Nitrogen sources differentially affect respiration, growth, and carbon allocation in Andean and Lowland ecotypes of Chenopodium quinoa Willd.

Chenopodium quinoa Willd. is a native species that originated in the High Andes plateau (Altiplano) and its cultivation spread out to the south of Chile. Because of the different edaphoclimatic characteristics of both regions, soils from Altiplano accumulated higher levels of nitrate (NO3-) than in the south of Chile, where soils favor ammonium (NH4 +) accumulation. To elucidate whether C. quinoa ecotypes differ in several physiological and biochemical parameters related to their capacity to assimilate NO3- and NH4 +, juvenile plants of Socaire (from Altiplano) and Faro (from Lowland/South of Chile) were grown under different sources of N (NO3- or NH4 +). Measurements of photosynthesis and foliar oxygen-isotope fractionation were carried out, together with biochemical analyses, as proxies for the analysis of plant performance or sensitivity to NH4 +. Overall, while NH4 + reduced the growth of Socaire, it induced higher biomass productivity and increased protein synthesis, oxygen consumption, and cytochrome oxidase activity in Faro. We discussed that ATP yield from respiration in Faro could promote protein production from assimilated NH4 + to benefit its growth. The characterization of this differential sensitivity of both quinoa ecotypes for NH4 + contributes to a better understanding of nutritional aspects driving plant primary productivity.

Transport of Vitamin C in Cancer.

Significance: Vitamin C is a powerful antioxidant that has an intricate relationship with cancer and has been studied for more than 60 years. However, the specific mechanisms that allow malignant cells to uptake, metabolize, and compartmentalize vitamin C remain unclear. In normal human cells, two different transporter systems are responsible for its acquisition: glucose transporters (GLUTs) transport the oxidized form of vitamin C (dehydroascorbic acid) and sodium-coupled ascorbic acid transporters (SVCTs) transport the reduced form (ascorbic acid [AA]). In this study, we review the mechanisms described for vitamin C uptake and metabolization in cancer. Recent Advances: Several studies performed recently in vivo and in vitro have provided the scientific community a better understanding of the differential capacities of cancer cells to acquire vitamin C: tumors from different origins do not express SVCTs in the plasma membrane and are only able to acquire vitamin C in its oxidized form. Interestingly, cancer cells differentially express a mitochondrial form of SVCT2. Critical Issues: Why tumors have reduced AA uptake capacity at the plasma membrane, but develop the capacity of AA transport within mitochondria, remains a mystery. However, it shows that understanding vitamin C physiology in tumor survival might be key to decipher the controversies in its relationship with cancer. Future Directions: A comprehensive analysis of the mechanisms by which cancer cells acquire, compartmentalize, and use vitamin C will allow the design of new therapeutic approaches in human cancer. Antioxid. Redox Signal. 35, 61-74.

Isotopic niche partitioning in two sympatric howler monkey species.

OBJECTIVES: Ecological similarity between species can lead to interspecific trophic competition. However, when ecologically similar species coexist, they may differ in foraging strategies and habitat use, which can lead to niche partitioning. As the body tissues of consumers contain a stable isotope signature that reflects the isotopic composition of their diet, stable isotope analysis is a useful tool to study feeding behavior. We measured the isotopic niche width, which is a proxy for trophic niche width, of mantled (Alouatta palliata) and black (A. pigra) howler monkeys. Specifically, studied populations in allopatry and sympatry to assess whether these species showed niche partitioning. MATERIALS AND METHODS: Between 2008 and 2012, we collected hair samples from 200 subjects (113 black and 87 mantled howler monkeys) and used continuous flow isotope ratio mass spectrometry to estimate δ13 C and δ15 N. We described the isotopic niche width of each species in allopatry and sympatry with the Bayesian estimation of the standard ellipse areas. RESULTS: In allopatry, isotopic niche width and isotopic variation were similar in both species. In sympatry, black howler monkeys had a significantly broader isotopic niche, which was mainly determined by high δ15 N values, and included the majority of mantled howler monkeys' isotopic niche. The isotopic niche of mantled howler monkeys did not differ between sympatry and allopatry. CONCLUSIONS: The coexistence of these ecologically similar species may be linked to trophic niche adjustments by one species, although the particular features of such adjustments (e.g., dietary, spatial, or sensory partitioning) remain to be addressed.

