Analysis of protein incorporation of radioactive isotopes in the Chinese hamster ovary cell cycle by electronic sorting and gel microelectrophoresis

The patterns of [3H]-leucine and [32P]-phosphate incorporation of proteins extracted with varying molarities of sodium chloride were analyzed from nuclei physically sorted from six fluorescence windows after propidium iodine staining of the G0 + G1 and G2 + M phases of the Chinese hamster ovary (CHO) cell cycle. Eight hundred nanograms of protein were used in each electrophoretic analysis obtained from 200,000 nuclei, a portion of the sample, from each window. Autoradiography was performed in a two-dimensional polyacrylamide gel ultra-microelectrophoresis apparatus (UMEA) designed and fabricated in this laboratory. There was a net reduction and/or loss of [3H]-leucine- and [32P]-phosphate-labeled protein regions from the autoradiographs occurring primarily in the G2 + M phase. Two phosphorylated proteins that were stage specific were observed in partitions of the G2 + M phase. The use of isolated proteins and the coelectrophoresis of these markers demonstrated the similarity in mobility of a number of proteins seen in the autoradiographs of proteins extracted with high and low salt molarities and implied they are synonymous. Coelectrophoresis indicated that a substantial number of high molecular weight proteins that decreased or disappeared at late stages of G2 + M and early mitosis were composed, in part, of nucleolar proteins.

Initiation of DNA synthesis in the liver and other tissues of adult mice by a growth factor (EACF) isolated from acellular fluid of the Ehrlich ascites carcinoma

The mitogenic effect of a new growth factor that we recently isolated from the acellular ascitic fluid of the Ehrlich ascites carcinoma grown in vivo was examined. We have called this factor EACF (Ehrlich ascites carcinoma factor). EACF caused initiation of DNA synthesis in the liver, submandibular gland, exorbital lacrimal gland and epithelium of the tongue of adult mice after i.p. injection at a protein concentration of 3 micrograms per 25 g of body weight. For all tissues examined, except the tongue, EACF initiated DNA synthesis at about 48 to 60 h after injection, with the maximum effect at approx. 85 h, and the stimulatory effect lasting approx. 60 h. The initiation of DNA synthesis in liver, which is normally characterized by only an occasional cell passing through the S phase, by EACF is of particular interest. The initiation of DNA synthesis in the liver was not prevented by hypophysectomy. Evidence also indicates that a similar heat-labile growth promoting factor(s) is present in calf serum.

Circadian biological time influences the effect adriamycin has on DNA synthesis in mouse bone marrow, ileum and tongue but not Ehrlich ascites carcinoma

Adriamycin (ADR; 10 mg/kg) was given to mice bearing a 5-day-old Ehrlich ascites carcinoma (EAC) at two different circadian times: 05.00 and 17.00 h. The incorporation of tritiated thymidine into DNA (DNA synthetic activity; DNA-SA) was studied in the epithelium of the tongue, ileum, bone marrow and the EAC over a 120-hour period after treatment. ADR at 05.00 h was more perturbing of DNA-SA in the normal organs than was ADR at 17.00 h. ADR at 05.00 h caused greater inhibition of DNA-SA for longer periods of time than did ADR at 17.00 h. Thus, the point in the circadian system of the host when ADR was given significantly affected the result obtained in the normal organs. This was not true for the EAC. DNA-SA in the EAC responded in an almost identical manner regardless of whether the ADR was given at 05.00 or at 17.00 h.

Circadian influence on the metaphase arrest technique in mouse cornea (light microscopy study) and rectum (flow cytometry study)

Vincristine (VC) was used to arrest metaphases in the epithelium of the cornea and rectum. The cornea was studied by light microscopy (mitotic index). The rectum was analyzed by flow cytometry (%G2 + M). The results of a dose range finding study showed that 3.0 mg/kg body weight VC did not increase the number of metaphases in the cornea or the %G2 + M for the rectum over that recorded for a dose of 1.0 mg/kg VC. Therefore 1.0 mg/kg VC was selected as the dose to use. Mice were kept on a 12:12 light-dark cycle with light from 0600 to 1800. Mice were treated with 1.0 mg/kg VC at either 0200 or 1400. 0200 is a time when the native mitotic index is increasing toward a peak level, which is attained at 0800-1000 under these conditions. 1400 is a time when the mitotic index is decreasing to trough level, which is attained at 2000 to 2200. In one experiment, subgroups of mice were killed at +3 (0500 or 1700) and +6 (0800 or 2000) hours after VC. In a replicate experiment subgroups were killed at +2 (0400 or 1600), +4 (0600 or 1800), and +6 (0800 or 2000) hours after VC. The data from the cornea (mitotic indices) and the rectum (%G2 + M) were graphed against time. For both organs the slope of the metaphase accumulation line was different when VC at 0200 data were compared to VC at 1400 data. The conclusion reached was that by changing the biological time of the experiment one can significantly change the slope of the line obtained with the stathmokinetic technique.

