Antitumor effect of combination of cyclophosphamide, adriamycin and platinum (CAP) versus cyclophosphamide, adriamycin and 5-fluorouracil (CAF) in metastatic breast cancer.

The aim of the present study was to evaluate the antitumor effect of two drug combinations in disseminated breast cancer. Eighty-one patients divided into two groups entered this nonrandomized study. Group 1 included 32 patients treated with CAP combination: Cyclophosphamide--200 mg/m2 on days 1, 3 and 5 + adriamycin--40 mg/m2 on day 1 + cisplatin--30 mg/m2 on days 1, 3 and 5. Group 2 included 49 patients treated with CAF combination: Cyclophosphamide--100 mg/m2 on days 1 to 14 + adriamycin--30 mg/m2 on days 1 and 8 + 5-fluorouracil--500 mg/m2 on days 1 and 8. All patients had at least 2 courses of chemotherapy. In Group 1 the remission rate was 50% (16 patients) including 3 complete (9%) and 13 partial remissions (41%). In Group 2 the remission rate was 39% (18 patients) with 8 complete (16%) and 10 partial remissions (23%). The analysis of duration of the remissions showed a tendency towards longer duration after treatment with CAP combination (25 versus 15 months for the complete remissions, and 14 versus 11 months for the partial remissions).

Hyperfractionated radiotherapy for Burkitt-type lymphoma. Radiobiological aspects.

A case of Burkitt-type lymphoma treated by accelerated hyperfractionated irradiation combined with the COP chemotherapy is presented. The effectiveness of treatment was evaluated on the basis of the growth curve and the radiobiological aspects are discussed. During the treatment, the initial volume doubling time (Td) of 15 days was shortened to 4.5 days suggesting accelerated tumor growth. From dose response curve estimated for clinical data taken from literature, an effDo of 1.37 Gy was calculated. Surviving fraction after 58 Gy given in the twice-a-day regimen (b. i. d.) was 10(-19) suggesting local tumor control. However, only partial remission was observed. This nonradical effect may likely result in accelerated repopulation of surviving tumor clonogenic cells. This suggests that such a fast growing tumor as Burkitt-type lymphoma (Tpot = 1 day) should be irradiated using three instead two fractions per day combined with adjuvant or concomitant chemotherapy with a short intervals between cycles.

Interleukin 2 enhances the efficiency of immunotoxins in the treatment of mice with ascitic tumors.

Two multivalent immunotoxins (ITs) with cytotoxic potential against Thy 1.2-expressing tumor cells were used in association with mouse interleukin 2 (IL2) for treatment of mice bearing ascitic EL4 lymphomas. The combined treatment, ITs + IL2, induced an enhanced antitumor effect revealed by a significant prolongation of the survival time of mice as compared to the simple treatment with ITs or IL2 alone. According to the survival of mice treated by combined therapy, the proportion of killed tumor cells rose up to 94% as resulted from the dose-dependent curve of the survival of nontreated mice versus the number of tumor cells inoculated.

Carcinoembryonic antigen, neuron-specific enolase and creatine kinase-BB as tumor markers for carcinoma of the lung.

Carcinoembryonic antigen (CEA), neuron-specific enolase (NSE) and creatine kinase-BB (CK-BB) were estimated in blood serum of 75 patients with primary lung carcinoma and of 20 patients with nonmalignant lung diseases. CEA and NSE were determined by immunoenzymatic method using monoclonal antibodies (Abbott CEA-EIA and Roche NSE-EIA) and CK-BB was assayed using kits supplied by Boehringer-Mannheim (Monotest CK-NAC aktiviert). Enhanced levels of CEA were observed in 64% of patients with lung carcinoma, mainly with adenocarcinoma. Increased activities of NSE and CK-BB were obtained in 47% and 39% of patients, respectively, principally of those with small cell carcinoma. The CEA level was dependent on the stage of advanced NSCLC carcinoma and of NSE and CK-BB on the stage of advanced SCLC carcinoma. The complex analysis of the three markers has given 100% specificity of test.

The role of glutathione in evaluating the efficacy of antimetabolites in transplanted tumors.

Levels of glutathione (GSH) in tumor cells play an important role in determining the clinical responses to certain anticancer agents. In the present work 5-fluorouracil and 5-fluorodeoxyuridine have been used as antineoplastic agents against transplanted Ehrlich ascites carcinoma. The glutathione levels in the tumor cells and liver tissues of the host animals have been studied by a specific histofluorescence method. Significant changes have been observed in the glutathione level of the host, tumor bearing and treated group of animals, the implications of which have been discussed.

