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Biomedical subjects

H K Slocum

Publications and source records attributed to H K Slocum.

At least 55 records · Page 3Linked to original sources
PubMed1986

Growth of human urological tumors on extracellular matrix as a model for the in vitro cultivation of primary human tumor explants.

The goal of this study was to establish an optimal in vitro growth assay system for human urological tumor explants. Bovine corneal endotelial cell extracellular matrix (ECM) coated dishes were evaluated as a growth substrate for tumor cultures. Growth success for different urological carcinomas (prostatic, bladder, kidney, and testicular) was compared after seeding fresh surgical explants onto bovine corneal endothelial cell ECM and plastic culture flasks. Tumor samples were disaggregated enzymatically, and 1 X 10(4) cells were seeded onto the different substrates using RPMI 1640 medium containing 10% fetal calf serum and/or different growth factors, nutrients, and hormones. Cell growth on ECM was quantitated on days 7-15 by [3H]thymidine uptake, cell counting, and total protein. Tumor cells were characterized by flow cytometry and cytology. It was observed that ECM provides superior culture conditions for urological carcinomas. By increasing the initial number of cells plated on ECM and by adding different growth factors or hormones, the growth rate for specific tumor types was increased significantly. Several tumors (11 cases) grown on ECM were examined under the light microscope, and in all cases pre- and post-cytology confirmed malignancy. Tumor cells maintained on ECM and transplanted into nude mide retained their tumorigenic and morphological characteristics. Clinically aggressive tumors were associated with extensive ECM degradation. In addition, the growth of fresh human tumors on ECM provides a biologically relevant model system (for assessing the invasiveness of tumors in vitro) and should also be useful for drug evaluation studies.

Cell Adhesion↗
PubMed1985

Limitations of drug sensitivity testing in soft agar for clinical management of patients with ovarian carcinoma.

Thirty specimens from 28 patients (15 previously treated, 13 previously untreated) with ovarian carcinoma were studied in a soft agar colony-forming assay to determine whether or not the assay could be useful for treatment planning. There were sufficient colonies for drug testing in 23 cases. An in vitro drug response was found in 12 of 106 drug tests. In vivo-in vitro correlations could be made for 28 drug trials in 16 patients. Eight patients were not evaluated for response because they were clinically disease free after debulking surgery. Single agents were evaluated in vitro, although most patients received combination chemotherapy. In 23 cases the tumor was resistant in vitro and in vivo. There were two false-negative and three false-positive results. Cell aggregates that may artificially increase growth rates and apparent in vitro drug resistance were a major problem technically. In view of the problems identified, the assay in its current form should not be used routinely to direct therapy.

Aged↗
PubMed1984

Flow cytometric analysis of DNA aneuploidy in primary and metastatic human solid tumors.

DNA histograms were measured by flow cytometry for 656 human solid tumors (365 primary and 291 metastatic). The proportion of aneuploid cells in cell suspensions obtained by mechanical disaggregation was significantly higher than those obtained after enzymatic disaggregation (collagenase + DNAse) of the same tumor. A strong correlation was observed between the values of DNA-indices measured after staining with propidium iodide and with 4',-6-diamidino-2-phenylindole (r = 0.97). Aneuploid cells were observed in 430 tumors (66%); 30 of these had two aneuploid stemlines, and two had three aneuploid stemlines. The overall frequency of aneuploidy was 61% among primary and 71% among metastatic tumors. The median value of the DNA index was 1.67 for 224 primary aneuploid tumors and 1.68 for 206 metastatic aneuploid tumors. For most diseases, the largest proportion of aneuploid primary and metastatic tumors had DNA-indices in the hypertriploid region. No major differences in frequency and degree of aneuploidy was observed between primary and metastatic tumors. For carcinomas of the bladder and prostate, frequency of aneuploidy was higher among poorly differentiated, than among moderately and well-differentiated tumors. For carcinomas of the breast and for sarcomas, tumors with DNA-indices of greater than 2.0 were observed mostly in the poorly differentiated group. For patients with carcinomas of the bladder and prostate most tumors at earlier stages of disease were diploid; whereas most tumors at later stages of disease were aneuploid. For patients with carcinomas of the ovary, colon, and kidney, no relationship between stage of disease and aneuploidy was evident.

Aneuploidy↗
PubMed1984

Proliferative characteristics of primary and metastatic human solid tumors by DNA flow cytometry.

