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Biomedical subjects

B Drewinko

Publications and source records attributed to B Drewinko.

At least 91 records · Page 5Linked to original sources
PubMed1981

Biological properties of the human colonic adenocarcinoma cell line SW 620 grown as a xenograft in the athymic mouse.

The biological and cell kinetic properties of the poorly differentiated human colonic adenocarcinoma cell line SW 620 grown as xenografts in BALB/c athymic mice are described. The SW 620 cells consistently produced tumors when inoculated i.v., i.p., and s.c. The lowest cell inoculum requirements were seen i.p. where 10(7) cells produced a 100% incidence. Intravenous inocula (10(5) to 10(8) cells) produced microscopic lung colonies within 30 days, becoming macroscopic nodules after 60 days. Subcutaneous tumors exhibited a marked Révész effect, using a thromboplastic brain extract which increased both tumor incidence and growth rate. All SW 620 xenografts presented a poorly differentiated morphology with extensive necrotic foci. No metastatic involvement was noted in any murine tissues. No demonstrable levels of carcinoembryonic antigen were present in the sera of animals bearing s.c. xenografts greater than 5.0 cu cm. Early SW 620 xenografts (0.3 to 0.6 cu cm) exhibited a characteristically human cell kinetic profile (Tc congruent to 34 to 43 hr; Ts congruent to 22 hr), with a growth fraction of 30.5% as measured by the primer-available DNA polymerase-index and a high cell loss factor (45%). Among late xenografts (1.1 to 1.6 cu cm), the kinetic events noted were an increase in the Tc, cell loss and, unexpectedly, an increase in the primer-available DNA polymerase index. A colony formation assay was established with the use of mechanical mincing plus collagenase (150 IU/ml; 37 degrees; 30 min), which produced a mean plating efficiency of 33.6 +/- 7.2% (S.E.) for s.c. xenografts (range, 14.6 to 51.0%). The SW 620 xenograft model possesses the biological and cell kinetic profile of many human colonic adenocarcinomas in situ. These properties, coupled with the capacity for large-scale xenograft production, should provide a clinically relevant model for the screening of potential antitumor agents and procedures.

Adenocarcinoma↗
PubMed1981

The growth fraction of human myeloma cells.

Greater reductions of tumor load in patients with multiple myeloma may result from therapeutic strategies that are based on a better knowledge of growth kinetics. We have previously shown that the labeling index of myeloma cells remains unchanged when tumor mass is reduced and that the cells of relapsing patients have differnt biologic properties than the cells present before melphalan-prednisone therapy. This study investigated the growth fraction (GF) of myeloma cells at various disease stages using continuous i.v. infusions of tritiated thymidine. We studied 17 patients on 22 occasions (4 untreated, 2 unresponsive, 6 in remission, and 10 in relapse). All untreated an unresponsive patients and 5 of 6 patients in remission had a GF of less than 4%. GF was defined in these studies as the maximum percentage of labeled plasma cells exposed continuously to tritiated thymidine. Relapsing patients, with the most rapid tumor doubling times, had GF ranging from 14% to 83%. The plasma cell transit time through the proliferative compartment for all of the relapsing patients ranged from 6.6 to 11.9 days and the calculated intrinsic cell loss ranged from 50% to 86%. These findings support our model for the growth kinetics of multiple myeloma that assumes that the entire tumor mass issues from a small proportion of proliferating cells and that the growth kinetics of myeloma cells in relapsing patterns differ from those in untreated and unresponsive patients. Therapeutic trials with cycle-active agents need further investigation in selected relapsing patients who are likely to have a high growth fraction.

Female↗
PubMed1980

Treatment of cultured human colon carcinoma cells with fluorinated pyrimidines.

