Cumulative effect of nonstandard radiation.

Experimental data on cumulative effect of nonstandard beams are evaluated and analyzed in terms of cell kinetic model. The dependence of RBE on the dose per fraction is derived. The repopulation is shown to diminish RBE. The ratio of RBEs for late and acute injury is discussed. The "neutron TDF" proposed for clinical purposes is criticized.

Cancer of the larynx in Warsaw and in selected rural areas.

Incidence of the laryngeal cancer especially in males, dramatically increased in Poland. Patterns and time trend of the laryngeal cancer, based on the data from Warsaw Cancer Registry from 1963-1977 have been presented. Tobacco and alcohol consumption in Poland has been discussed considering the observed increase in laryngeal incidence.

DNCB and PPD skin testing in breast cancer.

DNCB and PPD skin testing was performed in 152 breast cancer patients. Bates' instruction with a plea for uniformity was used (Cancer, 43, 1979, 2306). Majority of patients were tested while being diagnosed and prior to the treatment. There were no differences in the reactivity within early operable breast cancer patients (Stage I and II) with respect to nodal involvement. Patients with N1 reacted in the same manner as those with N0. The reactivity of patients with locoregionally advanced disease (Stage III) was similar to that of Stage I and II patients. Significantly lower responsiveness was found in Stage IV patients, the depressed response to DNCB being more pronounced than to PPD.

Tumorigenic action of repeated subcutaneous administration of N-methyl-N-formylhydrazine in mice.

N-Methyl-N-formylhydrazine (MFH), an ingredient of the edible false morel mushroom, was administered to Swiss mice as 40 weekly subcutaneous injections at 20 micrograms/g body weight for females and 10 micrograms/g body weight for males. The treatments gave rise to statistically significant incidences of lung tumors: 56% in females and 40% in males. The administration of the chemical resulted in no detectable carcinogenic effect in other organs. The findings are discussed in light of the results from earlier studies with this compound.

An anticancer drug prospidine: failure to reveal antimitotic and clastogenic action on regenerating mouse liver.

Prospidine is an anticancer drug used in oncological practice in the USSR. It is characterized by only a slight toxicity and the absence of such side-effect as the hemopoiesis suppression. The mechanism of tumor growth inhibition by prospidine is still open to question. The present study was undertaken to reveal the potential mutagenic properties of prospidine, using regenerating mouse liver as rapidly proliferating cell system. Animals were given a single (900 or 1500 mg/kg) or daily (200 mg/kg for 9 days) injections of prospidine before or after partial hepatectomy. The mitotic activity, the duration of the cell cycle periods and the frequency of chromosome aberrations in ana-telophase were determined. The data show that unlike other alkylating drugs prospidine fails to suppress cell proliferation or to induce marked chromosome-breaking effects. The only mild effect observed was some prophase and prometaphase prolongation.

Factors associated with prognosis in human breast cancer. I. Predictors for rate of evolution and relapse.

The associations of several clinical factors with general survival, percentage of relapse and survival in the group of patients who relapsed were analyzed in a series of 399 Stage II breast cancer patients operated and irradiated at the Institute of Oncology and Radiobiology in Havana. In another series of 187 patients these associations were studied in regard to the presence of estradiol receptors in the tumors. Factors related to the presence of estrogen receptors were unrelated to the percentage of relapse in long term follow-up. Age and menstrual status were related to the presence of estradiol receptors and to survival inside the group of patients who relapsed but were unrelated to the percentage of relapses. Lymph node status was mainly associated with the percentage of relapses but not related to the presence of estradiol receptors. Other factors (parity and age at first childbirth), related to the presence of receptors, did not clearly influence prognosis. Lactation influenced positively survival inside the relapse group without any clear association with hormone receptors. Results are discussed in terms of a model considering particular host--tumor interaction: The probability of relapse and the speed of evolution of the systemic disease, mutually independent, but determining the prognosis.

Cytologic grading in relation to the clinical stage of the breast cancer.

Cytologic grading which may be performed at the same time as diagnostic cytology seems to be of a value in the pathobiology of the breast cancer. Other methods, such as mammography, termography, xenography, histological grading and some biological markers help to establish biological behavior of the tumor and appropriate treatment approach. In spite of the progress in diagnosis and therapy many problems remain to be clarified. In agreement with VORHERR a progress may be expected only from the development of novel approaches such as diagnosis before systematic spread has occurred or by the availability of efficient chemotherapy to kill all disseminated cancer cells.

