Meta-tyrosine: A powerful anti-metastatic factor with undetectable toxic-side effects

Concomitant tumor resistance (CR) is a phenomenon in which a tumor-bearing host is resistant to the growth of secondary tumor implants and metastasis. While former studies have indicated that T-cell dependent processes mediate CR in hosts bearing immunogenic small tumors, the most universal manifestation of CR induced by immunogenic and non-immunogenic large tumors had been associated with an antitumor serum factor that remained an enigma for many years. In a recent paper, we identified that elusive factor(s) as an equi-molar mixture of meta-tyrosine and ortho-tyrosine, two isomers of tyrosine that are not present in normal proteins and that proved to be responsible for 90% and 10%, respectively, of the total serum anti-tumor activity. In this work, we have extended our previous findings demonstrating that a periodic intravenous administration of meta-tyrosine induced a dramatic reduction of lung and hepatic metastases generated in mice bearing two different metastatic murine tumors and decreased the rate of death from 100% up to 25% in tumor-excised mice that already exhibited established metastases at the time of surgery. These anti-metastatic effects were achieved even at very low concentrations and without displaying any detectable toxic-side effects, suggesting that the use of meta-tyrosine may help to develop new and less harmful means of managing malignant diseases, especially those aimed to control the growth of metastases that is the most serious problem in cancer pathology.

La resistencia concomitante antitumoral (RC) es el fenómeno según el cual un individuo portador de tumor inhibe el crecimiento de implantes tumorales secundarios y metástasis. Si bien desde hace tiempo se sabe que la RC inducida por tumores inmunogénicos de pequeño tamaño es generada por mecanismos inmunológicos dependientes de células T, por otro lado, la manifestación más universal de la RC, generada tanto por tumores inmunogénicos como no-inmunogénicos de gran tamaño, había sido asociada con un (unos) factor sérico antitumoral cuya naturaleza permaneció elusiva por años. En un trabajo reciente, nuestro grupo de trabajo identificó este factor como la mezcla equi-molar de meta-tirosina y orto-tirosina, dos isómeros de tirosina que no están presentes en proteínas normales y que demostraron ser responsables del 90% y 10%, respectivamente, de la actividad antitumoral total del suero. En este trabajo, continuamos nuestras investigaciones demostrando que la administración periódica de meta-tirosina reducía drásticamente el número de metástasis pulmonares y hepáticas en ratones portadores de dos tumores murinos altamente metastásicos y disminuía dramáticamente la mortandad (de 100% a 25%) de ratones con metástasis ya establecidas al momento de la extirpación quirúrgica del tumor. Estos efectos anti-metastásicos se lograron aun con muy bajas concentraciones de meta-tirosina y sin efectos tóxicos perceptibles, lo que sugiere que su uso puede ayudar a diseñar nuevas y menos nocivas estrategias para el tratamiento del cáncer, especialmente aquellas destinadas a controlar el crecimiento metastásico, que es el problema más grave en la enfermedad oncológica.

Development of dog mammary tumor xenograft in immunosuppressed Swiss albino mice.

Development and study of dog mammary tumour xenograft in immunosuppressed Swiss Albino Mice adds a new dimension in cancer research as dog tumors have many similarities with human tumors regarding progression, histopathology, molecular mechanism, immune response and therapy. Failure of the immune system to recognize and eliminate cancer cells leads to cancer progression and the fight between immune cells and cancer cells has a great role in understanding the mechanism of cancer progression and elimination. Rejection and acceptance of tumour xenograft depends on efficiency of CD4+, CD8+ and NK cell populations. In the present investigation, dog mammary tumor xenograft in cyclosporine-A and γ-irradiated, immunosuppressed Swiss Albino mice was developed and the immune cell status of graft accepted and rejected mice was assessed. It was observed that all the major immune cells (CD4+, CD8+ and NK cells) play an equal role in tumour rejection.

