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Biomedical subjects

S E Shackney

Publications and source records attributed to S E Shackney.

At least 55 records · Page 3Linked to original sources
PubMed1983

Schedule dependence of vincristine lethality in Sarcoma 180 cells following partial synchronization with hydroxyurea.

The effects of exposure to 0.1, 0.5, or 2 microM vincristine for 4 hr were studied in Sarcoma 180 cells at various times after synchronization with 5 mM hydroxyurea for 1 hr. Maximum sensitivity to the lethal effects of vincristine was observed at 10 to 14 hr after hydroxyurea exposure at the higher vincristine concentrations, compared to a period of a maximum sensitivity to a second dose of hydroxyurea at 8 to 12 hr. Serial flow cytometry studies indicated that the apparent decrease in sensitivity to vincristine at 14 to 18 hr was due to the division of cells in the leading segment of the synchronized wave and their entry into the relatively resistant G1 phase prior to vincristine exposure. Synchronized cells that had not divided at the time of vincristine exposure were blocked transiently in G2. Serial metaphase index studies suggested that the G2 cells closest to the end of the cell cycle at the time of vincristine exposure were likely to exhibit the greatest degree of mitotic disorganization when they overcame the G2 block and entered metaphase. The present studies suggest that sensitivity to vincristine increases progressively as cells approach mitosis. The molecular mechanisms underlying this phenomenon are considered in relation to the increase in cell tubulin content during the course of cell cycle progression.

Animals↗
PubMed1982

Artifacts associated with mithramycin fluorescence in the clinical detection and quantitation of aneuploidy by flow cytometry.

Ethanol-fixed cells stored at 4 degrees C exhibit fixation time-dependent hyperchromatism in comparison with freshly fixed cells when stained with mithramycin and examined by flow cytometry. This hyperchromatism has been found to be temperature-dependent, developing fully within 72 hr at room temperature, and within 2 hr at 37 degrees C. Cells from normal donors that are stained with mithramycin exhibit spurious aneuploid peaks. These spurious aneuploid peaks can be eliminated by incubating ethanol-fixed cells at 37 degrees C for 2 hr prior to staining; true aneuploidy is not affected by this procedure. In rare instances, cytoplasmic fluorescence can be observed in mithramycin-stained cells. In addition, unexplained hypochromatism and hyperchromatism can be observed in some clinical samples, particularly in human melanoma. The effects of these unexplained staining artifacts can be minimized or eliminated by adopting strict criteria for the clinical detection of aneuploidy by flow cytometry.

Aneuploidy↗
PubMed1982

Increased relative effectiveness of doxorubicin against slowly proliferating sarcoma 180 cells after prolonged drug exposure.

Doxorubicin (ADR) lethality was studied in Sarcoma 180 cells grown in vitro during log phase and early plateau phase. For both log phase and plateau phase cells, ADR lethality increased progressively with continuous drug exposure, and was dependent on drug concentration at every point in time. For any given level of toxicity to log phase cells, greater killing of plateau phase cells was achieved with prolonged drug exposure. The inhibition of DNA synthesis by ADR was delayed in onset, and increased gradually, both at low and high drug concentrations. The data suggest that the dependence of ADR lethality on proliferation rate and the higher therapeutic ratio in plateau phase cells with prolonged drug exposure are not directly related to the ADR effects on DNA synthesis.

Animals↗
PubMed1981

Patterns of cell proliferation and cell migration in the Sézary syndrome.

The patterns of cell proliferation and cell migration were studied in three patients with the Sezary syndrome using autoradiographic techniques. Cell labeling patterns following pulse labeling with tritiated thymidine in vivo indicated that Sezary cells proliferate actively in skin and in lymph nodes but that few if any Sezary cells proliferate in the peripheral blood. In two of the patients serial samples were obtained. Label dilution patterns in skin and blood over time suggested that circulating Sezary cells originated in extracutaneous sites where cells were proliferating more rapidly than in the skin. Cells labeled in extracutaneous sites of proliferation appear rapidly in the blood, and their transit time through the peripheral blood compartment is short. Circulating Sezary cells may then be deposited in the skin where they resume proliferation at a low rate. Thus, while Sezary cells proliferate in both cutaneous and extracutaneous sites, proliferation appears to be more rapid in extracutaneous sites such as lymph nodes. This suggests that trials of systemic therapeutic approaches should be undertaken.