Aggregation of α- and ß- caseins induced by peroxyl radicals involves secondary reactions of carbonyl compounds as well as di-tyrosine and di-tryptophan formation.

The present work examined the role of Tyr and Trp in oxidative modifications of caseins, the most abundant milk proteins, induced by peroxyl radicals (ROO•). We hypothesized that the selectivity of ROO• and the high flexibility of caseins (implying a high exposure of Tyr and Trp residues) would favor radical-radical reactions, and di-tyrosine (di-Tyr) and di-tryptophan (di-Trp) formation. Solutions of α- and ß-caseins were exposed to ROO• from thermolysis and photolysis of AAPH (2,2'-azobis(2-methylpropionamidine)dihydrochloride). Oxidative modifications were examined using electrophoresis, western blotting, fluorescence, and chromatographic methodologies with diode array, fluorescence and mass detection. Exposure of caseins to AAPH at 37 °C gave fragmentation, cross-linking and protein aggregation. Amino acid analysis showed consumption of Trp, Tyr, Met, His and Lys residues. Quantification of Trp and Tyr products, showed low levels of di-Tyr and di-Trp, together with an accumulation of carbonyls indicating that casein aggregation is, at least partly, associated with secondary reactions between carbonyls and Lys and His residues. AAPH photolysis, which generates a high flux of free radicals increased the extent of formation of di-Tyr in both model peptides and α- and ß- caseins; di-Trp was only detected in peptides and α-casein. Thus, in spite of the high flexibility of caseins, which would be expected to favor radical-radical reactions, the low flux of ROO• generated during AAPH thermolysis disfavours the formation of dimeric radical-radical cross-links such as di-Tyr and di-Trp, instead favoring other O2-dependent crosslinking pathways such as those involving secondary reactions of initial carbonyl products.

Arabidopsis HIPP27 is a host susceptibility gene for the beet cyst nematode Heterodera schachtii.

Sedentary plant-parasitic cyst nematodes are obligate biotrophs that infect the roots of their host plant. Their parasitism is based on the modification of root cells to form a hypermetabolic syncytium from which the nematodes draw their nutrients. The aim of this study was to identify nematode susceptibility genes in Arabidopsis thaliana and to characterize their roles in supporting the parasitism of Heterodera schachtii. By selecting genes that were most strongly upregulated in response to cyst nematode infection, we identified HIPP27 (HEAVY METAL-ASSOCIATED ISOPRENYLATED PLANT PROTEIN 27) as a host susceptibility factor required for beet cyst nematode infection and development. Detailed expression analysis revealed that HIPP27 is a cytoplasmic protein and that HIPP27 is strongly expressed in leaves, young roots and nematode-induced syncytia. Loss-of-function Arabidopsis hipp27 mutants exhibited severely reduced susceptibility to H. schachtii and abnormal starch accumulation in syncytial and peridermal plastids. Our results suggest that HIPP27 is a susceptibility gene in Arabidopsis whose loss of function reduces plant susceptibility to cyst nematode infection without increasing the susceptibility to other pathogens or negatively affecting the plant phenotype.

Síndrome de malnutrición, inflamación y aterosclerosis en la insuficiencia renal crónica terminal / Malnutrition-inflammation-atherosclerosis syndrome in terminal chronic kidney disease

ha tomado relevancia clínica en la hipótesis del síndrome malnutrición, inflamación y aterosclerosis, que asocia la inflamación a la disfunción endotelial y sirve como marcador de un nuevo tipo de malnutrición vinculado a la inflamación crónica, la proteína C reactiva, como factores predictores de enfermedades cardiovasculares. Las principales causas de fallecimientos en los pacientes que reciben hemodiálisis crónica son las cardiovasculares, las que explican en conjunto cerca del 50 % de las mismas en las que influye de manera directa la malnutrición, inflamación y aterosclerosis. Objetivos: profundizar en el conocimiento de la malnutrición, inflamación y aterosclerosis en los pacientes con insuficiencia renal crónica terminal. Métodos: se realizó revisión bibliográfica de la insuficiencia renal crónica y sus nexos con el síndrome de malnutrición, inflamación y aterosclerosis en investigaciones publicadas en idioma inglés y español. Se revisaron 66 artículos originales, de ellos 17 en SciELO, 16 en PubMed, 12 en EBSCO; nueve en revistas extranjeras de Nefrología, tres en revistas médicas cubanas y nueve en libros de autores cubanos y extranjeros, en formato impreso los tres últimos. Se revisaron 66 artículos y se escogieron los 29 más relevantes. Conclusiones: el síndrome de malnutrición, inflamación y aterosclerosis puede ser el responsable de la alta morbimortalidad que presentan los pacientes con insuficiencia renal crónica terminal.

