Macroplastic and Microparticle Pollution in Beach Sediments from Urias Coastal Lagoon (Northwest Mexico).

This study investigates the occurrence and characteristics of macroplastic and polymer microparticles in the Urias coastal lagoon's beach sediments, in northwest Mexico. Coastal lagoons, productive and vulnerable ecosystems, are impacted significantly by anthropogenic activities, leadings to their pollution by various contaminants, including plastics. Our research involved sampling sediments from four sites within the lagoon that were influenced by different human activities such as fishing, aquaculture, thermoelectric power plant operations, industrial operations, and domestic wastewater discharge. Our methodology included collecting macroplastics and beach sediment samples, followed by laboratory analyses to identify the plastic debris' size, shape, color, and chemical composition. The results indicated a notable presence of macroplastic items (144), predominantly bags, styrofoam, and caps made of polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET). The polymer microparticles were mainly fibers, with cotton and polyester as the most common polymers, suggesting a significant contribution from clothing-related waste. The dominant colors of the microparticles were blue and transparent. High densities were observed in areas with slower water exchange. Our findings highlight the urgent need for better waste management practices to mitigate plastic pollution in coastal lagoons, preserving their ecological and economic functions.

Interactive effects of palladium (Pd) and microplastics (MPs) on metal bioaccumulation and biological responses in the Mediterranean mussel, Mytilus galloprovincialis.

This study investigates the potential of MPs as carriers of pollutants as they can strengthen bioaccumulation of toxic metals on marine organisms. For the first time, the interaction of the metal palladium (Pd) with the widespread MPs, both with increasing concentrations in water environments from anthropogenic sources, was tested. Mytilus galloprovincialis, an important seafood product, was exposed to Pd (24 h) in two ways: water-dissolved and MPs-adsorbed, with depuration followed for 144 h. Quantification of Pd in tissues shown an accumulation 2-3 times higher (59 % of initial Pd) for mussels exposed to MPs-adsorbed Pd and higher in digestive gland than when exposed to water-dissolved Pd (25 %; higher in gills). Additionally, it was demonstrated that Pd induced oxidative stress and altered the feeding behavior of mussels. Therefore, this work support MPs as being vectors of metals (i.e. Pd) to enhance their bioaccumulation on marine organisms which highlights ecological risk of these emerging pollutants.

First insight into microplastic groundwater pollution in Latin America: the case of a coastal aquifer in Northwest Mexico.

Microplastics have been studied on biota and other environmental domains, such as soils. Despite the importance of groundwater as a resource for millions of people worldwide as drinking water and personal hygiene, domestic, agricultural, mining, and industrial purposes, there are very few studies concerning microplastics in this domain around the world. We present the first study in Latin America addressing this topic. Six capped boreholes were analyzed in terms of abundance, concentration, and chemical characterization, at three different depths, from a coastal aquifer in Northwest Mexico. This aquifer is highly permeable and affected by anthropogenic activities. A total of 330 microplastics were found in the eighteen samples. In terms of concentration, the interval ranged from 10 to 34 particles/L, with an average of 18.3 particles/L. Four synthetic polymers were identified: isotactic polypropylene (iPP), hydroxyethylcellulose (HEC), carboxylated polyvinyl chloride (PVC), and low-density polyethylene (LDPE); with iPP being the most abundant (55.8%) in each borehole. Agriculture activities and septic outflows are considered the potential regional sources of these contaminants into the aquifer. Three possible transport pathways to the aquifer are suggested: (1) marine intrusion, (2) marsh intrusion, and (3) infiltration through the soil. More research about the occurrence, concentration, and distribution of the different kinds of microplastics in groundwater is needed to have a better understanding of the behavior and health risks to organisms, including human beings.

Effect of Phytase Level and Form on Broiler Performance, Tibia Characteristics, and Residual Fecal Phytate Phosphorus in Broilers from 1 to 21 Days of Age.