Mouse renal 4T1 cell engraftment as a model to study the influence of hypoxia in breast cancer progression

PURPOSE: To develop a mouse model to study the influence of hypoxia in breast cancer progression and metastasis. METHODS: The 4T1 cell line was used to engraft the kidneys of female BALB/c mice. Placing an aneurysm clip on the kidney hilum, hypoxia can be directed to tumor site. Histological evaluation was used to analyze the morphological changes induced by ischemia in kidney cortex, and to verify the metastatic potential. RESULTS: 4T1 cells can be engrafted into the renal cortex and the renal ischemia caused by using a clip to clamp the renal hilum induces hypoxia at the tumor site. This procedure maintains the ability of 4T1 cells to metastasize. In fact, our preliminary results showed that tumor hypoxia precipitates the metastatic dissemination of tumor cells. After 14 days of engraftment, lung metastases were observed only in mice that were subjected to tumor hypoxia. CONCLUSION: This model can help us to understand how low oxygen tension mediates hypoxia-induced proteomic and genomic changes in breast cancer.

RE: Differential Diagnosis of Axillary Inflammatory and Metastatic Lymph Nodes in Rabbit Models by Using Diffusion-Weighted Imaging: Compared with Conventional Magnetic Resonance Imaging

No abstract available.

Differential Diagnosis of Axillary Inflammatory and Metastatic Lymph Nodes in Rabbit Models by Using Diffusion-Weighted Imaging: Compared with Conventional Magnetic Resonance Imaging

OBJECTIVE: This experiment aims to determine the diagnostic value of diffusion-weighted imaging (DWI) in the differentiation of axillary inflammatory lymph nodes from metastatic lymph nodes in rabbit models in comparison with conventional magnetic resonance imaging (MRI). MATERIALS AND METHODS: Conventional MRI and DWI were performed at 4 weeks after successful inoculation into the forty female New Zealand white rabbits' mammary glands. The size-based and signal-intensity-based criteria and the relative apparent diffusion coefficient (rADC) value were compared between the axillary inflammatory lymph nodes and metastatic lymph nodes, with histopathological findings as the reference standard. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the diagnostic performance of the aforementioned criteria and rADC value in differentiating the axillary inflammatory lymph nodes from metastatic lymph nodes. RESULTS: Thirty-two axillary inflammatory lymph nodes and 46 metastatic ones were successfully isolated and taken into pathological analysis. The differences of the aforementioned criteria between the two groups were not statistically significant (p > 0.05). However, the rADC value of the inflammatory lymph nodes (0.9 +/- 0.14) was higher than that of metastatic ones (0.7 +/- 0.18), with significant difference (p = 0.016). When the rADC value was chosen as 0.80, the area under the ROC curve is greater than all other criteria, and the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value for differentiating two groups were 86.2%, 79.3%, 81.2%, 84.2%, and 85.6%, respectively. CONCLUSION: Diffusion-weighted imaging is a promising new technique for differentiating axillary inflammatory lymph nodes from metastatic lymph nodes. Compared with routine magnetic resonance sequences, DWI could provide more useful physiological and functional information for diagnosis.

Hemosiderin: a new marker for sentinel lymph node identification / Hemossiderina: um novo marcador para identificação do linfonodo sentinela

PURPOSE: To evaluate and present our initial results of a new marker (hemosiderin) for mammary sentinel lymph node identification in an experimental model. METHODS: Skins mapped like a lymphatic duct draining to the axilla in patients submitted to breast biopsy, in our mastology service, stimulated us to try it in an animal model (female dogs). Our theory was that some blood derivate (hemosiderin) was captured by macrophages and accessed the lymphatic ducts in direction to the axilla. Six female dogs of no defined race were studied. We injected 0,2 ml of technetium on both superior mammary glands. After ten minutes, a 2,5 ml solution of hemolized blood (hemosiderin) from the own animal was injected in the subareolar lymphatic plexus on the left superior mammary gland and 2,5 ml of patent blue concomitantly and equally on the contralateral gland. Ten minutes after, incisions on both axilas were made to search, through the lymphatic mapping and a gamma probe, the sentinel lymph nodes. RESULTS: Seven brown sentinel lymph nodes were indentified and also radiomarked on the left axilla. Six blue sentinel lymph nodes were identified and also radiomarked on the right axilla. CONCLUSION: Preliminary studies of a potential new dye for sentinel lymph node identification are presented. It may be the change of the current use of the blue dyes and their severe side-effects on patients submitted to sentinel lymph node biopsies.

