Variations in the lipid profile of patients with chronic renal failure treated with pyridoxine

BACKGROUND: Hyperhomocysteinemia and lipid abnormalities are commonly found in patients with chronic renal failure; both are recognized as risk factors for atherosclerosis. The homocysteine-lowering effect of pyridoxine is controversial. This study was performed to determine the effect of a high dose of pyridoxine (300 mg i.v. three times a week) on plasma and red blood cell lipid profile and plasma homocysteine concentration in twelve chronic renal failure patients on regular hemodialysis. Fasting blood samples were taken at the beginning of the study (basal 1), after 30 and 60 days of treatment and 4 months after withdrawal (basal 2). RESULTS: Pyridoxine supplementation induced a significant decrease in total plasma homocysteine level and also a lowering effect in plasma total cholesterol and triglycerides. These biochemical data increased when the samples were taken at basal 2, reaching the levels obtained at the beginning of the experiment. LDL cholesterol increased whereas HDL cholesterol was reduced during the treatment. In erythrocyte membranes vitamin B6 therapy enhanced the cholesterol/phospholipid ratio as well as the fluorescence anisotropy of diphenyl-hexatriene. CONCLUSIONS: We conclude that high doses of pyridoxine represent an effective strategy to ameliorate both plasma homocysteine levels and lipid profiles in chronic renal failure patients, protecting them from atherosclerosis. Further research using a long-term treatment would be necessary in an attempt to restore the fatty acid pattern and the fluidity of red cell membranes

Phosphatidylcholine deficiency upregulates enzymes of triacylglycerol metabolism in CHO cells

We studied the regulation of triacylglycerol (TAG) metabolism by phosphatidylcholine (PC) in CHO MT58 cells, which are deficient in PC synthesis because of a temperature-sensitive CTP:phosphocholine cytidylyltransferase. At the permissive growth temperature (34°C), these cells contained 49% less TAG and 30% less PC than wild-type CHO K1 cells. Treatment with dipalmitoylphosphatidylcholine normalized both the PC and TAG levels. Despite low TAG levels, the incorporation of [14C] oleate into TAG was increased in CHO MT58 cells. The in vitro de novo synthesis of TAG and the activity of diacylglycerol acyltransferase were 90% and 34% higher, respectively. Two other key enzyme activities in TAG synthesis, acyl-CoA synthetase and mitochondrial glycerol-3-phosphate acyltransferase (GPAT), increased by 48% and 2-fold, respectively, and mitochondrial GPAT mRNA increased by ∼4-fold. Additionally, TAG hydrolysis was accelerated in CHO MT58 cells, and in vitro lipolytic activity increased by 68%. These studies suggest that a homeostatic mechanism increases TAG synthesis and recycling in response to PC deficiency. TAG recycling produces diacylglycerol and fatty acids that can be substrates for de novo PC synthesis and for lysophosphatidylcholine (lysoPC) acylation. In CHO MT58 cells, in which de novo PC synthesis is blocked, lysoPC acylation with fatty acid originating from TAG may represent the main pathway for generating PC.Instituto de Investigaciones Bioquímicas de La Plat

Integración de equipos de trabajo

Este documento pretende abordar los resultados arrojados dentro del Proyecto de Gestión del cambio, del talento humano y la efectividad organizacional, tomando en cuenta las aportaciones generadas por el PAP de primavera 2022. La investigación se basa en una metodología cualitativa, utilizando la observación participante dentro del marco de un taller impartido vía electrónica, tomando en cuenta las observaciones del personal a cargo y las perspectivas individuales de los colaboradores. Los principales resultados permitieron conocer: las necesidades específicas dentro de la empresa, las perspectivas individuales de los colaboradores respecto a su sentir en ámbitos laborales y el uso del reconocimiento de habilidades cómo método motivacional para la ejecución de los objetivos empresariales.ITESO, A.C

Alteración de la comunidad meiobentónica por efecto del pisoteo en la zona intermareal baja de playa arenosa