Background: biocompatibility of dialysis that exposes patients to endotoxins and other inductor substances of proinflammatory cytokines, has taken clinical relevance in the hypothesis of the malnutrition-inflammation-atherosclerosis syndrome that associates inflammation to endothelial dysfunction. C-reactive protein is used as a marker of a new type of malnutrition linked to chronic inflammation and the other factors as predictors of cardiovascular diseases. Internationally, cardiovascular diseases are the main causes of death in patients that undergo chronic haemodialysis and constitute the 50 % of these causes; malnutrition, inflammation and atherosclerosis have a direct influence. Objective: to deepen into knowledge of malnutrition, inflammation, and atherosclerosis in patients with last stage chronic renal failure. Methods: a bibliographic research about chronic renal failure and related to malnutrition syndrome, inflammation, and atherosclerosis was carried out in former publications in English as well as in Spanish in the medical literature, after analyzing the data found, the most interesting new and up-dated aspects were summarized. In order to better up comprehension, and organize searching the data was ordered into three main items: malnutrition, inflammation, and atherosclerosis. A total of 66 articles were reviewed, and the 29 most important ones were chosen as references. Conclusions: malnutrition syndrome, inflammation, and atherosclerosis can be responsible for the high morbimortality in patients with terminal stage chronic renal failure.

Sustained blockade of ascorbic acid transport associated with marked SVCT1 loss in rat hepatocytes containing increased ascorbic acid levels after partial hepatectomy.

The liver has an extraordinary regenerative capacity in response to partial hepatectomy (PHx), which develops with neither tissue inflammation response nor alterations in the whole organism. This process is highly coordinated and it has been associated with changes in glutathione (GSH) metabolism. However, there are no reports indicating ascorbic acid (AA) levels after partial hepatectomy. AA and GSH act integrally as an antioxidant system that protects cells and tissues from oxidative damage and imbalance observed in a variety of diseases that affect the liver. Although rat hepatocytes are able to synthesize AA and GSH, which are the providers of AA for the whole organism, they also acquire AA from extracellular sources through the sodium-coupled ascorbic acid transporter-1 (SVCT1). Here, we show that hepatocytes from rat livers subjected to PHx increase their GSH and AA levels from 1 to 7 days post hepatectomy, whose peaks precede the peak in cell proliferation observed at 3 days post-hepatectomy. The increase in both antioxidants was associated with higher expression of the enzymes involved in their synthesis, such as the modifier subunit of enzyme glutamine cysteine ligase (GCLM), glutathione synthetase (GS), gulonolactonase (GLN) and gulonolactone oxidase (GULO). Importantly, rat hepatocytes, that normally exhibit kinetic evidence indicating only SVCT1-mediated transport of AA, lost more than 90% of their capacity to transport it at day 1 after PHx without evidence of recovery at day 7. This observation was in agreement with loss of SVCT1 protein expression, which was undetectable in hepatocytes as early as 2h after PHx, with partial recovery at day 7, when the regenerated liver weight returns to normal. We conclude that after PHx, rat hepatocytes enhance their antioxidant capacity by increasing GSH and AA levels prior to the proliferative peak. GSH and AA are increased by de novo synthesis, however paradoxically hepatocytes from rat subjected to PHx also suppress their capacity to acquire AA from extracellular sources through SVCT1.