The percentage of cells in S-phase (S-index) was calculated from DNA histograms of 453 primary and metastatic human solid tumors (predominantly bladder, breast, colorectal, renal, prostate, ovarian and lung carcinomas, melanomas, and sarcomas). S-indices varied widely among both primary and metastatic tumors (1-48%); there was no significant difference in S-indices between primary and metastatic tumors. The S-indices for aneuploid tumors were significantly higher than for diploid tumors. When data for all aneuploid tumors were analyzed collectively, there was no significant relationship between S-index and DNA ploidy index. However, for colorectal and ovarian carcinomas S-indices increased, and for lung carcinomas S-indices decreased with elevation in the degree of DNA-ploidy. Lung carcinomas had the highest S-indices. Comparison of flow cytometry (FCM) and cytology data indicated that for most diploid tumors S-indices reflect the proportion of S-phase cells among a mixed population of normal and tumor cells. For most aneuploid tumors, the proportion of tumor cells estimated cytologically was similar to the proportion of aneuploid cells estimated by FCM. For a small proportion of aneuploid tumors a comparison of cytology and FCM data indicated the presence of a predominant diploid tumor stemline and a minor stemline with aneuploid DNA content. There was a wide spread in the values of S-indices within tumor groups defined by degree of differentiation and stage of disease at surgery.

Aneuploidy↗
PubMed1984

Serial cytogenetic analysis of a recurrent malignant melanoma.

A metastatic malignant melanoma in a 54-yr-old white female was examined cytogenetically on three different occasions. We found two different clones, one hypodiploid and another hypertriploid; however, both clones had the same markers [i.e., der(6),t(6;17), and der(17),t(1;17)]. Detailed analysis of the histopathology and clinical course suggests that these two different clones reflected different morphology and results of therapy.

Chromosome Aberrations↗
PubMed1983

Correlation of tumor-cell growth in four semisolid systems.

The correlation of the colony growth of cells disaggregated from human melanoma, sarcoma, lung, and ovarian carcinomas were studied in four different semisolid tissue culture assays: (a) the soft agar assay of Pluznik and Sachs; (b) the soft agar assay of Hamburger and Salmon; (c) the soft agar-methyl cellulose assay of Buick et al.; and (d) the methyl cellulose assay of Ogawa et al. There was no colony growth of tumor cells achieved in 15 of 15 cases assayed in Ogawa's methyl cellulose assay. The plating efficiency of the above mentioned tumors was similar in the assays of Pluznik and Sachs, Hamburger and Salmon, and Buick et al. However, the tumor take rate differed among these three systems. The assay of Buick et al. appears potentially useful for analysis of the biology of human tumors.

Adenocarcinoma↗
PubMed1982

Relationship between plasma Ara-C and intracellular Ara-CTP pools under conditions of continuous infusion and high-dose Ara-C treatment.

Plasma level Ara-C and Ara-U in vivo and intracellular Ara-CTP pools in vivo and in vitro were measured using high-performance liquid chromatography and radioimmunoassay. Plasma Ara-C during High Dose therapy was found in two phases; one, a peak at t1/2 of approximately 5-8 minutes, the other approaching that of Continuous Infusion with a t1/2 of about 6 to 8 hours. There appears to be no relationship between peak levels of plasma Ara-C and intracellular Ara-CTP formed during High Dose therapy. Intracellular Ara-CTP pools were found to be higher in peripheral blood than in bone marrow during High Dose treatment and were also higher in bone marrow of patients treated with High Dose rather than conventional dose Ara-C. In vitro experiments with various concentrations of Ara-C on patient cells prior to treatment suggest that patients may benefit from High Dose therapy when an increase in intracellular Ara-CTP occurred with higher extracellular concentrations of Ara-C. In patients with metabolically sensitive cells containing the necessary enzymes to activate Ara-C to Ara-CTP, where resistance is due to limited drug transport, High Dose therapy may prove beneficial. Conversely, in patients with no increase in Ara-CTP pools in vitro due to a depletion of activating enzymes, High Dose treatment may not be warranted. Therefore, it may be possible to determine patients most likely to benefit from High Dose chemotherapy by measuring pre-treatment in vitro intracellular Ara-CTP.

Arabinofuranosylcytosine Triphosphate↗
PubMed1981

The soft agar clonogenicity and characterization of cells obtained from human solid tumors by mechanical and enzymatic means.

