Differential DNA methylation and CTCF binding between the ESR1 promoter a of MCF-7 and MDA-MB-231 breast cancer cells.

BACKGROUND: ESR1 is expressed by 60-70% of breast tumours. it's a good prognosis factor and the target of hormone therapy. Optimization of ESR1 reactivation therapy is currently ongoing. Here we probe if the transcription factor CTCF plays a role in the differential expression of ESR1 in the breast cancer cell lines MCF-7 (ESR1+) and MDA-MB-231 (ESR1-). METHODS AND RESULTS: Knockdown of CTCF in MCF-7 resulted in decreased ESR1 gene expression. CTCF binds to the promoter of ESR1 in MCF-7 but not in MDA-MB-231 cells. CTCF ESR1 binding sites are unmethylated in MCF7 but methylated in MDA-MB-231 cells. CONCLUSION: ESR1 expression in MCF7 cells is dependent on CTCF expression. CTCF can bind to specific regions of the promotor of ESR1 gene in MCF-7 cells but not in MDA-MB-231 cells, this correlates with the methylation status of these regions and could be involved in the transcriptional regulation of ESR1.

Glucocorticoid-dependent expression of IAP participates in the protection against TNF-mediated cytotoxicity in MCF7 cells.

BACKGROUND: Glucocorticoid receptor (GR) activation has been associated with breast cancer cell survival in vitro. Glucocorticoid (GC)-dependent protection against tumor necrosis factor (TNF)-induced cell death has been well characterized in MCF7 luminal A breast cancer cells. The GR activates a variety of protective mechanisms, such as inhibitors of apoptosis proteins (IAPs). However, the relative contribution of the GR-dependent expression of IAPs in the protection of cell death has not, to our knowledge, been evaluated. METHODS: MCF7 cells were used for all experiments. GR was activated with cortisol (CORT) or dexamethasone (DEX) and inhibited with mifepristone (RU486). Cell viability was determined in real-time with the xCELLigence™ RTCA System and at specific endpoints using crystal violet stain. The mRNA levels of the eight members of the IAP family were measured by qRT-PCR. The protein levels of GR, PR, ERα, HER2, PARP1, c-IAP1 and XIAP were evaluated by Western blot analysis. The knockdown of c-IAP1 and XIAP was accomplished via transient transfection with specific siRNAs. GR activation was verified by a gene reporter assay. Via the cBioportal interphase we queried the mRNA levels of GR and IAPs in breast cancer tumors. RESULTS: RU486 significantly inhibited the anti-cytotoxic effect of both GCs. PARP1 processing was diminished in the presence of both GCs. The combined treatments of GCs + TNF increased the relative mRNA levels of Survivin>c-IAP1 > NAIP>Apollon>XIAP>Ts-IAP > ML-IAP > c-IAP2. Additionally, GR mRNA content increased with the combined treatments of GCs + TNF. Sustained levels of the proteins c-IAP1 and XIAP were observed after 48 h of the combined treatments with GCs + TNF. With c-IAP1 and XIAP gene silencing, the GC-mediated protection was diminished. In the breast tumor samples, the GR mRNA was coexpressed with Apollon and XIAP with a Pearson coefficient greater than 0.3. CONCLUSIONS: The effect of GCs against TNF-mediated cytotoxicity involves increased mRNA expression and sustained protein levels of c-IAP1 and XIAP. The antagonist effects of RU486 and the qRT-PCR results also suggest the role of the GR in this process. This finding may have clinical implications because the GR and IAPs are expressed in breast tumor samples.

Reassignment of crispatene, isolation and chemical characterization of stachydrine, isolated from the marine mollusk Elysia crispata.

The molluscan genus Elysia Risso, 1818 (Sacoglossa) is composed of shell-less herbivore sea slugs. From these marine organisms, polyketides such as polypropynates have been isolated and showed cytotoxic, antibiotic, and antifungal, and antiviral properties. In this work, we reported the isolation, and structure elucidation of two compounds isolated from marine mollusk E. crispata. Both compounds isolated, crispatene (1) and stachydrine (2), were purified by HPLC. The chemical structure of compound (1) was reassigned through 1D and 2D NMR experiments and high-resolution electrospray ionization mass spectrometry (HRESIMS). On the other hand, this is the first time that compound (2) has been found in this species of mollusk or the marine environment, previously, (2) has only been found in terrestrial plants or bacteria in symbiosis with plants.

