Estado actual de la transmisión de la toxoplasmosis por productos cárnicos en Costa Rica

"La toxoplasmosis es una enfermedad que aunque casi siempre cursa en una modalidad de tipo crónica usualmente asintomática, eventualmente puede causar problemas en el ser humano como aborto y lesiones oculares. Por tal razón, conocer las posibles fuentes de contaminación al ser humanoes importante y en este estudio se tiene como objetivos revisar la literatura en cuanto a la trasmisión por productos cárnicos y determinar la positividad por Toxoplasma gondii en dos tipos de productos cárnicos para consumo humano, comparando los datos actuales con los obtenidos hace más de 10 años."

Effect of <i>Trypanosoma lewisi</i> (Kinetoplastida: Trypanosomatidae) on the infection of white rats with <i>Toxoplasma gondii</i> (Eucoccidia: Sarcocystidae) oocysts

White rats were inoculated with 10 6 trypomastigotes of Trypanosoma lewisi, simultaneously or two days before and after inoculation with 10 5 oocysts of T. gondií. A greater number of cysts was found in the brain of the animals having concomitant inoculations, as compared with rats inoculated with either one of the two parasites. An apparent immunosuppressive effec! is Iikely. Since both orgartisms can be found in rats, ít is possible that infections with T. lewisi, could make this rodent another intermediate host for Toxoplasma infections

Sodium tungstate regulates food intake and body weight through activation of the hypothalamic leptin pathway

AIMS

Sodium tungstate is an anti-obesity drug targeting peripheral tissues. In vivo, sodium tungstate reduces body weight gain and food intake through increasing energy expenditure and lipid oxidation, but it also modulates hypothalamic gene expression when orally administered, raising the possibility of a direct effect of sodium tungstate on the central nervous system.

METHODS

Sodium tungstate was administered intraperitoneally (ip) to Wistar rats, and its levels were measured in cerebrospinal fluid through mass spectrometry. Body weight gain and food intake were monitored for 24 h after its administration in the third ventricle. Hypothalamic protein was obtained and subjected to western blot. In vitro, hypothalamic N29/4 cells were treated with 100 µM sodium tungstate or 1 nM leptin, and protein and neural gene expression were analysed.

RESULTS

Sodium tungstate crossed the blood-brain barrier, reaching a concentration of 1.31 ± 0.07 mg/l in cerebrospinal fluid 30 min after ip injection. When centrally administered, sodium tungstate decreased body weight gain and food intake and increased the phosphorylation state of the main kinases and proteins involved in leptin signalling. In vitro, sodium tungstate increased the phosphorylation of janus kinase-2 (JAK2) and extracellular signal-regulated kinase-1/2 (ERK1/2), but the activation of each kinase did not depend on each other. It regulated c-myc gene expression through the JAK2/STAT system and c-fos and AgRP (agouti-related peptide) gene expression through the ERK1/2 pathway simultaneously and independently.

CONCLUSIONS

Sodium tungstate increased the activity of several kinases involved in the leptin signalling system in an independent way, making it a suitable and promising candidate as a leptin-mimetic compound in order to manage obesity.

[The immunosuppressant effect of T. lewisi (Kinetoplastidae) infection on the multiplication of Toxoplasma gondii (Sarcocystidae) on alveolar and peritoneal macrophages of the white rat]