Cáncer de pulmón de células no pequeñas: presentación de caso / Cancer of lung of cells not children: presentation of case

Fundamento: el adenocarcinoma es el tipo de cáncer más frecuente de pulmón en las mujeres y entre las personas que no fuman crece con mayor lentitud, pero tiende a metastizar antes y de manera más amplia. Sólo alcanza la curación una minoría de los pacientes. Objetivo: presentar el caso de un paciente portador de adenocarcinoma de células no pequeñas de localización pulmonar. Caso Clínico: paciente de 58 años de edad, masculino, fumador en el que las manifestaciones paraneoplásicas precedieron a las propias del tumor por más de siete meses de evolución. Conclusiones: por la poca curabilidad del cáncer de pulmón es que se presenta este caso con evolución favorable y supervivencia de más de dos años y medio tras la cirugía y tratamiento oncoespecífico.

Background: adenocarcinoma is the most frequently type of lung cancer in women and is non-smoker people. Adenocarcinoma developes slower, but tends to metastasize sooner and spreads widely. Only a few number of patients reachs cure. Objective: to present a clinical case of adenocarcinoma carries with big pulmonary cells. Case clinical: a 58 years old male smoker patient is presented, paraneoplasics manifestations preceded that of the tumor properly, during more than seven months of valuation. Conclusions: this case is presented don account of few curability refered in lung cancer, with favorable evolution and more than 2, 5 years of survivance after surgery, oncologic treatment and immunotherapy. A review of concerned literature in relation with clinical aspects, diagnosis and therapeutics about this tumor, lees frequently in male was presented.

Comportamiento de la mortalidad del adulto en hemodiálisis crónica / Mortality of the adult in chronic hemodialysis

Fundamento: la hemodiálisis permite a más de dos millones de personas de todo el mundo vivir por muchos años; para ello es necesario garantizar la calidad de la misma que es igual a la suma de múltiples detalles que la integran y que a largo plazo determinan la calidad de vida del enfermo y su supervivencia. Objetivo: determinar el comportamiento de la mortalidad del adulto en el programa de hemodiálisis crónica. Métodos: se realizó un estudio observacional descriptivo retrospectivo para determinar el comportamiento de la mortalidad del adulto en el programa de hemodiálisis crónica en el servicio de Nefrología del Hospital Universitario Manuel Ascunce Domenech, provincia de Camagüey desde enero de 2003 hasta diciembre de 2012, donde fueron incluidos todos los pacientes fallecidos. Las variables seleccionadas fueron: edad, sexo, causas de IRC-T, acceso vascular, anemia, hipoalbuminemia, hipertensión, hipotensión arterial y causas de muerte. Los datos fueron obtenidos de los expedientes clínicos, registros de fallecidos, certificados de defunción e informes necrópsicos. Resultados: la mortalidad predominó en pacientes diabéticos masculinos, mayores de 60 años de edad quienes presentaron accesos vasculares transitorios para hemodiálisis. Conclusiones: las enfermedades cardiovasculares fueron responsables del mayor número de muertes.

Background: hemodialysis gives two million people all over the world the opportunity of living for many years; that is why guaranteeing the quality of this procedure is necessary. This quality is equivalent to the combination of multiple details, which make it up and at long term determine the quality of life and survival of the patient. Nevertheless, there are some individual risk factors that modify the evolution of the patients in dialysis and impede improving the results of the treatment, presenting a high mortality and worse quality of life for patients. Objective: to determine how adult mortality behaves in the chronic hemodialysis program in the nephrology service in the Manuel Ascunce Domenech provincial hospital from January 2003 to december 2012. Methods: a descriptive observational retrospective study was carried out in order to determine the behavior of adult mortality in the chronic hemodialysis program in the nephrology service in the “Manuel Ascunce Domenech” provincial hospital from January 2003 to december 2012. All the deceased patients were included in the study. The variables related to the patient were age, sex causes of TCRD, vascular access, anemia, hypoalbuminemia, hypertension, hypotension, and causes of death. The data were obtained from clinical records, deceased records, death certificates, and necropsy records. Results: mortality predominated in diabetics patients (32, 3 %), men (59 %), and people older than 60 years old (49, 6 %) who presented in 50, 3 % transitory haemodialysis vascular accesses. Conclusions: cardiovascular pathology, followed by infections, predominated as direct cause of death.

Deleterious Effect of p-Cresol on Human Colonic Epithelial Cells Prevented by Proanthocyanidin-Containing Polyphenol Extracts from Fruits and Proanthocyanidin Bacterial Metabolites.