Sera from women with different metabolic and menopause states differentially regulate cell viability and Akt activation in a breast cancer in-vitro model.

Obesity is associated with an increased incidence and aggressiveness of breast cancer and is estimated to increment the development of this tumor by 50 to 86%. These associations are driven, in part, by changes in the serum molecules. Epidemiological studies have reported that Metformin reduces the incidence of obesity-associated cancer, probably by regulating the metabolic state. In this study, we evaluated in a breast cancer in-vitro model the activation of the IR-ß/Akt/p70S6K pathway by exposure to human sera with different metabolic and hormonal characteristics. Furthermore, we evaluated the effect of brief Metformin treatment on sera of obese postmenopausal women and its impact on Akt and NF-κB activation. We demonstrated that MCF-7 cells represent a robust cellular model to differentiate Akt pathway activation influenced by the stimulation with sera from obese women, resulting in increased cell viability rates compared to cells stimulated with sera from normal-weight women. In particular, stimulation with sera from postmenopausal obese women showed an increase in the phosphorylation of IR-ß and Akt proteins. These effects were reversed after exposure of MCF-7 cells to sera from postmenopausal obese women with insulin resistance with Metformin treatment. Whereas sera from women without insulin resistance affected NF-κB regulation. We further demonstrated that sera from post-Metformin obese women induced an increase in p38 phosphorylation, independent of insulin resistance. Our results suggest a possible mechanism in which obesity-mediated serum molecules could enhance the development of luminal A-breast cancer by increasing Akt activation. Further, we provided evidence that the phenomenon was reversed by Metformin treatment in a subgroup of women.

IFI27/ISG12 Downregulates Estrogen Receptor α Transactivation by Facilitating Its Interaction With CRM1/XPO1 in Breast Cancer Cells.

The estrogen receptor alpha (ERα) is a ligand-activated transcription factor whose activity is modulated by its interaction with multiple protein complexes. In this work, we have identified the protein interferon alpha inducible protein 27 (IFI27/ISG12) as a novel ERα-associated protein. IFI27/ISG12 transcription is regulated by interferon and estradiol and its overexpression is associated to reduced overall survival in ER+ breast cancer patients but its function in mammary gland tissue remains elusive. In this study we showed that overexpression of IFI27/ISG12 in breast cancer cells attenuates ERα transactivation activity and the expression of ERα-dependent genes. Our results demonstrated that IFI27/ISG12 overexpression in MCF-7 cells reduced their proliferation rate in 2-D and 3-D cell culture assays and impaired their ability to migrate in a wound-healing assay. We show that IFI27/ISG12 downregulation of ERα transactivation activity is mediated by its ability to facilitate the interaction between ERα and CRM1/XPO1 that mediates the nuclear export of large macromolecules to the cytoplasm. IFI27/ISG12 overexpression was shown to impair the estradiol-dependent proliferation and tamoxifen-induced apoptosis in breast cancer cells. Our results suggest that IFI27/ISG12 may be an important factor in regulating ERα activity in breast cancer cells by modifying its nuclear versus cytoplasmic protein levels. We propose that IFI27/ISG12 may be a potential target of future strategies to control the growth and proliferation of ERα-positive breast cancer tumors.

Effect of Interleukin-17 in the Activation of Monocyte Subsets in Patients with ST-Segment Elevation Myocardial Infarction.

Interleukin- (IL-) 17 is increased in acute myocardial infarction (AMI) and plays a key role in inflammatory diseases through its involvement in the activation of leukocytes. Here, we describe for the first time the effect of IL-17 in the migration and activation of monocyte subsets in patients during ST-segment elevation myocardial infarction (STEMI) and post-STEMI. We analyzed the circulating levels of IL-17 in patient plasma. A gradual increase in IL-17 was found in STEMI and post-STEMI patients. Additionally, IL-17 had a powerful effect on the recruitment of CD14++CD16+/CD14+CD16++ monocytes derived from patients post-STEMI compared with the monocytes from patients with STEMI, suggesting that IL-17 recruits monocytes with inflammatory activity post-STEMI. Furthermore, IL-17 increased the expression of TLR4 on CD14 + CD16 - and CD14++CD16+/CD14+CD16++ monocytes post-STEMI and might enhance the response to danger-associated molecular patterns post-STEMI. Moreover, IL-17 induced secretion of IL-6 from CD14++CD16- and CD14++CD16+/CD14+CD16++ monocytes both in STEMI and in post-STEMI, which indicates that IL-17 has an effect on the secretion of proinflammatory cytokines from monocytes during STEMI and post-STEMI. Overall, we demonstrate that in STEMI and post-STEMI, IL-17 is increased and induces the migration and activation of monocyte subsets, possibly contributing to the inflammatory response through TLR4 and IL-6 secretion.

