Microarray-based genotyping and detection of drug-resistant HBV mutations from 620 Chinese patients with chronic HBV infection

Background: Research has shown that hepatitis B virus (HBV) genotypes are closely linked to the clinical manifestations, treatment, and prognosis of the disease. Objective: To study the association between genotype and drug-resistant HBV mutations in 620 Chinese patients with chronic HBV infection. Methods: HBV DNA levels were determined using real-time quantitative PCR in plasma samples. Microarrays were performed for the simultaneous detection of HBV genotypes (HBV/B, C, and D) and drug-resistance-related hotspot mutations. A portion of the samples analyzed using microarrays was selected randomly and the data were confirmed using direct DNA sequencing. Results: Most samples were genotype C (471/620; 76.0%), followed by genotype B (149/620; 24.0%). Among the 620 patient samples, 17 (2.7%) had nucleotide analogs (NA) resistance-related mutations. Of these, nine and eight patients carried lamivudine (LAM)-/telbivudine (LdT)-resistance mutations (rtL180M, rtM204I/V) and adefovir (ADV)-resistance mutations (rtA181T/V, rtN236T), respectively. No patients had both lamivudine (LAM)- and either ade-fovir (ADV) or entecavir (ETV) resistance mutations. Additionally, out of the 620 patient samples, 64.0% (397/620) were also detected with the precore stop-codon mutation (G1896A) by microarray assay. Conclusion: The results of the current study revealed that the prevalence of nucleotide analogs (NA)-resistance in Chinese hospitalized HBV-positive patients was so low that intensive nucleotide analogs (NA)-resistance testing before nucleotide analog (NA) treatment might not be required. In addition, the present study suggests that chronic HBV patients with genotype C were infected with fitter viruses and had an increased prevalence of nucleotide analogs (NA)-resistance mutations compared to genotype B virus. .

Maintenance of the corneal epithelium is carried out by germinative cells of its basal stratum and not by presumed stem cells of the limbus

The purpose of this investigation was to analyze the proliferative behavior of rabbit corneal epithelium and establish if any particular region was preferentially involved in epithelial maintenance. [3H]-thymidine was injected intravitreally into both normal eyes and eyes with partially scraped corneal epithelium. Semithin sections of the anterior segment were evaluated by quantitative autoradiography. Segments with active replication (on) and those with no cell division (off) were intermingled in all regions of the tissue, suggesting that the renewal of the epithelial surface of the cornea followed an on/off alternating pattern. In the limbus, heavy labeling of the outermost layers was observed, coupled with a few or no labeled nuclei in the basal stratum. This suggests that this region is a site of rapid cell differentiation and does not contain many slow-cycling cells. The conspicuous and protracted labeling of the basal layer of the corneal epithelium suggests that its cells undergo repeated cycles of replication before being sent to the suprabasal strata. This replication model is prone to generate label-retaining cells. Thus, if these are adult stem cells, one must conclude that they reside in the corneal basal layer and not the limbal basal layer. One may also infer that the basal cells of the cornea and not of the limbus are the ones with the main burden of renewing the corneal epithelium. No particular role in this process could be assigned to the cells of the basal layer of the limbal epithelium.

Neurochemical phenotype and birthdating of specific cell populations in the chick retina

The chick embryo is one of the most traditional models in developing neuroscience and its visual system has been one of the most exhaustively studied. The retina has been used as a model for studying the development of the nervous system. Here, we describe the morphological features that characterize each stage of the retina development and studies of the neurogenesis period of some specific neurochemical subpopulations of retinal cells by using a combination of immunohistochemistry and autoradiography of tritiated-thymidine. It could be concluded that the proliferation period of dopaminergic, GABAergic, cholinoceptive and GABAceptive cells does not follow a common rule of the neurogenesis. In addition, some specific neurochemical cell groups can have a restrict proliferation period when compared to the total cell population.

