Role of levamisole immunotherapy as an adjuvant to radiotherapy in oral cancer--immune responses.

Investigations were carried out to assess the effect of levamisole immunotherapy as an adjuvant to radiotherapy on the immune response of patients with squamous cell carcinoma of the oral cavity. Parameters assessed were leukocyte migration inhibition, response to PPD and oral cancer extract (OCA), lymphocyte transformation to PHA, circulating antibodies to OCA and circulating immune complexes (CIC). Comparisons were made between groups receiving levamisole (L), those receiving placebo (P) and normal controls. The results of a thirty-month follow-up are presented. Radiotherapy resulted in a depression of cell-mediated functions, reduction in antibody titer also showed a gradual increase with time of follow-up. Levamisole, however, appeared to reduce the levels of CIC.

Cranial irradiation of children with soft-tissue sarcomas arising in parameningeal sites.

Soft-tissue sarcomas arising in parameningeal sites are characterized by the potential of a direct meningeal invasion. In order to improve survival rates, we started a treatment program which included whole cranial irradiation with a dose of 24-30 Gy and primary tumor irradiation with 55-65 Gy, and polychemotherapy with vincristine, actinomycin D and cyclophosphamide, and, in some cases, adriamycin. Results in a series of 9 children treated by this program were compared with a historical group of 12 children without cranial irradiation. In the group with extended irradiation to brain, survival was 40%, stabilized at the 13th month of treatment, and 38.1%, respectively, if orbitary tumors were excluded. In the historical group these values were only 20.83% and 15.67%, respectively. The differences were statistically significant.

Trends and patterns in lung cancer incidence in four cities of Eastern Europe, 1971-1980.

The trends of age-adjusted and age-specific lung cancer incidence rates showed over the period of 1971-1980 substantial differences in four selected towns of Eastern Europe. The downward age-adjusted trends in males coincided in Berlin with the possible beginning of their downturn in the whole country, while their decline in both sexes in Bratislava could be related to the change of demographis factors. In the other two towns studied--Cracow and Tallinn--the substantial increase of lung cancer incidence in males corresponded with the similar evolution in both respective countries (Poland and Estonia). The rising trends in females in both mentioned towns could be more or less compared with their dramatic increase in some developed countries. The rising trends of age-specific rates in younger age groups of males do not indicate meanwhile the positive influence of low-tar or filter-tipped cigarettes on lung cancer incidence in males observed recently in some countries.

Evaluation of Mannich bases of styryl ketones and related hydrazones for activity against P388 leukemia.

A Mannich base namely 4-dimethylaminomethyl-1-phenyl-1-penten-3-one hydrochloride was shown to have far greater activity than 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) towards P388 leukemia cells in vitro. However, the compound was inactive in an in vivo P388 murine screen, and the object of this study was to discern molecular features which conferred in vivo activity. Mannich bases containing electron-attracting substituents in the aryl ring had in vivo potency in contrast to the analogs which had electron-donating groups in the ring. A number of hydrazones of the Mannich bases were prepared as potential prodrugs and did not enhance bioactivity. This observation was probably due to a lack of facile hydrolysis of the hydrazones to the corresponding Mannich bases in vivo since high resolution 1H NMR spectroscopy revealed that representative hydrazones either did not regenerate the ketones or produced them only in minute quantities at pH values normally encountered in living tissues.

Therapy of P388 leukemia with benzaldehyde.

Optimal schedules of benzaldehyde (50-100 mg kg-1 intraperitoneally) on day 1 or on several days after inoculation of 10(5) P388 leukemia cells to DBA 2J mice increased survival by 70-100%. No significant prolongation of survival was observed between the various schedules of benzaldehyde treatment. Significantly longer survival was observed on day 30 after benzaldehyde treatment with 100 mg kg-1 on day 1 or 50 mg kg-1 on days 1-4 as compared to untreated controls, but no cure was achieved with any schedule and dose of benzaldehyde. No or minimal activity of benzaldehyde on L1210 and L5178Y leukemias, Ehrlich adenocarcinoma and Yoshida sarcoma was observed.

Some approaches to the perfection of histooncological diagnoses.