The present study evaluated the individual and combined effects of coated and uncoated phytase on broiler performance, tibia characteristics, and residual phytate phosphorus (P) in manure. Two repeated studies were conducted using 240-day-old Cobb 500 by-product male broilers per trial. For each trial, birds were assigned to four treatments with four replicate battery cages per treatment (60 birds/trt) and grown for 21 days. Treatments included: (1) negative control (NC), (2) NC + 1000 phytase units (FTU) coated phytase (C), (3) NC + 1000 FTU uncoated phytase (U), and (4) NC + 500 FTU coated + 500 FTU uncoated phytase (CU). Data were analyzed with a one-way ANOVA and means were separated using Tukey's HSD. In the pooled data for both trials, all treatments with dietary phytase had a higher body weight (BW) and feed consumption (FC) than the NC on day 21 (p < 0.05). Similarly, a six-point reduction was observed for day 1 to 21 feed conversion (FCR) for U and CU (p < 0.05). All treatments with phytase inclusion differed from the NC in every evaluated parameter for bone mineralization (p < 0.05) and had significantly lower fecal phytate P concentrations compared to the NC (p < 0.05). Overall, bird performance was essentially unaffected by phytase form, indicating that combining phytase forms does not appear to offer any advantage to the evaluated parameters from day 1 to 21.

Microplastics in the tissues of commercial semi-intensive shrimp pond-farmed Litopenaeus vannamei from the Gulf of California ecoregion.

The omnipresence of microplastics (MPs) in marine and coastal environments has attracted attention owing to their effects on various organisms, including humans. We present the first study of MPs in the gastrointestinal tract (GT), gills (GI), and exoskeleton (EX) of the farmed whiteleg shrimp Litopenaeus vannamei from commercial aquaculture facilities in northwestern Mexico that have operated semi-intensively for the last two decades. We found that the number of MP items per tissue was 7.6 ± 0.6 in the GT, 6.3 ± 0.9 in the GI, and 4.3 ± 0.9 in the EX, with an average of 18.5 ± 1.2 MP items per shrimp (1.06 items/g, wet weight [ww]). MP concentrations were 261.7 ± 84.5, 13.1 ± 1.8, and 2.6 ± 0.6 items/g (ww) in the GT, GI, and EX, respectively. Microplastics ranged from 30 to 2800 µm in size (360 ± 39 µm) with fibers (∼90.8%), filament-shape (∼93.4%), and transparent (∼47.7%) being the most common ones. Polyethylene (∼54.5%) and polyamide (∼24.2%) were the most commonly identified polymers, although polyesters (∼12.1%), polystyrene (∼6.1%), and nylon (∼3.0%) were also found. The abundance of MPs in farmed L. vannamei may be related to their feeding habits and the availability of MP sources in aquaculture facilities.

Subtotal content and geochemical fractionation of potential toxic elements in agricultural soils from Mocorito River basin in NW Mexico: environmental and health implications.

Agricultural soils were collected from Mocorito river basin, to determine potentially toxic elements (PTEs) subtotal concentrations and geochemical fractionation, and evaluate their environmental and health risks. All sites showed low As and Cr concentrations. Subtotal concentrations (mg/kg) ranged between 6.8 and 25.6 for As, 1.9 and 2.5 for Cd and 22.5 and 55.1 for Cr. These values were classified as moderately contaminated for As, while a considerable contamination was presented for Cd and Cr. Geochemical partitioning revealed that PTEs are strongly linked with residual phase. Arsenic was associated with amorphous Fe-oxyhydroxides. Ecotoxicological indices showed from low (As and Cr) to considerable (Cd) potential ecological risk factors; potential non-carcinogenic risks by As, Cd and Cr, and potential carcinogenic risks by As and Cr. Lithogenic and anthropogenic sources were identified. Arsenic and Cr showed lithogenic influence, while Cd increased, caused by nearby activities, representing an environmental and health risk.

The urban contrast: A nationwide assessment of avian diversity in Mexican cities.

In this study we focused on urban bird diversity across Mexico, a megadiverse country, with a special focus on the relative role of urban greenspaces and heavily-built sites. We considered a country-wide approach, including 24 different sized Mexican cities. Our aims were to describe the urban bird diversity in focal cities and further assess the relationships between it and the biogeographic region where cities are located, their size, elevation, and annual rainfall. Additionally, we evaluated differences in the functional composition of bird communities in both studied urban scenarios (i.e., urban greenspaces, heavily-built sites). Our results confirm that urban greenspaces are home to a large proportion of species when contrasted with heavily-built sites. While total species richness and species richness of greenspaces were related with the cities' biogeographic region -with higher species richness in the Neotropical region and Transition Zone-, the relationship did not hold true in heavily-built sites. We found that annual rainfall was negatively related to bird richness in heavily-built sites, suggesting that species from arid systems can be more tolerant to urbanization. Regarding the bird functional group assessment, results show a clear differentiation between the functional groups of greenspaces and those of heavily-built sites, with granivores and omnivores associated with the latter and a highly diverse array of functional groups associated with urban greenspaces.

