helper T lymphocyte precursor frequencies for graft-versus-host disease and graft-versus-leukaemia effects in allogeneic bone marrow transplantation.

Helper T lymphocyte precursor (HTLp) frequencies determined by limiting dilution analysis were studied in the graft-versus-host direction to assess the predictive value for outcome in allogeneic BMT. The HTLp frequencies correlated with the degree of HLA disparity. HTLp frequencies from 28 HLA-identical sibling BMT pairs had a median of 1:557 362 (range 1:9511 to <1:2 500 000). The HTLp frequencies from 20 HLA-matched unrelated and partially HLA-matched related BMT pairs had a median of 1:88 110 (range 1:4139-1:736 123). The HLA-identical sibling BMT pairs were split evenly into high and low HTLp frequency groups above and below 1:500 000. There was a trend towards a higher risk for acute GVHD > or =grade II (P = 0.075) in the high frequency group. There was no difference in TRM. The high HTLp frequency group had a significantly higher risk for chronic GVHD (P = 0.04), a significantly lower risk for relapse (P = 0.01), as well as a significantly better overall survival (P = 0.045) and leukaemia-free survival (P = 0.008). The HLA-matched unrelated and partially HLA-matched related BMT pairs were split evenly into high and low HTLp frequency groups above and below 1:90 000. There was a significantly higher risk for acute GVHD > or = grade II (P = 0.007) in the high HTLp frequency group. There was a trend towards a higher TRM in the high HTLp frequency group (P = 0.05). There were no differences in chronic GVHD, risk of relapse, overall survival and leukaemia-free survival. Analyzing all 48 patients the risk of acute GVHD > or = grade II and TRM was significantly higher (P = 0.012 and 0.021, respectively) with HTLp frequencies >1:100 000 and there was a trend towards a higher risk of relapse (P = 0.058) with low HTLp frequencies <1:400 000. Patients in the intermediate HTLp frequency group 1:100 000-1:400 000 had a trend towards improved survival (P = 0.059). The HTLp frequency seems to detect clinically significant differences in alloreactivity, that can be useful in donor selection and graft engineering.

Adolescent↗
PubMed1999

Design of limiting dilution analysis experiments for helper T lymphocyte precursor frequency determination in the context of allogeneic bone marrow transplantation.

Helper, interleukin 2 (IL-2) producing, T lymphocyte precursor (HTLp) frequency determination by limiting dilution analysis (LDA) is of value for quantifying alloreactivity in allogeneic bone marrow transplantation (BMT). LDA assays are labour-intensive and time-consuming to perform and the numbers of donor and recipient cells available are limited. It is therefore important that the design of the experiment yields reliable frequencies with a minimum of effort and a realistic cell requirement. We have critically evaluated the methods proposed for LDA design by Strijbosch et al. [Strijbosch, L.W., Buurman, W.A., Does, R.J., Zinken, P.H., Groenewegen, G., 1987. Limiting dilution assays. Experimental design and statistical analysis. J. Immunol. Methods 97, 133] and by Blackett and Gordon [Blackett, N.M., Gordon, M.Y., 1996. Optimizing limiting dilution assays: frequency and 'ability' measurements of haemopoietic progenitor cells. Br. J. Haematol. 92, 507 (see comments)] and found them inadequate for this application. The estimation of the HTLp frequency is traditionally based on the single-hit Poisson model and the adequacy of this model was compared with that of a double-hit model. The results were in favour of the single-hit model. Ten different LDA experimental designs were explored by Monte Carlo simulations. The optimal design exploits the maximal numbers of cells that can be obtained for analysis to estimate HTLp frequencies in the range 1:1,000,000-1:20,000 with a coefficient of variation of 10-20% and with a minimum of manual labour.

Bone Marrow Transplantation↗
PubMed1998

Evaluation of X-radiation and UV-B radiation for elimination of 3H-thymidine incorporation into responder cells in the IL-2 producing helper T lymphocyte precursor assay.

