Phonotactic knowledge of word boundaries and its use in infant speech perception

The development of a lexicon critically depends on the infant's ability to identify wordlike units in the auditory speech input. The present study investigated at what age infants become sensitive to language-specific phonotactic features that signal word boundaries and to what extent they are able to use this knowledge to segment speech input. Experiment 1 showed that infants at the age of 9 months were sensitive to the phonotactic structure of word boundaries when word-like units were presented in isolation. Experiments 2 to 5 demonstrated that this sensitivity was present even when critical items were presented in context, although only under certain conditions. Preferences for legal over illegal word boundary clusters were found when critical items were embedded in two identical syllables, keeping language processing requirements and attentional requirements low. Experiment 6 replicated the findings of Experiment 1. Experiment 7 was a low-pass-filtered version of Experiment 6 that left the prosody of the stimulus items intact while removing most of the distinctive phonotactic cues. As expected, no listening preference for legal over illegal word boundary clusters was found in this experiment. This clearly suggests that the preferential patterns observed can be attributed to the infants' sensitivity to phonotactic constraints on word boundaries in a given language and not to suprasegmental cues.

Chemosensitivity testing of xenografted squamous cell carcinomas of the head and neck region

Eight squamous cell carcinomas from the head and neck region were established as xenograft lines in nude mice and tested for their sensitivity to the antineoplastic drugs bleomycin and cisplatin. Tumor volume, histology, DNA flow cytometry and mitotic activity were used as parameters. One out of the 8 tumours appeared to be highly sensitive to bleomycin, while three other tumours were sensitive to both bleomycin and cisplatin. These observations are in good correlation with the reported data in patients. All chemosensitive tumours showed regrowth after the cytotoxic drug treatment had been completed. No change was seen in the chemosensitivity of other features of the regrown tumours, not even after repeated exposure to the drugs. Comparison of the tumour volume with the other parameters applied indicated that the tumour volume of squamous cell carcinomas was not always a reliable parameter for testing chemosensitivity, because of the important contribution of keratin to the tumour volume. It is concluded that additional parameters such as histological examination, DNA flow cytometry or mitotic activity are necessary in order to draw reliable conclusion on xenografts with a large avital component. In addition, DNA flow cytometry has proved to be very useful for the rapid screening of drug sensitivity.

Intracellular localization of meso-tetraphenylporphine tetrasulphonate probed by time-resolved and microscopic fluorescence spectroscopy

The effects of solvent pH on spectral properties and fluorescence decay kinetics were investigated in order to characterize the microenvironment of meso-tetraphenylporphine tetrasulphonate (TPPS4) taken up by cells. Steady-state absorption and fluorescence spectra of TPPS4 in buffer solutions of different pH were used to identify a ring protonated species at pH less than or equal to 4. This dictation could also be distinguished from the unprotonated form by its altered fluorescence decay time (3.5 vs. 11.4 ns). In addition, time-resolved spectroscopy gave some evidence of a monocationic species existing at pH 6-9. This was concluded from the occurrence of another component with a decay time of 5 ns. Measurements of the spectral and kinetic properties of the fluorescence emission of single epithelial cells (RR1022) incubated with TPPS4 indicated that the sensitizer was mainly localized in a microenvironment with a pH of 5, a value which occurs intracellularly only within lysosomes. Cells kept in the dark exhibited the characteristic spectra of both the dication and the neutral form. The fluorescence decay showed two components with decay times of 2.6 ns and 10.6 ns. Irradiation of the cells changed the decay times to 4.6 ns and 13.4 ns and the dication fluorescence emission peak vanished, which is in accordance with the results obtained from buffer solutions at pH greater than or equal to 6. Therefore, we deduce that the photodynamic action leads to a rupture of the lysosomes and that the sensitizer is released into the surrounding cytoplasm.