Drug modulation of chromosomal protein subtypes during specific phases of the submaxillary cell cycle

The H1 subtype proteins a, b, c, d, e, and 1 degree and the high mobility group (HMG) proteins 14 and 17 were extracted from submaxillary gland (SMG) nuclei treated in vivo and sorted from specific phases of the cell cycle, and analyzed by gel electrophoresis. Significant differences in these proteins were noted between quiescent (GO) phase nuclei and proliferating nuclei in both stained and autoradiographic gels. Stimulation of the SMG into cell division with DL-isoproterenol-HCl alone or in conjunction with sodium phenobarbital (PB) provided a system for the analysis of drug effects in stained, 3H lysine, and 32P pulse-labeled nuclear proteins obtained from different phases of the cell cycle.

Effect of biological time on the determination of the LD50 of 5-fluorouracil in mice

The LD50 was determined for 5-fluorouracil (FU) in mice at 11.00 and 23.00 h during one 24-hour period. These times were chosen because in mice kept on a light-dark cycle, with lights on from 06.00 to 18.00 h, the natural circadian rhythm in DNA synthetic activity in many different normal organs attains peak levels around 24.00 h (mid-dark) and through levels around 12.00 h (mid-light). The LD50 of FU, in milligrams per kilogram body weight, was much higher (450-500 mg/kg) at 11.00 than at 23.00 h (250-300 mg/kg). Since the biology of the living animal oscillates significantly on a daily or circadian basis, it is understandable that the degree of susceptibility or resistance to drugs should also fluctuate over the circadian period. Determination of the LD50 of a drug at that point in time when the animal is naturally resistant to that drug will result is a false appraisal of the toxic effects to the drug. To assess correctly the risk a drug poses, it should be tested at its time of maximal susceptibility in the living animal.

Effect of cyclophosphamide on circadian rhythms in mitosis and DNA synthesis in normal mice and mice bearing the Ehrlich ascites carcinoma

A single dose of 50 mg/kg of cyclophosphamide (cytoxan or CTX) was given to non-tumor-bearing mice and to mice bearing the Ehrlich ascites carcinoma (EAC). Circadian profiles in mitotic index and/or DNA-synthetic activity (DNA-SA: incorporation of tritiated thymidine into chemically isolated DNA) were monitored in normal organs and in the EAC. Mice were standardized to and kept on a 12 h: 12 h light-dark cycle with light from 06.00 to 18.00 h (CST or central standard time). In non-tumor-bearing mice, CTX at 05.00 h was more disruptive of the normal circadian profiles than was CTX at 17.00 h. CTX at 17.00 h was selected as the treatment to attempt to induce changes in DNA-SA of the EAC but concomitantly preserve the normal phasing of the circadian rhythms in the normal organs. Except for the bone marrow, CTX at 17.00 h did not perturb the normal circadian patterns in the normal organs (cornea, tongue, spleen, liver, ileum, rectum) of the EAC-bearing mice. CTX did cause a significant and prolonged inhibition of DNA-SA in the EAC. However, CTX-treated, EAC-bearing mice did not live significantly longer than saline-treated EAC-bearing mice.

