Importancia de la leche y sus potenciales efectos en la salud humana / Importance of milk and its potential efects on human health

El Código Alimentario Argentino establece: "Con la denomi-nación de leche sin calificativo alguno, se entiende el producto obtenido por el ordeño total e ininterrumpido, en condiciones de higiene, de la vaca lechera en buen estado de salud y ali-mentación, proveniente de tambos inscriptos y habilitados por la Autoridad Sanitaria Bromatológica Jurisdiccional y sin aditivos de ninguna especie"1. La leche de vaca es un componente cuantitativamente útil en la alimentación humana en gran parte debido al acceso generali-zado a partir de su industrialización y comercialización. Su com-posición la hace de interés para adaptar su uso y prescripción en distintos momentos de la vida y en la promoción de la salud.Según estudios de investigación, los efectos no se limitarían exclu-sivamente a su valor nutricional, sino que sumarían otros poten-ciales en determinadas patologías como la enfermedad cardiovas-cular, algunos tipos de cáncer, hipertensión arterial, en patología ósea o dental y en la lucha frente al sobrepeso y la obesidad.Por este motivo, el Grupo de Trabajo Alimentos de la Sociedad Argentina de Nutrición realizó esta revisión sobre los potenciales efectos de la leche: virtuosos o adversos.

Biotecnologia translacional: hemopressina e outros peptídeos intracelulares / Translational biotechnology: hemopressin and other intracellular peptides

A biotecnologia é uma prática antiga, sendo utilizada desde o antigo Egito para a produção de pão e cerveja. No mundo contemporâneo, a biotecnologia tem sido utilizada de diversas formas, incluindo o tratamento de doenças. No universo acadêmico, a biotecnologia tem permitido um avanço rápido do conhecimento. Neste artigo, fazemos um breve resumo sobre o que é biotecnologia, sua relação com o processo de inovação e produção de biofármacos. No universo acadêmico, a biotecnologia tem contribuído de forma decisiva para a descoberta de novas moléculas bioativas, como no caso da hemopressina e de diversos outros peptídeos intracelulares.

Biotechnology has been used since ancient Egypt for the production of bread and beer. In the modern world, biotechnology has been used in several ways, including for the treatment of diseases. In academia, biotechnology has allowed a rapid advance of knowledge. In this article, we make a brief summary of what is biotechnology and its relation to the process of innovation and production of biopharmaceuticals. In academia, biotechnology has contributed decisively to the discovery of new bioactive molecules, such as in hemopressin and several other intracellular peptides.

Current progress in shrimp endocrinology-a review.

One problem in aquaculture is obtaining brood because many commercially important species are incapable of spontaneous maturation under artificial conditions. Commercial shrimp hatcheries commonly use eyestalk ablation to stimulate gonadal maturation in shrimps. Research has been conducted on the inhibition of reproductive maturation by hormones originating in the eyestalk glands and on other endocrine sources (e.g.,brain, thoracic ganglion, ovary, mandibular organ, androgenic gland and Y-organs) to determine their roles. Alternate techniques for acceleration of gonad maturation through the use of synthetic hormones or neurotransmitters may benefit aquaculture. Neurohormones and neuroregulators have been shown to accelerate gonadal maturation but an effective delivery technique must be developed for use in a large-scale aquaculture operation.

Fasting-induced Down-regulation of NADPH-diaphorase in the Magnocellular PVN of Rats

In this study, we examined if glucocorticoids are required for the fasting-induced decrease of neuronal nitric oxide synthase (nNOS) in the magnocellular division of the paraventricular nucleus (PVN). Rats were adrenalectomized, subjected to 48 h of food deprivation with/without dexamethasone (5 mg/ kg, 4 subcutaneous injections with 12 h intervals), and the brain slices were processed for NADPH-diaphorase (NADPH- d) staining, a histochemical marker for nNOS in neuronal cells. In food deprived adrenalectomized rats, but not in free fed intact rats, dexamethasone significantly decreased NADPH-d staining in the magnocellular PVN. We previously reported that food deprivation decreases nNOS in the magnocellular PVN of intact rats. Thus, the present results together with our previous report suggest that although glucocorticoids are required for fasting-induced nNOS down-regulation in the magnocellular PVN, glucocorticoids may not be directly involved and some other molecular signals produced by food deprivation may play a pivotal role over glucocorticoid in the regulatory pathway for nNOS expression in this brain region.