Autoradiography↗
PubMed1981

Kinetic effects of sangivamycin in sarcoma 180 in vitro.

The lethal and sublethal effects of sangivamycin (SGM) were studied in sarcoma 180 in vitro in relation to drug concentration and duration of drug exposure. SGM lethality was found to be dependent on both drug concentration and duration of drug exposure. Pronounced effects on cell survival were observed only when SGM exposure was prolonged; with prolonged drug exposure, small increments in SGM concentration resulted in large increases in cell killing. Log-phase cells were more susceptible to the lethal effects of SGM than were early-plateau-phase cells. Measurements of incorporation of [3H]thymidine and [3H]uridine into the acid-insoluble cell fraction demonstrated inhibition of both DNA and RNA synthesis by SGM which was also dependent on drug concentration and duration of drug exposure, reflecting the lethality characteristics of SGM. As SGM concentration was increased, DNA synthesis was inhibited more rapidly than was RNA synthesis. Flow cytometry demonstrated a concentration- and time-dependent accumulation of cells in the late S and G2-M region of the DNA histogram. Our findings indicate that maximum lethality is obtained by prolongation of SGM exposure, and they suggest that pharmacokinetic studies may be important for determining regimens which provide such exposure in humans.

Animals↗
PubMed1981

Schedule-dependent synergism of combinations of hydroxyurea with adriamycin and 1-beta-D-arabinofuranosylcytosine with adriamycin.

The lethal effects of combinations of adriamycin (ADR) and either hydroxyurea (HU) or 1-beta-d-arabinofuranosylcytosine (ara-C) were studied in relation to drug-scheduling interval in Sarcoma 180 cells grown in vitro. Drug lethality was determined by cell cloning in soft agar. Serial kinetic changes induced by a priming dose of HU or ara-C were monitored by flow cytometry and related to schedule-dependent cell killing by ADR. All drug exposures were for 1 hr. When ADR was given together with either HU or ara-C, cell log kill was additive. However, when ADR was given after exposure to either HU or ara-C, cell killing was increased up to 200- to 500-fold, respectively. Maximum schedule-dependent synergism was observed at a drug-scheduling interval of 2 hr; schedule-dependent synergism decreased as the interval between drugs was increased beyond 2 hr. Schedule-dependent synergism was not observed when the same drug combinations were given in reversed order. Drug-induced changes in the DNA histogram were not seen until 5 hr after HU exposure and 8 hr after ara-C exposure. Thus, the schedule-dependent synergism between ADR and either HU or ara-C cannot be explained by cell cycle blockade with synchronization of cells in S phase.

Animals↗
PubMed1980

A study of drug-induced kinetic perturbations in the marrow of a patient with neuroblastoma.

The kinetic perturbations induced by vincristine, cyclophosphamide, and adriamycin were studied in the bone marrow of a patient with neuroblastoma. Serial marrow samples were studied by dual parameter (Coulter volume and DNA content), flow cytometry, and radioautography, and findings were correlated with cytomorphologic changes. Multiparameter studies were useful in sorting out the various sequences of drug-induced kinetic changes. Distinctive effects of vincristine were observed at 2 and 24 hours after drug administration. An early drug-induced proliferative response was observed between 2 and 48 hours after initiation of therapy. Cell damage was apparent on day 4, with recovery in cell proliferative rate observed on days 6 through 9. The kinetics of perturbation may be useful in identifying temporal windows for optimum scheduling of chemotherapeutic agents in man.

Adolescent↗
PubMed1980

Dual parameter flow cytometry studies in human lymphomas.