Induction by 5-fluorouracil of a major phase difference in the circadian profiles of DNA synthesis between the Ehrlich ascites carcinoma and five normal organs

DNA synthetic activity (DNA-SA) was measured by the incorporation of tritiated thymidine (TDR) into chemically isolated DNA. DNA-SA was monitored every 3 h over a 60-h period in the Ehrlich ascites carcinoma (EAC), tongue, bone marrow, ileum, stomach and rectum in mice which had received 50 mg/kg 5-fluorouracil (FU) at 17:00 h. FU was given in an attempt to induce major phase differences in the circadian profiles of DNA-SA between the EAC and the normal organs. Subsequent to the FU treatment, a time period 15 h in duration, was identified when DNA-SA in the EAC was at or near a maximal level (125-190 cpm/micrograms DNA) whereas DNA-SA in all 5 normal organs was at or near a minimal level (less than 60 cpm/micrograms DNA). Induction of such quantitative (actual levels of DNA-SA) and qualitative (180 degrees circadian phase change) differences between the normal and neoplastic cells in the same host should be useful in designing a more effective chemotherapeutic protocol for this tumor-host situation.

Preparation and stability of sixteen murine tissues and organs for flow cytometric cell cycle analysis

Three different technical protocols were used to prepare samples for flow cytometric (FCM) analysis. Each protocol developed worked best for only certain organs. Protocol I involved mincing small pieces of fresh tissue in the propidium iodide (PI) staining solution and filtering through packed glass wool. The organs that were prepared by protocol I were: submandibular gland, urinary bladder, liver, thymus, bone marrow, spleen, lung, kidney and testis. Protocol II involved exposure of the organ to 0.5% acetic acid for 48 h prior to mincing in the PI. The organs that were prepared by protocol II were: uterus, rectum, colon, ileum, and heart. Protocol III utilized an exposure to 0.5% acetic acid, pepsinization, and then staining with PI. The tissues that were prepared by protocol III were the epithelium of the anterior surface of the cornea and the epithelium of the surface of the tongue. A total of 16 different organs and tissues were successfully prepared. For each organ, averaged DNA histograms were analyzed by nonparametric and parametric programs and the results (phase fractions) are presented in tabular form. Several of the organs used came from animals exposed to 1.0 mg/kg vincristine (VC) for 5-6 h to test the capability of the different protocols to detect the enlargement of the G2 + M compartment by the accumulation of VC-arrested mitotic figures. The stability of the many different sample preparations was tested by comparing averaged DNA histograms obtained on the day of sample preparation to averaged DNA histograms of the same set of samples after storage at 4 degrees C, with or without fixation in 10% phosphate-buffered formalin, for days to weeks. After staining with propidium iodide, fixation of the sample with a final concentration of 2-3% phosphate-buffered formalin, was the procedure adopted to assure sample stability. The demonstration of sample stability permits sample preparation to occur at one site followed by transport of the samples to the FCM laboratory at another geographical location. The major findings of this work were a) technical protocols were developed which resulted in acceptable nuclear suspensions for FCM from 16 different murine organs or tissues, b) the stability of these samples can be assured by fixing the PI stained nuclear suspension with formalin, and c) each different protocol was capable of detecting and preserving at least some of the mitotic figures arrested and collected by vincristine.

Initiation of DNA synthesis in the parotid salivary gland of adult mice by a factor isolated from acellular fluid of the Ehrlich ascites carcinoma

The rate of DNA synthesis in the parotid salivary gland of adult mice is very low. We have purified about 5 000-fold a mitogen from the acellular ascitic fluid of the Ehrlich ascites carcinoma which stimulates DNA synthesis in the parotid salivary gland in vivo. This stimulation of DNA synthesis was produced with a protein concentration of this mitogen of 3 micrograms per 25 g of body weight. The purification procedure included ammonium sulfate fractionation and DEAE Sephacel column chromatography. This potent, heat-labile mitogen is presumed to be a protein with a mol.wt. of 3.5 X 10(3) to 1.3 X 10(4). The data indicate that this new factor is quite different from epidermal growth factor and tumor growth factor. Hypophysectomy did not prevent the stimulatory effect of this mitogen on the parotid salivary gland, indicating that the pituitary gland is not involved directly in mediating the mitogenic effect.