The immunosuppressant effect of T. lewisi infection on the multiplication of T. gondii was compared in peritoneal (MP) and alveolar macrophages (MA) of white rat. Two animal groups were infected with T. lewisi and sacrificed after four days and seven days post infection. A group without infection was maintained as a control. The number of intracellular parasites (tachyzoites) (IT) was counted by light microscopy, calculating the rate infection rate per 100 total cells (TC) and per infected cells (IC) for each group of phagocyte cells. The relation quotient IT, TC or IC multiplied percent, provided a statistical ratio (RE) of the relative number of parasites in both cellular types for each time interval. MA as well as MP obtained after 4 days showed a significant increase in the multiplication of T. gondii with respect to the control. Unlike the MP (which had an increase in the multiplication of T. gondii the fourth day of infection with T. lewisi diminishing towards the seventh day), the MA had an increase in the multiplication of the parasite from the fourth to the seventh day. This difference can be related to the route of infection used for the experiments, that affect the MP directly with a greater effect in comparison with the MA of the lungs. Lung compartment will be affected later, when the infection becomes systemic between the fourth and sixth day of infection. The immunity against T. gondii is similar between both phagocytes, but the time of infection and the compartment where the cells are located, makes the difference in the response time against T. gondii. Supernatants from macrophage cultures or T. lewisi by rat did not induced any immunosuppression.

Trasmisión de toxoplasma gondii en Costa Rica: un concepto actualizado

Resumen: Los hallazgos más recientes en cuanto a la trasmisión del Toxoplasma gondii en Costa Rica nos indican que la ingestión de carne poco cocida, así como de algunos embutidos, en donde se ha encontrado el parásito en forma viable, son mecanismos de infección importante. Estos aspectos han hecho variar un poco la concepción anterior de que la ingestión de ooquistes del parásito era la principal, sino la única, vía de infección en nuestro país. Por ello se propone un nuevo ciclo de trasmisión para este parásito, comparándolo con el previamente establecido. Este nuevo patrón epidemiológico establece mayores posibilidades de infección con este parásito para los costarricenses.

Fenofibrate prevents Rosiglitazone-induced body weight gain in ob/ob mice

AIMS/HYPOTHESIS

Fibrates and thiazolidinediones are commonly used for the treatment of dyslipidemia and type 2 diabetes, respectively. The aim of this study was to investigate the effects on body weight as well as on glucose and lipid homeostasis of ligands for PPARalpha and PPARgamma, Fenofibrate and Rosiglitazone, alone or in association.

METHODS

Ob/ob mice were divided into four groups: control, and mice daily injected (intraperitoneally), either with 10 mg/kg Rosiglitazone, 100 mg/kg Fenofibrate or both molecules. Body weight and food intake were monitored daily. After 13 days of treatment, mice were killed, and blood samples were collected for posterior metabolite quantification. The liver and adipose tissues were dissected and weighed.

RESULTS

Body weight was significantly reduced or increased by Fenofibrate and Rosiglitazone, respectively. The effect of Rosiglitazone was prevented by coadministration of Fenofibrate. This was accompanied by a normalization of the daily food efficiency. Compared to those treated with Rosiglitazone, animals treated with Fenofibrate alone or in combination presented a decreased white adipose tissue mass. Fenofibrate or Rosiglitazone alone significantly reduced the levels of plasma lipid parameters. Surprisingly, Fenofibrate also decreased blood glucose levels in ob/ob mice, despite having no effect on insulin levels. By contrast, both glucose and insulin levels were decreased by Rosiglitazone treatment. Coadministration of both drugs improved all parameters as with Rosiglitazone. Fenofibrate restored almost normal hepatocyte morphology and significantly reduced the triglyceride content of the liver. This was accompanied by an increase in fatty acid oxidation in the liver in all groups receiving Fenofibrate.

CONCLUSION/INTERPRETATION

These biological effects suggest that combined therapy with a PPARalpha and a PPARgamma ligand is more effective in ameliorating, specifically, lipid homeostasis than in activating any of this receptor separately. Furthermore, Fenofibrate prevents one of the most undesirable effects of Rosiglitazone, namely increased adiposity and body weight gain.

