Recurso. Modelo de crecimiento de árbol individual para plantaciones de pino radiata en el noroeste de España

Individual-tree basal area and height increment models were developed with data from 130 permanent plots of Pinus radiata D. Don located in Galicia (northwestern Spain). Mixed-models techniques were used for model fitting. Covariates acting at tree and stand level were included as fixed effects. Estimated values of stand variables obtained from aggregation of individual-tree predictions were used in model evaluation. The developed models accounted for 54% of the variability in basal area increment and 36% of the variability in height increment, with mean errors of 16 cm2 and 0.36 m, respectively. These models, along with an existing individual-tree mortality model, constitute a whole individual-tree growth model that can be used to simulate forest management alternatives, helping in forest managers’ decision making.En este estudio se han desarrollado modelos de incremento en sección normal y altura de árbol individual, utilizando datos de 130 parcelas de Pinus radiata D. Don localizadas en Galicia. La técnica de modelos mixtos se utilizó en el ajuste de los modelos. Se incluyeron covariables que actúan a nivel de árbol y a nivel de rodal como efectos fijos en los modelos. En la evaluación de los modelos se utilizaron estimaciones de variables de rodal obtenidas por agregación de las predicciones de árbol individual. Los modelos desarrollados explicaron el 54% de la variabilidad en el incremento en sección normal y el 36% de la variabilidad en el incremento en altura, con errores medios de 16 cm2 y 0.36 m, respectivamente. Estos modelos, junto al modelo de mortalidad de árbol individual existente, forman un modelo de crecimiento de árbol individual que puede utilizarse para simular alternativas de gestión forestal, ayudando a la toma de decisiones de los gestores forestales

Anticancer Activity of Alkynylgold(I) with P(NMe2)3 Phosphane in Mouse Colon Tumors and Human Colon Carcinoma Caco-2 Cell Line

New alkynylgold(I) with P(NMe2)3 (HMPT) phosphane complexes, [Au(CC-R)(HMPT)] (R= 4-Ph, 4-MePh, 4-OMe, 4-Br, 4-Cl, 2-py, and 3-py) have been synthesized and characterized, including X-ray studies of complexes with R= 4-OMe and 4-Br; additionally, their physicochemical properties and anticancer activity have been tested. Due to the great water solubility of the HMPT phosphane, all the complexes exhibit an optimal balance of hydrophilicity/lipophilicity. Also, all of these complexes are quite stable in physiological conditions and interact well enough with the transport protein BSA. All complexes exhibit a higher anticancer activity against Caco-2 cells than cisplatin, and some of them do not present cytotoxic activity against enterocyte-like differentiated cells. The selective complexes are proapoptotic drugs by the exposure of phosphatidylserine, results that are also confirmed in primary cultures from mouse colon tumors. Complexes with a halogen unit also arrest the cell cycle in G2/M phase. It is thought that maybe these apoptosis processes are promoted by the observed oxidative damage in the membrane lipids, as a consequence of the inhibition of the thioredoxin reductase enzyme. Based on our results, we conclude that five of our complexes are good candidates to be used in chemotherapy

Computationally Guided Design of a Readily Assembled Phosphite- Thioether Ligand for a Broad Range of Pd-Catalyzed Asymmetric Allylic Substitutions

A modular approach employing indene as common starting material, has enabled the straightforward preparation in three reaction steps of P-thioether ligands for the Pd-catalyzed asymmetric allylic substitution. The analysis of a starting library of P-thioether ligands based on rational design and theoretical calculations has led to the discovery of an optimized anthracenethiol derivative with excellent behavior in the reaction of choice. Improving most approaches reported to date, this ligand presents a broad substrate and nucleophile scope. Excellent enantioselectivities have been achieved for a range of linear and cyclic allylic substrates using a large number of C-, N-, and O-nucleophiles (40 compounds in total). The species responsible for the catalytic activity have been further investigated by NMR in order to clearly establish the origin of the enantioselectivity. The resulting products have been derivatized by means of ring-closing metathesis or Pauson–Khand reactions to further prove the synthetic versatility of the methodology for preparing enantiopure complex structures