Effect of doxorubicin exposure on cell-cycle kinetics of human leukemia cells studied by bivariate flow cytometric measurement of 5-iodo-2-deoxyuridine incorporation and DNA content

Cell kinetics of two human leukemic cell lines, Molt-4 and K562, following a 2-h exposure to doxorubicin, were studied. DNA flow cytometry provided static information that for both cell lines a dose-dependent accumulation occurred at the G2 + M compartment that disappeared in time. Kinetic information was provided by time-monitoring cells labeled with 5-iodo-2-deoxyuridine (IdUrd) by two-parameter flow cytometry, analyzing the IdUrd label and the DNA content. The cell-cycle time (Tc) of exponentially growing Molt-4 cells was determined to be 20 h. Twenty-four hours after a 2-h exposure to 0.25 micrograms/ml doxorubicin, the Tc had increased to 23 h; following exposure to 1.0 micrograms/ml, it increased to 33 h. Cell kinetics of K562 cells following doxorubicin exposure were monitored in time up to 4 days. The average Tc of exponentially growing K562 cells was determined to be 24.7 h. Twenty-four hours following 2-h exposure to 0.25 or 0.5 micrograms/ml doxorubicin, the Tc were determined to be 28 and 32 h, respectively. After an additional 2 days, the Tc were both determined to be 24 h. The dose-dependent, reversible cell-cycle delay that persisted at least 48 h should be taken into account as an additional mode for decrease of a (tumor) cell population doubling time after exposure to doxorubicin.

Doxorubicin toxicity in relation to the proliferative state of human hematopoietic cells

The relation between the proliferative state of normal human hematopoietic cells and their sensitivity to doxorubicin was studied. T-lymphocytes were stimulated with phytohaemagglutinin/interleukin 2 before or after a 2-h exposure to doxorubicin (range 0-2 microgram/ml). The doxorubicin concentration that inhibited DNA synthesis in 50% of the lymphocytes, measured qualitatively with 5-iodo-2'-deoxyuridine incorporation, was significantly lower (a factor of 2.5) in case of drug exposure of stimulated lymphocytes compared to nonstimulated lymphocytes. These proliferation-dependent differences were not related to differences in cellular drug concentrations, as was determined with flow cytometry. Bone marrow cells were stimulated for 2 days with human placenta-conditioned medium before or after exposure to doxorubicin (range 0-2 microgram/ml), after which they were cultured in a bone marrow clonogenic assay. In analogy with the lymphocyte experiments, proliferation-dependent differences in drug sensitivity were found. The drug concentration that inhibited the growth of granulocyte-macrophage colonies (granulocyte-macrophage colony-forming units, CFU-GM) to 50% appeared significantly lower (a factor of 3.4) with drug exposure of stimulated bone marrow cells compared to nonstimulated bone marrow cells. The relative insensitivity of quiescent, but potentially proliferative cells to doxorubicin might explain the recovery of hematopoiesis after doxorubicin-induced bone marrow hypoplasia.

Modulation of the in vitro cytotoxicity of seven anticancer drugs by protein synthesis inhibition using sparsomycin

Inhibitors of protein synthesis may modify cell response to cytotoxic drugs. The influence of protein synthesis inhibition using sparsomycin (Sm) on the cytotoxicity of seven classical cytotoxic drugs, 5-FU, ARA-C, MTX, doxorubicin, melphalan, bleomycin and vincristine, was studied. Preincubations, simultaneous incubations and postincubations with Sm were investigated in vitro on CHO cells. Preincubation with Sm antagonized the activity of the S phase specific drugs 5-FU, ARA-C, MTX as well as vincristine, while postincubation with Sm enhanced their effect. A similar pattern was observed with doxorubicin. Preincubation with Sm had a potentiated non-S phase specific like bleomycin and cisplatin, but not melphalan. Postincubation with Sm had a potentiating effect on bleomycin but had no effect on melphalan. These results indicate a strong, schedule dependent effect of Sm on various drugs and suggest some potentially useful combinations to be tested in vivo.

