Molecular surveillance of microbial agents from cattle-attached and questing ticks from livestock agroecosystems of Antioquia, Colombia.

Ticks are obligate ectoparasites and vectors of pathogens affecting health, agriculture, and animal welfare. This study collected ticks from the cattle and questing ticks of 24 Magdalena Medio Antioquia region cattle farms. Genomic DNA was extracted from the specimens (individual or pools) of the 2088 adult ticks collected from cattle and 4667 immature questing ticks collected from pastures. The molecular detection of Babesia, Anaplasma, Coxiella and Rickettsia genera was performed by polymerase chain reaction amplification and subsequent DNA sequencing. In a total of 6755 Rhipicephalus microplus DNA samples, Anaplasma marginale was the most detected with a frequency of 2% (Confidence Interval- CI 1.68-2.36), followed by Babesia bigemina with 0.28% (CI 0.16-0.44), Coxiella spp. with 0.15% (CI 0.07-0.27), and Rickettsia spp. with 0.13% (CI 0.06-0.25). Molecular analysis of the DNA sequences obtained from the tick samples revealed the presence of Coxiella-like endosymbiont and R. felis. These results demonstrated the diversity of microorganisms present in R. microplus ticks predominantly associated with cattle and questing ticks from livestock agroecosystems, suggesting their role as reservoirs and potential biological vectors of these microorganisms on the studied sites. Also, it emphasizes the need to combine acarological surveillance with clinical diagnoses and control strategies on regional and national levels.

Chlamydia psittaci seropositivity in workers exposed to birds and review of the literature: Evidence of circulation in Antioquia / Seropositividad de Chlamydia psittaci en trabajadores expuestos a aves y revisión de la literatura: evidencia de circulación en Antioquia.

Introduction: Psittacosis is a zoonotic disease caused by Chlamydia psittaci, a bacterium classified as an agent with bioterrorist potential. It has caused multiple outbreaks in exposed poultry workers around the world. Colombia has no epidemiological follow-up of the infection and a big knowledge gap. Objectives: To determine the antibodies' frequency against C. psittaci in workers with occupational exposure to birds and to review the literature on studies conducted in Colombia. Materials and methods: We conducted a cross-sectional descriptive study with analytical intent on workers in contact with birds and reviewed the related literature in Colombia. IgM and IgG serum antibodies against C. psittaci were detected by microimmunofluorescence. The sociodemographic and exposure characteristics were expressed as frequencies and summary measures. Associated factors were explored by bivariate and multivariate analysis. The scientific and gray literature review was done with a structured search. Results: We analyzed 54 workers in contact with birds. Antibody prevalence was 31.5%. Slaughtering and evisceration by non-veterinarians was a risk factor for antibody presence. There are only four previous studies on C. psittaci in Colombia. Conclusions: Here, we present the first evidence of C. psittaci circulation among workers exposed to birds in Antioquia and the second report in the country. These findings contribute to the "One Health" public health strategy.

Introducción: La psitacosis es una enfermedad zoonótica causada por Chlamydia psittaci. Esta bacteria es catalogada como un agente con potencial bioterrorista y ha causado múltiples brotes en trabajadores con exposición laboral a aves en diferentes lugares del mundo. En Colombia, no se hace seguimiento epidemiológico de la infección y existe una gran brecha en el conocimiento. Objetivos: Determinar la frecuencia de anticuerpos contra C. psittaci en trabajadores con exposición laboral a aves y sus factores asociados. Además, revisar la literatura en relación con los estudios sobre el tema realizados en Colombia. Materiales y métodos: Se llevó a cabo un estudio descriptivo, transversal, con intención analítica, en trabajadores en contacto con aves y se revisó la literatura científica relacionada en Colombia. Se detectaron anticuerpos IgM e IgG contra C. psittaci en suero por microinmunofluorescencia. La descripción de las características sociodemográficas y de exposición se hizo con frecuencias y medidas de resumen. Se exploraron factores asociados por análisis bivariados y multivariados. La revisión de la literatura científica y gris se hizo con búsqueda estructurada. Resultados: Se analizaron 54 trabajadores en contacto con aves y se encontró una prevalencia de anticuerpos del 31,5 %. El ejercer funciones de sacrificio y faenado de las aves sin ser médico veterinario fue un factor de riesgo para la presencia de anticuerpos. Solo se encontraron cuatro estudios previos sobre C. psittaci hechos en Colombia. Conclusiones: Este estudio constituye la primera evidencia de la circulación de C. psittaci en trabajadores en contacto con aves en Antioquia y el segundo reporte en el país. Estos hallazgos aportan desde la salud pública a la estrategia One Health.