EFECTO DE LA DIETA SOBRE LA MODULACIÓN DE LA MICROBIOTA EN EL DESARROLLO DE LA OBESIDAD

Hoy en día, la microbiota gastrointestinal se ha transformado en un tema de investigación dinámica para  dilucidar su relación con  la dieta y la salud metabólica del huésped. En los últimos años se ha  reconocido que la microbiota intestinal presenta una interacción estrecha  en la regulación de la homeostasis inmune humana y el metabolismo, esto con lleva a nuevas oportunidades para la prevención de la obesidad y las enfermedades metabólicas asociadas como  la diabetes tipo 2, para generar estrategias en el  tratamiento de enfermedades metabólicos y sobre todo en esclarecer la prevalencia de la obesidad. En recientes investigaciones se ha establecido elementos que permiten establecer a la  microbiota intestinal como un mediador sobre el impacto de la dieta, el estado metabólico y el  peso corporal del huésped. Los mecanismos que permite una relación de la microbiota del intestino con la obesidad son generados  mediante la  combinación de modelos con animales de experimentación y ensayos clínicos. El reto fundamental  del tema  es la capacidad en  establecer  la causalidad de la relación entre la nutrición, la microbiota y la salud del huésped, así como los factores que inciden sobre los cambios en el peso corporal del individuo. Palabras clave: microbiota, tratamiento dietético, obesidad.  ABSTRACTToday, the gastrointestinal microbiota has been transformed into a dynamic research topic to elucidate its relationship with diet and metabolic health of the host. In recent years it has been recognized that the intestinal microbiota presents a close interaction in the regulation of human immune homeostasis and metabolism, leading to new opportunities for the prevention of obesity and associated metabolic diseases such as type 2 diabetes, to generate strategies in the treatment of metabolic diseases and especially in clarifying the prevalence of obesity. Recent research has established elements that allow establishing the intestinal microbiota as a mediator on the impact of diet, metabolic status and body weight of the host. The mechanisms allowing a relationship of the intestinal microbiota with obesity are generated by combining models with experimental animals and clinical trials. The fundamental challenge of the subject is the ability to establish the causality of the relationship between nutrition, microbiota and the health of the host, as well as the factors that influence the changes in the individual's body weight. Keywords: microbiota, dietary treatment, obesity

Resistin Regulates Pituitary Lipid Metabolism and Inflammation In Vivo

The adipokine resistin is an insulin-antagonizing factor that also plays a regulatory role in inflammation, immunity, food intake, and gonadal function and also regulates growth hormone (GH) secretion in rat adenopituitary cells cultures with the adipokine. Although adipose tissue is the primary source of resistin, it is also expressed in other tissues, including the pituitary. The aim of this study is to investigate the possible action of resistin on the lipid metabolism in the pituitary gland in vivo (rats in two different nutritional status, fed and fast, treated with resistin on acute and a chronic way) and in vitro (adenopituitary cell cultures treated with the adipokine). Here, by a combination of in vivo and in vitro experimental models, we demonstrated that central acute and chronic administration of resistin enhance mRNA levels of the lipid metabolic enzymes which participated on lipolysis and moreover inhibiting mRNA levels of the lipid metabolic enzymes involved in lipogenesis. Taken together, our results demonstrate for the first time that resistin has a regulatory role on lipid metabolism in the pituitary gland providing a novel insight in relation to the mechanism by which this adipokine can participate in the integrated control of lipid metabolism

Effect of Cynara scolymus and Silybum marianum extracts on bile production in pigs

