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Biomedical subjects

T G Pretlow

Publications and source records attributed to T G Pretlow.

At least 127 records · Page 7Linked to original sources
PubMed1976

Separation of tumor cells by density gradient centrifugation: recent work with human tumors and a discussion of the kind of quantitation needed in cell separation experiments.

The application of centrifugation to the purification of individual kinds of cells from tumors has been reviewed. Recent applications of a previously described isokinetic gradient to the purification of subpopulations of cells from human tumors are presented. Individual kinds of cells have been separated from Hodgkin's disease by a method described previously, and the cells from Hodgkin's disease which contain the tumor associated antigen described by Order and his colleagues have been identified for the first time. The importance of the thorough documentation of cell separation procedures is discussed, and we have specifically listed several kinds of data which we believe are important in the documentation of cell separation techniques.

Adenocarcinoma↗
PubMed1976

A characterization of human tonsillar lymphocytes after separation from other tonsillar cells in an isokinetic gradient of ficoll in tissue culture medium.

Purified human tonsillar lymphocytes responded less to mitogentic stimulation than did unseparated tonsillar cells. Their response to mitogens was restored when they were combined with cells from all other gradient fractions. We interpret our data as evidence that the majority of tonsillar lymphocytes require the presence of more rapidly sedimenting cells for a maximum response to the tested mitogens. The purified tonsillar lymphoyctes were 47.0% lymphocytes that have detectable surface immunoglobulin and 29.9% lumphocytes that form rosettes with sheep red blood cells. The predominant cell surface immunoglobulin was IgM. Digestion of the tonsil with trypsin yielded tenfold more plasma cells, more vialbe cells, and a larger proportion of blasts, histiocytes, and binucleated cells than were obtained by mechanical dissociation of the tissue.

B-Lymphocytes↗
PubMed1976

Heterogeneity among preparations of crude trypsin used to disaggregate the human tonsil.

Crude trypsin is the agent of choice for the disaggregation of human tonsil. A great variability which is not related to specific activity exists among lots of crude trypsin. An efficient lot of crude trypsin is necessary to obtain optimal proportions of tonsillar cells for the purification of lymphocytes and plasma cells by a previously reported technique.

Cell Count↗
PubMed1976

The use of glutaraldehyde-conjugated horseradish peroxidase-bovine serum albumin in the visualization of concanavalin A binding to tissue sections of human colonic tumor.

A method is reported for the preparation of glutaraldehyde cross-linked horseradish peroxidase conjugates for the visualization of concanavalin A binding to frozen sections. The binding of concanavalin A to tissue sections of human colonic tumor is used to compare staining by horseradish peroxidase conjugates and monomers. Without decreasing specificity, the use of progressively larger molecular weight conjugates provides progressively greater intensity of staining of the epithelial components of colonic carcinomas and normal colons.

Aldehydes↗
PubMed1976

Separation of cells with histochemically demonstrable acid phosphatase activity from suspensions of cells from human prostatic carcinomas in an isokinetic gradient of Ficoll in tissue culture medium.

This report describes the separation of cells exhibiting histochemically demonstrable acid phosphatase from suspensions of cells obtained from human prostatic carcinomas by velocity sedimentation. In the unseparated suspensions of cells, 40.5 +/- 7.7% of nucleated cells contained histochemically evident acid phosphatase. After cells were separated by velocity sedimentation, 86.4 +/- 9.4% of the nucleated cells in the purest fractions exhibited histochemically demonstrable acid phosphatase activity. More than 95% of these cells excluded trypan blue. To our knowledge, this is the first report of a method for the separation of viable epithelial cells from human prostatic carcinomas.

Acid Phosphatase↗
PubMed1975

Separation of cells exhibiting acid phosphatase activity from disaggregated hamster prostate cells in an isokinetic gradient of Ficoll in tissue culture medium.

Cells exhibiting histochemically demonstrable acid phosphatase were separated from suspensions of hamster prostate cells with velocity and isopyknic sedimentation. Unseparated suspensions of hamster prostate cells contained 57.2 plus or minus 11.3% cells with histochemically apparent acid phosphatase. After the cells were separated by velocity sedimentation in a previously described isokinetic gradient, the purest fractions from the gradient contained 97.2 plus or minus 0.8% cells with histochemically evident acid phosphatase. More than 99% of these separated cells excluded trypan blue. These cells were thought to be the acinar cells of the prostate. Isopyknic sedimentation was not as effective as velocity sedimentation for the purification of these cells.

