Effect of fluorodeoxyuridine on the sedimentation of nucleoids from HeLa cells in sucrose gradients.

Sedimentation properties of nucleoids from HeLa cells cultured for 6 or 24 h with 10(-6) M fluorodeoxyuridine (FdUrd) were studied in neutral sucrose gradients. Independently on the presence and concentrations of ethidium bromide in the gradient, nucleoids from FdUrd treated cells sedimented farther than those from untreated cells. However, the maximum relaxation of supercoiled DNA, observed at the concentration of 5 micrograms/ml of ethidium bromide, was significantly lower in cells treated with FdUrd, which indicated that prior incubation with FdUrd did not increase the degree of DNA supercoiling but altered by some way the conformation of DNA in nucleus. Previously we have found, that treatment of HeLa cells with FdUrd resulted in the stimulation of DNA synthesis, which proved to be resistant to ultraviolet and gamma-irradiation. From the present results it is possible to suggest, that alterations of chromatine structure should be included in facilitating of DNA synthesis on DNA template damaged by ultraviolet or gamma irradiation.

Influence of methoxamine, 5-hydroxytryptamine and physically induced low pH on thermal sensitivity and thermotolerance.

The influence of pH on split-dose hyperthermic response of non-resistant and thermotolerant Ehrlich tumors was studied. Vasoactive agents, methoxamine and 5-hydroxytryptamine (5-HT) and, mechanical interruption of the tumor blood flow by wire technique were applied in combination with hyperthermia at 72-hour intervals, where an increased thermal response was observed in Ehrlich tumor. A potential influence in suppressing the induction of thermotolerance (hyperthermia at 24-hour intervals) was evident in the case of 5-HT and methoxamine. These vasoactive agents and the wire technique showed a selective effect in reducing the tumor microcirculation as well as lowering its pH. However, unlike the wire technique, the pH was rather low in the postheating period in the case of 5-HT and methoxamine. Poor tumor vascularization induced by vasoactive agents or physical means would demonstrate a poor nutritional condition with a low pH, whereby an increase in thermal response would be obvious and may be expected to have maximal influence either in the decay or in delaying the induction of thermotolerance. A low tumor pH particularly during the postheating period may have some role against the development of thermotolerance.

Human neoplastic cell line distribution, immunoprecipitation and immunohistopathological study of a gp200 cell surface glycoprotein (LCA) detected by a monoclonal antibody elicited with an ALL cell line.

The antigen recognized by a newly produced monoclonal antibody (bra55; IgG1) elicited by the non-T, non-B acute lymphoblastic leukemia cell line REH 6, was expressed on all examined hemopoietic neoplastic cell lines (including non-T, non-B, T, B and myeloid leukemia cell lines), but not on examined nonhemopoietic human tumor cell lines (such as carcinoma, sarcoma, melanoma and neuroblastoma cell lines), as demonstrated by indirect immunofluorescence and enzyme-linked immunoassay. Specific immunoprecipitation of 125I-lacto-peroxidase radioiodinated cell surface proteins and sodium metaperiodate/tritiated sodium borohydride 3H-radiolabeled cell surface sialoglycoproteins followed by electrophoretic analysis (SDS-PAGE) demonstrated that the immunoprecipitated antigen is a cell surface 200 kDa sialoglycoprotein (on the non-T, non-B ALL cell line REH 6), with variation in its electrophoretic mobility (in the Mr range of 170,000-210,000) on different examined cell lines. These properties are characteristic for the leukocyte common antigen (LCA, T200). Immunoperoxidase staining of several normal and malignant tissues, as well as some nonhemopoietic tumor tissues confirmed the type of antigen tissue distribution pattern characteristic for LCA.

The immunological activities of components isolated from Corynebacterium parvum in mice injected with polyoma tumor cells.

The inhibition of polyoma tumor in CBA mice after immunization with different fractions of Corynebacterium parvum was investigated. Treatment with 200 micrograms of polysaccharide from culture filtrate before s.c. inoculation 2 X 10(6) of tumor cells induced antitumor effect in mice. Treatment with lower doses (1 microgram or 20 micrograms) after transplantation of tumor cells was not effective. Injection of lipopolysaccharide from Escherichia coli abolished a positive response on inhibition of polyoma tumor growth after immunization with Corynebacterium parvum fractions. Additionally, delayed-type hypersensitivity reaction to protein fractions contain tumor antigenic components of membrane vesicles from polyoma tumor cells in the mice immunized with different compounds of Corynebacterium parvum was very strong. These findings suggest that the Corynebacterium parvum preparations are capable to inhibit tumor growth and could be used in special circumstances in immunoprophylaxis.