Hard tick species (Acari: Ixodidae) and infestation in two livestock agroecosystems from Antioquia, Colombia.

Tick infestation affects about 80% of livestock globally while transmitting various pathogens causing high economic losses. This study aimed to determine the degree of tick infestation in two regions, North and Middle Magdalena in Antioquia, Colombia, to identify the ixodid tick species found and the associated risk factors. A cross-sectional study was carried out in 48 farms distributed in six municipalities of Antioquia. Two paddocks and eight bovines per farm were evaluated to estimate tick infestation (adults, nymphs, and larvae). Tick species were identified through a morphological and molecular analysis based on partial sequences of data obtained from DNA molecular markers, two mitochondrial (16S rRNA and COI), and one genomic DNA gene (18S rRNA). A multivariate Poisson regression model was applied to estimate the associated risk factors with ticks in cattle. Rhipicephalus microplus, Amblyomma patinoi and Dermacentor nitens were present in the livestock agroecosystems in the Middle Magdalena region; the highest incidence of tick infestation in cows and paddocks was reported in the municipality of Puerto Triunfo. The livestock agroecosystems in Middle Magdalena were characterized by a higher presence of adult R. microplus in cattle. Larval infestation of R. microplus, followed by D. nitens, was also found in paddocks. The multivariate analysis showed that the origin of cattle was the main risk factor associated with the presence of ticks (i.e., when cattle came from outside the farm). Cattle movement between farms in Middle Magdalena can contribute to the spread of ticks in this region.

Glutaminase isoforms expression switches microRNA levels and oxidative status in glioblastoma cells.

BACKGROUND: Glutaminase isoenzymes GLS and GLS2 play apparently opposing roles in cancer: GLS acts as an oncoprotein, while GLS2 (GAB isoform) has context specific tumour suppressive activity. Some microRNAs (miRNAs) have been implicated in progression of tumours, including gliomas. The aim was to investigate the effect of GLS and GAB expression on both miRNAs and oxidative status in glioblastoma cells. METHODS: Microarray profiling of miRNA was performed in GLS-silenced LN229 and GAB-transfected T98G human glioblastoma cells and their wild-type counterparts. Results were validated by real-time quantitative RT-PCR. Oxidative status and antioxidant enzymes were determined by spectrophotometric or fluorescence assays in GLS-silenced LN229 and T98G, and GAB-transfected LN229 and T98G. RESULTS: MiRNA-146a-5p, miRNA-140-3p, miRNA-21-5p, miRNA-1260a, and miRNA-92a-3p were downregulated, and miRNA-1246 was upregulated when GLS was knocked down. MiRNA-140-3p, miRNA-1246, miRNA-1260a, miRNA-21-5p, and miRNA-146a-5p were upregulated when GAB was overexpressed. Oxidative status (lipid peroxidation, protein carbonylation, total antioxidant capacity, and glutathione levels), as well as antioxidant enzymes (catalase, superoxide dismutase, and glutathione reductase) of silenced GLS glioblastoma cells and overexpressed GAB glioblastoma cells significantly changed versus their respective control glioblastoma cells. MiRNA-1246, miRNA-1260a, miRNA-146a-5p, and miRNA-21-5p have been characterized as strong biomarkers of glioblastoma proliferation linked to both GLS silencing and GAB overexpression. Total glutathione is a reliable biomarker of glioblastoma oxidative status steadily associated to both GLS silencing and GAB overexpression. CONCLUSIONS: Glutaminase isoenzymes are related to the expression of some miRNAs and may contribute to either tumour progression or suppression through certain miRNA-mediated pathways, proving to be a key tool to switch cancer proliferation and redox status leading to a less malignant phenotype. Accordingly, GLS and GAB expression are especially involved in glutathione-dependent antioxidant defence.