The importance of knowing the meiobenthic composition of coastal ecosystems has been enhanced for the evaluation of trophic relationships, especially as indicators of stress and pollution on beaches. This research aimed to determine the abundance and diversity of the meiofauna in the intertidal zone of Venao Beach and evaluate the effect of trampling by users on these organisms. The individuals were collected by using 29.85 mm diameter PVC nucleators, buried 0.05 m under the sediment, during low tide periods, on days with the presence and absence of people, over two months. In addition, the granulometric characteristics were evaluated and the variations in the beach profile were measured. Differences in species composition were observed between these periods, in addition, between areas of beach use with the presence of users, however, there was no relationship between abundance and richness, with the environmental characteristics evaluated, so it follows that the Hydrodynamic characteristics exert an effect on the distribution of organisms.La importancia del conocimiento de la composición meiobentónica de los ecosistemas costeros ha sido potenciada para la evaluación de las relaciones tróficas, sobre todo, como indicadores de estrés y contaminación en las playas. El objetivo de la presente investigación fue determinar la abundancia y diversidad de la meiofauna en la zona intermareal de playa Venao y evaluar el efecto del pisoteo de los usuarios sobre estos organismos. Los individuos fueron colectados mediante el uso de nucleadores de pvc de 0,029 m de diámetro, enterrados a 0,05 m bajo el sedimento, en períodos de marea baja, en días con presencia y ausencia de personas, en un lapso de dos meses. Además, se evaluó las características granulométricas y se midió las variaciones del perfil de la playa.  Se observó diferencias en composición de especies entre estos períodos, además, entre zonas de uso de la playa con presencia de usuarios, sin embargo, no hubo relación de la abundancia y riqueza, con las características ambientales evaluadas, por lo que se desprende que las características hidrodinámicas ejercen efecto sobre la distribución de los organismos

Phosphatidylcholine deficiency upregulates enzymes of triacylglycerol metabolism in CHO cells

We studied the regulation of triacylglycerol (TAG) metabolism by phosphatidylcholine (PC) in CHO MT58 cells, which are deficient in PC synthesis because of a temperature-sensitive CTP:phosphocholine cytidylyltransferase. At the permissive growth temperature (34°C), these cells contained 49% less TAG and 30% less PC than wild-type CHO K1 cells. Treatment with dipalmitoylphosphatidylcholine normalized both the PC and TAG levels. Despite low TAG levels, the incorporation of [14C] oleate into TAG was increased in CHO MT58 cells. The in vitro de novo synthesis of TAG and the activity of diacylglycerol acyltransferase were 90% and 34% higher, respectively. Two other key enzyme activities in TAG synthesis, acyl-CoA synthetase and mitochondrial glycerol-3-phosphate acyltransferase (GPAT), increased by 48% and 2-fold, respectively, and mitochondrial GPAT mRNA increased by ∼4-fold. Additionally, TAG hydrolysis was accelerated in CHO MT58 cells, and in vitro lipolytic activity increased by 68%. These studies suggest that a homeostatic mechanism increases TAG synthesis and recycling in response to PC deficiency. TAG recycling produces diacylglycerol and fatty acids that can be substrates for de novo PC synthesis and for lysophosphatidylcholine (lysoPC) acylation. In CHO MT58 cells, in which de novo PC synthesis is blocked, lysoPC acylation with fatty acid originating from TAG may represent the main pathway for generating PC.Instituto de Investigaciones Bioquímicas de La Plat

Diacylglycerol generated in CHO cell plasma membrane by phospholipase C is used for triacylglycerol synthesis