The shape of the initial part of the dose-dependent response curve of LoVo cells, an established human colon carcinoma cell line, exposed for 1 hr to graded concentrations of 5-FU depended on the medium supplement, i.e., fetal calf serum (FCS), in which the cells were treated and subsequently incubated for colony-formation. At concentrations of 50--100 micrograms/ml (equivalent to peak plasma levels following an in vivo bolus dose of 15 mg/kg) cell kill was completely prevented by FCS. The serum did not contain thymidine (TdR) but had significant amounts of uridine (UR). When 5-FU was delivered in dialyzed FCS, concentrations of 50--100 micrograms/ml achieved only a modest 15% cell kill after 1 hour treatment. Regardless of medium supplement, the killing effect of 5-FU did not increase beyond concentrations greater than 2,000 micrograms/ml. Increasing the exposure interval dramatically increased the killing of LoVo cells by 5-FU, although the effects of medium supplement on the degree of cell survival persisted for about 12 hours. Virtually all of the incorporated 5-FU was transformed into 5-FUR, and a very small proportion eventually was incorporated into nucleic acids, suggesting that the killing effect of 5-FU on LoVo cells is mediated mostly by ribosidation and not by conversion into the deoxyribonucleoside. This conclusion is supported by the failure of 5-FUdR to kill LoVo cells after a treatment interval of one hour, even at concentrations of 5000 micrograms/ml; yet after the same exposure interval, 5-FUR effectively killed cells at concentrations of 50--100 micrograms/ml. TdR afforded no protection from cell kill by 5-FU. In contrast, UR was capable of protecting LoVo cells from the lethal effects of both 5-FU and 5-FUR even at concentrations as low as 10 micrograms/ml. Ftorafur exposed to LoVo cells for 1 hour had a slight killing effect (about 20--25%) at concentrations ranging up to 2000 micrograms/ml. Although the lethal effect of ftorafur was slightly increased after longer periods of incubation, it failed to reach 90% even after intervals of 48 hours. The results on cellular sensitivity that we obtained for LoVo cells treated with various fluorinated pyrimidines differ substantially from those of other investigators who used different methods to assess cell killing on nonhuman and noncolonic cell systems. The predictive relevance of these data as compared to those obtained in other systems is justified by the suboptimal results with these agents in clinical practice.

Cell Line↗
PubMed1980

Serum CEA levels in a human colonic adenocarcinoma (LOVO) xenograft system.

The relationship between tumor size and circulating CEA titers was examined for a human colonic adenocarcinoma xenografted in Balb/C athymic mice. Xenograft material was derived from line LoVo, which produces moderate amounts of CEA, both in vitro and in vivo. No correlation was found between tumor size and serum CEA levels.

Adenocarcinoma↗
PubMed1980

A side-by-side evaluation of four platelet-counting instruments.

The performances of four instruments for counting platelets were evaluated in a side-by-side study: the Haema-Count MK-4/HC, an electronic impedance instrument that counts platelets in platelet-rich plasma; the Ultra-Flo 100, and the Coulter Counter Model S-Plus, electronic impedance instruments that count platelets in the presence of intact erythrocytes; and the AutoCounter, an optical instrument that counts platelets in the presence of lysed erythrocytes. The Ultra-Flo 100 and the S-Plus showed the best within-run precision, and all four instruments were considerably more precise than manual platelet counting, especially at low levels of platelet count. The four instruments were all linear in the ranges tested (5 to 650 x 10(9)/or greater), and sample carry-over was less than 0.7% for each. A noteworthy finding was that the erythrocyte concentration of the blood samples affected the displayed platelet count of the S-Plus and, to a lesser extent, that of the AutoCounter, in a predictable way, whereas it did not greatly affect the displayed count of the Ultra-Flo 100. In addition to differences in quality of performances, the four instruments differed considerably in speed and ease of operation and in cost.

Calibration↗
PubMed1980

Evaluation of automatic and semiautomatic coagulation assay instruments.

The precision of five instruments (Coag-A-Mate, Auto-Fi, Coagulyzer, Electra 600 and Fibrometer) in performing activated partial thrmboplastin time (PTT) assays were compared using three different coagulation reagent systems (Ortho, Dade, and General Diagnostics) utilizing normal and abnormal control reagents. There were wide variations in mean PTT values and co-efficient of variation (CV) among all instruments and for each instrument utilizing different reagents. The smallest CV was noted for The Coagulyzer using Dade reagents, the Coag-A-Mate using Dade and General Diagnostic reagents and the Auto-Fi using General Diagnostic reagents. Auto-Fi values were always longer than those determined with the Fibrometer whereas the optical detection instruments usually gave shorter values. The range of normal values for the prothrombin time (PT) and PTT assay was recorded simultaneously on blood samples of 52 healthy donors utilizing the Coagulyzer with Ortho reagents, the Coag-A-Mate with General Diagnostic reagents nd the Auto-Fi with Dade reagents. No differences were noted between male and female donors. There was a poor correlation among PT results recorded by all instruments. For the PTT assay, results obtained with the Coag-A-Mate and the Auto-Fi had a correlation of 0.84. The normal mean plus 2 or 3 standard deviations determined by the Auto-Fi and the Coag-A-Mate were used to classify blood samples from 263 patients as normal or abnormal when assayed by each instrument. For the PTT assay, coincidence was attained in 91.2% of the samples and discrepancies (a blood classified abnormal by one instrument and normal by the other) were evenly distributed for both instruments. For the PT assay, coincidence occurred in 85.1% of the cases and there was a statistically significant trend (P < 0.05) for the Auto-Fi in classifying abnormal samples categorized normal by the Coag-A-Mate.