Autologous transplantation of bone marrow purged in vitro with anti-CD7-(WT1-) ricin A immunotoxin in T-cell lymphoblastic leukemia and lymphoma

Seven patients with high-risk acute T-cell lymphoblastic leukemia (T-ALL) and six with T cell lymphoma (T-LL) were treated with autologous bone marrow transplantation (ABMT) after in vitro purging of their bone marrow with WT1 (CD7)-ricin A-chain immunotoxin. CD7 expression on the tumor cells showed large variations between the individual patients and was highly related to the specific cytotoxicity of WT1-ricin A. Incubation of bone marrow with up to 10(-8)mol/L WT1-ricin A in the presence of 6 mmol/L NH4Cl did not compromise the growth potential of the hematopoietic progenitors CFU-GM, CFU-GEMM, and BFU-E. Hematologic engraftment (greater than 10(9) leukocytes/L) occurred within a normal time period (median, 17 days). Seven patients are alive and in complete remission (CR) at 48+, 44+, 40+, 26+, 11+, 7+, and 6+ months after ABMT. Four patients relapsed within 6 months after ABMT. Two of them had the lowest CD7 expression on their tumor cells, the other two were transplanted in CR2 and CR3. Two patients died from transplantation related infections. The immunologic reconstitution was delayed, although the numbers of T cells reached normal levels within 1 month. The number of CD7+ cells remained low up to 1 year after transplantation. The T4/T8-ratio was decreased for at least 6 months. The T-cell response to mitogens recovered to normal levels after 1 year. This study shows that ABMT with WT1-ricin A purged bone marrow in high-risk T-cell malignancies results in a complete hematopoietic and a delayed immunologic reconstitution. The actuarial relapse free survival is 61% at 3 years.

Cytotoxic potential of anti-CD7 immunotoxin (WT1-ricin A) to purge ex vivo malignant T cells in bone marrow

With the perspective of bone marrow purging in autologous transplantation, we investigated the cytotoxicity of the anti-T cell immunotoxin (IT) WT1-ricin A (anti-CD7) to malignant T cells obtained from patients with T cell acute lymphoblastic leukaemia or lymphoma. The cytotoxic efficacy of IT was based on the extent of protein synthesis inhibition. Cytotoxicity of IT to malignant T cells showed a dependency on antigen density comparable to the T cell lines GH1, CEM, Jurkat, HSB-2 and HPB-ALL and was enhanced considerably in the presence of 6 mM ammonium chloride. The ultimate proof of cell kill can only be obtained from clonogenic assays; however, culturing of malignant T cells was not feasible. Therefore these assays were performed with the cell line CEM that expresses comparable amounts of CD7 antigen as malignant T cells of most patients. More than 6-logs of CEM appeared to be eliminated after incubation with 10(-8) M WT1-ricin A. Immunotoxins are only effective after entering the target cell. The pattern of internalization of the IT was determined by means of 125I-WT1. After internalization the CD7 antigen was re-expressed on the cell membrane. This enables a long incubation period resulting in an increased elimination of malignant T cells. Even after 16 h the IT was still accumulated intracellularly. This pattern of continuous uptake of IT was reflected in a gradually increasing cytotoxicity with incubation time. Effective bone marrow purging can be carried out without adverse effects on progenitor cells with 10(-8) M WT1-ricin A. At that concentration the antibody binding capacity was saturated. We showed that the protein synthesis inhibition in malignant T cells by WT1-ricin A is comparable to the inhibition in T cell lines and that high amounts of CEM cells can be killed. These data suggest that cell lines can be used to test the efficacy of IT to malignant T cells. WT1-ricin A appears to be very potent for the purging of autologous bone marrow from patients with T cell malignancies.

Relationship between internalization and cytotoxicity of ricin A-chain immunotoxins

Immunotoxins (ITs) appear to vary considerably in their killing efficiency towards antigen positive cells. In order to unravel the mechanisms underlying these differences, the parameters responsible for these variations were studied. The efficacy of the monoclonal antibodies (MoAbs) WT32 (CD3), OKT4 (CD4), T101 (CD5), WT1 (CD7) and WT82 (CD8) conjugated to ricin A-chain was expressed by the extent of protein synthesis inhibition of four leukaemic T cell lines (CEM, GH1, Jurkat and HPB-ALL). Large differences in cytotoxicity were observed. Efficient inhibition of protein synthesis was seen with anti-CD3 IT, anti-CD5 IT and anti-CD7 IT. In these cases the cytotoxicity was related to the antigen density on the target cell membrane. Anti-CD4 IT inhibited poorly and anti-CD8 IT was ineffective, even on cell lines with a high expression of the corresponding antigen. When antigen density and cytotoxicity were plotted for all CD antigens, no correlation could be found. Subsequently, internalization was studied with 125Iodine-labelled antibodies. Anti-CD7 showed the fastest internalization rate, followed by anti-CD3 and anti-CD5. Anti-CD4 and anti-CD8 antibodies were respectively moderately and hardly internalized. When the absolute amount of internalized MoAb was calculated, a highly significant correlation with cytotoxicity was found. We conclude that the degree of antigen expression is not so important as the absolute amount of antibody internalized in predicting the efficacy of ITs.