OBJETIVO: Avaliar e apresentar resultados preliminares de um novo marcador (hemossiderina) para a identificação de linfonodos sentinela mamários em um modelo experimental. MÉTODOS: Durante acompanhamento de dois casos de biópsias excisionais de tumores da mama, no nosso serviço de mastologia, observou-se trajeto pigmentado no quadrante inferior externo daquelas mamas, sugerindo ser marcação cutânea do ducto de drenagem linfática a partir da papila mamária em direção a axila homolateral. Levantamos a hipótese que um derivado sanguíneo (hemossiderina) foi capturado por macrófagos obtendo acesso aos ductos linfáticos em direção à axila. Seis cadelas sem raça definida foram estudadas. Injeção de 0,2 ml de tecnécio foi realizada em ambas as mamas superiores. Após 10 minutos, uma solução de 2,5 ml de sangue hemolizado (hemossiderina) do próprio animal foi injetado no plexo linfático subpapilar da mama esquerda e 2,5 ml de azul patente na mama contralateral concomitantemente e igualmente. Após mais 10 minutos, incisões axilares foram realizadas para a procura, pela coloração e com um gama probe, dos linfonodos sentinela. RESULTADOS: Sete linfonodos sentinela castanhos e radiomarcados foram identificados na axila esquerda. Seis linfonodos sentinela azuis e radiomarcados foram identificados na axila direita. CONCLUSÃO: São apresentados estudos preliminares de um potencial novo marcador para identificação do linfonodo sentinela. Este poderá mudar o uso dos corantes vitais e de seus efeitos adversos em pacientes submetidos à biópsia do linfonodo sentinela.

Papel de las células madre oncogénicas: en la resistencia terapéutica de tumores de mama / Role of oncogenes stem cells: in the treatment resistance of breast tumors

Las células madre oncogénicas constituyen una subpoblación de células tumorales que tienen la capacidad de auto-renovarse y de generar tumores heterogéneos en animales de experimentación. Estudios recientes han demostrado que las células madres oncogénicas juegan un papel central en la tumorigénesis, la progresión tumoral y la sensibilidad al tratamiento, lo que las convierte en blancos muy prometedores para el desarrollo de nuevas terapias antineoplásicas. En el caso particular del cáncer de mama estas células se descubrieron en el 2003. Tras su identificación, diversos estudios se enfocaron en identificar las actividades celulares que caracterizan a esta población, lo cual permitió saber que las células madres mamarias son más resistentes a la quimioterapia que el resto de las células tumorales. Al sobrevivir al tratamiento, estas pueden ser capaces de repoblar el tumor y producir recurrencia. El presente artículo tiene como objetivo resumir evidencia reciente que indica que tantos cambios en la expresión de transportadores de membranas como alteraciones en diversas vías de señalización participan en la quimiorresistencia de las células madre mamarias. Adicionalmente, esta revisión discute las posibles estrategias para vencer la resistencia terapéutica y lograr la erradicación de las células. Esas estrategias pueden ser la base para la generación de mejores terapias que prevengan la recurrencia de los tumores de mama.

The cancer stem cells are a subpopulation of tumor cells that display self renewal capability and generate heterogeneous tumors when injected into a experimentation animals. Recent studies have shown that stem cancer cells play a key role in the tumor development, progression, and treatment sensitivity, making cancer stem cells are very promising targets for the development of a new therapies for cancer. In the case of breast cancer, stem cells were discovered in year 2003. Since they identification, different studies have characterized the cell activities that distinguish this population. Now it is well known that breast cancer stem cells are more resistant to chemotherapy than the rest of the breast cancer cells. Given that cancer stem cells survive the treatment, they may be capable to repopulate the tumor, causing relapse. The present paper aims to summarize the recent evidence that indicates that changes in the expression of membrane transporters as well as alterations in various signaling pathways are involved in the generation of resistance in breast cancer stem cells. In addition, this review discusses the possible strategies to overcome drug resistance and to achieve the eradication of the cancer stem cells. These strategies may become the basis for the development of new therapies that block relapse in breast cancer.