O embrião de galinha é um dos mais tradicionais modelosde estudos da neurociência do desenvolvimento e seu sistema visual tem sido um dos mais exaustivamente estudado. Aretina tem sido utilizada como modelo para estudar o desenvolvimento do sistema nervoso. Aqui, nós descrevemos as características morfológicas que caracterizam cada estádio da retina em desenvolvimento e os estudos do período de neurogênese de algumas subpopulações de células neuroquímicamente específicas da retina usando uma combinação de imunohistoquímica e autoradiografia de timidina-tritiada. Conclui-se que o período de proliferação das células dopaminérgicas, GABAérgicas, colinoceptivas e GABAceptivas não segue uma regra comum. Além disso, alguns grupos celulares neuroquimicamente distintos podem ter um período de proliferaçãomais restrito quando comparado ao da população total destas células.

Telbivudina / Telbivudina

Es un análogo nucleósido sintético de la timidina, cuyo nombre químico es 1-( 2-deoxy-ß-L-ribofuranosyl)-5metiluracil, y ejerce su acción a través de la inactivación de la ADN polimerasa del virus de la Hepatitis B, mediante la inhibición competitiva de su sustrato natural , el 5-trifosfato timidina. Fue recientemente aprobado por el FDA para el tratamiento de la hepatitis B.

Telbivudine´s chemical name is 1-(2-deoxy-ß-Lribofuranosyl)-5-metiluracil. It is a synthetic nucleoside analogue of timidine with activity against HBV DNA Polymerase by competing with the natural substrate, timidine 5-triphosphate. It was recently approved by the FDA for hepatitis B treatment.

Estudos in vitro e in vivo de análogo da timidina marcada com complexo organometálico de tecnécio-99m para potencial uso em diagnóstico tumoral / Studies in vitro and in vivo of thymidine analog labeled with organometalic complex of technetium-99m for potential use in tumor diagnosis

Análogos da timidina têm sido marcados com diferentes radioisótopos devido ao seu potencial em monitorar a proliferação incontrolável de células. Considerando que o radioisótopo tecnécio-99m ainda mantém uma posição privilegiada devido às suas propriedades químicas e nucleares, este trabalho constituiu-se no desenvolvimento da marcação da timidina com o 99mTc, mediante o emprego de compostos organometálicos. Os objetivos principais foram a síntese do precursor carbonil-tecnécio-99m, marcação da timidina com este precursor, estudo da estabilidade, e avaliações radioquímicas e biológicas com animais sadios e portadores de tumor. A síntese do precursor organometálico e a marcação da timidina com este precursor foi realizada com > 97 por cento e > 94 por cento de pureza radioquímica, respectivamente, obtendo-se também uma boa estabilidade em até 6 h em temperatura ambiente. A transquelação frente aos aminoácidos cisteína e histidina apresentou perdas entre 8 e 11 por cento para concentrações de até 300 mM. Os ensaios de biodistribuição em camundongos sadios indicaram que o complexo radiomarcado apresentou um rápido depuramento sangüíneo e baixa captação nos demais órgãos, com predominância de excreção da droga pelo sistema urinário e hepatobiliar. A captação tumoral foi de 0,28 e 0,18 por centoDI/g para tumor de pulmão e mama, respectivamente. Os resultados obtidos sugerem maiores investigações em outros análogos da timidina.

Thymidine analogs have been labeled with different radioisotopes due to their potential in monitoring the uncontrollable cell proliferation. Considering that the radioisotope technetium-99m still keeps a privileged position as a marker due to its chemical and nuclear properties, this work was designed to develop a new technique of labeling of thymidine analog with 99mTc, by means of the organometallic compounds. The aims of this research were: synthesis of the organometallic precursor technetium-99m-carbonyl, thymidine labeling with this precursor, study of stability, and radiochemical e biological evaluation with healthy and tumor-bearing animals. The organometallic precursor and the labeling of thymidine with this precursor were resulted with a radiochemical pureness of > 97 percent and > 94 percent, respectively, with good radiochemical stability up to 6 h in room temperature. The cysteine and histidine challenge indicated losses between 8 and 11 percent for concentrations until 300 mM. The biodistribution assay in healthy mice revealed rapid blood clearance and low uptake by general organs with renal and hepatobiliary excretion. The tumor concentration was of 0.28 and 0.18 percentID/g for lung and breast cancer, respectively. The results imply more studies in other thymidine analogs.