Lymphokine activated killer cells and interleukin-2 production in patients with cervical carcinoma.

Lymphokine activated killer cells were generated from peripheral blood lymphocytes (PBL) in patients with cervical carcinoma. The cytotoxic potential of these cells was determined against three tumor cell lines (K-562, RAJI and MCF-7) using a short-term 51Cr-release assay. Both normals and patients showed comparable levels of LAK activity. Phenotypic analysis of cells having LAK activity showed a heterogeneous population. A significant increase in the expression of CD25 marker (IL-2R, Tac) of PBL population was observed after IL-2 culture. In addition, the indigenous ability of peripheral blood mononuclear cells to produce IL-2 in response to mitogen PHA was almost the same as observed in case of normal individuals.

Purine metabolism enzyme pattern, cytochemical characteristics and clinicopathologic features of CD10-positive childhood T-cell leukemia.

Purine metabolism enzyme pattern, cytochemical markers and clinicopathologic features of common acute lymphoblastic leukemia antigen (cALLA; CD10)-positive, CD10-negative T acute lymphoblastic leukemia (ALL), and cALLA-positive non-T, non-B ALL (common ALL; C ALL) of children were compared. The results of immunophenotyping of blast cells in 61 children with ALL who were treated and followed during the last 7 years at the Second Pediatric Clinic in Bratislava are presented. The aim of our study was to determine the correlation of CD10 marker expression with purine enzyme activities and clinical course in ALL of children. Immunologic phenotype performed by a panel of monoclonal antibodies in indirect immunofluorescence assay revealed 3 main ALL groups: Common ALL (C ALL), T ALL and CD10+ T ALL (C + T ALL). An additional exact cytochemical marker analysis was performed in these three ALL immunologic subtypes. Two enzymes of purine metabolism, i.e. adenosine deaminase (ADA) and purine nucleosidephosphorylase (PNP) were investigated in blast cells by paper radiochromatography. Life-table analysis revealed significant prognostic differences with regard to event-free survival and overall survival in followed groups of ALL patients. Our results showed a rather high frequency of mixed (C + T) ALL phenotype. The characteristic T ALL enzyme pattern (high ADA, low PNP) was present not only in T, but also in CD10+ T ALL blast cells. The T cell marker showed to be dominant in the determination of clinical course and prognostic significance in children with ALL; children with T and CD10+ T ALL phenotype, in contrast to C ALL phenotype, experienced more frequent relapses and a shorter event-free survival.

The influence of DNA-topoisomerase II inhibitors novobiocin and fostriecin on the induction and repair of DNA damage in Chinese hamster ovary (CHO) cells treated with mitoxantrone.

Novobiocin (NB) at the concentration of 2 mmol/l added to the culture medium together with mitoxantrone (MIT) (0.05-0.2 micrograms/ml) reduced the number of MIT-induced single-strand breaks of DNA to approximately one half measured by alkaline DNA unwinding and hydroxyapatite chromatography of DNA and similarly it reduced also the fraction of DNA linked to proteins measured by the K(+) -SDS precipitation method. Neither repair of the induced DNA breaks nor removal of the DNA-protein cross-links were markedly influenced by NB action. The specific inhibitor of topoisomerase II, fostriecin, exerted no effect on the induction of DNA breaks by MIT or their repair. Measurement of intracellular concentration of MIT has revealed that in the presence of NB the uptake of MIT into cells is reduced similarly as the number of induced DNA breaks to approximately one half. The combination of 0.1 mmol araC + 10 mmol HU slightly reduced the number of induced DNA breaks, but did not affect their repair. The present results suggest that (1) MIT induces DNA damage which is not repaired by excision repair, (2) MIT induces protein associated breaks of DNA, (3) topoisomerase II does not probably participate in the formation of DNA breaks induced by MIT, as the specific inhibitor of topoisomerase II, fostriecin exerts no effect on either the induction or repair of these breaks.

Changes in the toxicity and therapeutic efficacy of daunorubicin linked with a biodegradable carrier.