Inaccuracy, inadequate use of histooncological diagnosis and deficient use of the diagnostic scope have been found in our set of examinations. Responsibility for diagnostic errors resided most frequently in poor knowledge of the problem. Therefore more consistent postgraduate training in histooncological classification and codification is advisable. Periodically appearing revisions of the state of knowledge would also be a welcome contribution. Second diagnostic reading adds to the completeness and precision of oncological diagnosis, and should be more encouraged. Computer-based expert system helps to remind the users in specific situations of all the essential facts, thus making it sure that none of the diagnostic possibilities can be overlooked. The idea of systematic comparisons between the standard base of knowledge and practical histooncological diagnostics is an optimistic program of continuous inovation.

A comparative study of immunosuppressive acidic protein (IAP), CA 125 and acute-phase proteins as parameters for ovarian cancer monitoring.

The serum concentrations of immunosuppressive acidic protein (IAP), CA 125, alpha-1-antitrypsin (AL-1-AT), C-reactive protein (CRP) and ceruloplasmin (COP) were determined in 63 patients with ovarian carcinoma (mean age 56.9 +/- 11.1 years). The threshold value of IAP was 640 micrograms/ml (means + 2SD), of CA 125 35 U/ml, of AL-1-AT 4 mg/ml, of CRP 12 micrograms/ml, and of COP 600 ng/ml. Eighty-three analyses of the patients with ovarian cancer coincided with tumor progression and 124 samples with remission. In women with progressive ovarian carcinoma the median IAP serum concentrations (799.3 +/- 292 micrograms/ml) were significantly increased as compared to the values of the healthy control group (48 volunteers, mean age 37.8 +/- 13.8 years; IAP 452.0 +/- 146.0 micrograms/ml). The median serum concentrations of IAP (799.3 +/- 292.2 micrograms/ml), CA 125 (933.8 +/- 1442.1 U/ml). AL-1-AT (3.8 +/- 8.7 mg/ml), CRP (31 +/- 39 micrograms/ml) were significantly elevated with progression as compared to remission (IAP 511.8 +/- 111.9 micrograms/ml, CA 125 18.4 +/- 14.4 U/ml, AL-1-AT 2.8 +/- 4.1 mg/ml, CRP 13 +/- 11 micrograms/ml). This was not the case with COP (509 +/- 761 vs. 466 +/- 106 ng/ml). A correlation between increased serum values and confirmed tumor progression was encountered in 65.1% of the patients for IAP, in 80.7% for CA 125 and in 34.9% for CRP and AL-1-AT. 98.8% false negative serum values were found for COP. Seven out of 16 and 4 out of 16 CA 125 negative samples showed right positive IAP and right positive CRP and AL-1-AT values, respectively. 88.7% of the IAP values, 92.7% of the CA 125 values, 71% of the AL-1-AT values, 93.5% of the CRP and 100% of the COP values were right negative. Our results indicate that the simultaneous determination of CA 125 and IAP enhance the efficiency of tumor monitoring in patients with ovarian cancer.

Role of levamisole immunotherapy as an adjuvant to radiotherapy in oral cancer. II. Lymphocyte subpopulations.

The effect of radiotherapy and adjuvant levamisole immunotherapy on the lymphocyte subpopulations was investigated. Comparisons were made between the groups receiving levamisole, those receiving placebo and normal healthy controls. Results of a thirty-month follow-up are reported. Radiotherapy caused leukopenia and lymphopenia affecting all the subsets (T, B, TG, and TM), T lymphocytes were affected to a greater extent. This study demonstrates that levamisole does hasten the restoration of T lymphocytes, with the TM lymphocytes showing a faster repopulation in comparison to the TG lymphocytes.

Polyoma antigen driven T lymphocytes with antitumor and DTH activity in CBA mice.

T lymphocytes isolated from a bulk culture of splenocytes exposed in vitro to polyoma TAA and IL-2, taken from CBA mice with transplanted polyoma tumors, exhibited both antitumor and DTH activity to polyoma TAA, associated with the Lyt 1+ phenotype, and also showed an increased affinity to TAA. The antitumor efficacy of adoptive immunotherapy, consisting in the i.p. administration of these TAA-driven lymphocytes, showed time and IL-2 dependence, while transferred cells were capable of eliciting DTH independently of IL-2. The suppression of tumor growth observed in 70% of the animals in the optimal variant seems to result from the cooperation of transferred lymphocytes with the recipients own lymphocytes.