LYR71, a derivative of trimeric resveratrol, inhibits tumorigenesis by blocking STAT3-mediated matrix metalloproteinase 9 expression

Tumor migration/invasion is the main cause of tumor progression and STAT3 is needed to enhance tumor migration/invasion by up-regulating MMP-9. Thus, agents that inhibit STAT3 activation may be used as an anticancer drug. We present herein that 6-methyl-2-propylimino-6, 7-dihydro-5H-benzo [1, 3]-oxathiol- 4-one (LYR71) , a derivative of trimeric resveratrol, has an anticancer activity through inhibition of STAT3 activation. We found that LYR71 suppressed STAT3 activation and inhibited the expression and activity of MMP-9 in RANTES-stimulated breast cancer cells. In addition, LYR71 reduced RANTES-induced MMP-9 transcripts by blocking STAT3 recruitment, dissociating p300 and deacetylating histone H3 and H4 on the MMP-9 promoter. Furthermore, LYR71 inhibited tumor migration/invasion in RANTES-treated breast cancer cells and consequently blocked tumor progression in tumor-bearing mice. Taken together, the results of this study suggest that LYR71 can be therapeutically useful due to the inhibition effect of STAT3-mediated MMP-9 expression in breast cancer cells.

Histologia mamária após uso de esteróides sexuais - estudo em ratas / Breast histologic changes in female rats treated with sex steroids

OBJETIVO: Avaliar as alterações histológicas em mamas de ratas submetidas à terapêutica com estrogênio, progestogênio e tibolona. MÉTODOS: Estudo experimental com 40 ratas, sendo 20 sem prole (grupo A) e 20 com prole (grupo B). Todas as ratas foram castradas e, após quatro semanas, alocadas aleatoriamente em subgrupos: A1, A2, A3, A4, A5 e B1, B2, B3, B4, B5. Os esteróides foram administrados da seguinte forma: A1 e B1 - benzoato de estradiol; A2 e B2 - acetato de medroxiprogesterona; A3 e B3 - benzoato de estradiol e acetato de medroxiprogesterona; A4 e B4 - tibolona; A5 e B5 - placebo. Após dez semanas de tratamento, os animais foram sacrificados e suas glândulas mamárias submetidas à análise histológica. Os parâmetros avaliados foram: proliferação epitelial, atividade secretora e atipias epiteliais nas unidades de ductos ou alvéolos terminais. A associação entre os achados histológicos e os esquemas terapêuticos foi avaliada por meio do odds ratio e intervalo de confiança de 95 por cento. RESULTADOS: Alterações histológicas foram observadas em 29 ratas: hiperplasia moderada (52,5 por cento), hiperplasia alvéolo-nodular (42,5 por cento), atipia sem proliferação (35 por cento), hiperplasia leve (32,5 por cento), atividade secretora (20 por cento) e hiperplasia severa (5 por cento). Em ratas sem prole observou-se 1,3 mais chance, em relação ao grupo controle, de apresentar hiperplasia alvéolo-nodular no grupo que recebeu estrogênio, hiperplasia moderada no grupo tratado com progestogênio, e hiperplasia alvéolo-nodular e atipia sem proliferação epitelial com a associação entre estrogênio e progestogênio. CONCLUSÃO: Hiperplasia moderada e atipia epitelial associaram-se à terapia combinada de estrogênio e progestogênio, e o antecedente de prole reduziu a ocorrência destas alterações e de hiperplasia alvéolo-nodular.