Cyclic AMP levels of C6 glioma cells treated with cis-dichlorodiammine platinum (cis-DDP).

Rat C6 glioma cells were cultured for 3-4 days in MEM supplemented with bovine serum. After 10 min incubation of cells with 0.075, 1.0 or 7.5 micrograms ml-1 cis-DDP the basal cAMP levels (7.87 +/- 0.4 pmoles mg-1 protein) were not affected. In the presence of a phosphodiesterase inhibitor, IBMX, an increase of cAMP occurred; the later was more pronounced in cis-DDP treated cells than in the controls. This suggests that both adenylate cyclase and cAMP-phosphodiesterase were proportionally influenced at this period and that the stimulatory effect of cis-DDP on AC could be demonstrated only when increased activity of PDE had been blocked by IBMX. At later time intervals (10 h-40 h), a 5- to 17-fold elevation of cAMP levels was observed even in the absence of IBMX. Pretreatment of the cells with cis-DDP significantly potentiated cAMP accumulation in response to NE alone and to cis-DDP plus NE could be prevented to a large extent by propranolol; in cis-DDP treated cells the propranolol protection was more effective, both in the absence and the presence of IBMX. The pretreatment of cells with an alpha-blocker, Regitin, did not significantly influence cAMP accumulation. The results indicate that the cis-DDP stimulated cAMP response to NE is mediated via an interaction with beta-adrenergic receptors. The late increase in cAMP content may be a mediator of the morphological changes in these cells following exposure to cis-DDP.

Lung carcinoma in uranium miners, Czechoslovakia, 1976-1980.

The analysis of the clinical data of uranium miners suffering from lung cancer in the years 1976-1980 was made. In 299 diseased men with lung cancer verified by histology and/or cytology the average age was 56.2 years. There were 52.8% of epidermoid carcinomas, 32.8% of small cell carcinomas, 5% of adenocarcinomas, and 9.4% of other, mixed, undifferentiated carcinomas. This distribution differed from those reported previously. In 25 survivors of 5 years (8.4%), there were 21 patients radically operated in the Stage I or II of the disease. In 84% of survivors the cancer was epidermoid. The lung cancer in uranium miners has not any proper characteristics excluding the age of diseased persons which is about 10-15 years lower than in current male population suffering from lung cancer.

Chemo- and immunotherapy of an adenovirus-induced transplantable sarcoma in hamsters.

The subcutaneous transplantable adenovirus sarcoma (TAVS) in hamsters was created in 1972 at the Oncological Research Institute and maintained by serial subcutaneous transplantation. It showed the highest sensitivity against some alkylating drugs and antimetabolites--cyclophosphamide, sarcolysine, methotrexate and 6-mercaptopurine. In some degree, TAVS is able to differentiate antitumor drugs of one group by the intensity of their antitumor activity. Among the drugs, cyclophosphamide was the most active and 6-mercaptopurine and 5-fluorouracil the least active. Antitumor drugs of plant origin, antibiotics and methyl-CCNU had a weak activity on subcutaneous TAVS. Intramuscular TAVS showed a similar sensitivity, with some differences for olivomycin, bruneomycin and vinblastine. Intracerebral TAVS was sensitive against antitumor agents penetrating through the hemato-encephalic barrier and which were active against its subcutaneous and intramuscular form. BCG vaccine and levamisole applied separately did not show any activity on the growth of TAVS. Combined immunochemotherapy with cyclophosphamide plus BCG gave a better enhancement of the antitumor effect of the cytostatic than that of the combination of methotrexate plus BCG and cyclophosphamide plus levamisole. These results showed that TAVS in hamsters may be used as a suitable experimental model for pharmacological studies of antitumor agents and combined immunochemotherapy.

Mitomycin C induced chromosomal aberrations and sister chromatid exchanges (SCEs) in lymphocytes of patients with precancerous and cancerous lesions of the uterine cervix.