Urinary excretion of pterins in tumor-bearing patients.

In a group of 14 individuals without tumor disease and 125 patients with verified malignant tumors we checked the applicability of determination of the pterins concentration in urine by the procedure described by RAO et al. [3]. In total of 242 examinations were performed. The results were compared with the thin-layer chromatography and on the basis of these comparisons the method was modified. Correlation of the clinical conclusion and the values of tests was obtained in 76% of cases. In patients with undoubtedly persisting tumors the correlation was found in 73%, in a group of patients with the leukemia and lymphomas in 97%, with mammary carcinoma in 81%. Evaluation made in these patients prior to the chemotherapy initiation correlated in 100%. This simple test offers a possibility of the use in differential diagnosis of malignant process or in the course of the screening.

Modifications of microsomal and nuclear fractions by butylated hydroxyanisole and its effect on benzo(a)pyrene metabolites binding to macromolecules.

The effect of butylated hydroxyanisole (BHA) administration on the hepatic components of the monooxygenase system and lipid peroxidation in microsomal and nuclear fractions was investigated in male Swiss mice. Addition of BHA to the diet for 8 days increased significantly the content of cytochrome P-450 (by 50%) and two times the specific activities of NADH- and NADPH-cytochrome c reductases in liver microsomes and lowered the concentration of cytochrome P-450 in liver nuclei. Lipid peroxidation of liver microsomes obtained from BHA fed mice was higher (by 70%) as compared with the control. The inhibition of peroxidation was shown when BHA was added to the incubation mixture containing control microsomal fraction or liver homogenate. When benzo(a)pyrene (BP) was incubated with liver microsomes from BHA fed mice the binding of BP metabolites to microsomal macromolecules increased 5.5-fold compared with control. However, there was no such effect in case of liver nuclei. In view of these results it has been postulated that BHA can play not only preventive role in chemical carcinogenesis.

Using tropomyosin polymorphic phenomenon for detection of differences between rat spontaneous tumor cells and their in vitro oncovirus supertransformats.

Biochemical and immunological comparative studies of rat tumor cells of spontaneous origin and in vitro supertransformed cell populations have been done. We have focused on characterization of differences in tropomyosin molecular forms in the individual cell populations. Our experiments have shown that differences of tropomyosin forms exist not only between spontaneous transformants and supertransformants but also between supertransformants and normal rat fibroblasts. It means that superinfection of spontaneous transformants by avian sarcoma virus B77 have induced changes in tropomyosin synthesis but a pattern of tropomyosin forms in super-transformants has not been equal or similar to that of normal fibroblasts.

Purification and protein composition of endogenous rat viruses.

Endogenous retroviruses are not in the majority of cases the cause of any neoplasia, except for the laboratory conditions. As far as they might serve for the evolution of pathogenic retroviruses more attention should have been paid to them. In this paper we introduce some approaches to the purification of rat endogenous retroviruses to such a degree of purity that enabled satisfactory SDS-PAGE analysis of its structural proteins. Purities of samples obtained by usual purification methods, long-term isopycnic centrifugation at a high gravity force and velocity centrifugation are compared. Protein profile of rat endogenous virus in SDS-PAGE is compared with the ones of other retroviruses. For the first time the evidence was obtained for the striking similarity between electrophoretic protein profile of rat endogenous virus WERC and feline leukemia virus. The major structural proteins of rat endogenous retrovirus and feline leukemia virus cannot be distinguished even when resolution long gradient PAGE had been employed. The accordance of electrophoretic mobilities of major structural proteins in SDS-PAGE can indicate the relatedness of retroviruses.

Cell sensitivity to irradiation and DNA repair processes. I. DNA damage and its repair in Escherichia coli.

Basic types of DNA damage produced by gamma-radiation in cells are reviewed. Different DNA injuries are related to various levels of DNA repair processes, established in the case of Escherichia coli cells. The role of the balance of repair enzyme activities is considered in connection with the induction of enzymatic DNA double-strand breaks (DSBs). The concept of "metastable sites" has been introduced. "Metastable sites" are formed from great nucleolytic gaps. They are measured as DSBs although they can be repaired as single-strand breaks (SSBs). A simple mathematical model of the inactivation of different mutants of E. coli cells has been constructed on the basis of available experimental data. Kinetic equations of the model have been solved and some parameters estimated for both sensitive and resistant mutants.