The effects of the linkage of daunorubicin (DNR) and the synthetic biodegradable polymer polyhydroxyethyl-L-glutamine (PHEG) on general toxicity, therapeutic efficacy, and acute organ toxicity were investigated. General toxicity was assessed by means of mortality, or body weight changes of male CBA mice weighing 22-25 g after a single-dose i.p. administration of 5 or 2.5 mg/kg DNR, free or bound. Linked DNR at a larger lethal dose significantly increased mean survival time (18 versus 12 days). Surprisingly, free DNR at a smaller dose produced larger increases in body weight as compared with linked DNR. The linkage of DNR and PHEG did not markedly change the therapeutic activity in three murine hemoblastoses--plasmacytoma MOPS 406, leukemia P388 and hemoblastosis La. Acute (24 h) changes in cardio- and hepatotoxicity were studied on female Wistar rats weighing 208 +/- 5 g after a single dose of 5 mg/kg i.v. both free and linked DNR, as well as after an administration of the PHEG polymer alone (200 mg/kg i.v.). Free DNR caused a three-fold increase in creatine kinase (CK) activity, the identical dose of linked DNR caused only a 1.7-fold increase. Free DNR administration resulted in a decrease in heart rate, other tested drugs did not significantly change either blood pressure or heart rate. Free DNR did not change the kinetics of bromsulphalein (BSP) except for a decrease in extraction effectivity. Both linked DNR and polymer alone significantly changed some kinetic parameters of BSP. The results showed that the biodegradable polymer PHEG cannot be clinically used due to its hepatotoxic action. On the other hand, a decrease in total toxicity and cardiotoxicity resulting from the linkage of DNR and PHEG, the therapeutic efficacy being preserved, stimulates the efforts to find a suitable polymer carrier of anthracyclines without more serious side-effects.

Subrenal capsule assay of human tumor chemosensitivity.

Breast and colon tumor response to emoxyl, a nitroxyl derivative of daunomycin, was detected using human tumor heterotransplantation under the renal capsule of immunocompetent mice. The substitution of adriamycin by emoxyl in the combined therapy led to enhanced therapeutic efficacy. The evidence of enhanced response of breast tumors to emoxyl obtained during the histologic examination of xenografts is in good agreement with measurements of tumor fragment weight. It is suggested to use a quantitative kinetic index kappa calculated by the method of equivalent exponents for objective evaluation of tumor response to the drugs.

Some electrochemical characteristics of synthetic analogs of nucleic acid components. IV. 5-Cyano-, 5-carboxy- and 5-azaderivatives, and the effect of this substitution on potential carcinogenicity.

The relation between polarographic reduction, values of half-wave potentials, and the parameter of potential carcinogenicity (tg alpha) was studied in a series of synthetic analogs of natural nucleic acid components modified by different substituents at position 5 of the base. The series included pyrimidine nucleobases (5-cyanouracil, 5-carboxycytosine, 5-azacytosine), ribofuranosyl nucleosides (5-cyanouridine, 5-carboxycytidine, 5-azacytidine) as well as 2'-deoxy-5-azacytidine and 5-carboxy-1-beta-D-arabinosylcytosine. No direct correlation was found between the reducibility of the studied compounds and the parameter of potential carcinogenicity tg alpha since event a slight alteration in the structure of these molecules markedly affected the properties of these compounds.

NK-cell activity affected by some cytostatic drugs and their additives.

The direct effect of selected cytostatic drugs on natural killer (NK) cell activity was evaluated. Peripheral blood mononuclear cells from healthy donors were tested for their cytolytic activity in vitro in the presence of adriamycin, methotrexate, leucovorin, vincristin, cytosine arabinoside and teniposide. Most of the tested cytostatic drugs did not show to be active at concentrations comparable to their plasma level. However, diluents of some preparations (cytosine arabinoside, teniposide) containing organic solutions and stabilizing additives (e.g. benzyl alcohol) suppressed the NK activity more than chemotherapeutic agents alone. Thus teniposide, containing such additives, inhibited NK activity already at 5 mg/ml, while its peak plasma concentration was 23.8 mg/ml. The inhibitory concentrations of teniposide did not affect the target binding of effector cells and the expression of 14 tested leukocyte differentiation markers. This implies that a postbinding step of the lytic process was altered by the preparation. Likewise, no inhibition of lectin dependent cellular cytotoxicity by teniposide and its diluent was observed, suggesting that the lectin may substitute the missing lytic signal.