Baseline and mitomycin C (MMC)-induced chromosomal aberrations and sister chromatid exchanges (SCEs) in blood lymphocytes of patients with cervical precancerous and cancerous lesions and normal women were studied. The baseline frequency of chromosomal aberrations and SCEs revealed a significant increase in higher grades of precancerous (moderate and severe dysplasias) and cancerous lesions compared to those of controls. The MMC-induced chromosomal aberrations and SCEs did not show any differential response in the different groups studied. The results thus indicate that chromosomal instability as observed in precancerous and cancerous lesions is not associated with their sensitivity to mitomycin C.

Lactic acid concentration and acid-base balance in cerebrospinal fluid: observations of diagnostic importance in non-Hodgkin lymphoma.

Measurements of lactic acid concentration and gas analysis were performed in lumbar cerebrospinal fluid from 36 patients without malignant central nervous system involvement and four patients with meningeal dissemination of non-Hodgkin lymphoma. The upper lactic acid concentration in controls of 2.48 mmol/l was exceeded in all four patients, also in cases with low blast counts and normal protein and glucose content. The pH, pCO2, pO2 and standard bicarbonate concentration in spinal fluid of patients with meningeal dissemination in non-Hodgkin lymphoma did not show significant differences compared with other patients and controls. Determination of the lactic acid concentration in cerebrospinal fluid add information, relevant to the diagnosis of meningeal involvement in non-Hodgkin lymphoma.

Biochemical markers of malignant melanoma.

The excretion of Thormählen positive melanogens (TPM), zincuria, serum dopaoxidase activity of tyrosinase and serum sialic acid were determined in 60 patients with primary and/or metastatic cutaneous melanoma and in 20 healthy persons. On the basis of our results we can recommend the following of TPM urinary excretion and serum dopaoxidase activity in the course of malignant melanoma as specific markers of the tumor growth. The following of serum sialic acid in the course of malignant melanoma is valuable from the standpoint of prognosis of the disease. The following of zincuria in the course of malignant melanoma is not recommended because of its low value for monitoring melanoma patients.

Peptide and steroid hormone levels in pre- and postmenopausal breast carcinoma.

Circulating levels of LH, FSH, prolactin, estradiol, progesterone and testosterone were measured by radioimmunoassay in 15 premenopausal (PR-M) age matched healthy controls, 35 premenopausal breast cancer patients prior to therapy, 20 postmenopausal (PO-M) age matched healthy controls and 68-71 postmenopausal breast cancer patients prior to therapy. The patients had histologically proven breast cancer. In PR-M breast cancer group, the LH and progesterone did not differ significantly whereas prolactin showed marked elevation (p less than 0.001) and estradiol and testosterone showed significant decrease (p less than 0.001). The PO-M breast cancer patients exhibited remarkable increase in the levels of LH, FSH, prolactin and testosterone (p less than 0.001) whereas estradiol and progesterone showed little increase in the levels (p less than 0.2 and less than 0.1, respectively). From the results, it is concluded that prolactin and altered ratio of estrogen and androgen plays a major role in the genesis of breast cancer.

Nonmutagenicity of betel leaf and its antimutagenic action against environmental mutagens.

Betel leaf (Piper betel) water and acetone extract are nonmutagenic in S. typhimurium strains with and without S9 mix. Both the extracts suppress the mutagenicity of betel quid mutagens in a dose dependent manner. Moreover both the extracts of betel leaf reduce the mutagenicity of benzo(a)pyrene and dimethylbenzanthracene. Acetone extract is more potent than water extract in inhibiting mutagenicity of environmental mutagens.

Stage IIb, IIIb, and IVa carcinoma of the uterine cervix--results of treatment by radiotherapy in 649 patients.

During the period of January 1969 to December 1980, 649 patients have been treated by radical radiotherapy for Stage IIb, IIIb, and IVa carcinoma of the cervix uteri. This retrospective study was performed to assess therapeutical results in two groups of patients. Clinical staging and the methods of treatment were standard in both groups. Group I was treated by external irradiation of the pelvis minor with 60Co in combination with intracavitary radium administration. Group II patients were irradiated with a 42 MeV betatron according to the findings of lymphography, again in combination with radium brachytherapy. In Group I the 5-year survival rate was 59.2%, that in Group II was 66.7%. There was a statistically significant difference in the 5-year survival rate in Stage IIb patients of Group II (85.5%) against that in Group I (75.6%). The incidence of serious complications elicited by radiotherapy increased from 4.8% in Group I patients to 7.5% in Group II. Clinical stage, age at the time of diagnosis, findings of lymphography and tolerance to irradiation are prognostically important factors that influence the cure of the patients. On the basis of these findings, the possibilities of further therapeutic improvements are discussed.