Seasonal sebaceous patch in the nectar-feeding bats Leptonycteris curasoae and L. yerbabuenae (Phyllostomidae: Glossophaginae): phenological, histological, and preliminary chemical characterization.

Many species of bats secrete a wide variety of substances, frequently associated with olfactory communication. We characterized a seasonal phenomenon of dorsal sebaceous secretion in the Curaçaoan long-nosed bat, Leptonycteris curasoae, in Venezuela, and the lesser long-nosed bat, Leptonycteris yerbabuenae, in Mexico. The phenology of the sebaceous patch was determined, a histological analysis of the affected area was conducted using specimens of L. curasoae from Venezuela, and finally, a preliminary chemical characterization of the substance secreted was performed combining histochemical techniques with gas chromatography and mass spectrometry analyses. The sebaceous patch was detected exclusively in male adult specimens. Individuals presenting it had a variable area of fur covered with a fatty and odoriferous substance at the level of the interscapular zone. Occurrence of the sebaceous patch was cyclical and coincided with the mating season in Venezuela and Mexico. The following histological changes associated with occurrence of the patch were observed: increase of epidermis thickness and decrease of dermis and hypodermis thicknesses, increase in density of sebaceous glands, increase of percentage of skin covered by sebaceous glands, increase of size of sebaceous glands previous to secretion followed, and increase of the sebum volume within sebaceous glands previous to secretion. Several compounds tentatively identified as fatty acids, cholestanes and cholesterol were present in the sebaceous secretion. Based on the evidence obtained, we hypothesize that the sebaceous patch could be involved in olfactory communication, possibly related to mating behavior in these bats.

Effect of soluble factors derived from ZR 75.30 breast cancer cells on endothelial activation.

In this study, we analyzed soluble factors secreted by two Estrogen Receptor Positive (ER-α) human breast cancer cell lines, ZR 75.30 (luminal B) and MCF7 (luminal A), and evaluated their effect on endothelial activation. The composition of tumoral soluble factors (TSFs) was analyzed by ELISA (Bio-Plex). TSFs from ZR 75.30 cells expressed higher levels of TNF, IFN-γ, IL-6, and IL-8 compared to TSFs from MCF-7 cells. TSFs from ZR 75.30 cells induced a pro-adhesive phenotype in human umbilical vein endothelial cells (HUVECs), as characterized by increased monocytic cell adhesion, adhesion molecule expression and NF-κB activation and decreased IκB-α expression. Conversely, TSFs from MCF-7 cells exerted none of these effects on HUVECs. We then added TNF, IFN-γ, IL-6 or IL-8 alone or in combination with TSFs from MCF-7 cells to HUVECs. Only the combinations that included TNF induced endothelial activation. A neutralizing antibody against IL-1ß (this cytokine was not measured in the ELISA) had a modest blocking effect on cellular adhesion or the expression of adhesion molecules induced by TSFs from ZR 75.30 cells in HUVECs. However neutralizing antibodies against TNF, IFN-γ, IL-6 or IL-8 had no effect. Our results suggest that although TNF is an inducer of endothelial cell activation, it is not the only molecule that is responsible for this effect in TSFs from ZR 75.30 cells.

Genomic and non-genomic effects of glucocorticoids: implications for breast cancer.