Automation↗
PubMed1980

Observations on the synthesis of carcinoembryonic antigen by an established human colonic carcinoma cell line.

Some properties and kinetics of synthesis of the carcinoembryonic antigen (CEA-LoVo) produced by an established human colon carcinoma cell line were analyzed. CEA-LoVo was assayed by the method of Chu and Reynoso which was standardized against the activity of the First British Standard for CEA. CEA-LoVo was stable at -20 and 4 degrees C. At 37 degrees C, CEA-LoVo degraded at the rate of 1.4%/day in cell-free supernatants, and at the rate of 6.6%/day in the supernatants of monolayer cultures. CEA-LoVo was sensitive to enzymatic treatment ( approximately 55% loss) and extraction of PCA (greater than 70% loss). The elution profile of CEA-LoVo in concanavalin A-Sepharose B coincided with that of the First British Standard for CEA. No A or B blood group antigenic activity was noted. Studies employing immunofluorescent and horseradish peroxidase-labeled antibody techniques demonstrated heavy membrane and moderate intracytoplasmic localization. The greatest amount of net synthesis occurred for cells in stationary phase while CEA-LoVo release occurred maximally in lag phase.

Adenocarcinoma↗
PubMed1980

Observations on the synthesis of carcinoembryonic antigen by an established human colonic carcinoma cell line.

Some properties and kinetics of synthesis of the carcinoembryonic antigen (CEA-LoVo) produced by an established human colon carcinoma cell line were analyzed. CEA-LoVo was assayed by the method of Chu and Reynoso which was standardized against the activity of the First British Standard for CEA. CEA-LoVo was stable at -20 and 4 degrees C. At 37 degrees C, CEA-LoVo degraded at the rate of 1.4%/day in cell-free supernatants, and at the rate of 6.6%/day in the supernatants of monolayer cultures. CEA-LoVo was sensitive to enzymatic treatment with trypsin (approximately 55% loss)) and extraction of PCA (> 70% loss). The elution profile of CEA-LoVo in Concanavalin A-Sepharose B coincided with that of the First British Standard for CEA. No A or B blood group antigenic activity was noted. Studies employing immunofluorescent and horseradish peroxidase-labeled antibody techniques demonstrated heavy membrane and moderate intracytoplasmic localization. The greatest amount of net synthesis occurred for cells in the stationary phase while CEA-LoVo release occurred maximally in the lag phase.

Adenocarcinoma↗
PubMed1980

Flow cytometry of DNA content in human bone marrow: a critical reappraisal.

Because cytokinetic studies of the human bone marrow aspirate as a prognostic factor and as a monitor of drug perturbation are frequently inconsistent, we investigated reproducibility of DNA distribution measured by flow cytometry of DNA content in patients with morphologically normal bone marrow. In 15 patients, correlation was noted between DNA distributions simultaneously obtained on right and left iliac crest bone marrow aspirates (r = .588), although considerable variation in individuals was encountered. Much better reproducibility (r = .879) was achieved using bilateral core biopsy of bone marrow in these same patients. In 60 samples, comparison of DNA distribution between bone marrow aspirate and simultaneously obtained biopsy revealed higher relative proportions of S and G2 + M phase cells in biopsies (p less than 0.001), suggesting peripheral blood contamination of aspirate material. Brisk shaking of biopsy specimens in saline expelled a representative sample in the supernatant that could be subjected to simultaneous cytomorphological and cytokinetic analysis. To improve reproducibility of DNA content determinations in normal human bone marrow, bone marrow biopsy should be utilized.

Blood Cell Count↗
PubMed1980

A method to measure carcinoembryonic antigen neosynthesis by cultured colon carcinoma cells.