Dual parameter flow cytometry studies using Coulter volume and cell DNA content were carried out in monodisperse cell suspensions of 64 samples of human lymphoma, chronic lymphocytic leukemia, hairy cell leukemia, and benign lymphoid proliferations. Differences in mean Coulter volume among the lymphomas were due both to the intrinsic differences in mean G1 cell Coulter volume and to the presence of increased fractions of larger S and G2 cells, especially among the large B cell lymphomas. However, the relative contribution of large non-G1 cells to the overall population Coulter volume distribution was a relatively minor one; the presence of cells in S did not increase mean Coulter volume by more than 10%, even in samples with high S fractions. There was a good correlation between mean G1 cell Coulter volume and the log of the fraction of cells in S among the B cell lymphomas (r = 0.55). Evidence is presented that within individual samples, large cells proliferate more rapidly than small cells. This was seen in every case, both in the normal samples and in the lymphomas, and in the T cell lymphomas as well as in the B cell lymphomas. Aneuploidy was detected by flow cytometry in 11 cases; in 7 cases the aneuploid cell component could be analyzed separately from the diploid cell component on the basis of cell Coulter volume differences. The aneuploid components of diploid-aneuploid mixtures had higher S fractions than the diploid components in six of seven cases (0.16 +/- 0.04 [SE] vs. 0.08 +/- 0.02). These findings are considered in relation to the histopathological classification of the lymphomas, and in relation to the concept of clonal selection and clonal evolution of tumors.

Aneuploidy↗
PubMed1980

Electrolytic degradation of DNA fluorochromes during flow cytometric measurement of electronic cell volume.

Changes in flow cytometric measurement of DNA content can result from electrolytic chemical degradation of mithramycin, ethidium bromide, and propidium iodide during simultaneous measurement of electronic cell volume. Bench electrolysis also degrades these fluorochromes without changing the quantum yields, even when they are complexed to DNA. In the flow cytometer, electrolytic production of chlorine at the anode is the probable cause of this degradation, since exposure of these fluorochromes to chlorine gas produces the same effect. It is therefore advisable to measure the DNA content distribution alone before simultaneously measuring the DNA content and the electronic cell volume. If unavoidable effects on the DNA distribution are present, narrow forward-angle light scatter should be used as the cell size indicator during dual parameter measurements. Modifying instrument design by reversing electrode polarity might eliminate this problem.

Cytological Techniques↗
PubMed1979

Thymosin fraction V and intensive combination chemotherapy. Prolonging the survival of patients with small-cell lung cancer.

Patients with small-cell bronchogenic carcinoma who received intensive remission-induction chemotherapy randomly received either thymosin fraction V, 60 mg/sq m or 20 mg/sq m twice weekly, or no thymosin treatment during the initial six weeks of chemotherapy. Chemotherapy was then continued for two years. Thymosin administration did not increase the complete response rate. Patients receiving thymosin, 60 mg/sq m, had significantly prolonged survival times relative to the other treatment groups. This benefit was due to prolonged relapse-free survival in complete responders to treatment. The mechanism by which thymosin increased survival duration is unclear but may relate to restoration of immune deficits due to disease or treatment.

Antineoplastic Agents↗
PubMed1979

Cyclic alternating combination chemotherapy for small cell bronchogenic carcinoma.

Sixty-one protocol-eligible patients with small cell bronchogenic carcinoma received cyclic alternating combination chemotherapy with two or three non-cross-resistant drug combinations. No chest or prophylactic brain radiation therapy was used. Twenty-eight months after starting treatment, disease-free survival was 23% for patients achieving a complete response (CR) and 13% overall. Initial treatment consisted of high-dose cyclophosphamide, methotrexate, and CCNU (CMC) for 6 weeks. Patients then received vincristine, adriamycin, and procarbazine (VAP) for 6 weeks. The addition of VAP increased the CR rate from 42% to 74% in limited-disease patients and from 24% to 36% in extensive-disease patients. Half of the patients were randomized to a third combination of VO-16-213 and ifosfamide. These patients were cycled at 6-week intervals through the three drug regimens while the remaining patients were cycled between CMC and VAP. The addition of VP-16-213 and ifosfamide did not increase the CR rate or prolong survival. Only complete responders survived beyond 24 months. Sequential use of non-cross-resistant drug combinations represents one method for increasing the CR rate.

Antineoplastic Agents↗
PubMed1979

The T-lymphocyte as a diploid reference standard for flow cytometry.