Comparison of the effects of anti-Thy-1.2 monoclonal antibody and xenogeneic antithymocyte serum on the development of SaI tumor allograft in mice.

Using the model of Sarcoma I (SaI) (H-2a) tumor allograft transplanted to normal B10 (H-2b) mice and to B10 mice pretreated with ATS, we studied the effects of anti-Thy-1,2 monoclonal antibody (MTA) and compared them with those of rabbit polyvalent antiserum against mouse thymocytes (ATS). When administered shortly before tumor transplantation, MTA showed immunosuppressive effects, at one dose identical to those of ATS, at two doses exceeding ATS effects. In the period following the transplantation of SaI to normal mice, single doses of MTA and ATS showed weak antitumor effects. In mice immunosuppressed with ATS before the tumor transplantation the effects of each agent differed: MTA showed opposite immunomodulatory effects depending on the period of its administration, while ATS supported the primary growth of tumors independent of the time of administration. The results indicate that the immunomodulatory influence of MTA on the development of the tumor allograft is more selective than that of ATS.

Spontaneous acute lymphoblastic leukemia in Sprague-Dawley rats. II. Cytogenetic analysis of nine individual leukemias.

Nine spontaneous acute lymphoblastic leukemias (SD1-SD9) in Sprague-Dawley rats were investigated cytogenetically by G-banding. The chromosome numbers of metaphase cells in all studied SD leukemias were near diploid and in all leukemias numerical or structural abnormalities were found. Affected were chromosomes No. 11, 2, 13 and 1. A common finding in most leukemias was trisomy 11 observed either as simple trisomy (SD1, SD4 and 2 clones of SD6), or the translocation form of trisomy (SD3), or the tandem translocation t(11;13) in SD7, or the Robertsonian fusion -rob(2;11) in SD5. In SD9 and one cell clone of SD8 no apparent trisomy was found, but the cells contained an 11q+ marker. Among the rearranged chromosomes, chromosome 2 was most frequently involved. Der No. 2 with terminal deletion was found in some of SD3 metaphases and a probable partial duplication of chromosome 2 was found in SD6. The finding of trisomy 2 in SD5 and SD6 occurred rarely. Further structural rearrangements concerned No. 13, the involvement of which was evident in the 13q+ marker typical of SD2, one cell clone of SD6, SD7 and SD8 leukemias. 1q+ aberration was the common finding in SD3 and SD5, while 1q-was observed in all SD6 metaphases. According to the cytogenetic examination of SD leukemias, we considered that the changes of chromosomes 11, 2, 13 and 1 were nonrandom. Based on the similarity of chromosomal rearrangements in individual leukemias, probable breakpoints on the affected chromosomes could be determined. 11cen, 11q12, 2q32-33, 2q16, 13q22, 1q43 and 1q54 were found to be the most frequently afflicted regions in SD leukemias.

A mechanism by which human breast carcinoma cells escape the host immune system.

The experiments described in this study examined cell membrane oligosaccharides, malignancy-related cell phenotypes and tumor cell susceptibility to the killing effect of human cytotoxic cells. Short term breast carcinoma (BCa) cell lines were prepared from biopsies obtained from patients at each of the pathological Stages I, II, III and from patients with disseminated liver metastasis. Five patients at each stage donated the tissue. To obtain large enough quantities, the cells were cultured as monolayers for a brief period, then transferred to roller bottles using serum-free hormone defined medium. Natural killer (NK) cells, lymphokine (IL-2)-activated killer (LAK), tumor-infiltrating lymphocytes (TIL) and peripheral cytotoxic lymphocytes (CTL) from patients with BCa at PS I were used as the effector cells. Susceptibility of the tumor cells to the killing effects of the effector cells was monitored by the well established 4 h 51Cr-release assay technique. Growth factor expression, oncogenicity in athymic female mice and colonigenicity in soft agar were used as parameters to monitor breast carcinoma cell malignancy phenotypes. The cell membrane oligosaccharides were determined from the carbohydrate elution profiles from BioGel P-6 columns. The results indicate a correlation between progression of malignancy from PS I to the metastatic stage PS IV, and the magnitude of malignancy phenotypes, resistance to the host killer cells and oligosaccharide profile shift to a higher molecular size with increased sialylation and fucosylation of the carbohydrate moieties.

A case-control study of breast cancer in relation to oral contraceptive use in Slovenia.