[Intestinal parasites in howler monkeys Alouatta palliata (Primates: Cebidae) of Costa Rica]

Fecal samples of 102 howler monkeys (Alouatta palliata) from several sites of Costa Rica were studied for intestinal parasites. The zones studied were: Central Valley (San Ramón, Alajuela), Central Pacific (Chomes and Manuel Antonio National Park. Puntarenas), North Pacific (Palo Verde Park and Playa Potrero, Guanacaste). Chira Island in the Nicoya Gulf and Caribean area (Cahuita. Limón). Animals were anesthetized with dards containing Telazol in order to collect the fecal material; some monkeys defecated spontaneously and others by direct stimulation. Samples were studied in saline solution (0.85%) and a Iodine solution, or stained with Haematoxylin. The material was also cultured in Dobell culture medium to determine the presence of amoeba and flagellates. Strongvloides. Controrchis. Trypanoxyuris genera were found in 3.4% of the samples. In addition 16.7% to 80% of the animals showed protozoa infection with Endolimax, Entamoeba, Trichomonas and Giardia. It is discussed the relationships of parasite infection with environmental conditions, animal population and human presence, specially in the monkey conservation programs point of view.

[Effect of arthropod extracts on the multiplication of Toxoplasma gondii in mouse peritoneal macrophages]

Treatment of toxoplasmosis usually causes secondary effects. It is important to find active substances extracted from natural organisms. In this work we studied some arthropod extracts that have effect against Toxoplasma multiplication inside mouse macrophages. After studying 382 extracts, 23 were selected on the basis of the activity and we found that 13 extracts from orders Polydesmida, Lepidoptera, Orthoptera and Hymenoptera exerted an important inhibition of Toxoplasma multiplication.

Mitochondrial biogenesis in brown adipose tissue is associated with differential expression of transcription regulatory factors

The differentiation of brown adipocytes during late fetal development or in cell culture is associated with enhanced mitochondrial biogenesis and increased gene expression for components of the respiratory chain/oxidative phosphorylation system. We have shown that this is due to a rise in mitochondrial DNA abundance and the corresponding increase in mitochondrial genome transcripts and gene products, as well as to the coordinate induction of nuclear-encoded genes for mitochondrial proteins. We studied how the expression of key components of the transcriptional regulation of mitochondrial biogenesis is regulated during this process. Changes in the expression of nuclear respiratory factor-2/GA-binding protein a and peroxisome proliferator-activated-receptor gamma coactivator-1 (increase) were opposite to those of nuclear respiratory factor-1 and Sp1 (decrease) during the developmental and differentiation-dependent induction of mitochondrial biogenesis in brown fat. These results indicate that the relative roles of transcription factors and coactivators in mediating mitochondrial biogenesis 'in vivo' are highly specific according to the cell type and stimulus that mediate the mitochondriogenic process.

Prevalencia de microsporidios en orinas de pacientes referidos para urocultivo en la Región Pacífico Central

Justificación: La mayoría de las infecciones por microsporidios en el ser humano se han reportado en el tracto gastrointestinal, sin embargo, es posible hallarlos parasitando otros sitios anatómicos como el tracto genitourinario, en donde las patologías pueden variar desde uretritis hasta falla renal. Tradicionalmente esas infecciones se deben al género Encephalitozoon, parásito contra el cual el Albendazol ha demostrado ser un medicamento efectivo.Objetivo: Determinar la prevalencia de microsporidios en personas que son referidas al laboratorio para urocultivo, dados los antecedentes clínicos que presentan.Métodos: El procesamiento de las muestras incluyó su toma con técnica aséptica, su cultivo en los medios de Agar Sangre, MacConkey y Manitol – sal para su estudio por presencia de bacterias y/u hongos y la realización del antibiograma, según los parámetros establecidos por la CCSS para los urocultivos. Adicional a esto se centrifugó una alícuota de 9 ml separando 50 microlitos del sedimento urinario, al cual se le añadió igual volumen de KOH al 5%. Se hicieron frotis los cuales se fijaron con alcohol metílico una vez secos, y se tiñeron con la técnica tricrómica de Weber, obviando el paso de la decoloración y la deshidratación.Resultados: Se encontró un 25% de orinas positivas por microsporidios. Los pacientes con edades entre 26 y 55 años presentaron mayor positividad.Conclusiones: El porcentaje de prevalencia encontrado (25%) y el hecho de que estas infecciones pueden llegar a causar severos daños al ser humano, hacen imperativa la necesidad de realizar diagnósticos más certeros de esta parasitosis, para lo cual proponemos la tinción de Weber con la modificación presentada en este trabajo para el diagnóstico de las infecciones por microsporidios en el tracto urinario.