Human T lymphocyte differentiation antigens as target for immunotoxins or complement-mediated cytotoxicity

Graft-versus-host disease (GVHD) after allogeneic bone marrow transplantation (BMT) is initiated by immunocompetent T cells present in the graft. Selective elimination of distinct T-cell subsets or a sufficient, but not complete T-cell depletion, might abolish severe GVHD without graft rejection and loss of the anti-tumour potential. In this study we analysed the efficacy of different monoclonal antibodies (MoAb) WT32 (CD3), OKT4 (CD4), T101 (CD5), WT1 (CD7), and WT82 (CD8) with respect to their cytotoxicity to T cells either as immunotoxin (IT) or in combination with complement. The cytotoxic potential was assessed by protein synthesis inhibition and clonogenic assays. The ricin A conjugated MoAb exerted only a minor effect on blood or bone marrow T cells, although they were highly inhibitory to T-cell lines. However, in the presence of 20 mM ammonium chloride, IT directed against CD3, CD5, and CD7 were highly cytotoxic. IT directed against CD4 and CD8 were less effective, due to a low internalization. The complement-mediated cytotoxicity was efficient for all antigens used. The natural killer (NK) activity, as measured by cytotoxicity to K562, was hardly depressed by anti-CD3, anti-CD4, anti-CD5, and anti-CD8, but was eliminated by anti-CD7. All procedures used had only a minimal effect on haematopoietic progenitors as measured by CFU-GM and BFU-E assays. We concluded that, although the T-cell population can be eliminated with the combination of anti-CD3, anti-CD5, and anti-CD7 antibodies plus complement, IT with 20 mM NH4Cl appear to kill higher amounts of T cells. Selective elimination of CD4- and CD8-positive cells is effectively obtained by MoAb with complement.

Different susceptibilities of normal T cells and T cell lines to immunotoxins

In the context of ex vivo T cell elimination from bone marrow, the anti-T cell cytotoxic potential of immunotoxins (IT) prepared by conjugation of the monoclonal antibodies (MoAb) WT32 (CD3), T101 (CD5), and WT1 (CD7) to ricin A chain was evaluated. The cytotoxicity of IT was based on protein synthesis inhibition in human T cell lines: GH1, CEM, HPB-ALL, and Jurkat, and appeared closely related to the antigen density and internalization rate of and appeared closely related to the antigen density and internalization rate of the IT. Normal unstimulated T cells appeared to be rather insensitive to IT not due to a low antigen density or decreased internalization. The cytotoxicity of IT to T cells could be enhanced considerably by NH4Cl. Treatment of T cells with a cocktail of IT (10(-8) M) and 20 mM NH4Cl resulted in a 5000-fold cytoreduction as measured by clonogenic assays of limiting T cell dilutions, whereas the haematopoietic progenitor cells remained unaltered. Stimulation of T cells with phytohaemagglutinin (PHA) prior to incubation with IT considerably increased the sensitivity to IT treatment. Thus, normal T cells are less sensitive to anti-T cell IT than T cell lines and activated T cells. This suggests that a low protein synthesis is responsible for the resistance to IT. However, a high specific cytotoxicity of IT to normal T cells can be achieved in the presence of 20 mM ammonium chloride.