The protective effect of proanthocyanidin-containing polyphenol extracts from apples, avocados, cranberries, grapes, or proanthocyanidin microbial metabolites was evaluated in colonic epithelial cells exposed to p-cresol, a deleterious compound produced by the colonic microbiota from l-tyrosine. In HT29 Glc(-/+) cells, p-cresol significantly increased LDH leakage and decreased ATP contents, whereas in Caco-2 cell monolayers, it significantly decreased the transepithelial electrical resistance and increased the paracellular transport of FITC-dextran. The alterations induced by p-cresol in HT29 Glc(-/+) cells were prevented by the extracts from cranberries and avocados, whereas they became worse by extracts from apples and grapes. The proanthocyanidin bacterial metabolites decreased LDH leakage, ameliorating cell viability without improving intracellular ATP. All of the polyphenol extracts and proanthocyanidin bacterial metabolites prevented the p-cresol-induced alterations of barrier function. These results suggest that proanthocyanidin-containing polyphenol extracts and proanthocyanidin metabolites likely contribute to the protection of the colonic mucosa against the deleterious effects of p-cresol.

Behavioural and Glucocorticoid Responses of a Captive Group of Spider Monkeys to Short-Term Variation in Food Presentation.

The presentation of food may affect feeding competition and the well-being of captive social species. We hypothesized that feeding competition in a captive group of 5 black-handed spider monkeys (Ateles geoffroyi) should increase in response to certain food presentations in terms of size, distribution and quality of food, and that higher feeding competition should lead to an increase in agonism and physiological stress (measured by faecal glucocorticoid metabolites, FGCM) as well as to a decrease in affiliation, proximity among individuals and feeding activity. We used 5 experimental treatments representing different combinations of size, distribution and quality of food. We observed social interactions for 100 h, collected 6,500 proximity and feeding activity records, and gathered 226 faecal samples. When food was clumped, individuals spent less time feeding, and there was also significant individual variation in feeding activity within treatments. FGCM levels were higher when food was clumped. These results are probably linked to an increase in feeding competition when food is concentrated. At least in small groups of spider monkeys, dispersing food in two feeding stations may be sufficient to decrease differences among individuals in priority of access to food resources, hence reducing physiological stress and interindividual differences in feeding activity.

Cis-regulatory elements involved in species-specific transcriptional regulation of the SVCT1 gene in rat and human hepatoma cells.

Ascorbic acid is transported into cells by the sodium-coupled vitamin C transporters (SVCTs). Recently, we obtained evidence of differential regulation of SVCT expression in response to acute oxidative stress in cells from species that differ in their capacity to synthesize vitamin C, with a marked decrease in SVCT1 mRNA and protein levels in rat hepatoma cells that was not observed in human hepatoma cells. To better understand the regulatory aspects involved, we performed a structural and functional analysis of the proximal promoter of the SVCT1 rat gene. We cloned a 1476-bp segment containing the proximal promoter of the rat SVCT1 gene and generated deletion-derived truncated promoters of decreasing sizes and mutant promoters by modification of consensus binding sites for transcription factors by site-directed mutagenesis. We next analyzed their capacity to direct the transcription of a reporter gene after transfection into rat H4IIE and human HepG2 hepatoma cells, in experiments involving the coexpression of transcription factors whose consensus binding sequences are present in the SVCT1 promoter. This analysis revealed the presence of two critical cis-regulatory elements of the transcriptional activity of the rat SVCT1 gene promoter, sites containing consensus sequences for the binding of the transcription factors Bach1 and HNF4 that are not present in equivalent locations in the human SVCT1 gene promoter. Moreover, a consensus site for HNF1 that is crucial for the regulation of the human SVCT1 promoter is present in the SVCT1 rat promoter but has no effect on its transcriptional activity. These findings imply that regulation of vitamin C metabolism in the rat, a species with the capacity to synthesize large amounts of ascorbic acid, may differ from that of humans, a species that must obtain ascorbic acid from the diet through a transport mechanism that depends on proper SVCT1 expression.

The intake of maqui (Aristotelia chilensis) berry extract normalizes H2O2 and IL-6 concentrations in exhaled breath condensate from healthy smokers - an explorative study.