Inorganic elements in live vs dead nesting olive ridley marine turtles in the Mexican Pacific: Introducing a new statistical methodology in ecotoxicology.

This study reports the largest inorganic elements database in the blood of live marine turtles (Lepidochelys olivacea), with 241 live as well as 38 dead nesting turtles sampled and analyzed for 26 inorganic elements, including essential (Al, As, B, Ca, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, P, Se, S, V, and Zn) and non-essential elements (Cd, Li, Pb, Sr, Ti, Tl, and Hg). We compared inorganic element concentrations in live and dead olive ridleys from the arribada beach "La Escobilla" located on the Pacific coast of southeastern Mexico. The most outstanding result of our study is the higher Cd concentration in dead (mean 4.27 µg g-1 ww: min 0.01-max 81.5) compared with live animals (mean 0.14 µg g-1 ww: min 0.02-max 0.52). This population has been previously reported to have the highest Cd concentration worldwide in kidney and liver samples from marine turtles (with 150.88 ±â€¯110.99 and 82.88 ±â€¯36.65 µg g-1 ww, respectively). Other important findings of this study include the low Hg concentration along with the decrease in Pb over the years in this population. The study also uses a new statistical method - the iconography of correlations - in which all available information is used without removing individuals or variables with missing information for the whole analysis, which is a common problem in ecotoxicology. A major advantage of this method compared to other multivariate methods is that the missing information can be easily handled, because the correlations (2 variables) and partial correlations (3 variables) are estimated only with the available data using a one-at-a-time strategy.

Mercury interactions with algal and plastic microparticles: Comparative role as vectors of metals for the mussel, Mytilus galloprovincialis.

The adsorption and desorption of Hg onto and from microplastics (MP) and microalgae (MA) were investigated, and fitted using pseudo-first-order and pseudo-second order kinetics models. Then, the potential role of MP as vector for the entrance and accumulation of Hg (MP-Hg) in comparison to natural pathways (via MA -MA-Hg-, and dissolved -WB-Hg-) was investigated in mussel. Mussels were exposed to a single dose of Hg (2375 ng ind-1) for 4 h. Although the clearance of MP-Hg was relevant (82 %), it was lower than that of MA (95 %) and MA-Hg (94 %). The amount of the Hg accumulated and eliminated was higher in mussels exposed to MP-Hg (1417 ng Hg) than in those exposed to MA-Hg (882 ng Hg) and WB-Hg (1074 ng Hg). However, Hg accumulation was similar in the three mussel groups (≈800 ng Hg). This was related to the fast elimination of Hg still attached to MP by MP-Hg mussels. Hg was mainly accumulated in digestive gland in MA-Hg and MP-Hg mussels, and in gills in WB-Hg mussels. Overall, the results indicated that MP facilitated the entrance of Hg in mussel but also promoted Hg elimination, which could limit the toxicological risk of Hg adsorbed onto MP.

Biodynamics of mercury in mussel tissues as a function of exposure pathway: natural vs microplastic routes.

In the marine environment, metals can be present dissolved or adsorbed to suspended particles. In the last decades a new type of particle has been introduced, microplastics (MPs). The exposure route of pollutants influences their accumulation and distribution into tissues. A pulse-chase experiment was conducted in which mussels were exposed to Hg: adsorbed onto MPs and microalgae (MA) and dissolved (WB). Mussels accumulated the same amount of Hg independently of particle, due to the Hg loading in both particles and their acceptability were similar. The highest Hg accumulation occurred in gill when the Hg exposure was through water and in digestive gland when Hg was adsorbed to particles. More than 70% of the Hg uptake through MPs was quickly eliminated due to: i) part of the cleared MPs might not really be ingested but adhered to body surfaces of mussels, ii) MPs ingested were eliminated through faeces as they are non-nutritive particles which may be rejected in stomach preventing their entry into digestive gland and iii) high affinity of Hg on surface of MPs which meant that Hg was mainly eliminated jointly to MPs. The organic nature of MA facilitates the entry of Hg into digestive gland where MA are intracellularly digested releasing the Hg adsorbed onto their surfaces. In this case, Hg may reach deeper levels by translocation of the Hg incorporated into gland towards foot and remaining tissues, a process that might occur through haemolymph. All of the Hg accumulated in WB during the exposure was internally absorbed into tissues, and later translocated from gill to gland. Although Hg elimination rate in MPs mussels was greater than in the other exposure pathways, an important amount of Hg was maintained through the depuration period, thus we cannot and should not neglect the risk of MPs as vectors for mercury.