Glucocorticoids (GC) are essential steroid hormones for human life. They regulate a series of important processes by binding with three glucocorticoid receptors (GR) and activating genomic and non-genomic pathways. Activated cytoplasmic GR can directly bind DNA and transactivate or transrepress specific genes. Additionally, it can interact with other transcription factors to affect gene expression indirectly. The two membrane GR can interact with mitogen-activated protein (MAP) kinases or activate cAMP and Ca(2+)-dependent pathways, respectively. Glucocorticoids have been widely used as co-treatment of patients with breast cancer (BC) due to reduction of chemotherapy-induced side effects such as nausea, lack of appetite, and inflammation. However, GC may exert a direct effect on tumor response to chemotherapy. In vitro, GC inhibits chemotherapy, radiation and cytokine-induced apoptosis by upregulating antiapoptotic genes and detoxifying proteins. They also upregulate the proto-oncogene c-fms, tumor suppressor gene Nm23, several members of the epidermal growth factor (EGF) signaling pathway and the estrogen sulfotransferase signaling pathway, thus indirectly inhibiting estrogen receptor activation. They inhibit the proangiogenic gene (vascular endothelial growth factor (VEGF); Therefore, they could play a role in reducing angiogenesis. Interestingly, the phosphorylation status of ser-211 in the GR is dependent on the expression of the BRCA1 gene, a tumor suppressor gene that is mutated in the majority of patients with triple negative BC. Some clinical randomized trials have also attempted to address the effect of GC on patients with BC. Thus, in this review we summarize GC mechanisms of action and their participation in several facets of BC.

DESARROLLO E IMPLEMENTACIÓN DE UNA NORIA MODIFICADA COMO PROPUESTA SOSTENIBLE DE RECIRCULACIÓN DE AGUA PARA UNA ESTACIÓN PISCÍCOLA / DEVELOPMENT AND IMPLEMENTATION OF A MODIFIED WATERWHEEL AS A PROPOSAL FOR SUSTANTAINABLE WATER CIRCULATION FOR A FISHING STATION

Existen problemas de abastecimiento de agua en verano e invierno, en la Estación Piscícola de la Universidad de Caldas (Colombia). El trabajo muestra la manera como, por medio de un sistema de recirculación de agua, se provee a la Estación del líquido, de manera persistente, conservando parámetros fisicoquímicos aptos para el cultivo de peces. Cambios en el uso del suelo, como desarrollos urbanísticos, han generado impacto sobre la microcuenca que abastece la Estación. Surge la propuesta de reutilizar el agua mediante un modelo sostenible, adaptando un mecanismo ancestral: la Noria. Éste trabajo se desarrolló en tres etapas: recopilación de información, seguimiento e implementación de la propuesta. Para el montaje se requirió adaptar parte de la infraestructura existente de la Estación para recolectar el agua. El diseño de la Noria consta de un sistema de captación de agua (Cilindro con compartimentos) que impulsa un sistema de poleas y a su vez a la Noria modificada con canjilones, la cual capta agua (1,5 l/seg) y la elevan 7 m. Los parámetros físicoquímicos (temperatura, oxígeno y pH) y biológicos (macroinvertebrados acuáticos) permanecieron en rangos normales para un cultivo de peces tropicales. El diseño realizado es modular, no requiere energía eléctrica, ni mano de obra especializada para su mantenimiento, puede ser utilizado como una herramienta alterna en el sector agropecuario particularmente en el sector acuícola, donde se presenten dificultades hídricas, es de bajo costo y ambientalmente sostenible.

There are problems of water supply in the summer and the winter, in the Fishing Station of Universidad de Caldas (Colombia). This article shows how, by means of a water recirculation system, the Station is provided with the liquid persistently, keeping physicochemical parameters fit for fish farming. Changes in land use, such as urban development, have generated impact on the watershed that supplies the Station. Then, a proposal to reuse water through a sustainable model, adapting an ancestral mechanism surges: the Waterwheel. This work was developed in three stages: data collection, monitoring and implementation of the proposal. For the assembly adaption of part of the existing infrastructure of the Station to collect water was required. The design of the waterwheel consists of a water catchment system (cylinder with compartments) that drives a pulley system and in turn to the modified waterwheel with buckets, which capture the water (1.5 l / sec) and then raise it 7 m. The physicochemical parameters (temperature, oxygen and pH) and biological (macroinvertebrate) remained within normal ranges for a crop of tropical fish. The design developed is modular, it does not require electricity or skilled workforce for maintenance, it can be used as an alternative tool in agriculture particularly in the aquaculture sector where water difficulties arise, and it is inexpensive and environmentally sustainable .