Primary resistance of human immunodeficiency virus type 1 in a reference center in Recife, Pernambuco, Brazil

To assess the prevalence of primary resistance of human immunodeficiency virus type 1 (HIV-1) to antiretrovirals, 84 patients chronically infected with HIV without prior antiretroviral treatment from Northeast Brazil were studied. Genotyping was performed using the ViroSeqTM Genotyping System. Thimidine analog mutations occurred in 3 (3.6 percent) patients. Accessory mutations related to NRTI occurred in 6 (7.1 percent) and related to PI in 67 (79.8 percent). Subtypes B (72.6 percent), F (22.6 percent), B/F 3 (3.6 percent), and C (1.2 percent) were detected. A low prevalence of major mutations related to NRTI in patients chronically infected by HIV was observed.

Screening and fractionation of plant extracts with antiproliferative activity on human peripheral blood mononuclear cells

Three hundred and thirteen extracts from 136 Brazilian plant species belonging to 36 families were tested for their suppressive activity on phytohemaglutinin (PHA) stimulated proliferation of human peripheral blood mononuclear cells (PBMC). The proliferation was evaluated by the amount of [ H]-thymidine incorporated by the cells. Twenty extracts inhibited or strongly reduced the proliferation in a dose-dependent manner at doses between 10 and 100 æg/ml. Three of these extracts appeared to be non-toxic to lymphocytes, according to the trypan blue permeability assay and visual inspection using optical microscopy. Bioassay-guided fractionation of Alomia myriadenia extract showed that myriadenolide, a labdane diterpene known to occur in this species, could account for the observed activity of the crude extract. Using a similar protocol, an active fraction of the extract from Gaylussacia brasiliensis was obtained. Analysis of the H and13C NMR spectra of this fraction indicates the presence of an acetylated triterpene whose characterization is underway. The extract of Himatanthus obovatus is currently under investigation

A fucan from the brown seaweed Spatoglossum schröederi inhibits Chinese hamster ovary cell adhesion to several extracellular matrix proteins

Fucans, a family of sulfated polysaccharides present in brown seaweed, have several biological activities. Their use as drugs would offer the advantage of no potential risk of contamination with viruses or particles such as prions. A fucan prepared from Spatoglossum schröederi was tested as a possible inhibitor of cell-matrix interactions using wild-type Chinese hamster ovary cells (CHO-K1) and the mutant type deficient in xylosyltransferase (CHO-745). The effect of this polymer on adhesion properties with specific extracellular matrix components was studied using several matrix proteins as substrates for cell attachment. Treatment with the polymer inhibited the adhesion of fibronectin to both CHO-K1 (2 x 10(5))()and CHO-745 (2 x 10(5) and 5 x 10(5)) cells. No effect was detected with laminin, using the two cell types. On the other hand, adhesion to vitronectin was inhibited in CHO-K1 cells and adhesion to type I collagen was inhibited in CHO-745 cells. In spite of this inhibition, the fucan did not affect either cell proliferation or cell cycle. These results demonstrate that this polymer is a new anti-adhesive compound with potential pharmacological applications

Evaluación del Bioensayo de MTT para determinar la proliferación in vitro de linfocitos de bovino frescos y congelados / Evaluation of the MTT bioassay to determine in vitro proliferation of fresh and frozen bovine lymphocytes

Se llevaron a cabo cuatro experimentos para evaluar la proliferación in vitro (expresada como índice de estimulación, IE) de linfocitos de bovino, frescos y congelados, a concanavalina A (Con A) o antígeno de Anaplasma marginale, usando el bioensayo de MTT. En el primero, el IE de linfocitos de tres bovinos adultos en respuesta a Con A fue determinado durante seis semanas consecutivas usando el ensayo de MTT que mostró resultados reproducibles; el IE osciló entre 1.7 y 3.8. En el segundo, los linfocitos de dos bovinos adultos fueron congelados a -70§C durante seis semanas y su viabilidad fue evaluada semanalmente. La viabilidad promedio cambió de 99.5 por ciento (semana 0) a 89 por ciento en la semana cinco y disminuyó a 59 por ciento en la semana seis. En el tercero, el IE de linfocitos, frescos y congelados (tres semanas) de tres animales adultos, en respuesta a Con A, fue determinado usando el bioensayo de MTT; el IE promedio fue de 2 y de 1.5 para los linfocitos frescos y congelados, respectivamente. En el cuarto, la proliferación de linfocitos de un animal adulto recuperado de la infección con A. marginale y los de otro bovino adulto no infectado fueron probados contra un antígeno de A. marginale y determinada por medio de las pruebas de MTT y de incorporación de timidina-H3. El IE obtenido fue similar, 1.7 para MTT y 1.5 para Timidina-H3. Los resultados sugieren que el bioensayo de MTT y células congeladas pueden utilizarse como alternativas en la prueba de proliferación de linfocitos de bovino in vitro.