Impaired expression of the uncoupling protein-3 gene in skeletal muscle during lactation: fibrates and troglitazone reverse lactation-induced downregulation of the uncoupling protein-3 gene

The expression of uncoupling protein (UCP)-3 mRNA in skeletal muscle is dramatically reduced during lactation in mice. The reduction in UCP-3 mRNA levels lowers the amount of the UCP-3 protein in skeletal muscle mitochondria during lactation. Spontaneous or abrupt weaning reverses the downregulation of the UCP-3 mRNA but not the reduction in UCP-3 protein levels. In lactating and virgin mice, however, fasting increases UCP-3 mRNA levels. Changes in UCP-3 mRNA occur in parallel with modifications in the levels of free fatty acids, which are reduced in lactation and are upregulated due to weaning or fasting. Modifications in the energy nutritional stress of lactating dams achieved by manipulating litter sizes do not influence UCP-3 mRNA levels in skeletal muscle. Conversely, when mice are fed a high-fat diet after parturition, the downregulation of UCP-3 mRNA and UCP-3 protein levels due to lactation is partially reversed, as is the reduction in serum free fatty acid levels. Treatment of lactating mice with a single injection of bezafibrate, an activator of the peroxisome proliferator-activated receptor (PPAR), raises UCP-3 mRNA in skeletal muscle to levels similar to those in virgin mice. 4-chloro-6-[(2,3-xylidine)-pirimidinylthio] acetic acid (WY-14,643), a specific ligand of the PPAR-alpha subtype, causes the most dramatic increase in UCP-3 mRNA, whereas troglitazone, a specific activator of PPAR-gamma, also significantly increases UCP-3 mRNA abundance in skeletal muscle of lactating mice. However, in virgin mice, bezafibrate and WY-14,643 do not significantly affect UCP-3 mRNA expression, whereas troglitazone is at least as effective as it is in lactating dams. It is proposed that the UCP-3 gene is regulated in skeletal muscle during lactation in response to changes in circulating free fatty acids by mechanisms involving activation of PPARs. The impaired expression of the UCP-3 gene is consistent with the involvement of UCP-3 gene regulation in the reduction of the use of fatty acids as fuel by the skeletal muscle and in impaired adaptative thermogenesis, both of which are major metabolic adaptations that occur during lactation.

Inverse distribution of uncoupling proteins expression and oxidative capacity in mature adipocytes and stromal-vascular fractions of rat white and brown adipose tissues

To investigate relationships between the uncoupling protein (UCP) family and oxidative metabolism in fat pads, we measured the cytochrome oxidase activity, used as an index of oxidative capacity, and the mRNA content encoding UCP1, UCP2 and UCP3. Most oxidative potential was found in the stromal-vascular fraction (SVF) of brown fat and in mature adipocytes of white fat (inguinal and periovarian). Considering the whole fat pads, the oxidative potential observed in mature white adipocytes fraction was not negligible compared with that of brown adipocytes fraction. UCP1 and UCP3 were expressed exclusively in mature brown adipocytes. Whatever the deposit, UCP2 mRNA was mainly localized in the SVF. These results indicate that, in fat, high oxidative potential is not necessarily linked to high UCPs transcripts content and point out the oxidative capacity of SVF from brown fat.