Assessment of bacterial diversity of Rhipicephalus microplus ticks from two livestock agroecosystems in Antioquia, Colombia.

Rhipicephalus microplus is recognized as a tick species highly prevalent in cattle, with a wide pantropical distribution that seems to continue spreading geographically. However, its role as a biological vector has been scarcely studied in the livestock context. In this study, a 16S rRNA next-generation sequencing analysis was used to determine bacterial diversity in salivary glands and gut of R. microplus from two contrasting livestock agroecosystems in Antioquia, Colombia. Both the culture-independent approach (CI) and the culture-dependent (CD) approach were complementarily adopted in this study. A total of 341 unique OTUs were assigned, the richness showed to be higher in the Northern than in the Middle Magdalena region, and a high diversity was found at the phylum and genus levels in the samples obtained. With the CI approach, Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria were the most common phylum of bacteria regardless of the organ, or geographic origin of the specimens analyzed. While the relative abundance of bacteria at a phylum level with the CD approach varied between analyzed samples, the data obtained suggest that a high diversity of species of bacteria occurs in R. microplus from both livestock agroecosystems. Bacterial genera such as Anaplasma, Coxiella, and Ehrlichia, recognized for their implications in tick-borne diseases, were also detected, together with endosymbionts such as Lysinibacillus, previously reported as a potential tool for biological control. This information is useful to deepen the knowledge about microbial diversity regarding the relations between endosymbionts and pathogens and could facilitate the future development of epidemiological surveillance in livestock systems.

Metatranscriptomic virome assessment of Rhipicephalus microplus from Colombia.

Ticks (Ixodida) are hematophagous ectoparasites that harbor and transmit diverse species of viruses, some of which cause serious diseases with worldwide veterinary and human health consequences. Rhipicephalus microplus is an important cattle tick in Colombia, where it causes significant economic losses. Despite the importance of this tick, its viral profile is unknown. RNA sequencing was used in this study as a surveillance method for virus detection in R. microplus. Most of the viral origin contigs were assigned to two putative viruses: one chuvirus (Wuhan tick virus 2) and one phlebovirus-like (Lihan tick virus). In addition, viral contigs corresponding to two jingmenviruses previously reported in R. microplus from China and Brazil were detected, as well as a novel putative tymovirus, named here as Antioquia tymovirus-like 1 (ATV-like 1). The presence of some of these viruses across numerous regions in the world could have several explanations, including i) a long-term association between those viruses and R. microplus and ii) a consequence of livestock historical trade. Our results shed new light on the virus diversity of this tick species and provide a basis for further studies on the evolutionary history and pathogenic potential of these interesting viruses.

Nuclear Translocation of Glutaminase GLS2 in Human Cancer Cells Associates with Proliferation Arrest and Differentiation.