The role of humoral factors of regenerating liver in the development of experimental tumors and the effect of Rhodiola rosea extract on this process.

In experiment on rats with Pliss lymphosarcoma (PLS) it was shown that partial hepatectomy (PHE), a course application of Rhodiola rosea extract (RRE) or combined effects inhibit the growth of tumors by 37, 39 and 59%, respectively, and that of metastases by 42, 50 and 75%. In combined treatment the process of hepatic regeneration was completed in earlier terms versus the animals which underwent PHE, and proliferative activity of the tumor and metastases decreased by 15 and 59%, respectively, judging by the degree of 3H-thymidine incorporation into DNA of these tissues. The assessment of clonogenic activity of PLS cells taken in the animals of this group, using the method of diffusion chambers, revealed a significant decrease in this index versus the rats which underwent PHE or which were given RRE (number of colonies per chamber being 4.8 +/- 0.5; 8.6 +/- 0.9; 5.7 +/- 0.6, respectively; in control 13.8 +/- 1.5). The assumption that these effects are determined by factors originating from the regenerating liver was confirmed in experiments with double-layer agar systems. Inhibition of colony-forming activity of PLS cells was the maximum in application of the hepatocytes of the rats which underwent a complex of effects, as a feeder, versus the hepatocytes taken in intact or hepatectomized animals, or the rats which were given RRE (number of colonies per plate well being 4.6 +/- 0.3; 15.7 +/- 1.6; 7.4 +/- 0.8; 8.7 +/- 0.9, respectively; in the control 25.6 +/- 6.5). In experiments on mice with Ehrlich adenocarcinoma, the factors isolated from the liver of animals subjected to PHE against a background of RRE administration and from the liver of mice which were given RRE only, as well as operated or intact ones, inhibited the tumor growth to 63, 38, 35 and 21%, respectively.

Reaction to high-frequency electric impulses in two L cell sublines differing in high-frequency electric impedance and malignity.

Endogenous nitrate synthesis in selected infectious diseases and ulcerative colitis.

Investigations into acute and chronic diarrheal patients confirmed the results of animal experiments on the role of cytotoxic activated macrophages in endogenous formation of nitrates. Because a number of inflammatory diseases did not cause a nitrate release in urine, blood, and saliva, the general importance of nitrates to characterize the initiation and course of inflammations must be questioned.

Disorders in neuropsychological development and their relation to computed tomography brain scan in children with acute lymphoblastic leukemia in long-term remission.

In a group of 71 children with acute lymphoblastic leukemia in long-term remission lasting 4 to 15 years different disorders in their neuropsychological development were found. The disturbances observed were as follows: Emotional disorders in 88%, personality development disorders in 65%, mental retardation in 58%, signs of CNS dysfunction in 54%, and neurological disorder in 31% of children. Abnormal computed tomography brain scans were present in 49% of patients. They consisted mainly of two types: Hypodense areas of the white matter were observed in 23% and widening of the ventricular system and subarachnoidal spaces was present in 26% of children. Statistical evaluation showed significant relations between CT brain scan abnormalities (mainly hypodense changes) and neurological disorders as well as the presence of signs of CNS dysfunction and disorders of personality development. Emotional and mental changes did not correlate with abnormalities of CT brain scan findings.

Breast cancer in Argentina: case-control study with special reference to meat eating habits.

An exploratory case-control study of the role of diet in the etiology of breast cancer was conducted in Buenos Aires, Argentina, where the mortality rate for this disease is high and the consumption of meat, mainly beef, is unusually elevated (76.2 kilograms per head were reported for 1987). One hundred and ninety-six women with breast cancer admitted to the Institute of Oncology "Angel H. Roffo" and 205 controls were interviewed to obtain information on demographic, socio-economic and reproductive variables, on frequency of consumption of 40 food items, and on methods of cooking. Special emphasis was given to different kinds of meat. After controlling for other risk factors for breast cancer the major dietary associations observed were a statistically insignificant trend of increasing risk with amount of beef consumed, an increase in risk in women who ate more than 3 eggs per week, and an increase in risk in women who ate a variety of fried foods.

In vivo and in vitro effect of Cantastim, an immunomodulatory agent extracted from a highly pathogenic Pseudomonas aeruginosa strain.