Cyclospora cayetanensis: Revisión e informe del primer caso humano en Costa Rica

Resumen: La Cyclospora cayetanensis es uno de los tantos parásitos que se están adaptando rápidamente al hombre y que en conjunto con las especies de la criptosporidiosis y de la microsporidiosis, hoy se encuentran afectando a individuos tanto inmunosupresos como inmunocompetentes. El sida parece ser en todos estos casos el elemento común de inicio de la parasitosis humana con estos organismos, presentes usualmente en animales de una escala zoológica lejana. Luego de romper las barreras, estos organismos se adaptan al ser humano inmunológicamente normal. La ciclosporosis es conocida en el mundo entero pero en Costa Rica no había sido reportada hasta ahora. Este trabajo informa del primer caso humano en Costa Rica y como corolario se presenta una revisión de la parasitosis con el propósito de ayudar a profesionales interesados en el área de la salud a conocer, diagnosticar y combatir mejor.

Opposite regulation of PPAR-alpha and -gamma gene expression by both their ligands and retinoic acid in brown adipocytes

The peroxisome proliferator-activated receptors (PPARs) are lipid-activated transcription factors involved in the regulation of lipid metabolism and adipocyte differentiation. Little is known, however, about the control of the expression of the genes encoding each of all three receptor subtypes: alpha, delta, and gamma. We have addressed this question in the brown adipocyte, the only cell type that co-expresses high levels of the three PPAR subtypes. Differentiation of brown adipocytes is associated with enhanced expression of PPAR genes. However, whereas PPARgamma and PPARdelta genes are already expressed in preadipocytes, the mRNA for PPARalpha appears suddenly in association with the acquisition of the terminally differentiated phenotype. Both retinoic acid isomers and PPAR agonists, specific for either PPARalpha or PPARgamma, regulate expression of each PPAR subtype gene in the opposite way: they up-regulate PPARalpha and down-regulate PPARgamma. The effects on PPARalpha mRNA are independent of protein synthesis, whereas inhibition of PPARgamma mRNA expression depends on protein synthesis, except when its specific ligand prostaglandin J2 is used. Our results indicate a strictly opposite autoregulation of PPAR subtypes, which supports specific physiological roles for them in controlling brown fat differentiation and thermogenic activity.

Uncoupling protein-3 gene expression in skeletal muscle during development is regulated by nutritional factors that alter circulating non-esterified fatty acids

Uncoupling protein-3 gene expression in skeletal muscle is up-regulated during postnatal development of mice. A high-carbohydrate diet at weaning induces a decrease in uncoupling protein-3 mRNA levels that does not occur when mice were weaned onto a high-fat diet. Uncoupling protein-3 mRNA levels do not increase in response to fasting in young pups. Only after day 15 of life, when fasting increases serum non-esterified fatty acids, uncoupling protein-3 mRNA is up-regulated by starvation. Over-nutrition or under-nutrition during lactation increases or decreases, respectively, uncoupling protein-3 mRNA expression in skeletal muscle. Regulation of uncoupling protein-3 gene expression in skeletal muscle during development is mediated by ontogenic and nutritional factors determining changes in circulating non-esterified fatty acids.

Activators of peroxisome proliferator-activated receptor-alpha induce the expression of the uncoupling protein-3 gene in skeletal muscle: a potential mechanism for the lipid intake-dependent activation of uncoupling protein-3 gene expression at birth

The recently identified uncoupling protein-3 (UCP-3) gene, predicted to encode a new member of the family of uncoupling proteins, is preferentially expressed in skeletal muscle and has been related to phenotypes of obesity and type 2 diabetes. We have established that during mouse ontogeny, the expression of the UCP-3 gene is switched on in skeletal muscle just after birth. The induction of UCP-3 gene expression is dependent on the initiation of suckling and particularly on lipid intake. Treatment of newborn mice with activators of peroxisome proliferator-activated receptors (PPARs), such as clofibrate, bezafibrate, or (4-chloro-6-(2,3-xylidine)-pirimidinylthio)acetic acid (WY 14,643), mimics the action of food intake on UCP-3 gene expression. The specific ligand of PPAR-alpha WY 14,643 induces UCP-3 gene expression in a time- and dose-dependent manner, whereas the thiazolidinedione BRL 49653, specific for PPAR-gamma, has no effect. These treatments act without altering circulating free fatty acids. During development, skeletal muscle expresses constitutive levels of PPAR-delta mRNA, whereas expression of the PPAR-gamma gene is undetectable. PPAR-alpha gene expression is developmentally regulated in muscle as it is first expressed at birth, just before UCP-3 gene induction occurs. The induction of UCP-3 gene expression by WY 14,643 is impaired in skeletal muscle of premature neonates, which do not express PPAR-alpha. It is proposed that the UCP-3 gene is predominantly regulated in neonatal muscle by PPAR-alpha activation.