BACKGROUND: Respiratory diseases are associated with pulmonary oxidative stress and inflammatory processes. Though studies in animal models suggest that dietary polyphenols improve lung injury, no intervention studies were carried out in humans. The aim of this study was to determine whether the intake of an anthocyanin-rich maqui extract improved H2O2 and IL-6 concentrations in exhaled breath condensates (EBCs) from asymptomatic smokers. FINDINGS: 15 asymptomatic smokers with mild cigarette smoking (3 pack-year [2.4 - 7.7]) (mean [CI95%]) were recruited in this exploratory longitudinal study. They ingested 2 g of maqui extract (polyphenol content = 5.18 ± 2.00 g GAE/100 g; FRAP value = 27.1 ± 2.0 mmol Fe(++)/100 g), twice daily for two weeks. EBCs were collected before and after treatment and the changes in H2O2 and IL-6 concentrations were determined by fluorimetry and Elisa, respectively. The EBC contents of H2O2 and IL-6 H2O2 before and after treatment in smokers were also compared with those determined in single EBC samples from 8 healthy non-smokers subjects. At baseline, the H2O2 concentrations were higher and those of IL-6 lower in the smokers than in the non-smokers. Maqui extract significantly decreased H2O2 (p < 0.0002) and increased IL-6 (p < 0.004) in the EBC from smokers. The EBC concentrations of H2O2 and IL-6 after maqui administration did not differ between smokers and non-smokers. CONCLUSIONS: Maqui extract normalizes IL-6 and H2O2 concentrations in EBC from humans with mild smoking habits. If confirmed, these results suggest that dietary polyphenols might be considered as an interesting alternative for the dietary management of respiratory disorders.

Physiological and analytical validations of fecal steroid hormone measures in black howler monkeys.

The measurement of hormones in fecal samples allows for the noninvasive assessment of the endocrine status of free-ranging primates. However, procedures and techniques for hormone analysis in feces must be validated, both analytically and physiologically. Few studies have addressed the endocrinology of black howler monkeys (Alouatta pigra). Due to its conservation status, direct handling of individuals from this species and invasive sample collection are highly regulated, and therefore traditional methods for the validation of hormone assays, such as pharmacological challenges, are not allowed. As a consequence, sometimes studies of the fecal hormones of free-ranging black howler monkeys do not report physiological validations and therefore the biological reliability of such measurements cannot be assessed. In order to stimulate future research with this species, the present study aimed at providing methodological bases for fecal endocrine monitoring. Specifically, we compared the validity of two immunoassays (radioimmunoassays, RIA; solid-phase chemiluminescent enzyme immunoassay, SPCEI) performed with commercial kits to measure cortisol, testosterone, estradiol, and progesterone; and demonstrate how the physiological functions of these steroid hormones can be determined through non-pharmacological validations. We found no differences between the analytical validity of RIA and SPCEI assays to measure cortisol and testosterone, whereas for estradiol and progesterone RIA showed better results. Concerning the physiological validation of our assays, we demonstrated that: (1) comparisons between pre- and post-stress situations may be used to assess cortisol response, (2) comparisons between females and males may be used to assess variation in testosterone levels, and (3) comparisons between pregnant and non-pregnant females may be used to determine variation in estradiol and progesterone activity. The analytical and physiological validations that we performed demonstrate that there are currently commercial kits that allow for correct endocrine monitoring of this species, and that there are non-pharmacological alternatives to assess the biological validity of hormone measurements.

Control bacteriológico del agua de la red de distribución acueducto de las veredas Nápoles, Ponchos y Sebastopol en San Antonio de Tequendama / Bacteriological control of water distribution network of sidewalks aqueduct Naples, Ponchos and Sevastopol in San Antonio de Tequendama