Timing of DVT prophylaxis and risk of postoperative knee prosthesis infection.

This multicenter prospective study was performed to determine risk factors for knee prosthesis infection and the effect of timing doses of prophylactic low-molecular-weight heparins (LMWH) related to time of surgery on the risk of knee prosthesis infection. A total of 5496 consecutive patients who underwent total knee arthroplasty from 2005 to 2006 in 13 orthopedic centers were prospectively followed up for 6 months, and the incidence of knee prosthesis infection was recorded. A case control study was nested in the cohort. Case patients were matched to uninfected (control) patients, and the timing of perioperative LMWH was recorded as the main risk factor. Fifty patients developed postoperative knee prosthesis infection during the follow-up period, yielding an incidence of prosthesis infection of 0.91% (95% CI, 0.68%-1.20%). Forty-four patients were matched to 106 controls. Case patients received the first LMWH dose ±12 hours from the start of surgery more frequently than their control counterparts (odds ratio, 1.5; 95% CI, 0.73-3.0). After adjusting by main risk factors, no statistical association was found between close perioperative timing of LMWH and risk of prosthesis infection. Diabetes mellitus (adjusted odds ratio, 3.2; 95% CI, 1.2-8.8) and wound hematoma (adjusted odds ratio, 4.2; 95% CI, 1.1-16.5) were found to be independent risk factors for prosthesis infection.

Los métodos y procesos multicriterio para la evaluación / Multicrieria metthods and processes for assessment

El presente artículo tiene por objeto evidenciar las bondades que el método multicriterio otorga en las evaluaciones científicas que sean consistentes con un marco de racionalidad. Inicia haciendo referencia al método científico a través del cual el hombre trata de entender el mundo, construyendo uno artificial desde la ciencia. A continuación se reflexiona sobre el valor agregado que pueden proporcionar los métodos cualitativos al entregar una visión diferente del mundo, al tomar en consideración variables que no pueden ser expresadas cuantitativamente. Para finalizar se expone el método multicriterio como una herramienta útil para determinar el impacto de acciones a desarrollo sobre la sostenibilidad al incorporar los conflictos que existen entre objetivos económicos, ambientales y sociales, y entre distintos niveles de decisión en las evaluaciones científicas.

This article aims to make clear the benefits the multicriteria-method gives to scientific assessment which are consistent with a rationality framework. It begins by referring to the scientific method, through which humankind tries to understand the world building an artificial world from science. Afterwards a reflection on the added value qualitative methods as a methodology can give, is presented since they allow a broader worldview by taking into account variables that cannot be expressed quantitatively. Finally, a multicriteria-method is presented as a useful tool to determine the impact of actions on sustainability, while incorporating the existing conflicts between economic, environmental and social objectives, and between different levels of decision making in scientific assessment.

Bioequivalencia de una dosis de levofloxacina de laboratorios Leti (LL) comprimidos de 500 mg frente a levofloxacina de laboratorios sanofi aventis: tavanic® (LSA) tabletas de 500 mg, administrados en dosis única en voluntarios sanos / Bioequivalence of a dose of levofloxacin Leti laboratories (LL) tablets of 500 mg versus levofloxacin Sanofi Aventis laboratorie: tavanic® (LSA) tablets of 500 mg administered in single dose in healthy volunteers