OBJECTIVE: To evaluate the association of histologic changes in the breasts of female rats undergoing therapy with sex steroids. METHODS: An experimental study was conducted of 40 castrated female non-pubertal rats, 20 had given birth (Group B) and 20 had no offspring (Group A). After four weeks, these rats were randomly allocated to subgroups: A1, A2, A3, A4, A5 and B1, B2, B3, B4, B5. Steroids were given to subgroups as follows: A1 and B1 - estradiol benzoate; A2 and B2 - medroxyprogesterone acetate; A3 and B3 - estradiol benzoate and medroxyprogesterone acetate; A4 and B4 - tibolone; A5 and B5 - placebo. After 10 weeks of treatment, animals were sacrificed and their mammary glands were analyzed. Histologic parameters evaluated were: epithelial cell proliferation, epithelial cells with secretory activity; and cell atypia in terminal duct units and buds or terminal alveoli. The association between microscopic analysis and diverse therapeutic regimens were analyzed by calculating the odds ratio and its respective 95 percent confidence interval. RESULTS: Histologic changes were observed in 29 rats: moderate hyperplasia (52.5 percent), hyperplastic alveolar nodule (42.5 percent), epithelial atypia (35 percent), mild hyperplasia (32.5 percent), secretory activity (20 percent) and severe hyperplasia (5 percent). In rats with no offspring when compared to the control, 1.3 times more hyperplastic alveolar nodules were found in the group treated with estradiol, the same was true for moderate hyperplasia in the rats that received medroxyprogesterone acetate, hyperplastic alveolar nodules and epithelial atypia in the group treated with estradiol plus medroxyprogesterone acetate. In the rats with offspring 1.3 times more secretory activity was found with estradiol. CONCLUSION: Epithelial hyperplasia and epithelial atypia with no proliferation are strongly associated to combined therapy with estradiol plus medroxyprogesterone acetate, mainly in the rats without offspring.

Induction of experimental mammary carcinogenesis in rats with 7, 12-dimethylbenz(a)anthracene

OBJETIVO: Testar um modelo experimental de indução química de carcinogênese mamária em ratas. MATERIAL E MÉTODOS: Com 47 dias de vida, 20 ratas Sprague-Dawley, jovens e virgens, receberam por gavagem intragástrica 20 mg de 7,12-dimetilbenz(a)antraceno (DMBA). Oito e 13 semanas depois da injeção de droga as mamas das ratas foram examinadas. Ao final os animais foram sacrificados e fragmentos dos tumores foram estudados ao microscópio. RESULTADO: Oito semanas depois da injeção de DMBA 16 ratas apresentavam tumor nas mamas (80%). Com 13 semanas todas desenvolveram carcinomas de mama (100%), que foram confirmados por análise histopatológica. CONCLUSÃO: Este modelo experimental de indução química de carcinogênese mamária é factível e pode ser empregado em futuras pesquisas para avaliar o papel de substâncias biomoduladoras da tumorigênese.

Inducción de adenocarcinomas mamarios por progestagenos en ratones BALB/c. Progresión del tumor hormono-dependiente al autónomo / Progestin-induced mammary adenocarcinomas in BALB/c mice. Progression from hormone-dependent to autonomous tumors

We have developed an experimental model in which the administration of progestins induces mammary tumors in female virgin BALB/c mice. In this paper we review the morphological and biological features of progestin-induced tumors, such as estrogen receptor (ER) and progesterone receptor (PR) patterns of expression, hormone dependence and epidermal growth factor receptors (EGF-R) we also examine our data concerning the systemic effects of medroxyprogesterone acetate (MPA) as regards its stimulating EGF synthesis in salivary glands and its subsequent increase in serum. This growth factor seems to play an important role in the induction of mammary tumors. Direct MPA proliferative effects mediated by PR were demonstrated using primary cultures of progestin-dependent (PD) mammary tumors. Antiprogestins inhibited cell growth beyond control values, suggesting that PR are involved in cell proliferation even in the absence of the ligand. Progesterone-independent (PI) tumors expressing high levels of PR and ER are also inhibited by estrogen or antiprogestin treatment, suggesting that PR are involved in the control of autonomous tumor growth. Estrogen-resistant variants may be selected which may revert to an estrogen-sensitive phenotype after several transplants in untreated mice. The similarities between the tumors obtained with this model and human breast cancer as regards morphological features, evolution and the regulation of growth control converts this model into a useful tool to explore the mechanisms related with acquisition of hormone independence and autonomous tumor growth.