Chromotest estimation of SOS functions as a screening method for antitumor platinum complexes.

The chromotest which measures the induction of SOS functions in an Escherichia coli strain bearing the lacZ gene under the sfiA gene control was evaluated as a screening method for platinum complexes with antitumor activity. Four types of complexes were used: (a) those with two nitrogen ligands in cis position and chlorine or carboxylic acid as anionic ligand; (b) four nitrogen atoms surrounding platinum; (c) complexes involving sulphur and amino group of methionine; (d) complexes of tetravalent platinum. The trans-diaminodichloro complex was used as negative control. Groups (b) and (c) were inactive in the chromotest which correlated well with their absence of antitumor activity. Antitumor activity and a positive chromotest also correlated in group (d). In group (a), which includes complexes with well established antitumor activity, the chromotest separated complexes with fast and slow rate of hydrolysis. The results fitted well in the mutation induction test.

Immune response against P815X2 mastocytoma growing in syngeneic DBA/2 mice. IV. Lymph node immunoreactivity and cell-mediated cytotoxicity.

The in vitro cytotoxicity assay and the morphological in vivo analysis were used to follow the T cell reaction in tumor draining lymph nodes from DBA/2 mice bearing subcutaneously developing P815X2 mastocytoma. Mononuclear cells separated from local lymph nodes between days 8 and 14 following tumor inoculation were able to kill P815X2 cells in vitro. The maximal tumor-specific cytotoxicity was measured on day 10. Changes in lymph node morphology and in cellular contents of individual lymph node compartments were seen from day 12 onwards. The extensive expansion of the paracortex and the enlargement of the whole lymph node reached the peak on day 14. On days 12 and 14, a slight increase was also observed in the proportion of T lymphocytes. The results indicate that the tumor-specific cytotoxicity was detectable in tumor draining lymph nodes four days earlier than the morphological and cellular changes. The maximal cytotoxicity preceded the morphological peak reactions by two to four days.

Variability in response pattern of DMBA induced mammary tumors of Wistar rats.

The incidence and growth pattern of DMBA induced mammary tumors of Wistar rats in altered hormonal conditions induced by endocrine ablation were studied. Elevation of prolactin by pituitary stalk section, removal of primary source of estrogen by bilateral oophorectomy or both were done before administration of DMBA as well as after formation of palpable tumors. The results indicate that while estrogen is essential for the induction of these tumors, elevation of prolactin before administration of DMBA inhibits tumor incidence. From the overall responses (mean tumor volume) in the different groups it is evident that prolactin alone cannot maintain growth of these tumors, estrogen is also essential at least in a large percentage of tumors. The marked intertumor and intratumor differences in the response pattern to altered hormonal situations demonstrate close resemblances of this tumor model to the human breast cancer.

Clinical experience with the testing of serum proteinase activity by cathepsin B-like sensitive amino acid derivatives of 7-amino-4-methylcoumarine.

The proteolytic activity of serum against two synthetic polypeptide substrates conjugated with 7-amino-4-methylcoumarine which are known to be highly specific substrates for lysosomal cathepsin B-like cysteine proteinase, was studied in normal individuals and in patients with breast and colorectal cancer. The results showed that both substrates are cleaved in different ways and their hydrolysis is very poorly sensitive to inhibitors of cysteine proteinases. On the other hand, cleavage is intensively inhibited by disodium-EDTA which is known as an activator of cysteine proteinases. This indicates that lysosomal conditions are quite different from serum which is an unstable mixture of various enzymes and their substrates. It was also demonstrated that hydrolysis of the tested substrates is not probably realized by cysteine proteinases but it can be performed by cooperation of other serum proteinases. Moreover, our results confirmed that serum activity of these enzymes can be significantly higher in patients with breast cancer, particularly with metastasis, than in healthy women. A slight insignificant increase was observed also in patients with colorectal cancer.

Platinum cytostatics influence--the primary antibody response of mouse spleen cells in vitro.