Induction of differences in the circadian profiles of DNA synthesis between normal and neoplastic cell populations by hydroxyurea without perturbation of the normal circadian rhythms

This paper presents data which support a previously stated hypothesis that differences in phasing can be induced in the rhythms of DNA synthetic activity (DNA-SA) between normal and neoplastic cell populations in the same animal. The drug used was hydroxyurea (HU). Mice were standardized to a light-dark cycle with light from 06.00 to 18.00 h. Minimal disruption of the normal circadian pattern in DNA-SA in tongue, esophagus, and rectum occurred when 500 mg/kg HU was given at 17.00 h. The same dose of HU given at 05.00 h resulted in significant perturbation of the normal circadian pattern of DNA-SA in these organs. 500 mg/kg HU at 17.00 h did, however, significantly perturb DNA-SA in the Ehrlich's ascites cardinoma (EAC). To study this phenomenon further the following experiments were done in EAC bearing mice: (A) 500 mg/kg HU given at 09.00, 13.00 and 17.00 h; (B) 500 mg/kg HU given at 21.00, 01.00 and 05.00 h, and (C) 3,000 mg/kg given at 17.00 h. In general, the response of the normal organs to HU varied depending on the circadian time of treatment with HU, whereas the response of the EAC was more uniform regardless of when the HU was given. By plotting the data obtained from the 3 normal organs and the EAC on the same graph specific points could be identified when: (a) maximal DNA-SA occurred in the EAC and at the same time minimal DNA-SA occurred in tongue, esophagus, and rectum, or (b) various levels of DNA-SA occurred in the EAC, but, at the same time maximal or peak levels of DNA-SA occurred in the normal organs.

Pathologic effects of plasma from patients with thrombotic thrombocytopenic purpura on platelets and cultured vascular endothelial cells

The pathologic hallmarks of thrombotic thrombocytopenic purpura (TTP) include endothelial cell proliferation and subendothelial hyalin deposits in the microvasculature leading to symptomatic thrombotic occlusions. Plasma or sera from three consecutive patients with TTP were subjected to multiple analyses to determine whether they induce endothelial injury and/or platelet activation, two pathogenic mechanisms that may account for this disorder. Sera were utilized in a microcytotoxicity assay against cultured human umbilical vein endothelial cells (EC). These cells were assessed ultrastructurally and with immunofluorescence techniques to ascertain the nature of inflicted cell damage. Control plasmas were obtained from healthy volunteers as well as patients with immune complex disease and the adult hemolytic uremic syndrome. In the presence of TTP serum, cell kill of 3H-proline-labeled EC averaged 42% versus 8.6% for control sera. Cytotoxicity induced by an IgG fraction of TTP sera averaged 70% versus 16.8% for control IgG. Removal of IgG by immune precipitation diminished cytotoxicity by 70%. Using indirect immunofluorescence, IgG was detected on EC incubated with TTP serum but not on EC treated with control serum. Ultrastructural changes became apparent within 30 min after exposure of cultured EC to TTP serum. Virtually every cell developed numerous cytoplasmic inclusions rarely seen in EC in the presence of normal serum. Prolonged incubation with the TTP serum led to progressive cytolysis, terminating with complete cytoplasmic and nuclear degeneration. Plasma from all three patients with TTP caused spontaneous aggregation of normal washed platelets as monitored by aggregometry. No spontaneous aggregation occurred in response to control plasmas. These results indicate that the sera of the three TTP patients studied were able to mediate time-dependent immune destruction of human cultured endothelial cells and that their plasmas were capable of causing spontaneous aggregation of normal human platelets in vitro. It would seem likely that these mechanisms are also operative in vivo to produce the endothelial destruction as well as the thrombotic vascular occlusions seen in this disorder.

Hematologic manifestations and etiology of atrial myxoma

We have investigated the case of a woman, 44 years of age, who presented with erythrocytosis, thrombocytopenia and a right axial myxoma. Surgical removal of the tumor allowed correction of all hematologic abnormalities. A serum erythropoietin level obtained from the right atrium of the patient during pre-operative cardiac catheterization was twice those of 4 control patients (250 MIU vs. 131 MIU). Renal vein erythropoietin levels were normal. This implicates atrial myxomas as another tumor capable of erythropoietin production, and explains the heretofore mysterious polycythemia frequently reported to be associated with this tumor.