Resonancia magnética en el cáncer de mama tratado con neoadyuvancia: correlación radiopatológica de la respuesta / Magnetic resonance in breast cancer treated with neoadyuvant therapy: Radiopathological correlation of response

Objetivo: La quimioterapia neoadyuvante (QTN) es una modalidad de tratamiento fundamental en el cáncer de mama (CM). El objetivo de este estudio es analizar las respuestas radiológica (RR) y patológica (RP) de pacientes con CM sometidas a QTN, estudiar su concordancia y las variables relacionadas con dichas respuestas. Pacientes y métodos: Se incluyen 63 pacientes tratadas con QTN en las que se evaluó la RR con RM pre y post-QTN, y la RP, mediante la clasificación de Miller y Payne, tanto para la enfermedad mamaria como para la axilar. Se realizó un análisis univariante y multivariante de las variables clinicopatológicas para la RR y RP, así como un análisis de concordancia entre respuestas. Resultados: Los porcentajes de respuesta fueron del 52,4% para RR, del 63,5% para RP local y del 57,2% para RP axilar. Resultaron factores predictivos independientes de la RR: un BRCA+ y el tipo de curva en la RM post-QTN. El único factor predictivo para la RP en la mama fue el realce tumoral en la RM post-QTN y para la RP axilar: realizar la BSGC y receptores hormonales negativos. Aunque se identifica correlación entre RR y RP, esta solo fue significativa en la enfermedad axilar. Conclusiones: Existen factores predictivos de RR, RP en mama y RP axilar que hacen útil el uso de la RM en la valoración de la QTN. La concordancia entre RR y RP fue mayor a nivel axilar

Aim: Neoadjuvant chemotherapy (NAC) is a fundamental treatment in breast cancer (BC). The objective of this study was to analyse the radiological response (RR) and pathological response (PR) of patients with BC by studying the agreement between RR and PR and response-related variables. Patients and methods: The study included 63 patients treated with NAC. We evaluated RR with pre- and post-CT MRI and PR by the Miller and Payne classification, both for breast and axillary disease. Univariate and multivariate analyses of the clinicopathological variables for RR and PR were carried out, as well as an analysis of the concordance between responses. Results: The response rates were 52.4% for RR, 63.5% for local PR and 57.2% for axillary PR. Independent predictive factors of RR were BRCA positivity and the type of curve post-NAC on MRI. The only independent predictor of PR in the breast was tumor enhancement post-NAC on MRI, while independent predictors of axillary PR were performing SSNB and negative hormone receptors. Although there was a correlation between RR and PR, it was only significant in axillary disease. Conclusions: This study found predictive factors of RR, PR in the breast and axillary PR and consequently RMI is useful in the assessment of NAC. The concordance between RR and PR was greater in the axilla

Progreso de la educación médica en la región central de Cuba / Progress of medical education in the central region of Cuba

Fundamento: la Revolución cubana inició la descentralización de los estudios de Medicina en las universidades de Santiago de Cuba y Santa Clara. Objetivo: caracterizar el desarrollo de la educación médica en la región central en sus 50 años de existencia. Métodos: se realizó una investigación documental en la Universidad de Ciencias Médicas deVilla Clara, durante enero-mayo de 2016. Para ello se utilizaron métodos teóricos: histórico-lógico, análisis-síntesis e inducción-deducción; y empíricos: análisis de documentoshistóricos: informes, manuales, artículos periodísticos y expedientes.Resultados: estos 50 años han permitido identificar varias etapas históricas con características muy peculiares, entre ellas: génesis de los estudios médicos en la regióncentral (1960-1966), desarrollo de la Escuela de Medicina (1966-1973) y de la Facultad de Medicina (curso 1972-1973 hasta 1975), inicio de la enseñanza de las ciencias básicasbiomédicas y creación del Instituto Superior de Ciencias Médicas (1975-1981), ampliación dela formación de profesionales de la salud y principales logros (1985-1989), enfrentamiento al período especial (1991-1999), la Escuela Latinoamericana de Medicina, sus inicios en el curso 2001-2002, el proceso de universalización de la enseñanza; y una última, desde 2014-2015 hasta la actualidad. Conclusiones: la educación médica en la región central y después en Villa Clara harespondido a los cambios históricos, sociales y académicos del país; en todas sus etapas se perciben sus avances, concretados en el progresivo número de graduados, sus logros y el ajuste a las transformaciones emanadas de sus procesos universitarios(AU)