The helper T lymphocyte precursor (HTLp) assay is of value for predicting graft-vs.-host disease after allogeneic bone marrow transplantation. The assay is based on limiting dilution analysis and requires detection of the amount of interleukin 2 (IL-2) produced by one activated T cell. IL-2 is detected by 3H-thymidine (3H-TdR) incorporation into the IL-2 dependent cell line, CTLL-2. Detection of IL-2 in the whole culture volume of the wells in the microtiter plates increases sensitivity, but requires elimination of 3H-TdR incorporation into the responder cells in the HTLp assay. We have compared the ability of X-radiation and ultraviolet B (UV-B) radiation to eliminate 3H-TdR incorporation. X-irradiation of the cells reduced 3H-TdR incorporation by 90% with doses up to 400 Gy, but the incorporation was still 10 times higher than in wells with stimulator cells only. UV-B irradiation (with Philips TL 12 tubes) of the cells with > or = 2 J/cm2 decreased 3H-TdR incorporation to the level of wells with stimulator cells only. Neither X-irradiation nor UV-B irradiation of the cultures affected IL-2 produced in the assay or human recombinant IL-2 measured by 3H-TdR incorporation into the IL-2 dependent cell line, CTLL-2. HTLp frequencies determined after 25 Gy X-irradiation were higher (mean 1.5, range 1.02-2.2 times higher) than HTLp frequencies determined after UV-B irradiation with 2 J/cm2.

Biological Assay↗
PubMed1997

Effect of NCAM-transfection on growth and invasion of a human cancer cell line.

A cDNA encoding the human transmembrane 140 kDa isoform of the neural cell adhesion molecule (NCAM) was transfected into the highly invasive MDA-MB-231 human breast cancer cell line. Transfectants with a homogeneous expression of NCAM showed a restricted capacity for penetration of an artificial basement membrane. However, when injected into nude mice, both control and NCAM-expressing cell lines produced equally invasive tumors. Tumors generated from NCAM-transfected cells were heterogeneous, containing NCAM-positive as well as NCAM-negative areas, indicating the existence of host factors capable of modulating NCAM expression in vivo. In nude mice, NCAM-transfected cells developed tumors with longer latency periods and slower growth rates than tumors induced by NCAM-negative control cells, implying that NCAM may be involved not only in adhesive and motile behavior of tumor cells but also in their growth regulation. There was no indication of differences in cell proliferative characteristics between the different NCAM-transfected and the control transfected cells as determined by flow cytometric DNA analysis, suggesting an increased cell loss as the reason for decreased in vivo growth rate of the NCAM-transfected cells. The fact that NCAM expression influences growth regulation attributes a pivotal role to this cell adhesion molecule during ontogenesis and tumor development.

Cell Cycle↗
PubMed1995

Prognostic significance of DNA content in bladder cancer based on flow cytometric analysis of 249 transitional cell carcinomas.

The prognostic significance of DNA index (DI), S-phase fraction, and heterogeneity determined by flow cytometric DNA analysis was assessed in a prospective study of 249 newly diagnosed transitional cell carcinomas of the bladder. The median observation time was 4.8 years. A total of 456 subpopulations were detected. The S-phases could be estimated in 299 subpopulations. A DI > 1.25 or an S-phase above 9.7% were strongly correlated to invasiveness. One hundred and ten patients were treated with transurethral resection (TUR). Relapse-free survival could not be predicted by the DNA-derived parameters. Univariate analysis of survival showed prognostic significance of diploidy (0.98 < DI < or = 1.02, P = 0.02), hypotetraploidy (1.50 < DI < or = 1.96, P = 0.002), and S-phase size (P = 0.008). Multivariate analysis pointed to the T-classification (RR = 1.64) and hypotetraploidy (RR = 1.57) as prognostic parameters for survival of TUR-treated patients. One hundred and thirty-nine patients received radiotherapy (RT). A significantly better response was found for tumors with a subpopulation with a hypertetraploid DNA content (DI > 2.04, P = 0.05), and a significantly worse response for subpopulations with a maximum S-phase > 24.5% (P = 0.04). T-classification and histological grade had no predictive value. A logistic regression analysis indicated an estimated probability of response to RT of 77% for tumors with a DI > 2.04 and an S-phase < 24.5%, whereas tumors with a DI < 2.04 and an S-phase > 24.5% had only a 28% probability of response. The poor response to RT, predicted by an S-phase > 24.5%, translated into a poor survival, whereas the better treatment response found for patients with a DI > 2.04 did not result in a longer survival. Multivariate analysis pointed to S-phase (RR = 1.70), T-classification (RR = 1.60), and grade (RR = 0.65) as independent prognostic parameters for survival of RT-treated patients.

Adult↗
PubMed1995

Clonal dominance between subpopulations of mixed small cell lung cancer xenografts implanted ectopically in nude mice.