The diacylglycerol (DAG) signal generated from membrane phospholipids by hormone-activated phospholipases is attenuated by mechanisms that include lipolysis or phospholipid resynthesis. To determine whether the DAG signal might also be terminated by incorporation of DAG into triacylglycerol (TAG), we studied the direct formation of TAG from endogenous DAG generated by bacterial phospholipase C (PLC). When Chinese hamster ovary (CHO) cells prelabeled with [¹⁴C]oleate were treated with PLC from Clostridium perfringens for 6 h, [¹⁴C]phospholipid decreased 15% and labeled TAG increased 60%. This transfer of ¹⁴C label was even greater when the cells were simultaneously exposed to PLC and 100 μM oleic acid. PLC as well as oleate treatment concomitantly increased the TAG mass within the cell. Moreover, when phospholipids were prelabeled with [³H]glycerol, a subsequent increase in [³H]TAG indicated that an intact DAG moiety was channeled into the TAG structure. Incubating CHO cells with the diacylglycerol kinase inhibitor R59022 enhanced the formation of TAG from phospholipids hydrolyzed by PLC or by PLC in the presence of 100 μM oleate, but not by incubation with oleate alone, indicating that the DAG released from plasma membrane phospholipids does not require the formation of a phosphatidic acid precursor for TAG synthesis. Similarly, the diacylglycerol lipase inhibitor RHC 80267 did not alter TAG synthesis from plasma membrane DAG, further supporting direct incorporation of DAG into TAG. These studies indicate that DAG derived from plasma membrane phospholipid is largely used for TAG formation, and support the view that this mechanism can terminate DAG signals. The studies also suggest that a transport mechanism exists to move plasma membrane-derived DAG to the endoplasmic reticulum.Facultad de Ciencias MédicasInstituto de Investigaciones Bioquímicas de La Plat

Assessing the conservation value of waterbodies: the example of the Loire floodplain (France)

In recent decades, two of the main management tools used to stem biodiversity erosion have been biodiversity monitoring and the conservation of natural areas. However, socio-economic pressure means that it is not usually possible to preserve the entire landscape, and so the rational prioritisation of sites has become a crucial issue. In this context, and because floodplains are one of the most threatened ecosystems, we propose a statistical strategy for evaluating conservation value, and used it to prioritise 46 waterbodies in the Loire floodplain (France). We began by determining a synthetic conservation index of fish communities (Q) for each waterbody. This synthetic index includes a conservation status index, an origin index, a rarity index and a richness index. We divided the waterbodies into 6 clusters with distinct structures of the basic indices. One of these clusters, with high Q median value, indicated that 4 waterbodies are important for fish biodiversity conservation. Conversely, two clusters with low Q median values included 11 waterbodies where restoration is called for. The results picked out high connectivity levels and low abundance of aquatic vegetation as the two main environmental characteristics of waterbodies with high conservation value. In addition, assessing the biodiversity and conservation value of territories using our multi-index approach plus an a posteriori hierarchical classification methodology reveals two major interests: (i) a possible geographical extension and (ii) a multi-taxa adaptation

Revista de libros

Se reseñan las siguientes obras: * Rodolfo Mondolfo: Sócrates, segunda edición, revisada por el autor, Editorial Universitaria, Buenos Aires, 1959. N° 8 de la Colección Cuadernos. Yol. rústica, 63 páginas. * José Luis Lanuza: Una nube llamada Helena. Editorial Perrot. Colección La Torre de Babel, Buenos Aires, 1958. Yol. rústica. 170 páginas * Hans Aebli: Una Didáctica fundada en la Psicología de Jean Piaget. (Traducción por Federico Monjardín). Editorial Kapelusz. Buenos Aires. 1958. Volumen en rústica, 205 páginas * Miles Colean: Renovando nuestras ciudades. (Traducción del Ing. José M. Ahumada). Editorial Contémpora, Buenos Aires 1959; Volumen Rústica, 195 págs. * Armando Asti Vera: Estructura y método de una monografía. Ed. de la Universidad Nacional del Nordeste; Resistencia, 1959. Vol. Rúst., 52 págs. * Roberto Salama: Benito Lynch. Editorial La Mandrágora, Buenos Aires, 1959. Volumen Rústica, 318 páginas.Universidad Nacional de La Plat