Modulación de la angiogenesis inducida por linfocitos por proteinas de la matriz extracelular / Modulation of angiogenesis induced by lymphocytes by extracellular matrix proteins

La neovascularización es uno evento importante en el desarrollo y crecimiento tumoral. La liberación de células tumorales en la circulación no se observa en la fase avascular del crecimiento tumroal. Los linfocitos de ratones portadores de tumor son capaces de inducir una respuesta angiogénica cuando se inoculan intradérmicamente en la piel de animales singenéicos. Esta respuesta recibe el nombre de SLIA. En este trabajo se estudia proteínas presentes en la matriz extracelular, colágeno y fibronectina (FN) pueden modificar la respuesta antiogênica inducida por linfocitos de ratones portadores de tumor S13. El tratamiento de los linfocitos con FN o con el péptido Gly. Arg. Glyp. Asp. inhibió la angiogénesis. Por el contrario el colágeno y el péptido Gly. Arg. Gly. Asp. Ser no modificaron la respuesta neovascular inducida por los linfocitos de portadores de tumor

Differential cell behaviour on polylysine and gelatin in primary culture of mouse mammary adenocarcinoma.

Cells dissociated from spontaneous and transplanted tumours of C3HJax mammary gland have been cultured on polylysine and gelatin substrates. The isolated cells proliferated to form monolayers with high degree of organoid structure as indicated by formation of alveolar cavities. Differences were observed in the cell attachment, growth pattern, number and size of alveolar cavities, cells which lined the cavity and cell morphology on polylysine and gelatin substrates as compared to conventional cell culture plastic surface. On polylysine more than 90% cells attached rapidly, within 15-45 min after plating, with or without serum and formed confluent monolayers marked by presence of large and small alveolar cavities. Multiple interacting cell types took part in organization of the cavity. Cells lining the cavity constantly proliferated and rearranged to expand it. On gelatin, 60-70% cells attached over a period of 6-24 hr in presence of serum and formed confluent monolayers dominated by small alveolar cavities. Cells forming the cavities were epithelial in nature and cavities once formed did not increase in size. Upon subculture, the cell morphology on these substrates was strikingly different. On polylysine, the predominant cell type had numerous irregular microvilli whereas on gelatin, cells had smoother boundaries with a few stunted cytoplasmic extensions. The cell attachment on conventional surface was low, 40-50%. When seeded at high cell density, formation of alveolar cavities was suppressed and at low cell density, cultures were marked by contact inhibition of cells and failure to attain confluence. These results suggest differential behaviour and interaction of mammary tumour epithelium with the substrates used.

Inmunorregulación del crecimiento tumoral en un sistema murino / Immunoregulation of tumor growth in a murine model

Estudiamos la regulación del crecimiento tumoral y metastásico tanto por el propio tumor como por el sistema inmune, en un modelo murino. Sobrenadantes de cultivo de esplenocitos de portadores de tumor exacerban el crecimiento del propio tumor. Esta actividad desaparece luego de la cirugía tumoral pero con una cinética diferente dependendo de si el tumor es precoz o avanzado al tiempo de la cirugía. Las poblaciones esplénicas involucradas en la exacerbación varían durante el crecimiento del tumor mientras que las responsables de inducción de angiogénesis son siempre de naturaleza T. Con respecto de la autorregulación tumoral, encontramos que diferentes formas de antígenos tumorales (extractos tumorales, sobrenadantes de cultivo de células tumorales, células tumorales formolizadas) aumentan la diseminación metastásica, pero esta actividad está mediada por el sistema inmune del huésped. Por el contrario, sobrenadantes de cultivo de células tumorales no inducen exacerbación del tumor primario. Las células tumorales fueron tratadas con un modificador de membrana con la expectativa de alterar la respuesta inmune antitumoral

Informe especial: estudios tendientes a determinar las posibles propiedades antitumorales del veneno de cobra y del complejo crotoxina A y B / Special report: studies to determine the possible antitumoral properities of Cobra venom and of crotoxin complex A and B