Peptídeos natriuréticos nas miocardiopatias / Natriuretic peptide in cardiomyopathy

Os peptídeos natriuréticos descritos dos tipos A, B e C atuam dentro da complexa fisiopatologia da insuficiência cardíaca como moduladores da atividade vasoconstritora produzida principalmente pelo sistema renina-angiotensina-aldosterona e pelo sistema simpático. Dentre esses peptídeos, o tipo B (BNP) destacou-se pela maior facilidade de determinação, além da superioridade na correlação com os achados clínicos. Pelo fato de ser o BNP liberado com a distensão ventricular esquerda, sua correlação com insuficiência cardíaca passa a ser importante, sendo este peptídeo um excelente marcador de dispnéia de origem cardíaca em pronto socorro, além de ser um preditor de mortalidade em pacientes internados por insuficiência cardíaca descompensada. Diversos estudos estão apresentando dados que sugerem que os níveis de BNP e NT-proBNP podem ser fator preditor de mortalidade em insuficiência coronária, fator preditor de recorrência de fibrilação atrial, fator importante para determinar o início da disfunção ventricular em doença de Chagas, fator preditor de indicação cirúrgica em doença valvar e possível marcador de formas graves de cardiomiopatia hipertrófica.

Clonagem, identificaçäo e análise de genes de peptídios tóxicos da cascavel sul americana, Crotalus durissus terrificus. Implicações evolutivas e funcionais / Cloning South American rattlesnake Crotalus durissus terrificus toxin peptides genes analysis and identification. Evolutions and functional implications

O veneno de animais contém um arsenal de toxinas que desencadeia respostas fisiológicas e bioquímicas específicas. A crotamina, um peptídio catiônico (4,4 kDa, pI 9,5), é um dos componentes mais abundantes do veneno de cascavel Sul Americana (Crotalus durissus terrificus). No Brasil, há populações de C. d. terrificus que expressam ou näo a crotamina no veneno. Em um único espécime de C. d. terrificus crotamina-positivo, foram isolados cDNAs precursores de duas isoformas de crotamina, dentre as quais a crotamina Ile-19, presente somente no veneno de C. d. ruruima. Análise por Northern blot de RNA total e mensageiro de glâdulas de C. d. terrificus crotamina-positivo e -negativo, indica que a expressäo...

Guanylin peptides: cyclic GMP signaling mechanisms

Guanylate cyclases (GC) serve in two different signaling pathways involving cytosolic and membrane enzymes. Membrane GCs are receptors for guanylin and atriopeptin peptides, two families of cGMP-regulating peptides. Three subclasses of guanylin peptides contain one intramolecular disulfide (lymphoguanylin), two disulfides (guanylin and uroguanylin) and three disulfides (E. coli stable toxin, ST). The peptides activate membrane receptor-GCs and regulate intestinal Cl- and HCO3- secretion via cGMP in target enterocytes. Uroguanylin and ST also elicit diuretic and natriuretic responses in the kidney. GC-C is an intestinal receptor-GC for guanylin and uroguanylin, but GC-C may not be involved in renal cGMP pathways. A novel receptor-GC expressed in the opossum kidney (OK-GC) has been identified by molecular cloning. OK-GC cDNAs encode receptor-GCs in renal tubules that are activated by guanylins. Lymphoguanylin is highly expressed in the kidney and heart where it may influence cGMP pathways. Guanylin and uroguanylin are highly expressed in intestinal mucosa to regulate intestinal salt and water transport via paracrine actions on GC-C. Uroguanylin and guanylin are also secreted from intestinal mucosa into plasma where uroguanylin serves as an intestinal natriuretic hormone to influence body Na+ homeostasis by endocrine mechanisms. Thus, guanylin peptides control salt and water transport in the kidney and intestine mediated by cGMP via membrane receptors with intrinsic guanylate cyclase activity.