Cantastim is a biological product consisting of distinct molecules of phospholipids obtained from a peculiar Pseudomonas aeruginosa strain. It enhanced the IgM and especially the IgG responses of mice pretreated with Cantastim and then intraperitoneally inoculated with T-dependent antigens such as sheep erythrocytes; restored cellular immunocompetence as evidenced by an increase in the in vitro proliferative responses to T-cell mitogens and allogeneic stimuli of murine splenocytes from in vivo pretreated mice activated NK cytotoxicity, and inhibited in vivo growth of the Ehrlich ascites tumor. In vitro it stimulated the mitogenesis of mouse lymphocytes but did not exert such stimulatory effect on guinea pig or human lymphocytes. All these findings allow to define Cantastim as an immunomodulating agent influencing mainly the cell-mediated immune response.

Fluorescent double labeling of normal and malignant hematopoietic cells by monoclonal antibodies (FITC) and anthracycline cytostatic drug (Daunomycin): a cytometric technique for analysis of drug uptake in hematopoietic cell subpopulations.

A technique of simultaneous double labeling of normal and neoplastic hematopoietic cells with FITC-conjugated monoclonal antibodies directed to selectively expressed hematopoietic cell surface antigens (green fluorescence) and the anthracycline cytostatic drug (Daunomycin, red fluorescence) was described. Flow cytometric analysis of double labeled cells permitted anthracycline cell content determination in peripheral blood lymphocytes, granulocytes, monocytes from healthy donors, T- (MOLT-4), non-T, non-B (REH) and myelomonocytic (U-937) leukemic cell lines. After mixing peripheral blood lymphocytes from healthy individuals with cultured leukemic cells labeled on a restrictively expressed hematopoietic cell differentiation antigen (CALLA-CD10-, MHC class II-DR-antigen, a myelomonocytic differentiation antigen) detected by corresponding monoclonal antibodies (DGH-10-1-A9,Bra30, BraC8), the described technique allowed separate measurements of anthracycline content in leukemic cells vs. peripheral blood lymphocytes from healthy donors. Potential diagnostic aspects and research utilization of this technique are discussed.

The effect of partial hepatectomy on the genotoxicity of aflatoxin B1.

The influence of partial hepatectomy on the genotoxic effect of aflatoxin B1 (AFB1) mycotoxin in male Chinese hamsters (Cricetulus griseus) was studied after application of a single i.p. dose of 1.0 mg AFB1/kg. Changes in the fractions of proliferating bone marrow cells, values of the mitotic index of liver cells and morphologic changes in liver tissue were also monitored. Partial hepatectomy reduced significantly the mutagenic activity of AFB1 measured by the frequency of chromosome aberrations in bone marrow cells during 5 days. In hepatectomized animals AFB1 cytotoxicity was significantly reduced as evaluated by changes in the values of proliferating bone marrow cell fractions. There were no important morphologic changes in the liver. In hepatectomized AFB1 treated animals mitotic activity in liver tissue was substantially lower than in hepatectomized but AFB1 untreated animals.

Antigen shared by HeLa-like human cell line and gastric mucosa.

An antigen of human gastric mucosa immunologically related to the antigen of established HeLa-like cell lines (CL-GMA) is described. In gel-immunodiffusion test the antigen was revealed in 10/10 samples of normal gastric mucosa (including all parts of stomach), in 15/16 samples of cancer patients' gastric mucosa 5-10 cm distant from tumor and in 2/2 samples of ulcer patients' mucosa 5-10 cm distant from the ulcer. However, the antigen was undetectable at a distance 1-2 cm from ulcer. Homogenates of 39 embryonic organs and tissues were screened for the presence of CL-GMA. CL-GMA was detected in 7/7 samples of gastric mucosa. The antigen was revealed in trace amounts in 1/4 samples of small intestine mucosa and in 1/4 samples of spleen. Screening of 66 human tumors revealed CL-GMA in 13/16 samples of gastric cancer and in trace amounts in 2 tumors of non-stomach localization (larynx and rectum). Analysis of aceton-fixed paraffin sections by means of immunofluorescence revealed be CL-GMA in all parts of stomach. CL-GMA localized in the basal area of high columnar epithelial cells. The antigen was almost or totally undetectable in poorly differentiated adenocarcinomas of stomach and in tumors of other localization. We could not detect CL-GMA in the sera of various cancer patients by means of immunodiffusion and/or dot-blotting.

Strategies of reducing the carcinogenic risk of cytostatic agents on the basis of bioassay evaluation.