Interleukin 2 induction of proliferation in resting T lymphocytes requires contact with monocytes

Resting human T cells are known to express significant numbers of intermediate but none or barely detectable low and high a affinity IL-2 receptors (IL-2R). IL-2 alone failed to induce proliferation in these cells, However, in presence of small proportion of autologous monocytes, as low as 22 pM, IL-2 induced high levels of proliferation in resting T cells. Introduction of a semi permeable between the two cell types or addition of an anti-CD 11b mAb inhibited such induction of proliferation by IL-2. Neither recombinant IL-1 por IL-1 containing cell-free extracts from activated monocytes substituted for intact monocytes. Autologous B cells failed to replace monocytes. Using antigen-specific cloned human T cells we have shown a lack of requirement for antigen. The proliferation was inhibited by anti-IL-2R alpha mAb. IL-2 appears to be unique since neither IL-4 nor IL-6, alone or in presence of monocytes, led to induction of proliferation in resting T cells. Combination of IL-2 and monocytes induced proliferation in all T cell subpopulations (CD4, CD8, CD45RA and CD45RO) and antigen-specific clones examined. It also induces mRNA and surface expression of IL-2R alpha, appearance of high affinity IL-2R and induction of proliferation in large proportions of T cells. As in humans, the IL-2 induction of proliferation in murine resting T cell required contact with syngeneic monocytes, suggesting that such a mechanism of cells activation is highly conserved.

Hepatic regeneration after partial hepatectomy in mice infected with Schistosoma mansoni, at the acute and chronic phases of the disease

Outbred male albino mice normal or infected with 30 cercariae of Schistosoma mansoni (LE strain) were submitted to 65 percent hepatectomy during the acute (70 days) and chronic phase (160 days) phases of the disease. A group of the infected animals was treated with 400 mg/kg of oxamniquine during the acute phase before hepatectomy. Non-infected, infected and treated but not hepatectomized animals were kept as controls. Hepatic regeneration was evaluated by incorporation of tritiated thymidine, intraperitoneally injected into non-hepatectomized and hepatectomized animals, 24 hours after surgery. The results showed that removal of 65 percent of the hepatic parenchyma, during the acute phase, led to a statistically significant increase of thymidine incorporation, when compared with the uninfected hepatectomized controls. This phenomenon was not observed at the chronic phase. Treatment with oxamniquine administered during the acute phase led to a decrease in thymidine incorporation rate 160 days after infection (90 days after treatment) and 24 hours after hepatectomy. The data suggest that infection with S. mansoni represents a considerable stimulus for the regenerative capacity of the liver during the acute, but not the chronic phase of disease

Efecto citostática de la cumarina y la 7-hidroxicumarina en tres líneas celulares de adenocarcinoma pulmonar humano / Cystostatic effect of coumarin and 7-hidroxicoumarin on three human lung adenocarcinoma cell lines