Glutaminase (GA) catalyzes the first step in mitochondrial glutaminolysis playing a key role in cancer metabolic reprogramming. Humans express two types of GA isoforms: GLS and GLS2. GLS isozymes have been consistently related to cell proliferation, but the role of GLS2 in cancer remains poorly understood. GLS2 is repressed in many tumor cells and a better understanding of its function in tumorigenesis may further the development of new therapeutic approaches. We analyzed GLS2 expression in HCC, GBM and neuroblastoma cells, as well as in monkey COS-7 cells. We studied GLS2 expression after induction of differentiation with phorbol ester (PMA) and transduction with the full-length cDNA of GLS2. In parallel, we investigated cell cycle progression and levels of p53, p21 and c-Myc proteins. Using the baculovirus system, human GLS2 protein was overexpressed, purified and analyzed for posttranslational modifications employing a proteomics LC-MS/MS platform. We have demonstrated a dual targeting of GLS2 in human cancer cells. Immunocytochemistry and subcellular fractionation gave consistent results demonstrating nuclear and mitochondrial locations, with the latter being predominant. Nuclear targeting was confirmed in cancer cells overexpressing c-Myc- and GFP-tagged GLS2 proteins. We assessed the subnuclear location finding a widespread distribution of GLS2 in the nucleoplasm without clear overlapping with specific nuclear substructures. GLS2 expression and nuclear accrual notably increased by treatment of SH-SY5Y cells with PMA and it correlated with cell cycle arrest at G2/M, upregulation of tumor suppressor p53 and p21 protein. A similar response was obtained by overexpression of GLS2 in T98G glioma cells, including downregulation of oncogene c-Myc. Furthermore, human GLS2 was identified as being hypusinated by MS analysis, a posttranslational modification which may be relevant for its nuclear targeting and/or function. Our studies provide evidence for a tumor suppressor role of GLS2 in certain types of cancer. The data imply that GLS2 can be regarded as a highly mobile and multilocalizing protein translocated to both mitochondria and nuclei. Upregulation of GLS2 in cancer cells induced an antiproliferative response with cell cycle arrest at the G2/M phase.

Metabolic Reprogramming of Cancer by Chemicals that Target Glutaminase Isoenzymes.

BACKGROUND: Metabolic reprogramming of tumours is a hallmark of cancer. Among the changes in the metabolic network of cancer cells, glutaminolysis is a key reaction altered in neoplasms. Glutaminase proteins control the first step in glutamine metabolism and their expression correlates with malignancy and growth rate of a great variety of cancers. The two types of glutaminase isoenzymes, GLS and GLS2, differ in their expression patterns and functional roles: GLS has oncogenic properties and GLS2 has been described as a tumour suppressor factor. RESULTS: We have focused on glutaminase connections with key oncogenes and tumour suppressor genes. Targeting glutaminase isoenzymes includes different strategies aimed at deactivating the rewiring of cancer metabolism. In addition, we found a long list of metabolic enzymes, transcription factors and signalling pathways dealing with glutaminase. On the other hand, a number of chemicals have been described as isoenzyme-specific inhibitors of GLS and/or GLS2 isoforms. These molecules are being characterized as synergic and therapeutic agents in many types of tumours. CONCLUSION: This review states the metabolic pathways that are rewired in cancer, the roles of glutaminase isoforms in cancer, as well as the metabolic circuits regulated by glutaminases. We also show the plethora of anticancer drugs that specifically inhibit glutaminase isoenzymes for treating several sets of cancer.

Surface mycobiota of home-made dry cured sausages from the main producing regions of Argentina and morphological and biochemical characterization of Penicillium nalgiovense populations.

The characteristics and quality of home-made dry cured sausages can be recognized and associated with the region of origin. The characteristics of this type of sausages result from the superficial mycobiota that spontaneously colonizes the products. The aim of this study was to identify the house mycobiota associated with home-made dry cured sausages from different localities of Argentina and characterize the populations of Penicillium nalgiovense present by morphological and biochemical markers. To this end, 79 samples were collected from 10 localities of three main producing regions (Buenos Aires, Córdoba and La Pampa provinces). A total of 196 isolates belonging to six genera and 17 species were obtained. The predominant genus was Penicillium (134 of the isolates) and the predominant species was P. nalgiovense (108 isolates). The isoenzyme patterns of α-esterase (α-EST; EC 3.1.1.1) and Malate dehydrogenase NADP+(MDHP; EC 1.1.1.40) were characterized in 48 of these isolates (ten from Colonia Caroya, ten from Oncativo, ten from Tandil, nine from Mercedes and nine from La Pampa). A total of 26 bands were observed: 17 for α-EST and 9 for MDHP. α-EST was the most polymorphic isoenzyme, whereas MDPH presented no polymorphism. The results were subjected to numerical analysis. Cluster analysis revealed the formation of two groups: Group I formed by 24 isolates from Córdoba and Buenos Aires provinces and Group II with 24 isolates from La Pampa and Buenos Aires province. These data suggest the existence of morphological and biochemical variations among P. nalgiovense populations with different geographical origin.