El agua es empleada para satisfacer las necesidades básicas, pero a causa de su contaminación ocasiona un deterioro de la calidad de vida de la población. Por esto se han empleado indicadores de contaminación microbiológica, para verificar su calidad y evitar la propagación de enfermedades. El objetivo del presente proyecto es la determinación de la calidad bacteriológica (coliformes totales y Escherichia coli) del agua usada para el consumo de los habitantes de las veredas Nápoles, Ponchos y Sebastopol de San Antonio de Tequendama y así determinar si es apta para su consumo. La metodología incluyó la toma de muestra de cinco puntos de la red de distribución, una vez por mes durante tres meses, procesamiento de las muestras por el método filtración por membrana para determinar la cantidad de UFC/100mL de coliformes totales y E.coli. Los resultados muestran que el agua en estudio no es apta para consumo humano debido a que en los distintos puntos y meses de muestreo se encontró presencia de coliformes totales en un 100% y E. coli en un 86.6%, lo cual señala que estos indicadores se encuentran en una proporción mayor a lo establecido según la normatividad. Algunos de los microorganismos identificados son Citrobacter sp, Enterobacter sp, Klebsiella sp, Escherichia coli y otros como Hafnia sp., Arizona sp. y Serratia sp, que igualmente causan enfermedades. Se desarrolló un mapa de riesgo para conocer las causas de contaminación en la red de distribución, además se realizó una retroalimentación a la comunidad sobre la contaminación hídrica.

Histidine residues in the Na+-coupled ascorbic acid transporter-2 (SVCT2) are central regulators of SVCT2 function, modulating pH sensitivity, transporter kinetics, Na+ cooperativity, conformational stability, and subcellular localization.

Na(+)-coupled ascorbic acid transporter-2 (SVCT2) activity is impaired at acid pH, but little is known about the molecular determinants that define the transporter pH sensitivity. SVCT2 contains six histidine residues in its primary sequence, three of which are exofacial in the transporter secondary structure model. We used site-directed mutagenesis and treatment with diethylpyrocarbonate to identify histidine residues responsible for SVCT2 pH sensitivity. We conclude that five histidine residues, His(109), His(203), His(206), His(269), and His(413), are central regulators of SVCT2 function, participating to different degrees in modulating pH sensitivity, transporter kinetics, Na(+) cooperativity, conformational stability, and subcellular localization. Our results are compatible with a model in which (i) a single exofacial histidine residue, His(413), localized in the exofacial loop IV that connects transmembrane helices VII-VIII defines the pH sensitivity of SVCT2 through a mechanism involving a marked attenuation of the activation by Na(+) and loss of Na(+) cooperativity, which leads to a decreased V(max) without altering the transport K(m); (ii) exofacial histidine residues His(203), His(206), and His(413) may be involved in maintaining a functional interaction between exofacial loops II and IV and influence the general folding of the transporter; (iii) histidines 203, 206, 269, and 413 affect the transporter kinetics by modulating the apparent transport K(m); and (iv) histidine 109, localized at the center of transmembrane helix I, might be fundamental for the interaction of SVCT2 with the transported substrate ascorbic acid. Thus, histidine residues are central regulators of SVCT2 function.

Factores sociales que contribuyen a la morbi-mortalidad en pacientes con Insuficiencia Renal Crónica sometidos a hemodiálisis. Un estudio necesario / Social factors contributing to morbi-mortality in patients suffering from Chronical Kidney Insufficiency subjected to hemodialysis

Se realizó un estudio sobre los factores sociales que contribuyen a la morbi-mortalidad en pacientes crónicos sometidos a hemodiálisis en el servicio de nefrología del Hospital Provincial Manuel Ascunce Domenech de Camagüey. Entre los factores sociales más relevantes que atentan contra la calidad de vida y la supervivencia del paciente dialítico crónico se encontraron; la derivación tardía de los pacientes con Insuficiencia Renal Crónica a consultas Nefrológicas, las dificultades en la creación y supervivencia de los accesos vasculares, el escaso número de enfermeros por riñón artificial, las roturas de las máquinas de hemodiálisis, de las plantas de tratamiento del agua y las dificultades con transporte de los pacientes.

It was carried out a study about the social factors contributing to the morbi-mortality in chronic patients subjected to hemodialysis in the service of nephrology of the "Manuel Ascunce DomEnech" Provincial Hospital, in Camagüey. They were among the most outstanding social factors that attempt against the quality of life and the survival of the chronic dialytic patient, the late derivation of the patients with Renal Chronic Insufficiency in Nephrologic consultations, the difficulties in the creation and survival of the vascular accesses, the scarce number of male nurses for artificial kidney, the breaks of the hemodialysis machines, of the plants of water treatment and the difficulties with the patients' transportation.

Vitamin C is an essential antioxidant that enhances survival of oxidatively stressed human vascular endothelial cells in the presence of a vast molar excess of glutathione.