Determination of amsacrine in human nucleated hematopoietic cells

A new method has been developed for the determination of amsacrine (AMSA) in human nucleated hematopoietic cells. In order to prevent efflux during the cell separation procedure, white blood cells (WBCs) were separated from red blood cells by dextran sedimentation, leaving the WBCs in their natural environment. After cell counting, pelletting the cell suspension and correcting for the admixture of supernatant, AMSA was extracted from the WBCs and determined by high-performance liquid chromatography. Linearity of extraction was observed up to 40.10(6) cells. The inter-assay variation was 4.7%. Plasma and cellular concentrations were measured in five patients at the end of a 3-h infusion of 100 mg/m2 AMSA. A pharmacokinetic study of plasma and cellular AMSA concentrations up to 19 h after infusion was carried out. AMSA concentrations in WBCs correlated well with the plasma levels (n = 20, r = 0.967) with an accumulation factor compared to the plasma concentration of 2.6-9.8 in the patients studied. The method described is useful for studying cellular pharmacokinetics of AMSA in man.

Pharmacokinetics and toxicology of sparsomycin in beagle dogs

Sparsomycin is a cytotoxic drug exhibiting a broad spectrum of in vitro activity against murine tumors and many tumor cell lines. It also appears to be a potent stimulator of the antitumor activity of cisplatin against L1210 leukemia in vivo. However, because of its toxicity, the antitumor activity of sparsomycin on murine tumors in vivo has been disappointing. The purpose of our study was to investigate the pharmacokinetics of this drug as well as the possible mechanisms that produce sparsomycin toxicity. Tests on beagle dogs revealed that about 60% of the drug is eliminated by metabolic clearance, while 40% is eliminated by the kidneys. After a single bolus injection of 0.1 mg/kg sparsomycin without narcosis, sparsomycin was eliminated with a t beta 1/2 of 0.6-0.7 h, the AUC being 0.32-0.38 mg.h.l-1, and the volume of distribution (Vd) 0.26 l/kg. In addition to being subject to glomerular filtration, sparsomycin is probably also actively excreted and actively reabsorbed by the renal tubuli. Sparsomycin itself may inhibit its active tubular excretion, thus resulting in a decrease in the drug's renal clearance and its accumulation in the plasma. Sparsomycin appeared to be toxic primarily in the liver, disturbing its function and the synthesis of plasma proteins. Two out of five dogs developed hemorrhagic diathesis due to hypofibrinogenemia and deficiency of other blood-coagulation factors. Sparsomycin was not toxic to the bone marrow.

Modulation of placental alkaline phosphatase activity and cytokeratins in human HN-1 cells by butyrate, retinoic acid, catecholamines and histamine

The effects of butyrate and retinoic acid in combination with catecholamines or histamine on the HN-1 human head and neck squamous carcinoma cell line were investigated analysing cell proliferation, placental alkaline phosphatase (PLAP) activity, and relative cytokeratin content. Butyrate inhibited cell proliferation in agar, whereas retinoic acid induced a small inhibitory effect. Butyrate enhanced PLAP activity in a time related manner in contrast to retinoic acid, which had no significant effect. However, retinoic acid inhibited the efficacy of butyrate to induce PLAP activity. A synergistic enhancement of PLAP activity was demonstrated after treatment of butyrate pretreated cells with catecholamines or histamine. The beta-adrenergic antagonist propranolol partly inhibited the aforementioned enhancement of PLAP activity, whereas the alpha-adrenergic antagonist phentolamine further enhanced PLAP activity. Indirect labeling of keratins with a polyclonal antibody showed that cytokeratin content was enhanced by butyrate but not by retinoic acid. Further analysis of cytokeratin content using four monoclonal antibodies showed that labeling of cytokeratins (5 + 8) was increased by butyrate. PLAP activity could be modulated by a concerted action of either butyrate plus retinoic acid or butyrate plus catecholamines or histamine, indicating a possible role for PLAP in tumour cell proliferation.

In vitro proliferation of primary human head and neck squamous cell carcinomas evaluated by flow cytometry

In vitro proliferation of primary human head and neck squamous cell carcinomas was investigated using single cell suspensions and tissue explants of primary specimens and xenografts from 20 tumor specimens. The evaluations of the cells emerging in culture were performed with flow cytometry. Epithelial-like cells proliferated in serum-free medium, while no fibroblast-like cells were observed in culture. The epithelial-like cells could be subcultured several passages before senescence occurred. Conditioned medium or serum supplementation was necessary for a sustained outgrowth of malignant squamous cells as documented by flow cytometry. From a tumor line established in nude mice slowly proliferating tumor cells emerged. After 4-5 months in culture tumor cells seemed to be adapted to the culture conditions used. This resulted in a more consistent tumor cell proliferation. Early passage cultures from primary human head and neck squamous cell carcinomas are clearly difficult to obtain either from primary human specimens or from tumor lines established in nude mice.