A double-antibody radioimmunoprecipitation assay was used to measure the rate of incorporation of radioactive precursors into carcinoembryonic antigen (CEA) newly synthesized by cultured human colon carcinoma (LoVo) cells. Mixtures of 125I-labeled CEA and standard CEA were used to construct titration curves as a function of concentration, time of incubation, and temperature for goat anti-CEA serum and rabbit antigoat serum. In contrast to the zirconyl phosphate gel method, the double-antibody technique did not precipitate compounds with low molecular weights. Similar slopes were observed when standard CEA was used to inhibit immunoprecipitation of 125I-labeled CEA by both the zirconyl phosphate gel and the double-antibody techniques. When CEA produced by the colon carcinoma cells (CEA-LoVo) was used to inhibit immunoprecipitation of radioactive 125 I-labeled CEA, the curve was superimposed upon that elicited for standard CEA. CEA-LoVo incorporated significant amounts of [N-acetyl-3H]glucosamine, and chromatography of the 3H-labeled CEA-LoVo eluted with a peak superimposed upon that of the First British Standard for CEA. This method was subsequently used to estimate changes in the rate of CEA neosynthesis by LoVo cells as a function of culture age. The rate of incorporation of [N-acetyl-3H]glucosamine into CEA of LoVo cells in stationary phase was about three times that measured for cells in exponential growth. The technique described in this report has the advantage that labeling of CEA results from actual metabolic cellular activity. Therefore, it provides a tracer method to study the localization and kinetics of CEA synthesis by cultured colon cells.

Acetylglucosamine↗
PubMed1980

In vitro thermochemotherapy of human colon cancer cells with cis-dichlorodiammineplatinum(II) and mitomycin C.

The thermosensitivity of human colon adenocarcinoma (LoVo) cells was investigated as a function of temperature and duration of heating in exponentially growing cultures. At 39-43 degrees, time-dependent survival followed a simple exponential function. Do values decreased progressively with a rise in temperature, from Do at 40 degrees = 38 hr to Do at 42 degrees = 17 hr to Do at 43 degrees = 1.5 hr. thus indicating relative thermoresistance of LoVo cells compared to Chinese hamster ovary cells. Dose-dependent 1-hr survival of LoVo cells treated with cis-dichlorodiammineplatinum(II) and mitomycin C was effectively modified when treatment was conducted under hyperthermic conditions. For both agents and cultures in exponential and stationary growth phases, hyperthermia abolished the initial shoulder portion and steepened the subsequent exponential part of the survival curves for dose-modifying factors at the 10% survival level of 1.5 to 2.0 at 41 degrees and 2.6 to 2.8 at 42 degrees. This significant enhancement of drug-induced cell kill by moderate hyperthermia suggests that thermochemotherapy with mitomycin C and cis-dichlorodiammineplatinum(II) should be tested clinically with both regional and total-body hyperthermia.

Adenocarcinoma↗
PubMed1980

Lethal and cytokinetic effects of mitomycin C on cultured human colon cancer cells.

The lethal and cytokinetic effects of mitomycin C (MC) as a function of drug concentration and exposure time were assessed in cultured human colon adenocarcinoma (LoVo) cells using colony formation to determine cell survival and DNA flow cytometry to examine cell cycle perturbation. MC evoked threshold-exponential type 1-hr dose-dependent survival curves in both exponential and stationary growth phases (Dq = 0.4 microgram/ml; Do = 1.0 microgram/ml). In exponentially growing cultures, a given exposure dose of MC induced equitoxic effects regardless of the specific drug concentration and exposure time used with uninterrupted treatment. However, dose fractionation experiments revealed the ability of LoVo cells to partially repair sublethal damage from MC exposure. Cell cycle progression was reversibly delayed or blocked in G2, S, and G1 phases in this order of sensitivity, with a frozen cycle distribution after greater than or equal to 24 hr treatment with 5 microgram of MC per ml. The reversible delay in S-phase traverse without a significant subsequent G2 block may be exploitable for administration of S-phase-specific drugs to maximize cell kill.

Adenocarcinoma↗
PubMed1979

Effects of time, platelet concentration, and sex on the human platelet aggregation response.

The platelet aggregation responses induced by adenosine diphosphate (ADP) and collagen were characterized by parameters defining rate and extent of reaction. Values were compared on the basis of platelet concentration, time elapsed between sample collection and test performance, and sex of donors. Rate and extent of aggregation varied as a function of platelet concentration. Maximal responses were obtained for platelet concentrations greater than 100,000/microliter. Results from samples processed after 90 min of incubation at room temperature were consistently and significantly lower than those obtained from samples processed immediately. ADP-induced aggregation responses elicited by samples from male and female normal donors differed significantly. This indicates that comparisons between normal and patient results should be made with sex-matched individuals to avoid erroneous interpretations.

Adenosine Diphosphate↗