Many of the beneficial effects on productive performance observed when vegetable extracts are incorporated as feed additives in intensive farming can be explained by an increase in bile production. An experiment was conducted to study choleretic and cholagogue effect of a Cynara scolymus extract formulation and of silymarin in pigs. Pigs were cannulated with a T-tube catheter in the bile duct. Bile production was continuously measured and re-infused to the duodenum through Oddi’s sphincter at the same production rate. Treatments: Group A (n = 6), commercial feed; Group B (n = 6), C. scolymus extract (300 g/tonne) and Group C (n = 6), silymarin (300 g/tonne). Bile production was recorded hourly for each animal during 24 h. Total bile acids’ concentrations in bile, just before and one hour after meals were evaluated. Average daily bile production for pigs in group B was 66% higher than for pigs in groups A or C (P <.05). When bile acids’ concentrations before and after meals were compared, only pigs from group B exhibited an increase (P =.0023). From this study, it was concluded that neither choleretic nor cholagogue effects are attained with silymarin supplementation. On the contrary, C. scolymus extract increases bile production and secretion in pigs.Fil: Martínez, Guadalupe. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigación Veterinaria de Tandil. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigación Veterinaria de Tandil. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Centro de Investigación Veterinaria de Tandil; ArgentinaFil: Dieguez, Susana Nelly. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigación Veterinaria de Tandil. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigación Veterinaria de Tandil. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Centro de Investigación Veterinaria de Tandil; ArgentinaFil: Rodriguez, Edgardo Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigación Veterinaria de Tandil. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigación Veterinaria de Tandil. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Centro de Investigación Veterinaria de Tandil; ArgentinaFil: Decundo, Julieta María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigación Veterinaria de Tandil. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigación Veterinaria de Tandil. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Centro de Investigación Veterinaria de Tandil; ArgentinaFil: Romanelli, Agustina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigación Veterinaria de Tandil. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigación Veterinaria de Tandil. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Centro de Investigación Veterinaria de Tandil; ArgentinaFil: Fernández Paggi, María Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigación Veterinaria de Tandil. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigación Veterinaria de Tandil. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Centro de Investigación Veterinaria de Tandil; ArgentinaFil: Pérez, Denisa Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigación Veterinaria de Tandil. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigación Veterinaria de Tandil. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Centro de Investigación Veterinaria de Tandil; ArgentinaFil: Amanto, Andres Fabian. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencia Veterinarias. Departamento de Fisiopatología. Laboratorio de Toxicología; ArgentinaFil: Soraci, Alejandro Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigación Veterinaria de Tandil. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigación Veterinaria de Tandil. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Centro de Investigación Veterinaria de Tandil; Argentin

Effect of fosfomycin, Cynara scolymus extract, deoxynivalenol and their combinations on intestinal health of weaned piglets

Weaning is a challenging stage of pig farming. Animals undergo environmental, social and dietary changes leading to weaning stress syndrome. In order to compensate for the detrimental effects of weaning stress, antibiotics and natural extracts are used as feed additives, sometimes without fully understanding the interactions between them or even with low concentrations of mycotoxins that are frequently present in feed. The aim of this study was to evaluate the effect of fosfomycin (FOS), Cynara scolymus extract (CSE), deoxynivalenol (DON) and their combined administration on intestinal health of weaned piglets. The experiment was designed as a 2 × 2 × 2 factorial arrangement with 3 factors (FOS, CSE and DON treatments), 2 levels each (presence and absence) and 3 repeats. Weaned piglets (n = 24) were randomly divided in groups to receive the different treatments, namely DON administered in diet (50 μg/kg BW), FOS administered into the drinking water (30 mg/kg BW), CSE administered in diet (15 mg/kg BW) and all their combinations. After 15 d, the animals were euthanized and gastrointestinal tract samples were immediately taken to evaluate gastrointestinal pH, Enterobacteriaceae to lactic acid bacteria (E:L) ratio, volatile fatty acid (VFA) concentrations, disaccharidase (lactase, sucrase and maltase) activity, histology (intestinal absorptive area [IAA] and goblet cells count) and mucus ability to adhere pathogenic Escherichia coli. From our results, FOS and CSE treatments, individually or combined, produced a lower E:L ratio, an enhanced production of butyrate, increased disaccharidase activity (particularly maltase), and a greater IAA and goblet cells count along with an increase in pathogenic bacteria adherence to intestinal mucus. Deoxynivalenol did not show interactions with the other factors and its administration produced decreases on VFA, disaccharidase activity and goblet cells count. In conclusion, weaning piglets receiving diets containing FOS, CSE or both exhibited evident beneficial intestinal effects compared to animals receiving diets free from these compounds. On the contrary, the presence of DON at sub-toxic concentrations produced detrimental effects on intestinal health. The knowledge of the physiological and pathological gut changes produced by these compounds contributes to understand their potential productive consequences.Fil: Martínez, Guadalupe. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigación Veterinaria de Tandil. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigación Veterinaria de Tandil. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Centro de Investigación Veterinaria de Tandil; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencia Veterinarias. Departamento de Fisiopatología. Laboratorio de Toxicología; ArgentinaFil: Dieguez, Susana Nelly. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigación Veterinaria de Tandil. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigación Veterinaria de Tandil. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Centro de Investigación Veterinaria de Tandil; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencia Veterinarias. Departamento de Fisiopatología. Laboratorio de Toxicología; ArgentinaFil: Fernández Paggi, María Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigación Veterinaria de Tandil. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigación Veterinaria de Tandil. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Centro de Investigación Veterinaria de Tandil; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencia Veterinarias. Departamento de Fisiopatología. Laboratorio de Toxicología; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Veterinarias. Departamento de Producción Animal; ArgentinaFil: Riccio, Maria Belen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigación Veterinaria de Tandil. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigación Veterinaria de Tandil. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Centro de Investigación Veterinaria de Tandil; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencia Veterinarias. Departamento de Fisiopatología. Laboratorio de Toxicología; ArgentinaFil: Pérez, Denisa Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigación Veterinaria de Tandil. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigación Veterinaria de Tandil. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Centro de Investigación Veterinaria de Tandil; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencia Veterinarias. Departamento de Fisiopatología. Laboratorio de Toxicología; ArgentinaFil: Rodriguez, Edgardo Mario. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Veterinarias. Departamento de Sanidad Animal y Medicina Preventiva; ArgentinaFil: Amanto, Fabian Andres. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Veterinarias. Departamento de Producción Animal; ArgentinaFil: Tapia, Maria Ofelia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigación Veterinaria de Tandil. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigación Veterinaria de Tandil. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Centro de Investigación Veterinaria de Tandil; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencia Veterinarias. Departamento de Fisiopatología. Laboratorio de Toxicología; ArgentinaFil: Soraci, Alejandro Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigación Veterinaria de Tandil. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigación Veterinaria de Tandil. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Centro de Investigación Veterinaria de Tandil; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencia Veterinarias. Departamento de Fisiopatología. Laboratorio de Toxicología; Argentin