The sensitivity testing of Wilms' tumors to cytostatic agents with an autoradiographic in vitro short-term test.

Sensitivity of 15 Wilm's tumors in children was tested towards cytostatic agents in vitro by means of an autoradiographic short-term test. Sensitivity was measured as a magnitude of the inhibition of 3H-thymidine, resp. 3H-uridine incorporation. The test was performed with Adriamycin, Actinomycin D. Daunomycin, Bleomycin, Cyclophosphamide, Ifosfamide, Trenimon, and Arabinosylcytosine. None of the tumors is resistant to all substances, they are responsive against 2 or more drugs. The most effective drugs tested are Adriamycin, Actinomycin D and Cyclophosphamide. The tumors show a marked individual sensitivity pattern. This behavior is explained mainly by the usually high proliferative activity of Wilms' tumors. The possibilities and limits of long-term and short-term methods for sensitivity testing are discussed critically. For the evaluation of the results of in vitro testing and in vivo effectiveness the close correlation should be considered between the type of cytostatic agent and proliferation kinetics of the tumor, cytostatic agent and effect on tumor metabolism as well as the effect of the cytostatics and the nucleic acid precursors used for the short-term test. Despite the methodological limitations preclinical testing should be preferred to unselected chemotherapy.

Serum alkaline-stable acid thiol proteinase--a possible marker for primary liver carcinoma.

Activities of alkaline phosphatase (ALP), gamma-glutamyl transferase (GMT), lactate dehydrogenase (LD), beta-glucuronidase (GLU) and cathepsin B-like (CB-like) were determined in blind-coded sera from 50 patients with primary liver carcinoma, liver cirrhosis and acute hepatitis, and from 40 control subjects of comparable age range. CB-like activity averaged 700% (p less than 0.01), 1590% (p less than 0.01) and 1600% (p less than 0.01) of control subjects in liver cirrhosis (n = 30), acute hepatitis (n = 5) and primary liver carcinoma (n = 15), respectively. In acute hepatitis group we have found significant correlation between CB-like and GLU activities (r greater than 0.95). This correlation, however, was not observed in primary liver carcinoma suggesting that alteration in CB-like activity is not due to generalized increases in lysosomal membrane instability. The primary liver carcinoma group exhibited also the modest increments in serum ALP, GMT and LD activities (p less than 0.01). This increment, however, was not detected in any of acute hepatitis or liver cirrhosis patients. For the first time the alkaline-stable form of CB-like in human serum is described. This form representing 40% of overall CB-like activity was present in all primary liver carcinoma patients. This form, however, was not present in sera of any of control subjects or in sera of patients with acute hepatitis and liver cirrhosis with the exception of two men, in whom we have probably dealing with an early stage of primary liver carcinoma. Although the nature of the increment in CB-like activity in cancer remains to be determined, such analyses may help to the early detection of malignant hepatoma (primary liver carcinoma).

The chromosomes of L1210 mouse leukemia cells: G-banding, C-banding, and Ag-staining.

The karyotype of L1210 mouse leukemia cells was studied using G-banding, C-banding and Ag-staining methods. In modal chromosome number and G-banding patterns we were interested in the differences between line A and B carried by DBA/2 mice in our laboratory. Both lines had the modal chromosome number of 38. Lines differed significantly in the average number of nine chromosomes per karyotype, whereas in marker chromosomes significant difference was found only in M2 and M6. Marker M1 t(5, 12) was present in 95% of cells in line A and 100% of cells in line B. More than 50% of cells in both lines contained M2, M11, M13 and M14. X-Chromosome and chromosome No. 4 were most frequently absent. More than 80% of cells in both lines had only one chromosome No. 5, and trisomy of chromosome No. 15 was found in 50% of cells in line A and 40% in line B. Values for disomy were low for all chromosomes in both lines. Marker M1 t(5, 12) possessed C-banding material at the proximal end of translocated chromosome No. 5 and NOR at the proximal end of translocated chromosome No. 12. Marker M2 t(1, 12) without NOR had the C-banding material located at the proximal end of chromosome No. 1.

Endodermal sinus (yolk sac) tumors in pediatric oncology. Report on 14 cases.