Glutamine Addiction In Gliomas.

Cancer cells develop and succeed by shifting to different metabolic programs compared with their normal cell counterparts. One of the classical hallmarks of cancer cells is their higher glycolysis rate and lactate production even in the presence of abundant O2 (Warburg effect). Another common metabolic feature of cancer cells is a high rate of glutamine (Gln) consumption normally exceeding their biosynthetic and energetic needs. The term Gln addiction is now widely used to reflect the strong dependence shown by most cancer cells for this essential nitrogen substrate after metabolic reprogramming. A Gln/glutamate (Glu) cycle occurs between host tissues and the tumor in order to maximize its growth and proliferation rates. The mechanistic basis for this deregulated tumor metabolism and how these changes are connected to oncogenic and tumor suppressor pathways are becoming increasingly understood. Based on these advances, new avenues of research have been initiated to find novel therapeutic targets and to explore strategies that interfere with glutamine metabolism as anticancer therapies. In this review, we provided an updated overview of glutamine addiction in glioma, the most prevalent type of brain tumor.

Glutamate and Brain Glutaminases in Drug Addiction.

Glutamate is the principal excitatory neurotransmitter in the central nervous system and its actions are related to the behavioral effects of psychostimulant drugs. In the last two decades, basic neuroscience research and preclinical studies with animal models are suggesting a critical role for glutamate transmission in drug reward, reinforcement, and relapse. Although most of the interest has been centered in post-synaptic glutamate receptors, the presynaptic synthesis of glutamate through brain glutaminases may also contribute to imbalances in glutamate homeostasis, a key feature of the glutamatergic hypothesis of addiction. Glutaminases are the main glutamate-producing enzymes in brain and dysregulation of their function have been associated with neurodegenerative diseases and neurological disorders; however, the possible implication of these enzymes in drug addiction remains largely unknown. This mini-review focuses on brain glutaminase isozymes and their alterations by in vivo exposure to drugs of abuse, which are discussed in the context of the glutamate homeostasis theory of addiction. Recent findings from mouse models have shown that drugs induce changes in the expression profiles of key glutamatergic transmission genes, although the molecular mechanisms that regulate drug-induced neuronal sensitization and behavioral plasticity are not clear.

Portal vein thrombosis in patients with cirrhosis: just a common finding or a predictor of poor outcome?

 Background & Aims. It is unclear whether portal vein thrombosis (PVT) unrelated to malignancy is associated with reduced survival or it is an epiphenomenon of advanced cirrhosis. The objective of this study was to assess clinical outcome in cirrhotic patients with PVT not associated with malignancy and determine its prevalence. MATERIAL AND METHODS: Retrospective search in one center from June 2011 to December 2014. RESULTS: 169 patients, 55 women and 114 men, median age 54 (19-90) years. Thirteen had PVT (7.6%). None of the patients received anticoagulant treatment. The PVT group was younger (49 [25-62] vs. 55 [19-90] years p = 0.025). Child A patients were more frequent in PVT and Child C in Non-PVT. Median Model for End Stage Liver Disease (MELD) score was lower in PVT (12 [8-21] vs. 19 [7-51] p ≤ 0.001) p ≤ 0.001). There was no difference between upper gastrointestinal bleeding and spontaneous bacterial peritonitis in the groups. Encephalopathy grade 3-4 (4 [30.8%] vs. 73 [46.8%] p = 0,007) and large volume ascites (5 [38.5%] vs. 89 [57.1%] p= 0,012) was more common in non-PVT. Survival was better for PVT (16.5 ± 27.9 vs. 4.13 ± 12.2 months p = 0.005). CONCLUSIONS: We found that PVT itself does not lead to a worse prognosis. The most reliable predictor for clinical outcome remains the MELD score. The presence of PVT could be just an epiphenomenon and not a marker of advanced cirrhosis.