A missing high-spin molecule in the family of cyano-bridged heptanuclear heterometal complexes, [(LCuII)6FeIII(CN)6]3+, and its CoIII and CrIII analogues, accompanied in the crystal by a novel octameric water cluster

Three isostructural cyano-bridged heptanuclear complexes, [{CuII(saldmen)(H2O)}6{MIII(CN)6}](ClO4)3$\cdotp$8H2O (M = FeIII 2; CoIII, 3; CrIII 4), have been obtained by reacting the binuclear copper(II) complex, [Cu2(saldmen)2(mu-H2O)(H2O)2](ClO4)2$\cdotp$2H2O 1, with K3[Co(CN)6], K4[Fe(CN)6], and, respectively, K3[Cr(CN)6] (Hsaldmen is the Schiff base resulted from the condensation of salicylaldehyde with N,N-dimethylethylenediamine). A unique octameric water cluster, with bicyclo[2,2,2]octane-like structure, is sandwiched between the heptanuclear cations in 2, 3 and 4. The cryomagnetic investigations of compounds 2 and 4 reveal ferromagnetic couplings of the central FeIII or CrIII ions with the CuII ions (JCuFe = +0.87 cm-1, JCuCr = +30.4 cm-1). The intramolecular Cu-Cu exchange interaction in 3, across the diamagnetic cobalt(III) ion, is -0.3 cm-1. The solid-state1H-NMR spectra of compounds 2 and 3 have been investigated

Role of Folic Acid in the Therapeutic Action of Nanostructured Porous Silica Functionalized with Organotin(IV) Compounds against Different Cancer Cell Lines