Introducción: Las cumarinas son productos naturales ampliamente distribuidos en la naturaleza. En el humano el principal metabolito de la cumarina es la 7-hidroxicumarina, el cual es la forma activa del compuesto. Estos y otros compuestos relacionados presentan actividades biológicas de importancia terapéutica, entre las cuales destaca su efecto antitumoral. Objetivo: Evaluar la actividad antiproliferativa de estos dos compuestos sobre tres líneas celulares de cáncer y pulmón. Material y métodos: Se emplearon tres líneas celulares de adenocarcinomas de pulmón (SK-LU-1, 1.3.15 y 3A5A) para determinar el efecto de los fármacos utilizando experimentos de exposición única a concentraciones de 10 µg/mL a 80 µg/mL. El efecto sobre la proliferación celular se evaluó mediante ensayos de incorporación de timidina tritiada al cabo de 24 h y 48 h de exposición a los fármacos. Resultados: Se presentó un efecto inhibitorio de ambos compuestos sobre cada una de las líneas celulares estudiadas, presentando mayor actividad la 7-hidroxicumarina. La sensibilidad entre las distintas líneas celulares fue dependiente de la concentración y el tiempo de exposición. En este sentido las líneas 1.3.15 y 3A5A que fueron recientemente establecidas a partir de pacientes del INER y caracterizadas morfo e inmunofenotípicamente, presentaron mayor sensibilidad al efecto inhibitorio tanto a 24 H como a 48 H. Conclusiones: Estos resultados indican que las células tumorales de pulmón son blanco del efecto antiproliferativo de estos compuestos naturales; sin embargo, es necesario realizar un mayor número de protocolos experimentales básicos y clínicos que confirmen la utilizaciòn de la 7-hidroxicumarina sola o en combinación con la terapia que se emplea en el tratamiento del cáncer pulmonar

Efecto in vitro de prazicuantel sobre la actividad de Giardia intestinalis / In vitro effects of praziquantel over the trophozoites of Giardia intestinalis

Se realizó un estudio in vitro para conocer el efecto farmacológico de prazicuantel sobre los trofozoítos de Giardia intestinalis cepa P-1. Después de cultivarlos axénicamente, con cinco diferentes concentraciones de prazicuantel (de 0.32 hasta 1.62 nM/mL) durante 24 h a 37ºC, la viabilidad y la CI50 evaluada por la captación de colorante fluorogénico con citometría de flujo mostró un desplazamiento logarítmico de 10º a 10 a la tercera lo que correspondió a una concentración de 1.28 nM/mL. La incorporación de H3 metil-timidina como parámetro de crecimiento celular a 50 por ciento alcanzó 1.20 nM/mL de prazicuantel y el efecto citotóxico calculado por la capacidad de lisar células CHO (células de ovario de hámster chino) marcados con Cr51 se observó para la CI50 en una concentración de 1.05 nM/mL. Con estos tres parámetros se puede inferir qué viabilidad a 50 por ciento se observó a concentraciones más altas de prazicuantel comparadas con la capacidad para dividirse, así como el efecto citolítico, en donde la concentraciones más altas de prazicuantel comparadas con la capacidad para dividirse, así como el efecto citolítico, en donde la concentración de prazicuantel fue la más baja a lo que se atribuye la cualidad de apagar radicales libres, sin embargo, esto no fue proporcional al incrementar la concentración suponiéndose una importante capacidad detoxificante en Giardia. Se concluye que prazicuantel desarrolló actividad farmacológica en protozoarios, lo que le hace susceptible de emplearse contra la giardiasis

Effects of epidermal growth factor on the [3H]-thymidine uptake in the SK-N-SH and SH-SY5Y human neuroblastoma cell lines

The studies on the factors that regulate the biology of the neuroblastoma cell lines may ofter important information on the development of tissues on organs that derive from the neural crest. In the present paper we study the action of epidermal growth factor (EGF) on two human neuroblastoma cell lines: SK-N-SH which is composed at least of two cellular phenotypes (neuroblastic and melanocytic/glial cells), and its pure neuroblastic subclone SH-SY5Y. The results show that EGF (10 ng/ml) significantly stimulates the incorporation of [3H]-thymidine in the SK-N-SH cells only in the presence of fetal bovine serum (FBS) (control = 58285 + 9327 cpm; EGF= 75523 + 4457; p<0.05). Such effect is not observed in the presence of a chemical defined medium, that is, in the absence of FBS (control = 100997 + 4375; EGF = 95268 + 4683; NS). In the SH-SY5Y cells the EGF does not modify the incorporation of [3H]thymidine either in the presence of 10 percent of BFS (control = 113838 + 6978; EGF = 119434 + 9411; NS) or in its absence (control = 46197 + 3335; EGF = 44472 + 3493; NS). The results here reported suggest that: a) EGF may effect the proliferation of cells derived from a primary human neuroblastoma; b) this is evident by the EGF-induced increase of [3H]-thymidine incorporation in SK-N-SH cells; c) it is required the presence of other growth factors, present in the FBS, for the mitogenic action to be accomphished; d) since the pure neuroblastic SH-SY5Y cell line are refractory to the EGF, the effects observed in SK-N-SH cells probably occur on the melanocytic/glial cell subpopulation.