T-lymphocytes prepared from the peripheral blood of normal individuals exhibit uniform postmitotic DNA contents that are constant from individual to individual when fixed in ethanol and stained with mithramycin, or when fixed in formalin and stained with acriflavine-Feulgen and analyzed by flow microfluorometry. T-lymphocytes fixed by either method are stable on storage for several months. These cells are suitable for use as an external diploid reference standard for flow cytometric detection of cells with abnormalities in postmitotic content exceeding 5% of diploid reference. Cells with abnormalities in postmitotic DNA content of less than 5% can be detected in mixtures containing both normal and malignant cells by multiparameter analysis.

DNA↗
PubMed1979

A dynamic interpretation of multiparameter studies in the lymphomas.

A general approach to the analysis of cellular life cycle traverse patterns is described. This approach is exemplified in human lymphomas, using Coulter volume and DNA content measurements obtained by flow cytometry. Among the B-cell tumors the large-cell lymphomas generally show larger fractions of DNA-synthesizing cells and a higher degree of proliferative activity than the small B-cell lymphomas. Paired cell-by-cell measurements of Coulter volume and DNA content can be used to distinguish large aneuploid tumor cells from smaller diploid cells in mixed cell populations. The paired measurements can also be used to explore the kinetic properties of subpopulations within individual tumor samples. It can be shown that within individual lymphoma samples there are subpopulations of large cells that have greater proliferative activity than the small cells.

Cell Cycle↗
PubMed1978

Growth rates of small cell bronchogenic carcinomas.

In reviewing a series of 144 patients with small cell bronchogenic carcinoma, 12 were found to have serially measurable roentgenographic lesions prior to therapy. Although caliper-based measurements and a silhouette cutout method gave comparable sets of tumor doubling time data, inter-observer variability was less with the silhouette cutout method. Tumor doubling times in small cell bronchogenic carcinoma ranged between 25 and 160 days, with a median of 77 days, a log mean of 81 days, and an arithmetic mean of 91 days. There was no apparent relation between tumor doubling time and tumor location, histologic subtype, response to therapy, or patient survival. The data indicate that small cell bronchogenic carcinoma of the lung is a relatively slowly growing tumor. Assuming that late subclinical disease exhibits growth characteristics that are similar to those seen in the clinical stages of growth, it can be estimated that residual body tumor burdens of 1 X 10(6) cells may be followed by tumor recurrence times of 2 years or longer; the likelihood of "cure" should not be entertained in patients with disease-free intervals shorter than 4-5 years.

Carcinoma, Bronchogenic↗
PubMed1978

Growth rate patterns of solid tumors and their relation to responsiveness to therapy: an analytical review.

The clinical doubling times of human solid tumors are reviewed. Methods are also described for estimating subclinical tumor doubling times, and these methods are applied to Wilms' tumor, choriocarcinoma, Burkitt's tumor, and breast cancer. Rapidly growing tumors are often responsive to therapy, and such complete responses are often quite durable. Slowly growing tumors respond less favorably to therapy, and responses are generally not durable. Rapidly growing tumors in advanced stages are similar in their response behavior to the slowly growing tumors. A strategy based on cell kinetics principles and tumor doubling time data is proposed for improving therapeutic results in responsive tumors. Data on clinical and subclinical tumor doubling times are used to distinguish early recurrences from late recurrences in a given tumor type. Early recurrences call for intensification of induction therapy, whereas late recurrences call for prolongation of consolidative therapy. This strategy may also apply in adjuvant therapy of slowly growing tumors.

Humans↗
PubMed1978

Streptozotocin in advanced small cell bronchogenic carcinoma: an ineffective nonmyelosuppressive agent.

Thirteen patients with advanced small cell bronchogenic carcinoma (SCBC) received at least three weekly cycles of iv streptozotocin (STZ). There were no objective responses. Four patients progressed by the third week of therapy and an additional eight by the fourth week. Toxicity was acceptable especially in view of the extensive prior therapy. STZ is unlikely to be of benefit in combination chemotherapy regiments for SCBC.

Aged↗