Expression of Gls and Gls2 glutaminase isoforms in astrocytes.

The expression of glutaminase in glial cells has been a controversial issue and matter of debate for many years. Actually, glutaminase is essentially considered as a neuronal marker in brain. Astrocytes are endowed with efficient and high capacity transport systems to recapture synaptic glutamate which seems to be consistent with the absence of glutaminase in these glial cells. In this work, a comprehensive study was devised to elucidate expression of glutaminase in neuroglia and, more concretely, in astrocytes. Immunocytochemistry in rat and human brain tissues employing isoform-specific antibodies revealed expression of both Gls and Gls2 glutaminase isozymes in glutamatergic and GABAergic neuronal populations as well as in astrocytes. Nevertheless, there was a different subcellular distribution: Gls isoform was always present in mitochondria while Gls2 appeared in two different locations, mitochondria and nucleus. Confocal microscopy and double immunofluorescence labeling in cultured astrocytes confirmed the same pattern previously seen in brain tissue samples. Astrocytic glutaminase expression was also assessed at the mRNA level, real-time quantitative RT-PCR detected transcripts of four glutaminase isozymes but with marked differences on their absolute copy number: the predominance of Gls isoforms over Gls2 transcripts was remarkable (ratio of 144:1). Finally, we proved that astrocytic glutaminase proteins possess enzymatic activity by in situ activity staining: concrete populations of astrocytes were labeled in the cortex, cerebellum and hippocampus of rat brain demonstrating functional catalytic activity. These results are relevant for the stoichiometry of the Glu/Gln cycle at the tripartite synapse and suggest novel functions for these classical metabolic enzymes.

Glutamine, glucose and other fuels for cancer.

Tumor cells suffer a metabolic reprogramming which allows them to use metabolic fuels (glucose, glutamine, lipids) through anabolic fates to support their enhanced proliferation and other carcinogenesis-related features. The present review tries to address and summarize the broad and growing information available about this reprogramming, whose pieces, put together, make up a complex scheme that encompasses different complexity scales, from cells to systemic networks.

Both GLS silencing and GLS2 overexpression synergize with oxidative stress against proliferation of glioma cells.

UNLABELLED: Mitochondrial glutaminase (GA) plays an essential role in cancer cell metabolism, contributing to biosynthesis, bioenergetics, and redox balance. Humans contain several GA isozymes encoded by the GLS and GLS2 genes, but the specific roles of each in cancer metabolism are still unclear. In this study, glioma SFxL and LN229 cells with silenced isoenzyme glutaminase KGA (encoded by GLS) showed lower survival ratios and a reduced GSH-dependent antioxidant capacity. These GLS-silenced cells also demonstrated induction of apoptosis indicated by enhanced annexin V binding capacity and caspase 3 activity. GLS silencing was associated with decreased mitochondrial membrane potential (ΔΨm) (JC-1 dye test), indicating that apoptosis was mediated by mitochondrial dysfunction. Similar observations were made in T98 glioma cells overexpressing glutaminase isoenzyme GAB, encoded by GLS2, though some characteristics (GSH/GSSG ratio) were different in the differently treated cell lines. Thus, control of GA isoenzyme expression may prove to be a key tool to alter both metabolic and oxidative stress in cancer therapy. Interestingly, reactive oxygen species (ROS) generation by treatment with oxidizing agents: arsenic trioxide or hydrogen peroxide, synergizes with either KGA silencing or GAB overexpression to suppress malignant properties of glioma cells, including the reduction of cellular motility. Of note, negative modulation of GLS isoforms or GAB overexpression evoked lower c-myc and bcl-2 expression, as well as higher pro-apoptotic bid expression. Combination of modulation of GA expression and treatment with oxidizing agents may become a therapeutic strategy for intractable cancers and provides a multi-angle evaluation system for anti-glioma pre-clinical investigations. KEY MESSAGE: Silencing GLS or overexpressing GLS2 induces growth inhibition in glioma cell lines. Inhibition is synergistically enhanced after arsenic trioxide (ATO) or H2O2 treatment. Glutatione levels decrease in GLS-silenced cells but augment if GLS2 is overexpressed. ROS synergistically inhibit cell migration by GLS silencing or GLS2 overexpression. c-myc, bid, and bcl-2 mediate apoptosis resulting from GLS silencing or GLS2 overexpression.