With the aim to investigate a possible association between oral contraceptive (OC) use and breast cancer occurrence, 534 women aged 24--54 years with newly diagnosed breast cancer and 1989 individually matched hospital controls were interviewed during 1980--1983. The overall risk for ever-users vs. never-users estimated by logistic regression and adjusted for several possible confounding factors was 1.62 (p less than 0.05). The analysis of potential biases indicated that this risk may be overestimated, especially because the controls might not be fully representative of the basic population. The risk was increasing with total duration of OC use, reaching the highest value by more than 7 years of use. As to the latency, the risk was the highest for women starting pill use 4--8 years before diagnosis, thus suggesting that OCs might act as promoters rather than initiators of tumor growth. There was no substantial difference in risk between women starting pill use before 25 years of age and those starting it later. The number of users before first term pregnancy was too small to warrant relative risk estimation. Interaction (significant) was found between OC use and family history of breast cancer; there was no such evidence in other subgroups of women being at baseline breast cancer risk. There were no significant differences in the distribution of cases and controls classified by individual OC formulations used. The increased relative risk for users was concentrated in early stages of breast cancer, most likely owing to detection bias. Considering the indicated biases, the results of the study may not be quite conclusive as to the adverse effect of OCs on the breast, but they call for further investigation of this problem.

Monitoring of effects of cis-diamminedichloroplatinum (II). IV. In vivo effect of cis-diamminedichloroplatinum (II) on the function of mouse spleen cells: antibody formation and cell proliferation.

The effect of the cytostatic drug Platidiam (Lachema, Brno, Czechoslovakia; effective substance cis-DDP) on the primary antibody response of mouse spleen cells in tissue culture, blastic transformation of spleen cells after PHA stimulation, body and spleen weight, number of peripheral blood leukocytes, lymphocytes, polymorphonuclear leukocytes (PMNL) and reticulocytes was studied. The substance was administered to inbred C3H mice at single doses of 0.83 mg/kg, 2.5 mg/kg, and 3.35 mg/kg i.p. at time intervals of 3, 7, 14, and 21 days before testing. The weight of the mice decreased only from the third day after the dose of 3.35 mg/kg. The spleen weight was not influenced significantly. The peripheral blood leukocyte number increased on the 7th day after cytostatic application, lymphocyte number was less influenced. After cis-DDP application the ratio between lymphocytes and PMNL changed in favor of PMNL. The greatest increase of PMNL was recorded on the 7th day after cis-DDP administration. The number of nucleated spleen cells increased on the 7th day. Suppression of hematopoiesis appeared after all doses in the number of reticulocytes within 3 days, rapid regeneration from the 7th to the 14th day. The primary antibody response increased on the 3rd and 7th days, at further intervals it dropped to 20-70% in relation to the drug dose. The blastic transformation test was increased only on the 14th day after the substance application at the dose of 0.83 and 2.5 mg/kg. The dose 3.35 mg/kg suppressed the cell proliferation at all intervals tested.

Lipid peroxidation in the nuclear fraction of rat lungs induced by hydralazine.

Hydralazine (1-hydrazinophthalazine) was administered in drinking water as a 0.0312% solution to randomly bred female Wistar rats during 3 weeks. The average daily intake of this compound was 6.74 mg for a rat. The treatment resulted in lipid peroxidation in the nuclear fraction of the lungs. This lipid peroxidation was detected spectrophotometrically by the appearance of a peak at 233-235 nm in the spectrum of chloroform-methanol extract. The close proximity of DNA may make it a possible target for attack by free radicals.

A study on the effect of vitamin A deficiency and supplementation on tumorigenesis in mice.

The effect of vitamin A deficiency and supplementation on the incidence of tumors, tumor growth and life expectancy was assessed in a murine model. Although the nature of response varied with respect to the tumor types studied, in general an increase in incidence of tumor take and further growth was noted with a concomitant fall in the survival rates in the group maintained on a vitamin A deficient diet. Supplemental vitamin A produced a prolongation of the latent period and delayed appearance of the tumor, reduced incidence and growth and improved life expectancy. Such effects seem to be mediated by a direct action of the vitamin on tumor cells, as well as through the host immune system, as revealed by nucleic acid synthetic patterns and nature of changes in the lymphocyte/neutrophil ratio, thymus weight and PHA-induced blastogenesis of peripheral lymphocytes.