La presente investigación fue encomendada por el CONICET (Consejo Nacional de Investigaciones Cientificas y Técnicas) para determinar las posibles propriedades antineoplásicas del veneno de Cobra (Naja Naja Siamensis) VC) y del Complejo Crotoxina a y B (CCAB), purificado a partir del veneno de Crotalus durissus terificus (cascavel sudamericana). La coordinación de las investigaciones estuvo a cargo de los Dres. Baldi y Mordoh, y la ejecución de la parte experimental fue llevada a cabo por los restantes autores. Se utilizaron diversos sistemas experimentales: 1) lúneas celulares in vitro: de origen murino, normales (3T3 A31), o transformadas (M-A31, Ki-A31 y BP-A31) o de origen humano (adenocarcinoma mamario: MCF-7 y T47D). el efecto de las drogas fue determinado a 1, 10 y 100 ng/ml de VC y CCAB, solas o en combinación. En ninguna de las líneas celulares mencionadas se observaron cambios significativos en la velocidad de crecimiento o en la morfología celular; 2) desarrollo in vivo del Sarcoma 180 (S180) en ratones Balb/c: el VC a dosis de 21 ó 26 ng/g (inyecciones i.p. a los días 10, 11, 20, 21, 30 y 31 post-inoculo tumoral) no afectaron el crecimiento ni la sobrevida de los animales. Dosis de CCAB de 6 ng/g o 9 ng/g ]con el mismo esquema de inoculación anterior) no afectaron el crecimiento de s180 hasta los 25 días de desarrollo tumoral. Entre los días 25 y 30 la dosis de 9 ng/g determinó una evolución tumoral más rápida. La combinación de 13 ng/g VC y 4,5 ng/g CCAB con iguales tiempos de inyección no afectaron el desarrollo tumoral. La histología de los tumores de los animales tratados y controles no evidenció cambios significativos; 3) desarrollo in vivo del carcinoma de Ehrlich en ratones Swiss: se probó el efecto de CCAB (9 ng/g inyectados i.p. a los días 8, 9, 16, y 17) sin obtenerse modificación del desarrollo tumoral;...

Evoluçäo do carcinoma mamário: novos parâmetros imunopatológicos de avaliaçäo; estudo experimental em camundongos (MuMT), III. Líquido ascítico / Course of breast carcinoma: new immunopathological parameters of evaluation; experimental study in mice (MuMT), III. Ascitic fluid

Cem camundongos Swiss fêmeas inoculados por via intraperitonial com células tumorais de MuMT (carcinoma de Ehrlich, forma ascítica) e sacrificados diariamente, em grupos de cinco animais, durante os 20 dias de experimentaçäo. A formaçäo do líquido ascítico foi constatada a partir do 3§ dia (0,28 ml), aumentando para 0,48 ml no 6§ dia, e atingindo o máximo de 15,28 ml próximo ao 20§ dia (morte dos animais). A proporçäo de células tumorais variou acentuadamente no decorrer dos 20 dias da experimentaçäo. As células encontradas no 2§ dia se apresentaram 95% lisadas e as células íntegras inexistentes. Ao contrário, no fim da experimentaçäo constatou-se 6% de células lisadas e 85% de células íntegras. Nos primeiros dias a lise predominante foi a de tipo citotóxico, desencadeada pelas plaquetas, linfócitos T e monócitos. Entre o 6§ e 10§ dia a lise foi devida aos granulócitos. A lise por mecanismo näo citotóxico foi inversa ao porcentual de polimorfonucleares neutrófilos, diminuindo de 80% nos primeros 12 dias para 33% no 18§ dia

Effect of Antioxidants on the Incidence of 7, 12-dimethylbenzanthracene-induced Mammary Tumor in Rats

The inhibitory effect of selenium, vitamin E, and BHA on DMBA-induced mammary tumorigenesis in rats was investigated. Dietary vitamin E (200 IU/Kg diet) alone could not reduce the tumor incidence at 25 weeks after DMBA administration (10mg DMBA/rat) when selenium was deficient. Selenium supplementation (2ppm in drinking water) to rats fed a practical diet (0.17 ppm Se) reduced the tumor incidence to 14.3% from 75% at 27 weeks after DMBA administration. Dietary supplementation of BHA (0.75%) also reduced the incidence of DMBA-induced mammary tumor to 42.9% at 27 weeks after DMBA-treatment. Rats fed a diet deficient in both selenium and vitamin E contained significantly lower glutathione peroxidase activity and higher malondialdehyde in muscle. However, supplementation of selenium or BHA to the rats fed a practical diet did not alter the malondialdehyde content and glutathione peroxidase activities in muscle, skin and mammary gland. Dietary selenium increased the tissue selenium level. DMBA-induced mammary tumorigenesis was reduced by antioxidants tested but the anticarcinogenic effect of selenium or BHA seems to be independent of glutathione peroxi-dase activity.