Fourteen cases of the endodermal sinus tumors in children are reported. The most frequent localization was the vagina, next presacral region, ovary and testis. No ovarian case was observed under 3 years of age.

Circulating levels of inhibin in cancer.

Study on frequency distribution of serum inhibin levels--a peptide hormone involved in suppression of follicle stimulating hormone--was carried out using a specific radioimmunoassay developed in this laboratory, on 237 sera from normal men and women, from male and female patients with cancer prostate, lung, stomach and breast, and from patients with non-malignant disease of the respective organ. The mean serum inhibin levels in patients with malignant and non-malignant disease of prostate (90 +/- 19 ng/ml and 54 +/- 8 ng/ml) were significantly higher than found in normal men (31 +/- 9 ng/ml). However, the levels in cancer of stomach (70 +/- 9 ng/ml) and lung (45 +/- ng/ml) were higher than those in normal as well as benign condition of stomach and lung. The mean serum inhibin in case of women with cancer of breast (27 +/- 5 ng/ml) and lung (53 +/- 16 ng/ml) were significantly higher than those found in normal women (15 +/- 2 ng/ml) and in women with benign disease of breast (10 +/- 3 ng/ml) and lung (21 +/- 4 ng/ml). Considering the levels in individual patient basis, 66% of the patients with cancer of stomach had higher inhibin concentration than the uppermost limit of inhibin found in normal men and in contrast none in benign disease of stomach.

Serum amylase and isoamylases in malignant bone tumors.

In 26 hosts of malignant bone tumors the serum amylase activities have been studied. The mean value of total serum amylase was found to be slightly elevated in the sera of patients with malignant bone tumors compared to that found in sera of blood donors. The P:S ratio of isoenzymes was found significantly (p greater than 0.01) shifted towards the S type in sera of the hosts of malignant bone tumors. The levels of the S type of isoenzymes were found to be significantly higher also in comparison to the mean values of these isoenzymes found in the sera of blood donors. Assay of the homogenate of the extirpated tissue of an osteogenic sarcoma clearly showed the amylase activity to exceed that found in patients' sera. This elevation of the total activity was found to be mainly due to the increased production of the S type of isoenzyme in the malignant tissue. The usefulness of these findings for diagnosis and prognosis purposes in bone malignancy is discussed in this paper.

Acute phase protein profiles in hairy-cell leukemia. Study in 50 patients. Effects of splenectomy.

Serum levels of 15 "positive and negative acute-phase proteins" were measured in 50 patients with hairy-cell leukemia (HCL) and in normal controls. The specific analysis of the protein levels was completed with the combined data of total serum protein and zonal electrophoresis. In HCL patients all electrophoretic globulin fractions were significantly increased, while the albumin fraction was decreased. The changes in albumin levels were more apparent in the nonsplenectomized patients, while the total protein was increased in the splenectomized cases as well as in the total HCL series. Compared with the control groups, in the nonsplenectomized patients both the mean relative increments in the level of some positive acute-phase proteins (such as orosomucoid) and the mean relative decrements in the level of some negative acute-phase proteins (such as alpha 2HS-glycoprotein) were 3 times the values found in the splenectomized patients. The occurrence of elevated values of C-reactive protein was significantly higher in the nonsplenectomized patients than in the splenectomized ones. These differences between the acute-phase proteins of the two subgroups of HCL patients were in agreement with erythrocyte sedimentation rate values. This indicates that the acute-phase protein formula is generally more favorable in splenectomized cases than in nonsplenectomized patients, at least during the first two post-splenectomy years.

Stimulation of postirradiation DNA synthesis in ultraviolet irradiated HeLa cells by fluorodeoxyuridine.

The influence of precultivation with fluorodeoxyuridine (FdUrd) on the rate of overall DNA synthesis in ultraviolet (UV) irradiated HeLa cells has been studied. HeLa cells were pretreated either for 24 h with FdUrd, or for 6 h with FdUrd + 18 h in FdUrD-free medium before UV irradiation (10 Jm-2). Both pretreatments stimulated the rate of DNA synthesis not only in unirradiated but also in UV irradiated cells. It is concluded that precultivation of HeLa cells with FdUrd increased the UV resistance of DNA synthesis in comparison with untreated cells.

Enhancement of the radiation effect by fibrinolysin and quantitative pattern of the change of tumor radiosensitivity.