This article described strategies that can be used to reduce the carcinogenic risk of cytostatic chemotherapy and summarizes our recent experimental results. Reduction of neoplasms caused by the carcinogenic potency inherent in cytostatic agents can be obtained. (A) by chemical modifications such as: (1) exchanging a chlorine atom in N, N'-bis-(2-chloroethyl)-N-nitrosourea (BCNU) in the chloroethyl group at N'-position for a hydroxyl group to form the less carcinogenic analog N-(2-chloroethyl)-N'-(2-hydroxyethyl)-N-nitrosourea (HECNU); (2) linking chlorambucil to the steroid prednisolone to obtain a conjugate (prednimustine) with distinctly lower carcinogenic potential than chlorambucil; (3) progressive ring halogenation of phenyl-triazenes to generate agents with decreased long-term toxic risk; (B) by replacing cyclophosphamide within the carcinogenic drug combination of cyclophosphamide, methotrexate and 5-fluorouracil (CMF) by vincristine to form the combination VMF which has no detectable carcinogenic potential; (C) by coadministration of cyclophosphamide and mesna to achieve a dose-related reduction of cyclophosphamide-induced urinary bladder carcinomas; (D) by administration of dinaline, a compound which reduces the spontaneous incidence of malignant tumors in rats. These examples demonstrate that the carcinogenic risk of single agents and drug combinations used for antineoplastic chemotherapy has successfully been reduced, as assessed in long-term bioassays. Such strategies should be considered in the treatment of patients with long life expectancy following cytotoxic chemotherapy.

C-band heterochromatin variants in individuals with neoplastic disorders: carcinoma of breast and ovary.

C-band heteromorphism was studied in 106 females, including 71 patients with breast cancer or ovarian cancer. Size heteromorphism and localization variants (inversions) were scored separately. Compared to 22.86% of controls, 70.42% of the cancer patients were heteromorphic for the size of C-band. The localization variants were observed in only 8.57% controls, whereas 42.25% of cancer patients carried such variants. Taking both the criteria together, compared to 31.43% controls, 80.28% cancer patients were C-band heteromorphic. The present study supports the reported association between presence of C-band heteromorphism and occurrence of a malignant disease.

Cytogenetic analysis and population study in P3HR-1 cell line derived from Burkitt's lymphoma.

P3HR-1 cell line derived from Burkitt's lymphoma was chosen as a model for studying the development of the cell population during long-term cultivation from the cytogenetic point of view. Fifty G-banded karyotypes at two different passage levels were analyzed, using also C-, Q- and Ag-staining. The modal chromosomal number at the 15th passage was 49, at the 75th passage 48. At the 15th passage considerable heterogeneity of karyotypes was found. Only four metaphases had an identical karyotype: 49, XY, +7, +21, +psu dic mar, dup(1) (q21q42), del(1) (p ter----q23:), t(8;14) (q24;q32), 16qh+. This clone turned out to be important in the further development of the cell population. At the 75th passage there was only one metaphase with this karyotype. Fifteen metaphases (30%) revealed a karyotype with only one difference from the karyotype mentioned above: deletion of a part of the short arm of one chromosome 7. Further 16 metaphases (32%) had 48 chromosomes, where one chromosome 7 was missing in comparison with the above mentioned karyotype, and 3 metaphases (6%) with 48 chromosomes, where the loss of chromosome 21 and deletion of a part of the short arm of one chromosome 7 were found. These three clones could have originated from the clone described at the 15th passage through loss of a whole or part of chromosome, or both; i.e. the clone forming 8% of the cell population at the 15th passage gave rise to 70% of the cell population during 60 passages in vitro (30 weeks of cultivation). Cytogenetic analysis at two different passages enables the observation of the dynamic changes in the cell population. A wide gamut of cell clones enables heterogenous selection influences in vitro.

Possible relationship between abnormal melanosome structure and cytotoxic phenomena in malignant melanoma.