Strong Acid Mixture and Sequential Geochemical Arsenic Extractions in Surface Sediments from the Santa Maria La Reforma Coastal Lagoon, Mexico: A Bioavailability Assessment.

Thirty-three sediment samples were collected from the Santa Maria La Reforma coastal lagoon and digested by way of a strong acid mixture and sequential arsenic (As)-extraction method to determine the arsenic (As) content and bioavailability. The As content was determined by atomic fluorescence spectrometry. In addition, grain-size analyses were performed, and organic carbon, carbonate, and iron (Fe) and manganese (Mn) concentrations were determined. Fe and Mn determination was performed by atomic absorption spectroscopy. A Pearson correlation matrix and As enrichment factors were calculated. Sediment concentrations from Santa Maria La Reforma ranged from 3.6 to 25 µg As g(-1) with an average of 13.4 ± 7.6 µg As g(-1). The highest values were observed in the northern (Playa Colorada), north-central (Mocorito River discharge zone), and southern zones ("El Tule" agricultural drain). Most samples were classified as exhibiting no or minor As enrichment and were lower than the threshold effect level (TEL; 7.24 µg g(-1)) for biota (MacDonald et al. in Ecotoxicology 5:253-278, 1996). Low bioavailable As values (<3 %) were measured in the majority of the sediment. The highest As percentages were associated with the oxyhydroxide fraction (F5). The results indicate that As bioavailability is negligible.

Integración del sistema de salud cubano: hecho relevante para el desarrollo de la docencia médica / The integration of the Cuban health system: A relevant event for the development of the medical teaching

Fundamento: se abordaron las acciones emprendidas por el Gobierno Revolucionario cubano para la organización de un sistema que integrase las actividades relacionadas con la salud pública y eliminase la fragmentación existente, incluyendo la docencia médica. Objetivo: precisar las particularidades y hechos relevantes que caracterizaron el proceso de integración del sistema de salud cubano, desde el punto de vista docente-asistencial-investigativo, hasta la creación del sistema único de salud.Métodos: se realiza una investigación documental y entrevistas a informantes clave que brindaron información sobre la temática, además se emplean métodos teóricos que permitieron el análisis del objeto de estudio sustentado en la interacción de lo histórico y lo lógico. Se efectúa la triangulación metodológica para arribar a consideraciones integradoras.Resultados: no existió una clara política de integración del sistema de salud cubano entre 1959 y 1961, la integración interna se inicia al dictarse las leyes 958 y 959 en agosto de 1961, las cuales sentaron las bases legales para su desarrollo. A partir de 1962 se desarrolla este proceso, que concluye en 1970 con la integración total del mutualismo, la industria farmacéutica y la docencia médica media, unido a la declinación del subsistema privado y las estrechas relaciones con las universidades para la formación médica.Conclusiones: se abordó la integración del Sistema Nacional de Salud, entre 1959 y 1970. Se precisa que la integración se hizo realidad a partir de 1962, de forma paulatina, hasta concretarla a principios de la década de 1970(AU)

Comisión Territorial de Grados Científicos: su contribución al desarrollo doctoral en la provincia Villa Clara / The territorial commission of scientific degree: its contribution to the development of Ph. Ds. in Villa Clara Province