The effects of three platinum containing cytostatic drugs--cis-DDP, CBDCA, and OXO--on in vitro primary antibody production after the treatment of mouse spleen cells with these compounds were studied. The technique of Marbrook was employed, the antibody response was assessed according to the number of plaque-forming cells (PFC) after the antigenic stimulation by sheep red blood cells (SRBC) in vitro. All of the three platinum complexes studied had inhibitory effect on antibody response at concentrations of 1 X 10(-5) to 1 X 10(-7) mol/l without affecting the viability of the mouse spleen cells. A comparison of the effectiveness of the three cytostatic drugs showed that cis-DDP was the most potent inhibitor. To obtain a similar inhibitory effect with CBDCA and OXO, concentrations 10 times as high as that in cis-DDP were required, depending on the time relation to antigenic stimulation. The lowest inhibitory effect on antibody production was observed in CBDCA. These drugs acted either after a simultaneous administration or 48 h after the antigen, i.e., at the time of maximal proliferation and differentiation of the cells. DNA synthesis must undoubtedly have been affected as well.

Terminal deoxynucleotidyl transferase in acute leukemias by direct immunofluorescence.

TdT (terminal deoxynucleotidyl transferase) can be detected by radio enzymatic assay, biochemical assay in cell extracts, serum or plasma, and intracellularly in the smear by indirect immunofluorescent methods. The IgG fraction of anti-TdT serum is conjugated with fluoresceinisothiocyanate and used directly on the cytospin smears of methanol fixed bone marrow/blood smears. The mice thymocytes and peripheral mononuclear cells of healthy donors were used as positive and negative controls, respectively, for TdT. 64% of our cases of ALL were found to be TdT+. The lymphoblasts of L1 morphology (FAB classification) were more frequently positive for TdT as compared to blasts with L2 morphology. 71% of our cALLa positive blasts in acute lymphoblastic leukemias were TdT+ve as compared to 58% of T-ALL blasts. 75% of PAS positive ALL cases were positive for TdT as well. Only 57% of the cases when acid phosphatase showed unipolar positivity (T type) were positive for TdT. 12% of cases with acute myeloid leukemia (6/47) were TdT+ve and 33% of CML in blastic crisis had TdT+ve blasts. Biochemical assay and IF assay for TdT were in good correlation in our study.

Supplementary characteristics of anti-MHC class II monoclonal antibodies elicited by an ALL cell line: immunofluorescence cytofluorometry, C-dependent cytotoxicity, two-dimensional analysis of antigen.

Monoclonal antibodies directed to MHC class II antigen(s), elicited by a non-T, non-B ALL cell line, were characterized by immunofluorescence flow cytofluorometry and ELISA immunofiltration measurements of their immunoreactivity with selected neoplastic hemopoietic cell lines, determination of their complement-dependent cytotoxic activity against isolated peripheral blood B and T lymphocytes and by two-dimensional electrophoretic analysis (isoelectric focusing, SDS-PAGE) of radiolabeled, immunoprecipitated by these antibodies cell surface antigens. Patterns of these immunological reactivities, as well as two-dimensional radioimmunoprecipitation patterns (acidic heavy chain p35 and basic light chain p30) of antigens recognized by these antibodies confirm their anti-MHC class II specificity. One of these antibodies (braFB6; IgG2b) displayed identical pattern of expression on cell lines and cell types as the typical anti-MHC class II antibodies, but immunoprecipitated only a single chain p30 radioiodinated cell surface protein (with two-dimensional pattern close to the beta-chain of MHC class II DR antigen). These properties indicate the ability of braFB6 monoclonal antibody to recognize a nonpolymorphic determinant of DP-MHC class II antigen.

Inducible high-affinity binding site for benzo(a)pyrene in cytosol from rat liver.