Clonal evolution of neoplastic cells during solid tumour growth leads to the emergence of new tumour cell subpopulations with diverging phenotypic characteristics which may alter the behaviour of a malignant disease. Cellular interaction was studied in mixed xenografts in nude mice and during in vitro growth of two sets of small cell lung cancer (SCLC) subpopulations (54A, 54B and NYH, NYH2). The tumour cell lines differed in cellular DNA content enabling flow cytometric DNA analysis (FCM) to be used to monitor changes in the fractional composition of the mixed cell populations. The progeny clone 54B was found to dominate the parent 54A clone when grown as mixed subcutaneous xenografts in nude mice, whereas no dominance was exerted during in vitro growth. The in vivo dominance could not be explained by differences in growth kinetics between the two tumour cell lines, and the interaction was not dependent on 54B being in excess in mixed tumours. The dominance was dependent on close in vivo contact as no remote effect on the growth of 54A was found when the dominating 54B cells were growing in the opposite flank of tumour-bearing mice. Irradiation inactivated 54B cells were unable to exert the dominating effect, indicating that the interaction required viable and proliferating cells. Clonal dominance was not found in mixed NYH-NYH2 tumours indicating that the dominance mechanism(s) may not always be operational between subpopulations in heterogeneous tumours. Recognition of interaction between tumour cell populations may result in a better understanding of the behaviour of heterogeneous human malignancies.

Animals↗
PubMed1994

Low-dose chemotherapy delays relapse of a dominated and resistant sub-population in a heterogeneous human SCLC xenograft in nude mice.

We investigated the influence of cellular heterogeneity on the response to low-dose BCNU chemotherapy of an artificially mixed human small-cell lung cancer (SCLC) xenograft in nude mice containing a BCNU-sensitive and dominating sub-population and a BCNU-resistant and undetectable (dominated) sub-population. The cell lines differed in DNA content, making them distinguishable by DNA flow cytometry (FCM). After 3 weeks of tumor growth, the mice were stratified according to tumor size and randomized to 2 different low-dose treatments with BCNU or no treatment. After a further 3 to 4 weeks, a high-dose treatment (LD10) was given to both groups of treated tumors. Changes in the relative proportions of and cell lines in the tumors were measured by FCM on fine-needle tumor aspirates. At the time of low-dose treatment, all the tumors were totally dominated by the sensitive cells. A temporary response was seen after low-dose treatment. After the high-dose treatment, a similar short response was seen. In the non-treated group, the sensitive cells continued to dominate. At the time of tumor regrowth after the low-dose treatment, most of the tumors continued to be dominated by the sensitive population. At the time of progression after the response to the high-dose treatment, the resistant cell line was the predominant population. If compared with a single high-dose BCNU treatment, the response of tumors treated with a low dose was superior, indicating that the presence of a dominating and slower growing sub-population influenced the outcome of the treatment.

Animals↗
PubMed1994

A dominated and resistant subpopulation causes regrowth after response to 1,3-bis(2-chloroethyl)-1-nitrosourea treatment of a heterogeneous small cell lung cancer xenograft in nude mice.

In order to address the question of the influence of a primarily chemoresistant tumor cell subpopulation on the progression of a heterogeneous tumor after cytotoxic therapy, in vitro established human small cell lung cancer cell lines of a 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU)-sensitive (592) and a resistant (NYH) tumor were used to produce mixed solid tumors in nude mice. Mixtures of 592/NYH (9:1 and 1:1) were inoculated s.c. After 3-4 weeks of tumor growth, the mice were stratified according to tumor size and randomized to treatment with BCNU 40 mg/kg i.p. (10% of lethal dose) or no treatment. Tumor growth curves were used to calculate the effect of the treatment, and changes in the relative proportions of 592 and NYH in the mixed tumors were monitored by flow cytometric DNA analysis by which the two cell lines were distinguishable due to differences in DNA content. A significant response was demonstrated in the 9:1 mixed tumors in which only 592 cells were detectable at the start of the treatment. The response was short and less pronounced compared with tumors containing only 592. In the regrowing tumors after treatment, only NYH was detected. In untreated 9:1 mixed control tumors, only 592 cells were detectable throughout the entire observation period. It is substantiated that the 592 cells were able to inhibit the growth of the NYH cells completely when grown together in 9:1 mixed tumors. This was not the case in the 1:1 mixed tumors. The 1:1 mixed tumors did not respond to BCNU, although 592 was eradicated. These results indicate that resistant and undetectable (dominated) subpopulations in heterogeneous tumors may be responsible for relapse and that the fractional size and the growth characteristics of the resistant subpopulation may determine the magnitude of the clinical response to cytotoxic treatment.

Animals↗
PubMed1994

Interaction between three subpopulations of Ehrlich carcinoma in mixed solid tumours in nude mice: evidence of contact domination.