Some immunological parameters in Hodgkin's disease.

Mononuclear cells in the peripheral blood of 69 previously untreated patients with Hodgkin's disease were investigated and their changes were followed up in the course of the disease. Before the initiation of the treatment, the total number of lymphocytes, cells with ring-shaped nucleolus, E-rosette forming cells and lymphocytes with dot-like ANAE positivity were decreased and ferritin-bearing lymphocytes significantly highly increased (p less than 0.01) when compared with healthy persons. In cells of the monocyte-macrophage lineage, only the total number of cells in initial state of transformation to macrophages (active nucleolus) was significantly highly increased (p less than 0.05). In comparison with early stages, only the changes of quiet, resting cells were significantly more pronounced in advanced disease (p less than 0.01 and p less than 0.05). An excessive depression of ring-shaped nucleolus-bearing cells was associated with B symptoms. Using a discriminant analysis method, the independent influence of these cells upon the immunocompetence of the patients has been proved. After the completion of primary treatment the changes of cells were more profoundly expressed. No complete restauration of immunocompetence has been found within 1-2 years in patients responding satisfactorily to therapy. Verified by the discriminant analysis, persistent imbalance of T-lymphocyte subpopulations plays the most important role in the immune defect of patients in the second year after the therapy and later.

Natural killer activity and antibody-dependent cellular cytotoxicity in patients with non-Hodgkin's lymphoma.

Natural killer (NK) activity and antibody-dependent cellular cytotoxicity (ADCC) of peripheral blood lymphocytes from untreated non-Hodgkin's lymphoma patients were found to be depressed, when tested against the human erythroblastoid cell-line K562. The percentage of active killer (AK) cells and that of target binding cells (TBC) of the patients were also inhibited. Treatment of the patients lymphocytes with interferon (IFN) caused an augmentation in their NK activity which was comparable with that seen in the controls. Lymphocytes from some of the patients and controls were cocultured with K562 cells for production of natural killer cytotoxic factors (NKCF). The NKCF released by the patients lymphocytes showed a reduced lytic activity against K562 target cells. The depression in all the activities reported here showed a correlation with the clinical status of the patients except in the case of ADCC. These results indicate that further characterization of the properties of NKCF will contribute the understanding of the mechanism of NK cytotoxicity.

Occurrence of carcinoembryonic antigen in tumor tissue and serum of breast cancer patients.

In 116 breast cancer patients, the levels of carcinoembryonic antigen (CEA) were determined before operation in the serum using RIA, and after operation in sections of breast tumor tissue using the immunohistological PAP technique. CEA circulating in the serum was found in 49 patients (42%). Elevated values (over 10 micrograms/l) were found in only 12 patients (10%). In histological specimens CEA positivity was found in 94 tumors (81%), however, in a majority of them the number of positive cells per section was low (1-10%). A comparison of positive and negative findings both in the serum and in the tumor specimens of individual patients showed that both serum and tumor sections were CEA positive in 40 patients (35%) and both localizations were CEA negative in 13 patients (12%). Although most patients had positive histological sections but negative sera (46%). Only 7% of patients had negative sections and positive sera. In 41 patients CEA could be examined both qualitatively (immunohistologically), and quantitatively in the cytosol of the same homogenized tumor. Of them, 30 patients (72%) had in the cytosol a CEA concentration exceeding 5 micrograms/g proteins, in 11 of the 41 patients (28%) no CEA was found. Immunohistological examination of CEA in this group gave positive results in 35 out of the 41 patients (85%), and only 6 tumors (15%) were completely negative. CEA was shown to be present in each histological type of the tumors studied, invasive ductal tumors being slightly more frequent and more positive than the lobular ones. No relation was observed to the structure of the tumors, nor to the degree of their differentiation. Thus, the examination of CEA levels can hardly contribute to the improvement of histological classification.

Sequential development of chronic lymphocytic leukemia in a patient with polycythemia vera.

A patient with a seven-year history of polycythemia vera treated by repeated phlebotomies and intermittent busulfan administration developed gradually lymphocytosis accompanied by thrombocytopenia in peripheral blood and in the bone marrow. A marked pathological monoclonal proliferation of the B-cell population was detected. The sequential development of chronic lymphocytic leukemia in the patient with polycythemia vera could be considered as a coincidence because there is no reliable explanation of this event at present.