Evaluación y comparación del efecto mitogénico del fluido peritoneal de pacientes con endometriosis mínima y avanzada / Valuation and comparison of mitogenic effect of peritoneal fluid in patients with mild and advanced endometriosis

Objetivo: Evaluar y comparar el efecto mitogénico del fluido peritoneal de mujeres con endometriosis mínima y severa sobre la proliferación de células estronales endometriales en cultivo. Materiales y Métodos: Se establecieron cultivos primarios de células estronales de endometrio humano. Se agregaron concentraciones crecientes de fluido peritoneal de pacientes con endometriosis mínima y severa, y de controles. Se evaluó incorporación de Timidina tritiada (3[H]-Timidina) como parámetro de síntesis de ADN en esas células. Resultados: El fluido peritoneal de mujeres con endometriosis mínima indujo un incremento significativo y dosis-dependiente de la incorporación de 3[H]-Timidina que osciló entre el 580 por ciento y el 1450 por ciento de los controles. El fluido peritoneal de pacientes con endometriosis severa provocó una inhibición del 51 por ciento en promedio de la proliferación celular comparando con células que fueron expuestas a fluidos peritoneales controles o a medio de cultivo suplementado con 2,5 por ciento de suero bovino fetal. Conclusiones: Se hallaron diferencias significativas en cuanto al efecto mitogénico del fluido peritoneal de pacientes con distintos estadíos de endometriosis. Las muestras provenientes de pacientes con endometriosis mínima indujeron un incremento de la proliferación celular, mientras que el fluido peritoneal de endometriosis severa inhibió significativamente el crecimiento de las células endometriales en cultivo

Intracytoplasmatic and extracellular interleukin-1 production by monocytes of lung and colorectal cancer patients

We studied the production of interleukin-1 (IL-1) by peripheral blood monocytes (Mo) from twelve normal subjects (NS) and eight and nine untreated lung and colorectal cancer patients (CP), respectively. No significant changes of extracellular IL-1 biological activity was observed between CP and NS by thymocyte proliferation assay. This result was independent that the cells were treated or not with lipopolisaccharide from E. coli (LPS, 10 Mug/ml). Moreover, CP present normal amount of antigenic IL-1 Beta in LPS treated Mo culture supernatants by enzyme-linked immunosorbent asay (ELISA). The biological activity of IL-1 released was not significant modified after indomethacin (Indo, 10-6M) and LPS+Indo treatments. Furthermore, patients showed a low percentage of LPS activated Mo with intracytoplasmatic IL-1 (alpha + beta) compared to normal values. These results were obtained by immuno-alkaline phosphatase staining using monoclonal antibody anti IL-1 (alpha + beta). In conclusion, CP had a reduced number of Mo with intracytoplasmatic IL-1 (alpha + beta) and the difference observed may depend on degradation or in the rate of synthesis of this cytokine.

Estudio de la regeneración hepática utilizando un nuevo modelo in vivo: "la hepatectomía total temporaria" / Study of liver regeneration with original model in vivo: \"temporary total hepatectomy\"

Luego de una hepatectomía parcial, se producen cambios metabólicos y expresión de protooncogenes en el hígado, con la aparición de substancias estimulantes en sangre periférica, que provienen de dentro (factores intrahepáticos) y fuera (factores extrahepáticos) del hígado. Si bien una señal para la regeneración está siempre presente, no es claro cómo estos factores interactúan para estimular la síntesis de ADN durante las primeras 24 horas. Es necesario conocer si estos factores están conectados entre sí, para poder interpretar correctamente el proceso regenerativo hepático y eventualmente estimular aún más la regeneración. Para responder a estos interrogantes hemos sometido a ratas machos tipo Wistar a una "Hepatectomía Total Temporaria", funcional, mediante la confección de un shunt-porto-cava con vena homóloga, hepatectomía parcial del 30 por ciento y exclusión de los lóbulos anteriores. Luego de 3 horas los lóbulos son reperfundidos y a las 22 horas se inyectan 50 µCi de 3H thymidina y el hígado es removido 2 horas después. Posterior a una "Hepatectomía Total Temporaria", la síntesis de ADN (10975 ñ 2599 DPM/mgr DNA) fue menor que en ratas sometidas a una hepatectomía del 30 por ciento (20150 ñ 2540 P<0,01) y marcadamente inferior que luego de una hepatectomía parcial del 70 por ciento (160315 ñ 22293 P<0,001). Mediante este original modelo queda demostrado que no existe una desconexión entre los factores intra y extra hepáticos que inician el impulso regenerativo por lo que la estimulación post hepatectomía debería hacerse teniendo en cuenta ambos factores