Fundamento: la formación doctoral en el área de las ciencias médicas es una condición necesaria para contribuir al desarrollo científico-tecnológico, la solución de importantes problemas de salud y el mejoramiento de los procesos que se desarrollan, de forma tal que se eleve la calidad de la atención médica, tanto en el sentido técnico, como en la satisfacción de los usuarios. Objetivo: identificar hechos relevantes que distinguieron la organización y desarrollo de la Comisión Territorial de Grados Científicos en la Universidad de Ciencias Médicas de Villa Clara.Métodos: se realizó una investigación documental de corte histórico durante el año 2014, se emplearon métodos teóricos que permitieron el análisis del objetivo de estudio, sustentado en la interacción de lo histórico y lo lógico y desde las dimensiones temporal y espacial; y empíricos: el análisis documental y entrevistas a informantes clave; se efectuó triangulación metodológica para arribar a consideraciones integradoras.Resultados: se abordaron algunos antecedentes históricos de la formación doctoral en el territorio, el desarrollo de la política de descentralización, el surgimiento de la Comisión Territorial de Grados Científicos y su consolidación como organismo rector para el desarrollo de estos procesos biomédicos, en la región central y específicamente en Villa Clara.Conclusiones: la fundación de la Comisión Territorial de Grados Científicos representó un paso de avance en la formación doctoral del territorio central y particularmente en Villa Clara, que ha tenido el mayor incremento de Doctores en Ciencias en los últimos 4 años(AU)

Hepatitis C virus infection in patients and family members attending two primary care clinics in Puebla, Mexico.

BACKGROUND: Approximately 180 million persons (~2.8%) globally are estimated to be infected by hepatitis C virus (HCV). HCV prevalence in Mexico has been estimated to be between 1.2 and 1.4%. The aim of present work was to determine the prevalence of HCV infection in patients and family members attending two primary care clinics in Puebla, Mexico. MATERIAL AND METHODS: Patients and their accompanying family members in two clinics were invited to participate in this study between May and September 2010. RESULTS: A total of 10,214 persons were included in the study; 120 (1.17%) persons were anti-HCV reactive. Of the reactive subjects, detection of viral RNA was determined in 114 subjects and 36 were positive (31%). The more frequent risk factors were having a family history of cirrhosis (33.1%) and having a blood transfusion prior to 1995 (29%). After a multiple logistic regression analysis only transfusion prior to 1995 resulted significant to HCV transmission (p = 0.004). The overall detected HCV genotypes were as follows: 1a (29%), 1b (48.5%), 2/2b (12.8%), and 3a (6.5%). CONCLUSION: The HCV prevalence in this population is in agreement with previous studies in other regions of Mexico.

Geosorption of As(III) from aqueous solution by red clays: kinetic studies.

The geosorption of As(III) on red clays from aqueous solution under different environmental conditions (i.e. initial concentration, pH and temperature) was studied. This process reached its equilibrium quickly (<120 min). A decrease of the percentage of adsorption was caused when the initial concentration was increased (0.1-10 mg As(III) L(-1)), in all the experimental pH levels (4-10). The optimal pH value for adsorption on red clays at 0.1 mg As(III) L(-1) was 10, while for 10 mg As(III) L(-1) was 4. There wasn't a significant effect of temperature on the As(III) adsorption. The kinetic pseudo-second order and the isothermal Langmuir were the models that best described the experimental data, suggesting an adsorption process in multistep. Likewise, there are not interactions between neighbor active sites on the red clay surface.

Periodización de la Salud Pública Cubana (1959-2009) / Periodization of the Cuban Public Health (1959-2009)

Este trabajo forma parte de una investigación histórica sobre el desarrollo de la Salud Pública cubana, llevada a cabo por el autor, y que ha sido publicada como libro de texto. Se realizó una revisión sobre la evolución del sistema de salud, que permitió enmarcar en cuatro etapas los 50 años estudiados; se argumentaron los hechos que fundamentan su existencia y sus características, entre los años 1959 y 2009

This paper is part of a historical research done by the author about the development of the CubanPublic Health, which has been published as a text book. It was performed a reviewing of theevolution of the health system, that allowed us to focus in four stages the 50 years studied;besides, there were argued the facts that corroborate its existence and characteristics between1959 and 2009.

Periodización de la Salud Pública Cubana (1959-2009) / Periodization of the Cuban Public Health (1959-2009)

Este trabajo forma parte de una investigación histórica sobre el desarrollo de la Salud Pública cubana, llevada a cabo por el autor, y que ha sido publicada como libro de texto. Se realizó una revisión sobre la evolución del sistema de salud, que permitió enmarcar en cuatro etapas los 50 años estudiados; se argumentaron los hechos que fundamentan su existencia y sus características, entre los años 1959 y 2009(AU)