In vitro modulation of cisplatin cytotoxicity by sparsomycin inhibition of protein synthesis

Inhibition of protein synthesis can alter cellular responsiveness to the classical anticancer drugs. The in vitro response of Chinese hamster ovary (CHO) cells to cisplatin with or without sparsomycin (Sm) was studied with the use of [3H]leucine and [methyl-3H]thymidine incorporation and clonogenic assay. Pretreatment of exponentially growing CHO cells with 1 microgram Sm/ml for 3 or 5 hours decreased [3H]leucine incorporation by 20% and resulted in significant resistance to cisplatin (P = .005). Sm in a concentration of 10 micrograms/ml reduced [3H]leucine and [methyl-3H]thymidine incorporation after 3 hours by 92 and 84%, respectively, and resulted in potentiation of the cisplatin cytotoxicity (P = .004). This effect was the same in the case of nonproliferating cells (P = .005), while protection due to Sm (1 microgram/ml) was seen only during cell proliferation. Simultaneous incubation and postincubation with Sm proved to have much less or no potentiating effect on cisplatin. The mechanisms of both protection and potentiation are still not clear, but our data indicate that Sm is a promising drug for further studies on the modulation of the cancer cell response to classical anticancer drugs.

Modulation of proliferation of a human head and neck squamous carcinoma cell line (HN-1) by catecholamines and histamine

The effects of catecholamines and histamine on the HN-1 human head and neck squamous carcinoma cell line were determined by analyzing binding of (-)125 I-iodocyanopindolol (delta-adrenergic antagonist), clonogenicity in soft agar, and cell cycle effects by dual-parameter flow cytometry. Binding studies revealed the presence of delta-adrenergic receptors with an affinity between 11-13 pM and a capacity between 5.8.-8.5 fmol/10(5) cells. A clonogenic assay demonstrated that both isoproterenol and histamine gave a minor inhibition of clonogenicity which could be reversed with propranolol and cimetidine respectively. Pretreatment with propranolol followed by isoproterenol treatment abolished the inhibitory effect of isoproterenol on clonogenicity. Catecholamines and histamine modulated the proliferation of HN-1 cells which was generated through receptor binding.

In vivo potentiation of cis-diamminedichloroplatinum (II) antitumor activity by pretreatment with sparsomycin

The influence of protein synthesis inhibition by sparsomycin (Sm) on in vivo cisplatin activity has been studied on BALBc X DBA2: F1 mice bearing L1210 leukemia i.p. Sm alone at the dose range from 0.5 to 3.0 mg/kg did not significantly improve animal survival. Sm potentiated cisplatin activity only when given 3 or 6 h prior to cisplatin (P less than 0.001). Sm 0.5-1.5 mg/kg 3 h prior to cisplatin resulted in a significant prolongation of animal survival (P less than 0.001) and 66% cures in each group versus 0% due to cisplatin alone. Sm pretreatment decreased weight loss due to cisplatin suggesting that it probably is able to decrease cisplatin toxicity.

Cell size, DNA, and cytokeratin analysis of human head and neck tumors by flow cytometry

Cell subsets have been discriminated in cell suspensions derived from 37 human head and neck tumors by means of light scatter, DNA, and cytokeratin flow cytometry (FCM). Cell dispersion was performed overnight at 4 degrees C in two different enzyme mixtures, i.e., trypsin/dithioerythritol and collagenase/DNase, under slight agitation of sliced tumor tissue. Cells were examined before and after fractionation on a discontinuous low-density bovine serum albumin (BSA) gradient. Forward and right-angle light scatter FCM of 23 tumor specimens revealed four main subpopulations with different size and structure. Fractionation of primary cell suspensions on a BSA gradient at unit gravity separated debris, small cells and large cells. DNA FCM of the enriched populations demonstrated a relation between large cells and DNA aneuploidy. Epithelial cells, as recognized by cytokeratin antibodies, were also related with large cells. The results demonstrated the usefulness of light scatter, DNA, and cytokeratin analysis of crude and fractionated tumor cell suspensions for assessment of the efficacy of a particular dispersion technique and to obtain information of the cell subsets dispersed.