Chronic lymphoproliferative disease of large granular lymphocytes.

An 80-year-old patient has been followed for hepato- and splenomegaly, hemolytic anemia, neutropenia with lymphocytosis with large granular lymphocyte predominance in his peripheral blood, with infiltration of bone marrow, liver and probably also spleen. Determination of surface markers of proliferating lymphocytes in peripheral blood showed a mixed phenotype of T suppressor/cytotoxic and natural killer cells (SIg-, E+, T3+, T8+, EAC+, Leu7-, N901+, NK9+, VIB C5 and VIB E3-, Ia-). An in vitro cytotoxic test showed the functional inactivity of the cells tested also after human leukocyte interferon stimulation. Chromosomal analysis neither of peripheral blood lymphocytes nor of bone marrow cells proved the monoclonality marker. Following long-term prednisone therapy, the improvement of anemia, later also neutropenia accompanied by the decrease of lymphocytes has been achieved. As the disease present in our patient was distinguished only in recent years and in our country has not been reported yet, the details on its clinical, morphologic, hematologic, cytogenetic and mainly immunophenotypic characteristics are given in this paper. The problems concerning classification of the disease and determination of its biological nature are discussed.

Cancer registry data: actuarial survival estimation in lung cancer patients.

Using the Kaplan-Meier method, actuarial survival data were estimated in cancer patients registered in the Cancer Registry of Health Institute of Uranium Industry during 1976-1983, and in those followed up for 3 years and longer after the initiation of their treatment. Due to the specificity of this registry, a more detailed analysis was feasible in 639 lung cancer men. The estimated probabilities of survival over 5 and 10 years respectively, were: In all lung cancers 0.10 and 0.08, in all Stage I and II lung cancers 0.24 and 0.20, of them in epidermoid carcinomas 0.31 and 0.25, in radically operated tumors 0.51 and 0.43, of them in epidermoid carcinomas 0.54 and 0.45 respectively. The results confirmed the principal importance of early diagnosis of bronchogenic cancer, especially of epidermoid carcinoma, at a resectable stage.

Tobacco smoking and exposure to dust and gas pollution in the place of work and lung cancer risk.

A case-control study has been applied to analyze lung cancer risk, isolating four histopathological groups: differentiated forms of cancer (most often carcinoma planoepitheliale and adenocarcinoma), undifferentiated carcinomas (mainly carcinoma microcellulare and solidum), cancers histologically undeterminated (carcinoma) and cancers not verified histologically, but confirmes radiologically and clinically. 210 patients have been compared with the group of 420 men not suffering from any form of cancer. The results of the undertaken attempt to evaluate lung cancers in relation to certain etiological factors (conditions in the microenvironment of the place of work and tobacco smoking) showed that the influence of tobacco smoking (independently of the kind of tobacco and the form of smoking) on lung cancer incidence was more and more firmly established, and the frequency of incidence increased with the length of the period of smoking. Tobacco smokers and those simultaneously exposed to various dusts and dusts with gases in their microenvironment of the place of work were characterized by higher lung cancer risk (in fact independently on the histological form of the neoplasms), as compared to nonsmokers and those never exposed to air pollution.

Effect of fluororotic acid on the sialylation of the chicken liver, hepatoma MC-29 and serum glycoconjugates.

Fluororotic acid, an orotic acid analogue which interferes with the nucleotide and RNA biosynthesis, was tested to determine its effect on: a) 14C-glucosamine and 14C-N-acetylmannosamine incorporation into acid-soluble nucleotide-sugars and into b) glycoconjugates from chicken liver and hepatoma induced by the avian leukosis strain Mc-29. In vivo metabolism studies indicated that this agent alters the nucleotide biosynthesis in both tissues investigated and causes a decrease in the sialylation rate of liver, hepatoma and serum glycolipids and glycoproteins.

Hyperthermia blocks reversibility of hydroxyurea and bipyridine induced synergistic inhibition of DNA biosynthesis in P388 murine leukemia cells.