By the use of the dextran-coated charcoal method the presence of a high-affinity binding site for benzo(a)pyrene in the cytosol from rat liver (R strain) has been demonstrated. This binder was saturable by ligand concentration and by time. Sucrose density gradient analysis after charcoal treatment revealed one major peak of radioactivity sedimenting at 4.4 S which was displaceable by a 100-fold molar excess of nonlabeled benzo(a)pyrene. Benzo(a)pyrene binding to liver cytosol was sensitive to protease treatment of the cytosol suggesting that the binder was a protein. Saturation and Scatchard plot analysis of benzo(a)pyrene binding indicated a high-affinity (Kd = 4.7 nmol) and a relatively low binding capacity (Bmax = 379 fmol/mg cytosolic protein), allowing, to denote this binder as a receptor for benzo(a)pyrene. Competition studies showed that this cytosolic receptor was distinct from steroid hormone receptors since benzo(a)pyrene binding was partially inhibited by aromatic carcinogens 3-methylcholanthrene and benz(a)anthracene but not by estradiol, progesterone or cortisol. R strain rats used in these experiments were sensitive to induction with 3-methylcholanthrene which produced the increase of cytochrome Pl-450 content in liver microsomes, enhanced the glutathione S-transferase activity in hepatic cytosol and produced liver hypertrophy in stimulated animals. All these effects were related to the dose of 3-methylcholanthrene used for the induction. Also, the cytosolic binding capacity for benzo(a)pyrene was increased in animals stimulated with 3-methylcholanthrene in a dose-dependent fashion. The 3-methylcholanthrene-induced binder displayed identical sedimentation velocity and kinetic parameters (Kd) to those characteristic for the benzo(a)pyrene receptor in hepatic cytosol from unstimulated animals. Conclusively, our results demonstrated that benzo(a)pyrene was bound to a receptor protein in rat liver cytosol which was inducible by the classical inducer 3-methylcholanthrene. The mechanism of induction of this receptor and its role in cell response to aromatic carcinogens still need to be elucidated.

Postirradiation utility of insulin in radiotherapy.

The radiobiological effect of insulin was studied under laboratory conditions to find its utility in radiotherapy. Balb/c mice receiving injections of insulin after irradiation exhibited rapid recovery from radiation effect. This was evident from the data on their life span, organ weights and spleen colony assay studies, carried out under conditions of whole body and partial body irradiation. This trend was absent in mice injected with insulin before irradiation. The results of experiments on E. coli B/r and HA cells irradiated in the presence of insulin under oxic conditions suggest radioprotective effect of insulin. The E. coli B/r cells irradiated in the presence of insulin under hypoxia, however, showed a moderate radiosensitizing effect of insulin.

Similarity in dynamics of single or double minute chromosomes incidence and number of chromosomal aberrations during long-term treatment of a human cell line with methotrexate.

The human cell line VUPT was treated with gradually increasing concentrations of methotrexate for 500 days. During this period of time the frequency of cells containing single or double minute chromosomes and the number of chromosomal aberrations were estimated. When the concentration of the drug increased, so did the frequency of cells with minute chromosomes, but after several days of adaptation to the given concentration of the drug the minute chromosomes disappeared again. The dynamics of the frequency of chromosomal aberrations resembled that of the minute chromosomes, but the change in the former cytogenetic parameter generally preceded corresponding changes in the latter. The results indicate a possible relationship between the development of chromosomal aberrations and the formation of minute chromosomes.

Mathematical model of Ehrlich ascites tumor growth from in vitro treated cells.

A mathematical model is proposed describing the dependence of lethality and average life-span in mice on the number of Ehrlich ascites tumor (EAT) cells inoculated both intact or treated in vitro with various agents. Particularly, the effect of ionizing radiation is discussed, and the effect of combined action of two agents is also considered.

A preliminary report on monoclonal antibodies against human uveal melanoma.

Mouse Sp2/10 myeloma cells were fused with spleen cells from mice that had been immunized with freshly obtained primary human uveal melanoma cells. Hybrids that produced antibodies binding to the uveal melanoma cells, but not to fibroblasts, uveal or retinal cells of healthy donors, were cloned. Extensive specificity tests showed that the antibodies produced by the ten clones bound strongly to fresh or short-time cultures of primary human uveal melanoma tumor cells (UMEL-H, UMEL-K). Weaker binding occurred with a human uveal melanoma cell line (VUP-1), and with human skin melanoma cell lines (HMB-2, B-HM8), respectively. Binding assays with carcinoma cells, fibroblasts, uveal and retinal cells were negative. An intensive screening of this type is now under way.

Activity of lymphocytes and antibodies derived from aging and adult rats bearing a MC-induced tumor in the syngeneic ADCC test.

