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T G Pretlow

Publications and source records attributed to T G Pretlow.

At least 145 records · Page 8Linked to original sources
PubMed1973

Separation of lipase-positive cells from suspensions of pancreas cells in an isokinetic gradient of Ficoll in tissue culture medium.

Lipase-positive cells were separated from suspensions of pancreas cells both by velocity sedimentation and by isopycnic sedimentation. Lipase-positive cells were 51.0 +/- 9.6% of the disaggregated pancreas cells in the starting sample suspension. The purest gradient fractions from experiments using velocity sedimentation for cell separation contained a mean of 98.8 +/- 0.6% lipase-positive cells. Cell separation using isopycnic centrifugation was less effective than cell separation using velocity sedimentation and resulted in a mean purity of only 89.8 +/- 6.8% lipase-positive cells. Lipase positivity was assessed using the Gomori technic with the conditions for fixation slightly modified to be suitable for disaggregated cells.

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PubMed1973

Separation of spleen colony forming units (CEU-S) from mouse bone marrow cells using velocity sedimentation in an isokinetic gradient of Ficoll in tissue culture medium.

Spleen colony forming cells (CFU-S) from mouse bone marrow were concentrated using velocity sedimentation in an isokinetic gradient of Ficoll (polysucrose) in tissue culture medium. Following separation, CFU-S were found as a sharp modal population of cells which was discrete from the modal populations of lymphocytes and other cell types. Despite the wide separation of lymphocytes, granulocytes and CFU-S in the density gradient, there was no appreciable resolution of CFU-S specifically committed to erythroid, granulocytic or undifferentiated colony formation. This suggests that committed stem cells either share identical physical properties or are not detected by the spleen colony assay. In the purest fractions from the isokinetic gradient, CFU-S were 2.8- to 4.7-fold purified when compared with mouse bone marrow before separation.

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PubMed1972

Separation of beating cardiac myocytes from suspensions of heart cells.

Heart cells were obtained in suspension after incubation with collagenase and hyaluronidase in Saline A. Cardiac myocytes were separated by isopycnic centrifugation in 88.6 to 92.4% purity from other heart cells with different densities, and by velocity or rate-zonal sedimentation, in 92.8 to 97.4% purity from heart cells with different diameters. A previously described computer integration of the differential sedimentation equation was used to determine the centrifugal force, duration of centrifugation and gradient design, which would permit the separation of cardiac myocytes from other heart cells by velocity sedimentation. The myocytes continued to contract rhythmically after being recovered from the density gradients. Velocity sedimentation was superior to isopycnic sedimentation for the separation of cardiac myocytes from heart cell suspensions because it gave the most highly purified myocytes, resulted in recovery of the largest proportion of myocytes in purified fractions from the gradient and required lower centrifugal forces for shorter periods of time. The potential significance of the availability of pure cardiac myocytes is discsused.

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PubMed1972

Separation of ascites myeloma cells, lymphocytes and macrophages by zonal centrifugation on an isokinetic gradient.

In attempting to quantitate immunoglobulin synthesis by ascites myeloma cells, we were surprised to note that malignant appearing cells never exceeded 35.9 = 28.0% of ascitic cells and exceeded 22.4 +/- 23.8% of ascitic cells on only one day between the transplantation of the tumor and the death of the host. The ascites tumor suspensions were separated primarily according to diameter, using a previously described isokinetic density gradient of Ficoll in tissue culture medium. This separation resulted in four modal populations of cells: red blood cells, lymphoid cells, macrophages and myeloma cells. The modal populations of macrophages and lymphoid cells always contained less than 0.2% myeloma cells. The purified cells were tested for tumorigenicity. The animal which received the largest number of cells from the macrophage zone received 296 times the number of cells which had been determined to be tumorigenic for myeloma cells. The animal which received the largest number of cells from the lymphoid zone received 1600 times the tumorigenic dose for myeloma cells. Neither of these animals has become ill 4 months after receiving the purified cells. We conclude that: a) Experimentalists who use ascites tumors are not justified in assuming that even easily detected quantitative differences between benign and malignant tissues would be reflected in analyses performed using unstandardized unexamined ascites tumor suspensions. b) In the case of the MOPC 104 mouse myeloma, cytologic criteria are adequate for distinguishing malignant cells from the inflammatory cells in the ascites suspension with a high degree of correspondence between cytologic appearance and biologic activity. c) Programmed gradient sedimentation in an isokinetic gradient of Ficoll in tissue culture medium is an effective means of separating malignant cells from benign cells in this particular ascites tumor.

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PubMed1968

Centrifugation of mammalian cells on gradients: a new rotor.

A short-arm rotor increases separation of viable mammalian cells, from mixtures, by low-speed centrifugation; continuous Ficoll density gradients in tissue-culture media are used. We describe the theory and experimental demonstration of the superior separation achieved with this new rotor.

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PubMedDate not supplied

A new human prostate carcinoma cell line, 22Rv1.

A cell line has been derived from a human prostatic carcinoma xenograft, CWR22R. This represents one of very few available cell lines representative of this disease. The cell line is derived from a xenograft that was serially propagated in mice after castration-induced regression and relapse of the parental, androgen-dependent CWR22 xenograft. Flow cytometric and cytogenetic analysis showed that this cell line represents one hyper DNA-diploid stem line with two clonal, evolved cytogenetic sublines. The basic karyotype is close to that of the grandparent xenograft, CWR22, and is relatively simple with 50 chromosomes. In nude mice, the line forms tumors with morphology similar to that of the xenografts, and like the parental CWR22 and CWR22R xenografts, this cell line expresses prostate specific antigen. Growth is weakly stimulated by dihydroxytestosterone and lysates are immunoreactive with androgen receptor antibody by Western blot analysis. Growth is stimulated by epidermal growth factor but is not inhibited by transforming growth factor-beta1.

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