Clonal interaction between three subpopulations of Ehrlich carcinoma were studied during growth as mixed solid tumours and as ascites tumours in immune-incompetent nude NMRI mice. The tumour cell lines differed in DNA content as determined by DNA flow cytometry (FCM). Tumour growth was evaluated by tumour growth curves including calculation of tumour volume doubling times, tumour weight on day 14, cell cycle times (per cent labelled mitoses) and cell cycle distributions (FCM). Two subpopulations (E1.15 and E1.95) showed nearly identical growth characteristics during both solid and ascites tumour growth. The third subpopulation (E1.80) grew more slowly. FCM on fine-needle tumour aspirates was used to determine the relative proportions of the cell populations in mixed solid tumours in which E1.95 showed a growth-dominating effect on E1.15. No such effect was demonstrated during single-cell tumour growth in ascitic fluid in which the cells had no intimate contact. Ascitic fluid from E1.95-bearing animals or radiation-killed E1.95 cells had no effect on the growth of E1.15, and no remote effect was seen when the two cell lines were growing in opposite flanks. This indicates that only viable E1.95 cells in close in vivo contact were able to induce growth inhibition of the E1.15 subpopulation. Both the E1.95 and the E1.15 cells dominated the E1.80 cells, but in these cases cell kinetic differences may have played a role as the E1.95 and the E1.15 lines grew faster than the E1.80. The E1.80 cell line had no dominating effect on the E1.15 or E1.95. It is concluded that non-immunologically mediated cellular dominance in heterogeneous tumours may contribute to the evolution of these tumours and may be involved in fundamental tumour biological phenomena.

Animals↗
PubMed1993

Expression of myc family oncoproteins in small-cell lung-cancer cell lines and xenografts.

A number of genes have altered activity in small-cell lung cancer (SCLC), but especially genes of the myc family (c-myc, L-myc and N-myc) are expressed at high levels in SCLC. Most studies have explored expression at the mRNA level, whereas studies of myc family oncoprotein expression are sparse. WE examined the expression of myc proto-oncogenes at the mRNA and protein level in 23 cell lines or xenografts. In the cell lines, the doubling time and the cell-cycle distribution, as determined by flow-cytometric DNA analysis, were examined to establish whether the level of myc-gene-family expression correlated with proliferative parameters. All tumours expressed at least one myc family member at the mRNA level. Exclusive c-myc mRNA expression was demonstrated in 8 tumours, L-myc in 7 and N-myc in I. Five tumours expressed both c-myc and L-myc, and 2 tumours expressed both c-myc and N-myc. In general, the level of expression of c-myc and N-myc was similar at the mRNA and the protein level. Expression of c-myc was positively correlated with the proliferative index (sum of S and G2+M phases) of cell lines, but not with the population doubling time. In general, L-myc-expressing cell lines had a low proliferative index. There was no systematic difference in myc expression between cell lines and xenografts of individual tumours.

Animals↗
PubMed1992

Toxicity and metabolism of 3'-deoxyadenosine N1-oxide in mice and Ehrlich ascites tumor cells.

The toxic effect of 3'-deoxyadenosine N1-oxide (3'-dANO) on mice, on their different organs, and on Ehrlich ascites tumor cells was studied. In both healthy and tumour-bearing animals, the lethal dose for 10% of the mice receiving i.p. injections (LD10) of 3'-dANO was estimated to be about 300 mg/kg x 4 days in one mouse strain (Theiller). In another mouse strain (NMRI), we obtained a markedly higher LD10 value (675 mg/kg x 5 days). At nonlethal doses (250 mg/kg x 4 days), we observed reversible neurological symptoms on days 4-12 after treatment, but no macroscopical or microscopical changes was detected in the brain, heart, thymus, lung, lymph node, spleen, liver, kidney, bone marrow, or gastrointestinal tract. At doses of 450 mg/kg x 4 days, severe neurological symptoms were observed, and atony of the gastrointestinal canal and damage to the kidney and liver were registered. Even at doses that were lethal to the mice, no histopathological change was observed in the bone marrow or in the gastrointestinal canal. Pharmacokinetics studies showed that after the i.p. injection of 3'-dANO, the maximal plasma concentration was reached after 10 min, after which it declined showing a half-life of about 40 min. A transient accumulation of 3'-deoxyadenosine triphosphate (3'-dATP) was observed within 24 h in the liver and kidney, with the maximal concentration being reached after about 2-3 h. 3'-dANO was excreted partly as the unchanged substance and partly as the metabolite 3'-deoxyinosine within 24 h. Flow-cytometric DNA analysis of Ehrlich tumor cells treated either in vitro or in vivo with 3'-dANO revealed no therapy-induced change in the cell-cycle perturbations, which indicates that cells were randomly killed during all phases of the cycle.