Cytotoxicity of natural killer cells: correlation with emperipolesis and surface enzymes

Cell-mediated cytotoxicity involving natural killer cells requires contact between effector and target cells for effective cytolysis. Ultrastructural studies of biopsies of primary human malignant melanoma showed mononuclear leukocytes to be located in close proximity to tumor cells and, on occasion, within the confines of the melanoma cell itself. This phenomenon, called emperipolesis, was examined in vitro to determine whether the same population of cells that exhibits emperipolesis is responsible for cytotoxicity. Since natural killer cells have been identified morphologically and functionally as large granular lymphocytes with surface receptors for the Fc portion of immunoglobulin (FcR+ cells), lymphocytes were depleted of FcR+ cells, and their cytotoxicity and ability to emperipolese were measured. Both of these properties were markedly diminished (88 and 85 per cent, respectively). Systematic comparison of emperipolesis and cytotoxicity from donors known to exhibit either high or low lymphocyte cytotoxicity showed perfect concordance. Ultrastructural analysis of in vitro emperipolesis revealed the emperipolesing lymphocytes to be FcR+ cells establishing identity with the large granular cells known to mediate cytotoxicity. The morphologic marker found in both FcR+ cells, purified by rosetting techniques, and in emperipolesed lymphocytes consisted of cytoplasmic parallel tubular arrays. Further studies designed to elucidate a mechanism for cytotoxicity and emperipolesis implicated cell surface proteases as mediators of these activities. Competitive inhibition of surface proteases with artificial and natural inhibitors markedly reduced both cytotoxicity and emperipolesis. Therefore, it is likely that lymphocytes that are FcR+ participate in cell-medicated cytotoxicity through mechanisms involving cell contact and enzyme-initiated damage of target cells. Emperipolesis represents one type of effector-target cell contact leading to cytotoxicity.

A critique of the practice of plotting data obtained in vivo on an 'hours after treatment' format

The erroneous and misleading conclusions that result when data obtained in vivo are plotted on an 'hours after treatment' format when compared to a 'time of day' or 'time of circadian period' format are illustrated. The mitotic index of the corneal epithelium and the amount of DNA synthetic activity in the tip of the tongue are the examples used. Animals were kept on a light-dark cycle with light from 06.00 to 18.00 CST. Treatment with an intraperitoneal injection of 0.2 ml of saline at 05.00 compared to treatment with saline at 17.00 resulted in no effect on either variable when the data were plotted on a 'time of day' format, i.e., the data from the group which received saline at 05.00 and the group which received saline at 17.00 were very reproducible. However, when the same data were plotted on the 'hours after treatment' format, the data were 180 degrees out of phase with each other. This resulted in many statistically significant differences between the two groups. These differences are artifactual when compared to the 'no effect' or 'no perturbation' situation seen when the data are plotted on the 'time of day' format.

Circadian rhythmicity in DNA synthesis in untreated and saline-treated mice as a basis for improved chronochemotherapy

DNA-synthetic activity (DNA-SA) was measured by liquid scintillation counting of the incorporation of tritiated thymidine into chemically isolated DNA from the tongue, stomach, terminal ileum, rectum, spleen, and bone marrow in mice standardized to a 12-hr light-12-hr dark cycle with light from 6 a.m. to 6 p.m. Central Standard Time. One group of 200 mice was not treated or not touched (NT). A second group of 200 mice ws given an injection of 0.9% NaCl solution (SAL) at 5 a.m. Beginning at 8 a.m., or 3 hr after treatment with SAL, 10 mice from both the NT and SAL groups were killed every 3 hr for 60 hr. Statistically significant circadian rhythms in DNA-SA were found in all organs in the NT group when the data were analyzed by the single-cosinor rhythmometric method. The amount of statistical error encountered in fitting a 24-hr cosine curve to the original data was smallest in tongue and progressively increased in stomach, rectum, spleen, ileum, and bone marrow. An explanation for this finding is presented which involves the histokinetic architecture of these organs. Treatment with SAL at 5 a.m. abolished the circadian rhythms in DNA-SA in spleen, bone marrow, and ileum, increased the overall level of DNA-SA in the rectum, and decreased the overall level of DNA-SA in ileum and spleen. The circadian rhythmicity of DNA-SA in all of the organs studied in the NT group, in general, attained peak activity sometime during the nocturnal period (active phase for mice). Trough levels of DNA-SA occurred during the diurnal or rest period. This observation is correlated with the known circadian rhythms in susceptibility-resistance to drugs which primarily or exclusively effect DNA-SA; i.e., the circadian rhythms in mortality to these drugs attain peak levels during the nocturnal period. This information forms the basis for a hypothesis which states that the most therapeutically advantageous situation would be to induce a significant circadian phase difference in the rhythms in DNA-SA between the normal and the neoplastic cell populations of a tumor-bearing host. Anti-DNA-SA therapy could then be given at a specific point in time when DNA-SA of the host was at or near trough levels and, concomitantly, DNA-SA of the tumor was at or near peak levels. This should result in maximal or selective toxicity to the tumor and, concomitantly, minimal toxicity or maximal protection of the normal tissues of the host.