Melanogenesis has been regarded as a hazard for pigment cells which are endangered by reactive quinones and semiquinones generated by this process. Normally the potentially cytotoxic species are confined to melanosomes by a limiting membrane and thus separated from the rest of the cell. Our electron microscopic investigation has demonstrated the presence of abnormal and incomplete melanosomes in human melanomas from epidermal and mucosal sites, in melanoma metastases, and in B16 mouse melanoma. We conclude that significant leakage of reactive melanin precursors including free radical species may occur from aberrant melanosomes in pigmented tumors. This would be expected to be reflected by fully extended physiological scavenging mechanisms, and by local and distant manifestations of cytotoxicity: Among these manifestations is free radical damage to the liver, detected by a thiobarbituric acid-reactive substances assay, in B16 melanoma-bearing mice. The efflux of toxic species from abnormal melanosomes may explain both the observed frequent occurrence of necrosis in melanomas and the therapeutic efficacy of tyrosinase substrates and may also be one of the factors influencing the extent of melanogenuria.

HPLC analysis of platinum cytostatics.

High performance liquid chromatography (HPLC) with diode array detector (DAD) was applied for the separation of platinum cytostatics (cisplatin, carboplatin and oxo-carboplatin). Their stabilities were studied in water and the influence of chloride anions, pH, temperature and time was discussed and rate constants of the aquation reactions at different conditions were calculated. Ligand exchange reactions cisplatin----carboplatin were evaluated using HPLC-DAD system. Detection limits for all studied cytostatics were determined and extraction recoveries for carboplatin in clinical samples (serum) were demonstrated for a wide range of concentrations together with the relative standard deviations. The solid-phase extraction procedure was recommended for clinical sample analysis represented by a model mixture and real patients' samples.

Determination of suramin in clinical samples using HPLC.

High-performance liquid chromatography (HPLC) was applied for the determination of suramin levels in serum samples from cancer patients treated with this drug. Ion-pair chromatography in combination with the deproteination procedure extraction and hydrolysis of complex serum proteins-suramin were recommended. Extraction recoveries and linearity for wide concentration range were evaluated. Detection limit of suramin in serum samples was determined (0.5 micrograms/ml), and concentration curves as the dependences of suramin concentration levels and time have been illustrated. Chromatographic conditions were optimized for minimal analysis time (max. 10 min) and suitable chromatographic resolution (Rij greater than 1.25).

Prognostic value of the epithelial membrane antigen (EMA) in the case of Hodgkin's disease.

The study deals with the results obtained from 155 lymph node biopsies of patients suffering from Hodgkin's disease (HD) who were treated by MOPP and radiotherapy in the same establishment. The specimens in paraffin have been examined for the presence of antigens using several monoclonal antibodies, particularly epithelial membrane antigen (EMA). There exists no correlation between the immunophenotypes towards EMA and histological types. Thirty-three patients whose responses were EMA (+) have the assurance survival more than 10 years on the level 32.4% while those 122 patients with EMA(-) had the same survival on 90% level (p less than 0.001). Thus a new prognostic tool has been found which enables to detect the likely therapeutic failures in the case of Hodgkin's disease.

Towards improved cancer diagnosis and treatment founded on current developments in the basic sciences: options for intensified European efforts. A consensus paper. Research Branch of the European Organization for Research and Treatment of Cancer (EORTC).

Immune regulation of mouse 5T2 multiple myeloma. I. Immune response to 5T2 MM idiotype.

The transplantable murine multiple myelomas (MM) of the 5T series originated spontaneously in the aging C57BL/KaLwRij mice. These murine malignancies offer an excellent model for experimental studies on different aspects of the human disease. With the aim to look for new treatment modalities, the influence of idiotype-specific immune response on the 'take' and the development of the 5T2 MM was studied. In the first experiment, long-lasting subcutaneous immunizations of syngeneic mice with the 5T2 MM immunoglobulin (Ig) showed a dose dependent anti 5T2 MM Ig idiotype-specific response. The majority of the optimally immunized mice showed no 'take' or they had a prolonged survival after intravenous inoculation with the 5T2 MM cells. All control mice, nonimmunized or immunized with an irrelevant 5T14 MM Ig, developed 5T2 MM with a typical lethal course. In the second experiment, delayed type hypersensitivity (DTH) reaction to the 5T2 MM idiotype was studied. Subcutaneous immunizations of syngeneic mice with 5T2 MM Ig or with 5T2 MM bone marrow cells resulted in a specific DTH reaction 48 hours after challenge with 5T2 MM bone marrow cells. No DTH reaction was obtained when intravenous immunization was used. These results indicate that 5T2 MM is sensitive to idiotype-specific immune regulation; they constitute a basis for further studies on treatment of already established MM in vivo.