The influence of hyperthermia (42 degrees C) on the reversibility of hydroxyurea- and the iron-chelator 2,2'-bipyridine-induced synergistic inhibition of DNA biosynthesis was studied in intact P388 murine lymphocytic leukemia cells in vitro. The cytotoxicity caused by hydroxyurea alone and in combination with bipyridine for 3 h at 37 degrees C and 42 degrees C was found to be completely reversible. However, the inhibition of DNA biosynthesis was irreversible when hydroxyurea- and iron-chelate-treated and washed cells at 37 degrees C were subjected to hyperthermia at 42 degrees C. A potentiation in DNA biosynthesis was also observed when the P388 cells were subjected to hyperthermia along with the combination of hydroxyurea and 2,2'-bipyridine. These effects are probably due to the heat-sensitive nature of the ribonucleotide reductase enzyme, the target site of the effect of hydroxyurea and 2,2'-bipyridine.

Decrease in intensity of DNA fluorescence caused by interaction between DNA and platinum complexes.

The decrease of DNA fluorescence caused by an impaired capacity of ethidium bromide to intercalate into the DNA reflected structural changes caused in the DNA molecule by its interaction with platinum complexes. This fall in DNA fluorescence was proportional to the length of exposure of DNA to the platinum complexes, and depended on the environment in which the interaction took place. The therapeutically active cisplatinum (cis-DDP) was more efficient to inhibit fluorescence in a solution of 4 X 10(-3) mol NaCl than its therapeutically inactive trans-isomer (trans-DDP). For comparison, the inhibition of DNA fluorescence was also studied in a solution of 10(-2) mol NaClO4. The inhibitory effect was elicited more rapidly, but no difference was found between the two isomers. We concluded that the larger effect of cis-DDP on DNA was induced by the 4 X 10(-3) mol concentration of NaCl. Since also the intracellular concentration of chloride ions is 4 X 10(-3) mol, it cannot be ruled out that the interaction between DNA and cis-DDP and trans-DDP in vivo might be influenced by the intracellular environment.

The study of cytotoxic effect of benfluron.

The efficiency of benfluron (B-F) was measured by determining the inhibition of cell proliferation in HeLa and V/79 cells. B-F induced an acute cytotoxic reaction in dependency on the concentration applied. A biphasic unbalanced growth was an integral part of this reaction. In connection with the decrease in cell proliferation which followed B-F treatment at micromolar concentrations, the protein:cell volume ratios increased while at nanomolar concentrations decreased. These variations must be taken into account when expressing and interpreting the results of cell metabolism. The glucose and amino acid metabolism of treated V/79 cells differed markedly when expressed as a function of cell number or as function of protein content per cell.

The mechanism of cytolytic and cytostatic activity of benfluron.

Benfluron at concentrations of 0.26 and 0.52 mumol l-1 inhibited the formation of V79 colonies in a concentration-dependent way. Diminution of the size of colonies of the treated cells was accompanied by a decrease in protein content per cell. At the same time an increase in metabolic activity was observed. Benfluron blocked the V79 cells in S and G2 phases of the cell cycle and at higher concentrations induced cell lysis documented by alterations in cell membrane permeability and morphology. The in vitro membrane effect of benfluron involved a biphasic modulation of the cardiac sarcolemmal (Na+ + K+)-ATPase activity.

Cytogenetic studies in polycythemia vera.

A group of 54 patients with the original diagnosis of polycythemia vera were subjected to cytogenetic examination. Six (17.6%) of the 34 cases examined in the period of the advanced phase of the polycythemia vera had a chromosomal change. Thirteen (65%) of the 20 patients undergoing the cytogenetic examination in the period when the polycythemia vera turned into another myeloproliferative disease showed chromosomal aberration. This suggests a relationship between the number of chromosomal changes and the transformation of the disease. No connection between the cytogenetic changes and myelosuppressive cures could be confirmed in our material. The chromosomal change 20q- considered to be the most frequent kind in the polycythemia vera was not discovered until in patients with the polycythemia vera transformed into a different myeloproliferative disease.

Skin tests with autologous cholesteryl hemisuccinate-treated tumor cells, DNCB and PPD and their relationship to prognosis in malignant melanoma patients.

Skin tests with autologous cholesteryl hemisuccinate-treated tumor cells were performed in Stage II malignant melanoma patients. In the majority of cases an evident reaction having features of delayed type hypersensitivity was noted. No significant correlation between this reactivity and subsequent course of the disease was found. The same was true for the results of DNCB and PPD skin testing. An analysis of the results of all three tests in the same patient revealed no prognostic significance of this score either.