Circadian rhythm in mitotic index of corneal epithelium: presence of Ehrlich ascites carcinoma and treatment with saline or hydroxyurea

A study of the circadian rhythm in the mitotic index (MI) of the corneal epithelium was completed in non-tumor-bearing mice and in mice bearing the Ehrlich ascites carcinoma (EAC). All mice were standardized to a light-dark cycle with 12 hours of light from 0600 to 1800 CST alternating with 12 hours of darkness from 1800 to 0600 CST. Treatments included injection with saline (SAL) or hydroxyurea (HU) at different circadian times. This investigation demonstrated that: (1) Data from untouched animals cannot serve as proper controls because treatment with SAL altered the level of the MI, but only during the diurnal, not the nocturnal, phase of the circadian cycle; (2) the presence of the EAC depressed the level of the MI, but this inhibition was only detected during the diurnal period; (3) treatment with 500 mg/kg HU injected at 0500 caused more perturbation in this rhythm than did treatment with 500 mg/kg HU at 1700; (4) when 500 mg/kg HU was given at 2000 and 0100 and 0500, the perturbation of the rhythm was greater than when 500 mg/kg HU was given at 0900 and 1400 and 1700; (5) when 3000 mg/kg HU was given at 1700 and compared to 500 mg/kg HU at 1700, little difference in the overall circadian profiles of these rhythms was observed, indicating that the circadian control mechanisms operating on the MI exerted a greater influence than did a dosage change from 500 to 3000 mg/kg HU; and (6) a comparison of the practice of plotting experimental and control data as "hours after treatment" versus using a "time of day" plot for the same data demonstrated that the "hours after treatment" plot is very misleading because it fails to account for the significant circadian oscillation in this in vivo system.

A critique of the practice of comparing control data obtained at a single time point to experimental data obtained at multiple time points

The normal circadian rhythm in DNA synthetic activity (DNA-SA) in the tip of the mouse tongue is presented. When this rhythm, obtained from mice which were not treated (NT) or handled, was compared to the rhythms obtained from mice treated with saline (SAL) or 25 mg/kg isoproterenol (IPR), no alteration in the rhythm was observed after either treatment. The conclusion from this chronobiological, experimental design was that IPR had no effect on DNA-SA in the tip of the tongue. However, when three single time points (08.00, 11.00 or 14.00) are selected from the SAL-treated, control rhythm and compared to the multiple time point data from the IPR-treated mice, three very different, statistically supported conclusions were reached. The common practice of obtaining data at only one time point in control animals and comparing these data to data obtained from drug-treated animals at multiple time points is an example of poor experimental design which results in erroneous conclusions and unnecessary confusion in the literature on in vivo research.

Combined chronochemotherapy of L1210 leukemic mice using 1-beta-D-arabinofuranosylcytosine, cyclophosphamide, vincristine, methylprednisolone and cis-diamminedichloroplatinum

When cyclophosphamide, 1-beta-D-arabinofuranosylcytosine, vincristine, methylprednisolone (P) and cis-diamminedichloroplatinum (CP) were administered to mice previously given injections of 4.5 or 5 million L1210 leukemia cells, the effectiveness of the 5-drug combination was influenced by the stage of the circadian system at the time of injection. By applying what we refer to as the chronobiological approach (timed treatment), in comparison with a homeostatic (time unqualified) approach, fewer deaths and less weight loss were found, as the result probably of lower drug toxicity. Despite a cure rate that ranged from 24 to 48% as a function of CP timing in the first study, the overall acute drug toxicity (ranging from 20 to 76%) was unacceptable as a treatment protocol. In a second study, by lowering dosages of all drugs but still administering the drugs in a chronobiological manner, death due to acute drug toxicity was reduced to zero while the percentage of cures ranged from 44 to 88% in animals treated with P at different circadian stages. In both studies the homeostatic approach was unsatisfactory because of overwhelming drug toxicity.