Ruminant feces used as inoculum for the in vitro gas production technique / Heces de rumiantes como fuente de inóculo para la técnica in vitro de producción de gases / Fezes de ruminantes como fonte de inoculo para a técnica in vitro de produção de gases

Background: ruminal feed fermentation can be studied through in vitro gas production. However, this technique requires fistulated animals from which to obtain the inoculum, which limits its use. Objective: the objective of this experiment was to evaluate the usefulness of feces instead of rumen fluid as the inoculum of reference, by determining the precision and accuracy resulting from both methods. Methods: six forage species (Gliricidia sepium, Panicum maximum, Pennisetum clandestinum, Lolium sp., Morus alba and Cynodon nlemfuensis) were incubated with bovine rumen fluid or feces to quantify gas production and dry matter degradation over time. Bacteria, fungi, and protozoa counts were assessed in both inocula. Results: cumulative gas production and gas production rate were higher for the ruminal inoculum during the initial incubation period. Ruminal liquid showed lower variability compared to its own mean. Conclusions: according to the Bland-Altman analysis, inocula are not interchangeable. The difference in gas production kinetics between both inoculum sources reflected a longer time to colonize the substrate and lower microbial concentration in the fecal fluid, which resulted useful solely in determining the extent of dry matter degradation.

Antecedentes: la fermentación ruminal de los alimentos puede ser estudiada a través de la técnica in vitro de producción de gases. No obstante, una de las limitaciones de la técnica es el requerimiento de animales fistulados para la obtención del inóculo. Objetivo: el objetivo de este experimento fue evaluar la utilización de las heces respecto al inóculo de referencia, líquido ruminal, a través de la determinación de la precisión y la exactitud. Métodos: para ello seis especies forrajeras (Gliricidia sepium, Panicum maximum, Pennisetum clandestinum, Lolium sp., Morus alba y Cynodon nlemfuensis) fueron incubadas con líquido ruminal y heces bovinas, cuantificando la producción de gas y la degradación de la materia seca en el tiempo. En los dos inóculos se realizó conteo de bacterias, hongos y protozoos. Resultados: la producción acumulativa de gas y la tasa de producción de gas durante el período inicial de incubación fueron superiores con el inóculo ruminal. En el análisis de repetibilidad, el líquido ruminal exhibió menor variabilidad respecto el valor medio obtenido. Conclusiones: el análisis de Bland-Altman permitió concluir que los dos inóculos no son intercambiables. La diferencia en la cinética de producción de gas entre ambas fuentes de inóculo reflejó el mayor tiempo de colonización del sustrato y la menor concentración de microorganismos en el fluido fecal, resultando sólo de utilidad para determinar la extensión de la degradación de la materia seca.

Antecedentes: a fermentação ruminal dos alimentos no rúmen pode ser estudada através da técnica in vitro de produção de gases. No entanto, uma das limitações da técnica é a exigência de animais fistulados para obter o inóculo. Objetivo: o objetivo deste experimento foi avaliar o uso das fezes em comparação ao inóculo de referência, líquido ruminal, através da determinação da precisão e exatidão. Metodos: seis forragens (Gliricidia sepium, Panicum maximum, Pennisetum clandestinum, Lolium sp., Morus alba e Cynodon nlemfuensis) foram incubadas com líquido ruminal e fezes bovinas, quantificando a produção de gás e a degradação da matéria seca no tempo. Contagem de bactérias, fungos e protozoários foi feita nos dois inóculos. Resultados: a produção acumulativa de gás e a taxa de produção de gás durante o período inicial de incubação foram maiores com o inoculo ruminal. Na análise de repetibilidade, o inoculo ruminal mostrou menor variabilidade ao redor do valor médio obtido. Conclusiones: a análise de Bland-Altman permitiu concluir que os dois inóculos não são intercambiáveis. A diferença na cinética de produção de gás entre as duas fontes de inóculo refletiu o maior tempo de colonização do substrato e a menor concentração de microorganismos no fluido fecal, resultando apenas útil para determinar a extensão da degradação da matéria seca.