Acid Phosphatase↗
PubMed1975

Separation of cells with histochemically demonstrable acid phosphatase activity from suspensions of human prostatic cells in an isokinetic gradient of Ficoll in tissue culture medium.

Collagenase, trypsin, and pronase were used in separate, parallel experiments to obtain cell suspensions from human prostates obtained from surgical resections and autopsies. All of the examined prostates demonstrated benign hyperplasia. The dissociation using pronase gave both the largest number of nucleated cells and the largest proportion of viable cells from prostates. Surgically resected prostates gave a larger number of cells per gram of tissue than prostates obtained from autopsy. Cells obtained from surgically resected prostates were separated both by isopycnic sedimentation and by velocity sedimentation in a previously described isokinetic gradient. We studied fifteen prostates obtained at surgery; using pronase, we obtained 2.1 plus or minus 3.5 times 10(6) cells/g. Of these cells, 34.0 plus or minus 14.7% contained histochemically demonstrable acid phosphatase. Cells from six prostates were separated by velocity sedimentation in the isokinetic gradients; in the purest fractions from the isokinetic gradients, 81.0 plus or minus 12.2% of nucleated cells had histochemically demonstrable acid phosphatase. The cells in the purest fractions appeared to be epithelial cells. More than 99% of these separated cells excluded trypan blue. Isopycnic sedimentation was not an effective means of purifying epithelial cells from human prostates.

Acid Phosphatase↗
PubMed1974

Separation of cells having histochemically demonstrable glucose-6-phosphatase from suspensions of hamster kidney cells in an isokinetic density gradient of Ficoll in tissue culture medium.

Suspensions of enzymatically disaggregated hamster kidney cells were separated primarily according to differences in diameter using velocity sedimentation in a previously described isokinetic density gradient and according to differences in density in an isopycnic density gradient. Cells which contained histochemically demonstrable glucose-6-phosphatase were thought to be cells from proximal tubules and constituted 46.5 +/- 14.1% of the cells in the starting sample suspension of disaggregated kidney cells. The purest gradient fractions from experiments using velocity sedimentation contained 98.0 +/- 0.6% cells which demonstrated glucose-6-phosphatase activity. More than 99.0% of these cells excluded trypan blue. Isopycnic sedimentation was not an effective means of purifying proximal tubule cells.

Animals↗
PubMed1974

Separation of hamster testicular cells in successive stages of differentiation by velocity sedimentation in an isokinetic gradient of Ficoll in tissue culture medium.

Recently there have been numerous studies of testicular cells which have used velocity sedimentation for several hours at 1g to separate the cells. In most cases these cells have been identified by their velocities of sedimentation rather than by their morphologic characteristics. Using velocity sedimentation at 55g for 21 minutes in a previously described isokinetic gradient of Ficoll in tissue culture medium, modal populations of mature sperm cells, red blood cells, spermatids with perforatoria, multinucleated cells and other round nucleated cells were separated from suspensions of testicular cells primarily according to differences in diameter. While these modal populations of morphologically identified cell types were well defined, they were frequently in overlapping zones of the density gradient and not widely resolved from each other.

Animals↗
PubMed1974

Separation of acinar cells from lactating mammary gland using velocity sedimentation in an isokinetic gradient of Ficoll in tissue culture medium.

This report describes a procedure for the purification of acinar cells from the disaggregated lactating mammary gland of the rat. Following disaggregation of the 15 days postpartum mammary gland, two qualitatively different kinds of cells which exhibited alkaline phosphatase activity were identified. These two populations of cells were separated in a previously described isokinetic gradient of Ficoll in tissue culture medium using a centrifugal force of 55g for 14 minutes. The larger of these two types of cells was found in a well-defined subpopulation of mammary cells, 97.4 +/- 0.8% of which lacked demonstrable adenosine triphosphatase activity by light microscopy. Ultrastructurally, these cells were identified as being almost exclusively acinar cells. The potential significance of this method is discussed.

Alkaline Phosphatase↗