Radiomodifying action of fibrinolysin was studied during radiation treatment in experimental transplanted tumors. It has been established that the application of fibrinolysin prior to radiation increases the inhibition of the growth rate of Pliss lymphosarcoma and Sarcoma 45, as evidenced by the decrease of the tumor volume, the increase of the dose change factor and the animals survival.

Occurrence of induced 6-thioguanine-resistant colonies in synchronized V79 cells after treatment with ftorafur. Effects of the S9 fraction.

The capacity of ftorafur to induce resistance to 6-thioguanine in V79 hamster cells was investigated. The treatment conditions were arranged in order to favor the induction of such gene mutations. The synchronous cells were treated in the beginning of S phase, i.e., when the replication of the genes responsible for the expression of resistance to 6-thioguanine took place. Part of the experiments was carried out in presence of the S9 microsomal fraction. The results showed that ftorafur was a weak mutagen after a short-term exposure in the presence of adequate amounts of the S9 fraction. In absence of the S9 fraction or when other than-optimal amounts were used, we repeatedly failed to detect any increase in the occurrence of mutated cells. Also the cytotoxic effects of this substance were investigated. We found that a short-term treatment of V79 hamster cells with lower concentrations of ftorafur resulted in decrease of growth rate, higher concentrations after a short-term treatment were in turn slightly toxic. Long-term treatments are, depending on the concentration and time of treatment used, considerably toxic.

Carcinoembryonic antigen, a tumor-associated glycoprotein induces defective lymphocyte function.

Standard carcinoembryonic antigen(s) (CEA) obtained commercially, and CEA preparations from cell membranes and spent media of cultured human malignant melanotic melanoma (HMMC-ShAc and HMMC-ShAm) and of human colon adenocarcinomas (Levo c, Levo m, SW-403 c and SW-403 m) suppressed human peripheral blood lymphocyte (PBL). CEA preparations obtained from products of in vitro synthesis mediated by mRNA coding for CEA enhanced, whereas glycosylation-deficient preparations of CEA obtained from tumor cells harvested from growth media supplemented with nontoxic levels, i.e. 0.3 microgram/ml of tunicamycin, had no effect on immunoglobulin synthesis by human PBL. CEA caused defective lymphocyte: sheep red blood cell rosette production. It is suggested that CEA is an immunoregulatory glycoprotein synthesized by human tumor cells. The carbohydrate moiety of the glycoprotein is the regulatory determinant.

Generation of new transforming viruses from SIRC cells "phenotypically transformed" in the medium with low concentrations of serum or calcium ions.

The work reported here demonstrates the possibility of rapid generation of highly transforming viruses from rabbit epithelial corneal cells (SIRC) originated from simian sarcoma associated virus (SSAV). The results of the experiments indicate a possible association of the phenomenon of "phenotypic transformation" with the expression of cellular genes with a potential transforming activity. SIRC/SSAV phenotypic transformation was induced by cultivation of these cells in the medium with a low concentration of serum or calcium ions. During subsequent infection of mink lung fibroblasts the authors succeeded in obtaining two new transforming SSAV isolates which induced transformation foci of various morphological types in cellular lines permissive for SSAV replication.

The lymphocyte activity of adenosine deaminase and enzymes of AMP metabolism in mammary carcinogenesis: the effect of thymostimulin.

Studies were undertaken on the activity of adenosine deaminase (ADA) and metabolic enzymes of AMP in the spleen and thymus cells of rats with DMBA-induced carcinogenesis of the mammary glands and on the effect of thymostimulin (TS) on this activity. In addition, we investigated the activity of ADA in the peripheral blood lymphocytes of the patients with premalignant diseases and cancer of the mammary glands (Stages I-IV) as well as the possibility of its enhancement by TS. The disturbances of these enzyme activities characterized by a decrease in ADA activity and an increase in activity of the AMP metabolism enzymes, predisposed for adenosine accumulation in lymphoid cells. Injection of TS normalized the ADA activity and decreased the activity of the AMP metabolic enzymes. Analogous results were obtained in the studies of ADA activity in the human materials. With the human tumor growth the in vitro effect of TS on the lymphocyte ADA activity decreased. We may suggest that measurement of the ADA activity in the lymphocytes may serve as a reliable tool to control the state of immune system and the effectiveness of immunotherapy with the thymic humoral factors.

Tumor and serum CEA content in gynecologic neoplasms.