Cellular glutathione levels may exceed vitamin C levels by 10-fold, generating the question about the real antioxidant role that low intracellular concentrations of vitamin C can play in the presence of a vast molar excess of glutathione. We characterized the metabolism of vitamin C and its relationship with glutathione in primary cultures of human endothelial cells oxidatively challenged by treatment with hydrogen peroxide or with activated cells undergoing the respiratory burst, and analyzed the manner in which vitamin C interacts with glutathione to increase the antioxidant capacity of cells. Our data indicate that: (i) endothelial cells express transporters for reduced and oxidized vitamin C and accumulate ascorbic acid with participation of glutathione-dependent dehydroascorbic acid reductases, (ii) although increased intracellular levels of vitamin C or glutathione caused augmented resistance to oxidative stress, 10-times more glutathione than vitamin C was required, (iii) full antioxidant protection required the simultaneous presence of intracellular and extracellular vitamin C at concentrations normally found in vivo, and (iv) intracellular vitamin C cooperated in enhancing glutathione recovery after oxidative challenge thus providing cells with enhanced survival potential, while extracellular vitamin C was recycled through a mechanism involving the simultaneous neutralization of oxidant species. Therefore, in endothelial cells under oxidative challenge, vitamin C functions as an essential cellular antioxidant even in the presence of a vast molar excess of glutathione.

Coexpression of hepatocyte growth factor/scatter factor (HGF/SF) and its receptor cMET predict recurrence of meningiomas.

Hepatocyte growth factor/scatter factor (HGF/SF) and its receptor, the cMET tyrosine kinase participate in cancer invasion, angiogenesis and metastasis in a wide variety of neoplastic cells. Meningioma is a bening tumour, however, it has a high rate of recurrence after surgery; the most important factor to predict relapse is the extent of surgical resection, several other potentially predictive factors have been studied with poor results. We examined by immunohistochemistry the expression of HGF/SF and its cMET receptor in a group of patients with benign meningioma with or without recurrence (n = 17 and n = 25, respectively), after a minimal follow-up of least 6 years. Expression and coexpression of HGF/SF and cMET were compared with cell proliferation index, vascular density and clinical outcome. Coexpression of HGF/SF and cMET in meningiomas had a significant association with cell proliferation index and with recurrence (P < 0.037). Determination of HGF and cMET coexpression in meningiomas could be used as a predictor of recurrence.

Angiotensin II, cell proliferation and angiogenesis regulator: biologic and therapeutic implications in cancer.

Angiotensin II (ANG II) is the main effector peptide in the renin-angiotensin system. It is generated by the activation of Angiotensin I through the Angiotensin II Converter Enzyme (ACE II). ANG II has multiple physiologic effects that regulate vascular tone, hormone secretion, tissue growth and neural activity. It has systemic (endocrine) and local (paracrine and autocrine) effects, favoring cell growth and differentiation through four types of receptors from which types 1 and 2 (AT(1) and AT(2)) are the most important. Stimulation of AT(1) leads to the activation of intracellular pathways that finally lead to vasoconstriction, inflammation and proliferation. The AT(2) receptor is mainly expressed in fetal tissue and scantly in the cardiovascular system under different circumstances. Its effects are opposite to those of the AT(1). The stimulation of AT(1) activates second messengers that lead to a rapid production of diacylglycerol and 1-4-5-inositol triphosphate, as well as to the activation of C protein. Several reports indicate that ANG II can induce neovascularization in experimental systems due to the expression of different growth factors such as angiopoietin 2, vascular endothelial factor, and its receptor, fibroblast growth factor, platelet derived growth factor, transforming growth factor beta and epidermal growth factor. Other mechanisms associated with ANG II induced angiogenesis are nitric oxide synthase and metalloproteinase expression, as well as inflammation induction. Angiogenesis is a fundamental process to tissue repair and development, and it participates in several pathologic processes. In addition, the AT(1) receptor is expressed in many malignant neoplasms and its blockade through ECA II inhibitors and ANG II antagonists has shown antineoplastic activity as well as angiogenesis inhibition in tumoral experimental models. This review discusses the mechanisms by which ANG II participates in neoplastic and non-neoplastic tissue angiogenesis and its possible therapeutic implications.