The purpose of the present paper was to demonstrate the antitumor activity of lymphocytes and antibodies in the antibody-dependent cell-mediated cytotoxicity test (ADCC) in relation to the tumor growth in adult and aging rats bearing a methylcholanthrene-induced sarcoma (MC-Sa). In the syngeneic system using the ADCC test effector spleen lymphocytes, 51Cr labeled MC-Sa target cells and anti-MC-Sa serum were derived from inbred male Wistar rats. It was found that adult and aging tumor-bearing rats possessed lymphocytes (LSa) and antibodies (Ab) which were active in ADCC. In comparative studies between the groups of adult and aging rats a reverse relationship between tumor growth and activity of LSa and Ab in the ADCC test has been found. Thus, the larger weight of tumors in the group of adult rats was followed by lower LSa and Ab activities in the ADCC test. On the other hand, the smaller tumor growth in the group of aging rats was followed by higher activities of LSa and Ab in this test. We suggest that the ADCC phenomenon could be one of the antitumor mechanisms especially effective in aging rats.

DNA synthesis, protein synthesis and platinum content following drug administration in cis-diamminedichloroplatinum(II) -sensitive and -resistant L1210 cells transferred from in vitro to in vivo conditions.

L1210 cells with in vitro induced drug resistance against cis-diamminedichloroplatinum(II) (cis-Pt(II] were inoculated in mice and several times transplanted. Then the effect of cis-Pt(II) on drug-sensitive and drug-resistant L1210 cells in mice was investigated. While the DNA and protein synthesis in drug-sensitive cells after in vivo cis-Pt(II) treatment was inhibited by 50%, that of drug-resistant cells remained virtually unaffected. The content of platinum in drug-sensitive cells was approximately three times higher in comparison with drug-resistant L1210 cells.

Lethal effect of glucose load on malignant cells.

Ehrlich ascites tumor (EAT) cells were treated by glucose load under anoxic conditions (for 15 or 60 min) and/or by gamma-radiation (20 Gy). The efficiency of the treatment was judged from the tumorigenic activity of EAT cell inocula. The markedly increased efficiency of the combined treatment of EAT cells by glucose load in anoxia and by gamma-radiation is due to the additive action of both agents. The glucose load in anoxia leads to extensive desintegration of tumor cells. Further, the lethal effect of various pH values on EAT cells was investigated. Different pH values were obtained by means of both glucose load and phosphate buffers. The effect was investigated by determining the tumorigenic activity of EAT cells tested in vivo in mice and by determining the radiosensitivity of treated EAT cells. The results allowed us to conclude that the same values of pH lead to the same effect on EAT cells independently of the way by which the given pH value was reached.

Leukoplakia of the vulva locally treated by 13-cis-retinoic acid.

Repeated topical application of 13-cis-retinoic acid resulted in complete disappearance of leukoplakia of the vulva in 8 out of 16 patients, among them 2 out of 3 with recurrence after vulvectomy. A considerable regression of leukoplakia was seen in 7 other patients, usually after 1 to 2 months of daily retinoid treatment. After 2-4 months of maintenance therapy and during 3-7 months of the follow up period no recurrences were seen. Side effects of treatment could be managed. Serum retinol level was found to be lower in patients then in healthy subjects. The results suggest that patients with chronic epithelial vulvar dystrophies could benefit from local retinoid treatment, especially in cases with advanced dystrophies until now qualified for vulvectomy.

In vitro modulation of adriamycin and mitoxantrone cytotoxicity by hyperthermia and diazepam, in human chronic myeloid leukemia cells.

Adriamycin and mitoxantrone are known antitumor agents. The use of these agents is limited by their toxicity to normal body tissue. This paper shows that it is possible to achieve greater log cell-kill by using these drugs in combination with hyperthermia and diazepam. Experiments were carried out on 22 human chronic myeloid leukemia samples. 10 micrograms/ml adriamycin and 1 microgram/ml mitoxantrone were used in combination with hyperthermia 42 degrees C, for 3 h and 1 h respectively, with and without diazepam (1 microgram/ml). Inhibition of incorporation of radiolabeled nucleic acid precursor (3H-thymidine) in treated cells as compared to the untreated cells was used as a measure of cytotoxicity. The statistical evaluation of the data shows that the enhancement of drug cytotoxicity due to hyperthermia and diazepam is highly significant (p less than 0.001) in case of both the drugs.