9-cis retinoic acid induces the expression of the uncoupling protein-2 gene in brown adipocytes

The expression of uncoupling protein-2 (UCP2) mRNA is up-regulated during the differentiation of brown adipocytes in primary culture. When differentiation of brown adipocytes is impaired, UCP2 mRNA expression is down-regulated. 9-cis Retinoic acid causes a dose-dependent induction of UCP2 mRNA levels in brown adipocytes, whereas all-trans retinoic acid has no effect. Specific agonists of retinoid X receptors (RXR) induce UCP2 mRNA expression, whereas specific activators of retinoic acid receptors do not. 9-cis Retinoic acid, acting through RXR receptors, is identified as a major regulator of the expression of the UCP2 gene in the brown fat cell.

Differential regulation of uncoupling protein-2 and uncoupling protein-3 gene expression in brown adipose tissue during development and cold exposure

The expression of the two novel uncoupling proteins genes, UCP2 and UCP3, is differentially regulated during prenatal maturation of brown adipose tissue in the mouse. UCP2 gene is expressed early in prenatal development, when neither UCP1 nor UCP3 gene expression yet occurs. UCP3 mRNA is absent at any stage of fetal life; it appears suddenly at birth and reaches adult levels in a few hours. UCP2 mRNA increased after birth but more slowly than UCP3 and UCP1 mRNA. Short-time exposure of adult mice to cold caused a rise in UCP2 or UCP1 mRNA levels but not in that of UCP3. The postnatal rise in UCP2 gene expression appears to be a response to the thermic stress associated with birth, similarly to UCP1, whereas different biological signals may be responsible for the surge in UCP3 gene expression at birth.

Elastoidin turn-over during tail fin regeneration in teleosts. A morphometric and radioautographic study

During teleostean fin regeneration the actinotrichia, rods of a collagen-like protein, the elastoidin, are immersed in the blastema, maintaining their apical position. In this epimorphic event the latter fact might be achieved by either a cellular carriage or a continuous turn-over of these hyperpolimerized fibrils. By means of a 3H-proline pulse and radioautographic chase experiment of the isolated actinotrichia we have found a turn-over of collagen within the structure. From these and additional morphometric results, we present in this work an operational hypothesis of how gradually differentiating blastemal cells and an appropriately shaped basal lamina, can control the number and distribution of actinotrichia which might be under the balanced control of their synthesis and degradation.

Inhibition of plant cytokinesis by deoxyguanosine and caffeine

The efficacy of 2'-deoxyguanosine (GdR) on the induction of binucleate cells in onion root tips was studied. GdR inhibits plant cytokinesis during the last part of the mitotic period. Apparently, this deoxynucleoside causes a considerable slowing down in the mitotic rate (50%) and also has a slight effect as an inhibitor of cytokinesis (30%). The effect on the mitotic rate was established with 1 mM colchicine (metaphase rate) and with 5 mM caffeine (telophase rate).Since 1 mM GdR has a remarkable potentiating action on inhibition of cytokinesis by caffeine, we postulate that GdR, or a phosphorylated derivative from it, inhibits cytokinesis by a similar mechanism as caffeine. According to our postulation, GdR interferes with a certain ATPase activity required for membrane fusion of the Golgi vesicles during plant cytokinesis.