The relationship of serum carcinoembryonic antigen (CEA) levels to tumor tissue CEA content, and tumor weight in patients with different genital tract neoplasms was studied. Two-step extraction of tumor tissues was performed using perchloric acid and 3 M KCl. Sera and tissue extracts were assayed for CEA content by double-antibody radioimmunoassay. No clear correlation was found between serum CEA and tumor CEA contents, tumor weight, and histological structure. Our results showed, however, that high CEA concentrations in tumor tissue (10 micrograms/g or higher) were accompanied by elevated values in plasma.

Unequal inhibition of protein synthesis in mitochondria of Zajdela hepatoma and rat liver after in vivo treatment with cis-diamminedichloroplatinum (II).

The effect of in vivo administered cis Pt(II) on mitochondrial and overall cellular protein synthesis in hepatocytes from regenerating rat liver and Zajdela hepatoma was examined. In both types of cells the overall cellular protein synthesis was inhibited by the drug approximately to the same extent (about 50%). Protein synthesis in mitochondria of Zajdela hepatoma was practically unaffected by the drug, whereas that in rat liver was inhibited similarly as was the overall cellular protein synthesis. Cis Pt(II) treatment had no detectable effect on the electrophoretic pattern of peptides synthesized in mitochondria of rat liver and Zajdela hepatoma. Relative content of cytochrome oxidase subunit IV to subunit II in Zajdela hepatoma mitochondria decreased upon cis Pt(II) treatment. The amount of platinum bound to Zajdela hepatoma mitochondria upon in vivo cis Pt(II) treatment was about two times lower than that bound to mitochondria of rat liver. It is concluded that protein synthesis in Zajdela hepatoma mitochondria is more resistant to in vivo cis Pt(II) treatment than the process in mitochondria of rat liver, and that this effect results from lower binding of cis Pt(II) and/or its derivatives to the tumor mitochondria.

Phorbol myristate acetate-stimulated production of interleukin 2 by T-cell lymphoma and constitutive production by derived hybridomas.

To isolate a stable tumor cell line source of IL-2 (TCGF), 19 murine T-cell lines and their derivatives were screened for both constitutive and mitogen-stimulated IL-2 production. The cloned subline of a mouse thymic lymphoma EL-4 designated as EL-4TF could be stimulated with PMA to produce 80 U/ml of IL-2. A TK- EL-4TFR mutant line has been selected from the EL-4TF cell population by treatment with 5-BrdUrd. The EL-4-TFR cells were stimulated with PMA and fused with the cells of thymic lymphoma BW5147. The resulting BH3 hybrid cell population was repeatedly cloned and tested for constitutive IL-2 production: two of the BH3 hybridoma clones were found to produce IL-2 constitutively. The IL-2 of EL-4TF origin was found to support permanent in vitro growth of IL-2 dependent, tumor-specific T killer cell line CTLL when present in culture medium at a concentration of at least 0.1 U/ml. Since the EL-4TF-derived IL-2 preparations were contaminated with PMA, it was of interest whether PMA alone has a growth-promoting activity in CTLL cell cultures. Permanent cultivation of CTLL cells in an IL-2-free medium containing PMA was not possible. However, both mitogenic and co-mitogenic effects of PMA on CTLL cells were observed.

Our experience with childhood histiocytosis X.

A retrospective analysis of the course of histiocytosis X in 16 children treated at our hospital over the past 15 years is presented. Nearly all of the patients were at generalized stages of the disease. In this study the staging according to Greenberg was used. The disease had a favorable course at Stages I and II, 1 patient at Stage III and 2 at Stage IV died. All the children were treated by chemotherapy, in some of them combined with radiotherapy. Individual patients differed from one another with respect to chemotherapeutic regimens. The actuarial survival rate was 78% for the whole group. Better results were obtained after a less intense but long-term treatment than after an intense but interrupted chemotherapy.

Morphologic and cytochemical study of L929 cell variants with different metastasizing ability in C3HA/Hab mice.

A morphologic (phase-contrast, TEM and SEM) and cytochemical study was performed on L929 cell variants that show different malignant behavior and lung colonization ability in C3HA/Hab mice. The paper presents and discusses the correlation between enhanced lung colonization ability and the expression in culture of rounded, risen, less attached morphologies. Also, a diminution in the activity of mitochondrial enzymes and number of these cell organelles was found for the cell variant selected for enhanced lung colonization ability.