"In vivo" and "in vitro" antitumoral action of Larrea divaricata cav

We previously reported that aqueous extract of Larrea divaricata Cav had an antiproliferative activity upon tumoral lymphoid cells (BW 5147), without affecting normal immunity. To determine the probable mechanism of the inhibitory action of the extract upon cell growth, the participation of intracellular signals involved in the inhibition of cell proliferation, namely the activation of adenylate cyclase system was studied. The production of cyclic 3', 5 adenosine monophosphate (cAMP) in presence and absence of extract was analized. The extract increased the cAMP levels, but neither the cAMP production nor the inhibitory effect of the extract on proliferation were blocked by a beta adrenergic receptor antagonist (propranolol) or by histaminergic receptor antagonistis (cimetidine and mepyramine). So, we concluted that the antiproliferative activity of the extract of BW 5147 cells would be mediated by an increase in cAMP intracellular levels no related to the activation of the membrane receptors here studied. In parallel, the extract was administered to a pregnant rat with a spontaneous mammarian carcinoma and "in vivo"antitumoral activity was found.

1, 25-Dihydroxyvitamin D3 stimulates growth and inhibits calcitonin secretion in a human C cell carcinoma cell line

1,25-Dihydroxyvitamin D3 (1,25D3), calcitonin (CT) and parathyroid hormone are the major calcium-regulating hormones. In addition, 1,25D3 has been reported to be a modulator of cell growth and differentiation in many tissues. recently, a suppressive effect of 1,25D3 on CT secretion and synthesis in C cells was demonstrated in vivo and also in vitro, but there are no data about in effects on thyroid C cell growth. We investigated the effects of [3H]-1,25D3 on basal and stimulated CT secretion and on [3H]-thymidine incorporation, using a human medullary thyroid carcinoma cell line (TT cells). After a 4-day expossure to 1,25D3, TT cells showed a dose-dependent inhibition of basal CT secretion (64 per cento of value for the control group at 100 nM 1,25D3). calcium (3mM) plus K+ (50mM) greatly increased CT secretion in both the control and vitamin D-treated groups. However, in the cells preincubated with 1,25D3 the stimulated CT levels less than observed in controls. A dose-dependent increase in [3H]-thymidine incorporation (200 per cent of the value for the at 100 nM 1,25D3) and in cell number (150 per cent of the value for the control group at 100 nM 1,25D3 after 72h) was observed in the groups treated with 1,25D3. 24,25D3 had no effect on CT secretion or cell growth compared to the control group. These data show that 1,25D3 decreased basal and Ca2+-stimulated CT secretion, a specialized function of these cells, and stimulated their growth. Hence, in contrast to its effects on other cell lines, 1,25D3 appears to induce a dedifferentiation on TT cell

Modulation of thymidine kinase activity: a biochemical strategy to enhance the activation of antineoplastic drugs

Thymidine kinase is a key enzyme responsible for the activation of several anticancer and antiviral drugs. As the first enzyme in the salvage pathway of thymidine, it is regulated by the feedback inhibition exerted by the end-product of the pathway, namely thymidine 5'-triphosphate. 5'-Aminothymidine is a non-toxic analogue of thymidine capable of interfering with this regulatory mechanism. In fact, it has been shown that 5'-aminothymidine increases the cytotoxicity and metabolism of various thymidine analogues currently in use of the clinic as antineoplastic agents. This mini-review article focuses in the evidence supporting the role of 5'-aminothymidine as a potential prototype drug for a new class of anticancer agents: drugs which affect the regulation of key metabolic pathways that determine the efficacy of agents with cytotoxic activity. The mechanism of action, antineoplastic activities and basis for selectivity in tissue culture models are also described