The synthesis, characterization and cytotoxic activity against different cancer cell lines of various mesoporous silica-based materials containing folate targeting moieties and a cytotoxic fragment based on a triphenyltin(IV) derivative have been studied. Two different mesoporous nanostructured silica systems have been used: firstly, micronic silica particles of the MSU-2 type and, secondly, mesoporous silica nanoparticles (MSNs) of about 80 nm. Both series of materials have been characterized by different methods, such as powder X-ray diffraction, X-ray fluorescence, absorption spectroscopy and microscopy. In addition, these systems have been tested against four different cancer cell lines, namely, OVCAR-3, DLD-1, A2780 and A431, in order to observe if the size of the silica-based systems and the quantity of incorporated folic acid influence their cytotoxic action. The results show that the materials are more active when the quantity of folic acid is higher, especially in those cells that overexpress folate receptors such as OVCAR-3 and DLD-1. In addition, the study of the potential modulation of the soluble folate receptor alpha (FOLR1) by treatment with the synthesized materials has been carried out using OVCAR-3, DLD-1, A2780 and A431 tumour cell lines. The results show that a relatively high concentration of folic acid functionalization of the nanostructured silica together with the incorporation of the cytotoxic tin fragment leads to an increase in the quantity of the soluble FOLR1 secreted by the tumour cells. In addition, the studies reported here show that this increase of the soluble FOLR1 occurs presumably by cutting the glycosyl-phosphatidylinositol anchor of membrane FR-α and by the release of intracellular FR-α. This study validates the potential use of a combination of mesoporous silica materials co-functionalized with folate targeting molecules and an organotin(IV) drug as a strategy for the therapeutic treatment of several cancer cells overexpressing folate receptors.Spanish Government RTI2018-094322-B-I00 CTQ2017-90802-REDTMinistry of Research and Innovation, CNCS-UEFISCDI within PNCDI III PN-III-P4-ID-PCCF-2016-014

P07-05. HIV and STI prevalence among men who have sex with men (MSM) recruited through respondent driven sampling (RDS) in Buenos Aires, Argentina

Fil: Pando, María A. Centro Nacional de Referencia para el SIDA; Argentina.Fil: Marone, Rubén. Nexo Asociación Civil; Argentina.Fil: Balán, Iván C. Columbia University. HIV Center for Clinical and Behavioral Studies; Estados Unidos.Fil: Dolezal, Curtis. Columbia University. HIV Center for Clinical and Behavioral Studies; Estados Unidos.Fil: Squiquera, Luis. Nexo Asociación Civil; Argentina. Fil: Balan, Iván C. Columbia University. HIV Center for Clinical and Behavioral Studies; Estados Unidos.Fil: Picconi, María Alejandra. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Servicio Virus Oncogénicos; Argentina.Fil: Gonzales, J. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Servicio Virus Oncogénicos; Argentina.Fil: Rey, Jorge. Hospital de Clínicas José de San Martín; Argentina.Fil: Fernandez Toscano, M. Hospital de Clínicas José de San Martín; Argentina.Fil: Rodriguez Fermepín, Marcelo. UBA. Laboratorio de Inmunología Clínica; Argentina.Fil: Gallo Vaulet, Lucia. UBA. Laboratorio de Inmunología Clínica; Argentina.Fil: Carballo Dieguez, Alex. Columbia University. HIV Center for Clinical and Behavioral Studies; Estados Unidos.Fil: Avila, María M. Centro Nacional de Referencia para el SIDA; Argentina.Background MSM constitute one of the populations most affected by HIV and other STIs in Argentina. Previous prevalence studies were based on convenience samples. RDS, a methodology designed to access hidden populations, is being used for the first time in Argentina to recruit MSM. Methods RDS recruitment started in November 2007 with 16 first generation participants (seeds) who were selected for their potential to tap in MSM networks. Recruitment is ongoing. Men must be 18 years of age or older, be residents of Buenos Aires, self-report having sex with men at least 10 times in their lives and at least once in the past six months. They must have a coupon indicating they have been referred by a study participant. Specimens are being collected for HIV and STI diagnosis. All data are weighted using the RDS Analysis Tool (RDSAT). Results To date, 333 MSM were recruited through RDS showing a prevalence of 11.3, 16.6, 7.9, 17.6, 4.0 and 88.3% for HIV, HBV, HCV, T. pallidum, Chlamydia and HPV, respectively. Chlamydia and HPV diagnoses were only performed in 73 and 79 participants, respectively. Among HPV positive individuals, 47.8% had almost one of these high risk types (16, 58, 33, 45, 18 and 31) and 32% had multiple infections with 2 or more types. Conclusion Compared with previous studies, these results show similar HIV, HBV and T. pallidum prevalences but higher HCV prevalence. For the first time, an elevated prevalence of HPV was detected on MSM, with high frequency of types associated with ano-genital cancer. Preliminary analyses of socio demographic data show that RDS helps recruit a diversity of MSM, particularly of lower socio-economic level usually missed with other recruitment methods. The high prevalence of coinfections in this population should be taken into account if MSM are part of vaccine trials given that STI may increase HIV sexual transmission