Evaluar la Bioequivalencia en 12 voluntarios sanos de la Levofloxacina de Laboratorios LETI (LL) comprimidos de 500 mg en dosis única, producto test, con la del producto de referencia: Levofloxacina de Laboratorios SANOFI AVENTIS, Tavanic® (LSA) tabletas de 500 mg. El grupo test recibió un comprimido de Levofloxacina de Laboratorios LETI (LL) de 500 mg, y el grupo de referencia recibió una tableta de Levofloxacina de Laboratorios SANOFI AVENTIS: Tavanic® (LSA) de 500 mg. Terminada esta primera fase de tratamiento, los voluntarios no recibieron medicación por 6 días consecutivos (período de lavado). Luego se procedió al cruce de los tratamientos, los voluntarios del grupo test recibieron la medicación del grupo referencia y viceversa. La extracción de sangre venosa se realizó a la hora 0, 0.5, 0.75, 1, 1.5, 2, 3, 6, 8, 14, 18 y 24 horas. Se determinaron los niveles plasmáticos de Levofloxacina de las muestras plasmáticas procedentes del estudio clínico, mediante el método cromatográfico por HPLC desarrollado y validado. Se obtuvo una Cmax de 1253.40+/-562.58 μg/mL para LL vs. 1317.42+/-439.64 μg/mL para LSA, el AUC0-24 fue de 9188.43+/-2406.64 μg/mL/h vs 8780.22+/-2305.99 μg/mL/h; y para el AUC0-∞ el resultado fue de 9933.17+/-2488.52 μg/mL/h vs. 9433.47+/-2399.71 μg/mL/h respectivamente. Las medias y sus intervalos de confianza para la Cmax y el AUC0-24 y AUC0-∞ se mantuvieron en los rangos aceptados para la demostración de bioequivalencia. Ambos productos son bioequivalentes y por lo tanto intercambiables.

To evaluated the bioequivalence in 12 healthy volunteers of the LETI Laboratories Levofloxacin (LL) tablets 500 mg single dose, test product with the product Reference: SANOFI AVENTIS Laboratories Levofloxacin, Tavanic® (LSA) 500 mg tablets. The test group received one tablet of levofloxacin LETI Laboratories (LL) of 500 mg, and the control group received a tablet Levofloxacin SANOFI AVENTIS Laboratories: Tavanic® (LSA) of 500 mg. After this first treatment phase, volunteers received no medication for 6 consecutive days (washout period). Then he proceeded to the crossing of the treatments, the volunteers of the group test group received the medication reference and viceversa. The venous blood collection was performed at time 0, 0.5, 0.75, 1, 1.5, 2, 3, 6, 8, 14, 18 and 24 hours. We determined plasma levels of levofloxacin in plasma samples from the clinical study, using HPLC chromatographic method developed and validated. Cmax of 1253.40 + / -562.58 μg/mL for the LL vs. 1317.42 + / -439.64 μg/mL for LSA, the AUC0-24 was 9188.43 + / -2406.64 μg/mL/h vs. 8780.22 + / -2305.99 μg/mL/h, and the AUC0-∞ the result was 9933.17 + / -2488.52 μg/mL/h vs. 9433.47 + / -2399.71 μg/mL/h, respectively. The mean and confidence intervals for Cmax and AUC0-24 and AUC0-∞ were maintained in the range accepted for the demonstration of bioequivalence. Both products are bioequivalent and therefore interchangeable.

Bioequivalencia de una dosis de levofloxacina de laboratorios Leti: proxime® (LL) comprimidos de 500 mg frente a levofloxacina de laboratorios Sanofi Aventis: tavanic® (LSA) tabletas de 500 mg, administrados en dosis única en voluntarios sanos / Bioequivalence of dose of levofloxacin Leti laboratories: proxime® (LL) 500 mg tablets of levofloxacin aganist Sanofi Aventi: tavanic® (LSA) 500 mg tablets given as a single dose in healthy volunteers

Evaluar la Bioequivalencia en 12 voluntarios sanos de la Levofloxacina de Laboratorios LETI: Proxime® (LL) comprimidos de 500 mg en dosis única, producto test, con la del producto de referencia: Levofloxacina de Laboratorios SANOFI AVENTIS, Tavanic® (LSA) tabletas de 500 mg. El grupo test recibió un comprimido de Levofloxacina de Laboratorios LETI: Proxime® (LL) de 500 mg, y el grupo de referencia recibió una tableta de Levofloxacina de Laboratorios SANOFI AVENTIS: Tavanic® (LSA) de 500 mg. Terminada esta primera fase de tratamiento, los voluntarios no recibieron medicación por 6 días consecutivos (período de lavado). Luego se procedió al cruce de los tratamientos, los voluntarios del grupo test recibieron la medicación del grupo referencia y viceversa. La extracción de sangre venosa se realizó a la hora 0, 0.5, 0.75, 1, 1.5, 2, 3, 6, 8, 14, 18 y 24 horas. Se determinaron los niveles plasmáticos de Levofloxacina de las muestras plasmáticas procedentes del estudio clínico, mediante el método cromatográfico por HPLC desarrollado y validado. Se obtuvo una Cmax de 1253.40+/-562.58 para la LL vs. 1317.42+/-439.64 para LSA, el AUC 0-24 fue de 9188.43+/-2406.64 vs 8780.22+/-2305.99; y para el AUC 0-∞ el resultado fue de 9933.17+/-2488.52 vs. 9433.47+/-2399.71 respectivamente.Las medias y sus intervalos de confianza para la Cmax yel AUC 0-24 y AUC 0-∞ se mantuvieron en los rangos aceptados para la demostración de bioequivalencia. Ambos productos son bioequivalentes y por lo tanto intercambiables