Animals↗
PubMed1990

A review of techniques and results obtained in one laboratory by an integrated system of methods designed for routine clinical flow cytometric DNA analysis.

Establishing flow cytometric DNA analysis as a clinical routine procedure requires adequate and proven guidelines, by which the data can be obtained and interpreted to directly influence management of the individual patient with a specific neoplasm. The present paper is intended as a contribution to such guidelines, of which only fragments are available today. We have previously described a system of methods, designed for routine flow cytometric DNA analysis. In the present status report our experience, based on approximately 18,000 samples (clinical and experimental) is summarised. Sample acquisition with fine-needle aspiration, storage at -80 degrees C, internal standardization by chicken (CRBC) and trout red blood cells (TRBC), staining with propidium iodide (PI), and analysis in the flow cytometer is recapitulated, with emphasis on previously unpublished aspects. The method of statistical analysis which has an integrating role is described in some detail. A lack of linearity between channel number and DNA content was determined experimentally, and the coefficient of variation (CV) was found to decrease with increasing channel number. The corrections in the algorithm of deconvolution made necessary by these findings are fundamental for estimating the end results. The zero point adjustment and procedures for changing from one batch of standards to another are described. A systematic approach to interpretation of DNA histograms is attempted and illustrated by data from clinical specimens of malignant lymphoma, breast cancer, small cell lung cancer, cancer of the oral cavity, and bladder cancer. Some problems are still unsolved and visual inspection is required to determine if the quality of the individual histogram is satisfactory. Inspection of the fluorescence/light scatter dot-plot provides additional information for the recognition of artifacts. The results stress that good quality DNA histograms with as small CVs as possible are important for interpretation of the data. It is essential that statistical methods are employed to extract the key end-point results. These are the number of subpopulations and their relative representation, and for each subpopulation the DNA index (DI) and the fractions of cells in the cell cycle phases. For the DNA data to have any rationally based impact on clinical decision making, it must be demonstrated that they have an independent prognostic value. Strategies for final evaluation are discussed. Multicenter trials on fresh material, to accrue quickly the number of patients necessary for firm conclusions, are suggested.

DNA↗
PubMed1989

Effect on growth and cell cycle kinetics of estradiol and tamoxifen on MCF-7 human breast cancer cells grown in vitro and in nude mice.

The effects of estradiol and tamoxifen (TAM) on the estrogen-dependent human breast cancer cell line MCF-7 grown in vitro and in nude mice were compared. The effect on growth was determined by cell number in vitro and by tumor growth curves in nude mice. The effects on the cell cycle kinetics were determined by repeated flow cytometric DNA analyses in vitro and in vivo and by the technique of labeled mitosis in nude mouse-grown tumors. Under in vitro conditions, estradiol induced a pronounced increase in S-phase fraction and cell number. TAM inhibited growth of MCF-7 cells with a concomitant increase in the G1 phase from 60% to 75%. In nude mice, MCF-7 only formed tumors in estradiol-supplemented mice. No differences were observed in growth and cell kinetics between 0.1 and 1.0 mg of estradiol. Daily i.p. injections of TAM resulted in tumor growth inhibition with shrinkage of tumors. The flow cytometric DNA analysis and percentage of labeled mitosis investigations revealed no significant differences in the proliferation kinetics of TAM-treated and control tumors. Calculating the cell loss factor demonstrated an increase from 69% in control tumors to 107% in TAM-treated tumors. These experiments have shown that the cell kinetic effect of TAM is different when MCF-7 cells are grown in vitro versus in vivo. In contrast to the in vitro data, the in vivo data indicate that the growth-inhibitory effect of TAM is not mediated through a perturbation of the cell cycle.

Animals↗
PubMed1989

Growth kinetics of four human breast carcinomas grown in nude mice.

The immune-deficient nude mouse with human tumor xenografts is an appropriate model system for performing detailed growth kinetic examinations. In the present study one estrogen and progesterone receptor-negative (T60) and three receptor-positive (Br-10, MCF-7, T61) human breast cancer xenografts in nude mice were investigated. The proliferative tumor characteristics were examined by growth curves, thymidine labelling technique, and flow cytometric DNA analysis performed on fine-needle aspirations. The results showed that the tumors had growth kinetics comparable to other human tumor types with cell generation times of 42 to 60 hours. The three receptor-positive tumors had slower growth rate, larger tumor volume doubling time, and smaller growth fraction and labelling index than the receptor-negative tumor. However, no single proliferation parameter was sufficient to characterize the growth kinetics of individual tumors or to describe proliferative differences between the tumors.

Animals↗