A two-step procedure for releasing cells from solid tumors has been applied to specimens of human melanoma, sarcoma, lung, colon, and breast carcinoma. The first population released mechanically has been compared with the population subsequently released enzymatically in tests of dye exclusion, ribonucleoside triphosphate pool sizes, intactness of DNA, and clonogenicity in soft agar. While greater numbers of dye-excluding cells are released in the enzymatic step, and these cells have higher ribonucleoside triphosphate pools and more intact DNA, both populations contain clonogenic cells in approximately equal numbers. Several semisolid media were employed in tests of clonogenicity, and all methods employing an agar underlayer appeared satisfactory and approximately equivalent in cloning efficiency. The methyl cellulose upper layer system facilitated implanting of pooled colonies into nude mice, which resulted in growth in the nude host and marked increase in cloning efficiency when the cells were replanted into soft agar-methyl cellulose plates. A comparison of four different areas of individual tumor specimens was made with cells released enzymatically and measuring cell yield, dye exclusion, ATP pool size, and uptake and metabolism of 5-fluoropyrimidines. Only relatively small variations were seen from one area to the next, with trypan blue exclusion exhibiting the least variation, and metabolism of fluorinated pyrimidines showing the most.

Animals↗
PubMed1981

Chromosomes and causation of human cancer and leukemia. XLIV. A method for chromosome analysis of solid tumors.

Mechanical and enzymatic disaggregation procedures have been utilized for the preparation of materials suitable for chromosome examination of tissues from various kinds of solid tumors. A great number of the cells disaggregated with the latter procedure were observed to attach to the bottom of culture flasks after 2 days in vitro; cells obtained with the former method were not attached. In general, the enzymatic procedure yielded a significantly larger number of viable cells that would undergo mitosis after short term culture and considerably improved the quality of banding as compared to the mechanical method. However, there were no significant differences among the basic karyotypes observed in the cells obtained by the mechanical approach versus those seen following the enzymatic method. This evidence, together with the high success rate of karyotyping in the enzyme-treated preparations, suggest that this should be the procedure of preference for cytogenetic examination of various tumors, particularly where in the past karyotypic examination has been very difficult, e.g., the early stages of tumor development.

Cells, Cultured↗
PubMed1981

Histopathologic technique for the morphological examination of fixed or frozen solid tumor cells in soft agar.

Two simple techniques are described for preparing sections from soft agar colony cultures of tumor cells. Tumor cells grown in soft agar can be frozen, sectioned, and stained and/or fixed in formalin, embedded in paraffin, sectioned, mounted on glass slides, and stained. The methods are simple and reproducible. These cells can be stained with various stains and the staining quality is excellent. The paraffin blocks and microscope slides can be stored for permanent record. The use of these techniques should provide better understanding of the histomorphologic characteristics of neoplastic cells which grow in soft agar and should expand and refine prognosis and diagnosis of malignant tumors.

Agar↗
PubMed1981

Characterization of cells obtained by mechanical and enzymatic means from human melanoma, sarcoma, and lung tumors.

Characterization of cells comprising solid tumors will facilitate the rational design of cancer chemotherapy for individual patients. We have prepared cell suspensions from human melanoma, sarcoma, and lung tumors by thinly slicing the tissue with a microtome and scalpels (mechanical release), followed by treatment with a mixture of collagenase II and DNase I (enzymatic release). This method of disaggregation resulted in two cell suspensions for each tumor specimen, and we characterized these suspensions by assessing their dye exclusion capability, ribonucleoside triphosphate pools, cytological profile and clonogenicity in soft agar. The enzymatic method thus yields cells in addition to those obtainable by a mild mechanical procedure, and these cells are similar in cytological profile and clonogenicity in soft agar to those released mechanically. Furthermore, the enzymatically released population is superior to that released mechanically for purposes requiring large numbers of dye-excluding cells having intact ribonucleotide pools.

Cell Count↗
PubMed1980

Colony growth in soft agar of human melanoma, sarcoma, and lung carcinoma cells disaggregated by mechanical and enzymatic methods.

The effect of mechanical and enzymatic disaggregation on human malignant melanoma, soft-tissue sarcoma and lung carcinoma colony growth in soft agar was studied. The enzymatic disaggregation was advantageous in most cases of melanoma and sarcoma, giving a larger number of colonies and increasing the probability of achieving growth in soft agar. Enzymatically treated pulmonary carcinoma cell populations had lower clonogeneic potential, especially in the case of anaplastic carcinomas. Morphological studies showed that the cells growing in soft-agar colonies had the same characteristics as those of the original tumor. A linear relationship was obtained between the number of enzymatically and mechanically treated tumor cells plated and the number of colonies. Delayed plating decreased the number of colonies.

Agar↗