To evaluated the bioequivalence in 12 healthy volunteers of the LETI Laboratories Levofloxacin: Proxime® (LL) tablets 500 mg single dose, test product with the product Reference: SANOFI AVENTIS Laboratories Levofloxacin, Tavanic® (LSA) 500 mg tablets. The test group received one tablet of levofloxacin LETI Laboratories: Proxime® (LL) of 500 mg, and the control group received a tablet Levofloxacin SANOFI AVENTIS Laboratories: Tavanic® (LSA) of 500 mg. After this first treatment phase, volunteers received no medication for 6 consecutive days (washout period). Then he proceeded to the crossing of the treatments, the volunteers of the group test group received the medication reference and viceversa. The venous blood collection was performed at time 0, 0.5, 0.75, 1, 1.5, 2, 3, 6, 8, 14, 18 and 24 hours. We determined plasma levels of levofloxacin in plasma samples from the clinical study, using HPLC chromatographic method developed and validated. Cmax of 1253.40 + / -562.58 for the LL vs. 1317.42 + / -439.64 for LSA, the AUC 0-24 was 9188.43 + / -2406.64 vs. 8780.22 + / -2305.99, and the AUC 0-∞ the result was 9933.17 + / -2488.52 vs. 9433.47 + / -2399.71, respectively. The mean and confidence intervals for Cmax and AUC 0-24 and AUC 0-∞ were maintained in the range accepted for the demonstration of bioequivalence. Both products are bioequivalent and therefore interchangeable

La transcriptasa reversa del VIH: estudios estructurales y cinéticos / The reverse transcriptasa of the HIV: structural and kinetic studies

La transcriptasa reversa (TR) es una polimerasa de ADN, compuesta por dos subunidades 66 y 51 KDa. Sintetiza ADN usando un ácido nucleico complementario como templado. Esta enzima posee tres actividades distintas: una polimerasa de ADN dependiente de ARN que sintetiza la cadena negativa del ADN proviral, una actividad polimerasa de ADN dependiente de ADN que cataliza la construcción de la hebra positiva y una actividad de RNAsa H. La TR del VIH utiliza un ARN de transferencia (ARNt) específico para llevar acabo la fabricación del ADN complementario, lo cual induce un cambio de conformación que afecta las actividades de la polimerasa. Diversos investigadores han encontrado que la afinidad del sustrato por la TR del VIH es significativamente alta; la Kd para un dNTP de la TR viral es 4nM, una de las más bajas encontradas para las polimerasas de ADN y posee a su vez valores de procesividad y selectividad de gran magnitud. Distintas evidencias remarcan el hecho de que la TR sufre un cambio conformacional cuando se encuentra acomplejada de la forma E-ADN-dNTP, y que esta acción puede ser inhibida por el apareamiento de un nucleótido incorrecto. La enzima debe acomodar los duplex generados de cada reacción y debido a esto la TR podría no ser capaz de restringir la geometría del apareamiento, como sucede para el resto de las polimerasas, originando la aparición de los diferentes mutantes del VIH. Los inhibidores de la transcriptasa reversa del VIH se pueden agrupar en tres categorías: análogos de nucleósidos, no nucleósidos y oligonucleótidos. Los inhibidores análogos de nucleósidos más utilizados clínicamente son: Lamivudina, Zerit, Retrovir, Videz, AZT o Zidoduvina y Viramune. Los no nucleósidos ya empleados en terapias son: Viramune y rescriptor. Por todas sus características, la TR del VIH se encuentra catalogada como una de las enzimas de mayor funcionalidad y complejidad que se haya estudiado