Flow cytometric evaluation of cell dispersion from human head and neck tumors

The preparation of single-cell suspensions from 25 human head and neck tumors is described. Dispersal was performed overnight at 4 degrees C under slight agitation of the tissue suspensions using various combinations of enzymes and additives. The cell suspensions were examined for number of cells released, viability, amount of debris, and DNA distribution by means of flow cytometry (FCM). It was shown that both trypsin/dithioerythritol (TD) and collagenase/D Nase (CDse) were of value in dispersing single cells from tumor tissue. In contrast to CDse, incubation with TD appeared to be cytolytic to normal lymphocytes. In a number of cases, DNA-FCM revealed ploidy abnormalities in a TD-suspension, which were not discernible in the concurrent CDse-suspension. Cell culture of primary cell suspensions corroborated the reliability of the DNA-FCM measurements. Pretreatment with CDse improved tumor disaggregation by TD and indicated a different dispersal capacity. Addition of Ca2+ and Mg2+ ions to the dispersal mixtures and preincubation of tumor slices in complete medium for 1 day before initiation of cell dispersion influenced favorably the quality of the cell suspension.

S-adenosylhomocysteine hydrolase activity during differentiation of HL-60 cells

Early changes in S-adenosylhomocysteine (SAH) hydrolase activity during DMSO-induced granulocytic differentiation of HL-60 cells were followed. Within 24 h a decrease of activity of SAH hydrolase could be detected in induced cultures but not in control cultures. This decrease could be shown to be associated with G1 phase of the cell cycle and was detected prior to phenotypic changes of the cells.

Lymphocyte isolation from human spleen by counterflow centrifugation employing two different flow chambers on line

Studies on splenic lymphocytes have hitherto been performed on single cell suspensions depleted of phagocytic cells by adherence to plastic or incubation with carbonyl iron. These techniques have the disadvantages of selective cell loss, suboptimal cell purification and cell activation. This paper describes purification of splenic lymphocytes by the use of counterflow centrifugation (CFC). The method was adapted to overcome pelleting of cells in the separation chamber to form a plug at the inlet and impede adequate flow. By combining 2 different separation chambers on line in 1 rotor this problem was overcome. Of all lymphocytes recovered after CFC 88.8 +/- 1.4% were collected in 2 pooled fractions with a purity of greater than or equal to 98% and a cell viability of 95%. After CFC, 80.8 +/- 12.1% of the viable cells loaded were recovered.

DNA-flow cytometry of blood and bone marrow in chronic myelogenous leukemia

Flow cytometric analysis of bone marrow aspirates and blood samples in 42 patients with chronic myelogenous leukemia (CML) at various disease stages was performed to determine the size of the S-phase compartment of bone marrow and blood. 25 healthy controls were studied for comparative information with both DNA-flow cytometry (DNA-FCM) and 3H-thymidine autoradiography. A correction procedure was applied for peripheral nucleated cell admixture in bone marrow aspirates. The fraction of peripheral nucleated cells in bone marrow aspirates (Fpb) in individual patients was considerable, especially in those with a very high white blood cell count (greater than 100 x 10(9)/l). The size of the S-phase compartments of bone marrow (% Sbm) in patients with CML at diagnosis and in patients at apparent hematological remission was of the same order of magnitude as in normal bone marrow. However, in 3 out of 4 patients at malignant metamorphosis in which the % Sbm could be reliably determined, this percentage was significantly higher than normal (p = 0.013). In 4 out of 11 patients at malignant metamorphosis aneuploidy was noticed. From these findings it is concluded that bone marrow cell proliferation in CML patients at diagnosis and during apparent remission is not essentially different from normal. However, at malignant metamorphosis changes occur in ploidy level and proliferative activity, which can be detected by DNA-FCM already in an early phase.