Oxidative stress in apoptosis and cancer: an update.

The oxygen paradox tells us that oxygen is both necessary for aerobic life and toxic to all life forms. Reactive oxygen species (ROS) touch every biological and medical discipline, especially those involving proliferative status, supporting the idea that active oxygen may be increased in tumor cells. In fact, metabolism of oxygen and the resulting toxic byproducts can cause cancer and death. Efforts to counteract the damage caused by ROS are gaining acceptance as a basis for novel therapeutic approaches, and the field of prevention of cancer is experiencing an upsurge of interest in medically useful antioxidants. Apoptosis is an important means of regulating cell numbers in the developing cell system, but it is so important that it must be controlled. Normal cell death in homeostasis of multicellular organisms is mediated through tightly regulated apoptotic pathways that involve oxidative stress regulation. Defective signaling through these pathways can contribute to both unbalance in apoptosis and development of cancer. Finally, in this review, we discuss new knowledge about recent tools that provide powerful antioxidant strategies, and designing methods to deliver to target cells, in the prevention and treatment of cancer.

Sulphur-containing non enzymatic antioxidants: therapeutic tools against cancer.

The prevention of oxidation is an essential process in all cells, as decreased antioxidant protection may lead to cytotoxicity, mutagenicity and carcinogenicity. The mechanisms by which oxidative stress contributes to carcinogenesis include modulation of gene expression and induction of genetic modifications. Cellular methylation and antioxidant metabolism are linked by the transsulfuration pathway, which converts the methionine cycle intermediate, homocysteine, to cysteine, the limiting reagent in glutathione synthesis. Taurine can protect cells from oxidant-induced injury scavenging strong oxidant and cytotoxic agents, and lipoic acid can regenerate glutathione. N-acetylcysteine has anticancer properties such as counteractions against mutagens and prevention of tumor progression. The oxidizing agents react with the thiol group of these non enzymatic antioxidants determining cellular redox potential, and modulating several biological events, since different redox-sensitive molecules are involved in many cell responses such as proliferation, growth arrest, and death. The high metabolic activity characteristic of cancer cells often upregulates oxidative stress protection mechanisms. In fact, glutathione depletion is an early hallmark observed in apoptosis and it has been demonstrated as a common feature of cancer.

Roles of dioxins and heavy metals in cancer and neurological diseases using ROS-mediated mechanisms.

Oxidants have critical functions inside healthy and unhealthy cells. Deregulated cell cycle and apoptosis, both regulated by oxidative stress, have been described as hallmarks of mitotic (cancer) and postmitotic (neuronal) cells. This review provides an updated revision of the oxidant effects of some environmental contaminants such as dioxins and the heavy metals cadmium, cobalt, and copper. Dioxins exert their toxic actions by acting on phase I and phase II enzymes, such as cytochromes P450, superoxide dismutase, and glutathione peroxidase, promoting cell proliferation, growth arrest, and apoptosis, affecting cancer homeostasis and neuronal function. Heavy metals manifest cytotoxic effects in various cells and tissues, and tight regulation of metals is essential to the health of organisms. Cadmium modulates gene expression and signal transduction and reduces activities of proteins involved in antioxidant defense, interfering with DNA repair and modifying cancer development and brain function. Cobalt provokes generation of reactive oxygen species and DNA damage in cancer cells and brain tissues, altering proliferation and differentiation and causing apoptosis. Copper is a key metal in cell division processes in both normal and tumor cells. Copper also has been shown to have an important role in neurodegenerative diseases such as Alzheimer disease, Parkinson disease, and amyotrophic lateral sclerosis.