Renal effects of uroguanylin and guanylin in vivo

Uroguanylin and guanylin are newly discovered endogenous heat-stable peptides that bind to and activate a membrane bound guanylyl cyclase signaling receptor (termed guanylyl cyclase C; GC-C). These peptides are not only found in blood but are secreted into the lumen of the intestine and effect a net secretion of electrolytes (Na+, K+, Cl-, HCO3-) and fluid into the intestine via a cyclic guanosine-3',5'-monophosphate (cGMP) mechanism. GC-C is also the receptor for Escherichia coli heat-stable enterotoxin (STa) and activation by STa results in a diarrheal illness. Employing mouse renal in vivo models, we have demonstrated that uroguanylin, guanylin, and STa elicit natriuretic, kaliuretic, and diuretic effects. These biological responses are time- and dose-dependent. Maximum natriuretic and kaliuretic effects are observed within 30-40 min following infusion with pharmacological doses of the peptides in a sealed-urethra mouse model. Our mouse renal clearance model confirms these results and shows significant natriuresis following a constant infusion of uroguanylin for 30 min, while the glomerular filtration rate, plasma creatinine, urine osmolality, heart rate, and blood pressure remain constant. These data suggest the peptides act through tubular transport mechanisms. Consistent with a tubular mechanism, messenger RNA-differential display PCR of kidney RNA extracted from vehicle- and uroguanylin-treated mice show the message for the Na+/K+ ATPase g-subunit is down-regulated. Interestingly, GC-C knockout mice (Gucy2c -/-) also exhibit significant uroguanylin-induced natriuresis and kaliuresis in vivo, suggesting the presence of an alternate receptor signaling mechanism in the kidney. Thus, uroguanylin and guanylin seem to serve as intestinal and renal natriuretic peptide-hormones influencing salt and water transport in the kidney through GC-C dependent and independent pathways. Furthermore, our recent clinical probe study has revealed a 70-fold increase in levels of urinary uroguanylin in patients with congestive heart failure. In conclusion, our studies support the concept that uroguanylin and guanylin are endogenous effector peptides involved in regulating body salt and water homeostasis.

Efectos de los factores de crecimiento sobre el hueso: sus implicancias para la implantología / Effects of growth factors on the bone: its implications for implantology

El control localizado de la masa ósea puede requerir la creación de nuevo hueso. La biotecnología nos permite acceder a moléculas que son determinantes en su generación. Aprender a emplear las formas recombinadas de estas moléculas puede permitirnos controlar clínicamente la cantidad de hueso disponible para mejorar la colocación de implantes en lugares con deficiencias óseas

Mecanismos moleculares de açäo hormonal / Molecular mechanisms of hormonal action

A característica principal dos hormônios é a sua habilidade em interagir com receptores altamente seletivos e ativar vias intracelulares do sinalizaçäo nos órgaos específicos. Após a interaçäo dos hormônios com seus receptores, uma seqüência de reaçöes pode levar ao aumento ou diminuiçäo na atividade de determinadas enzimas que, por sua vez, produzem a resposta fisiológica. Os hormônios säo bioquimicamente classificados em esteróides, peptídeos ou aminas e seus receptores diferem, basicamente, por sua localizaçäo, intra ou extracelular. No presente trabalho, o mecanismo molecular de açäo dos hormônios peptídicos (hidrofílicos) e esteróides (lipofílicos) é discutido.

Knob proteins in falciparum malaria.

Knob proteins play a significant role in the pathophysiology of cerebral malaria caused by Plasmodium falciparum. Most of these proteins are of parasite origin and can be divided into two major classes: (i) the cytoadherent proteins present at the surface of the knobs; and (ii) the submembranous structural proteins which are placed towards the cytoplasmic side in the knobs. Several surface proteins [viz., P. falciparum-infected erythrocyte membrane protein-1 (PFEMP-1), sequestrin, pfalhesin] and submembranous structural proteins [viz., knob-associated histidine-rich protein (KAHRP), PFEMP-2, PFEMP-3] of the knobs have been identified and characterized to a certain extent. The structural proteins interact with several host (e.g., spectrin, actin, band 4.1 etc.) as well as parasite (e.g., PFEMP-1) molecules to produce functional knobs. The surface proteins on the other hand interact with several adhesion molecules of the endothelial cell through receptor-ligand type of binding. Knob proteins are important from the point of view of malaria control since immunotherapeutic agents can be developed to block as well as reverse the cytoadherence phenomenon. The surface proteins are also good vaccine candidates except that they show a high rate of antigenic variation. Nevertheless, the use of ribozyme or antisense oligonucleotides to inhibit the expression of knob proteins (e.g., KAHRP alone or with surface protein) can be used as a molecular therapeutic agent.

Comunicación de gametos a distancia. Quimiotaxis y quimiocinesis del espermatozoide en mamíferos / At distance gamet communication. chemotaxis and chemokinesis of spermatozoo in mammals

La comunicación a distancia mediada químicamente entre el esperamatozoide o el óvulo como parte del proceso de fecundación a sido intensamente estudiado en especies de invertebrados con fecundación externa, sin embargo, su estudio en vertebrados, y especialmente mamíferos, abre un campo de gran interés. Los principales quimioatractantes en mamíferos que han sido encontrados incluyen a: péptidos de 1 a 20 KDa, proteínas, hormonas como progesterona, oxitocina, adrenalina y recientemente se han encontrado receptortes presentes en la cabeza del espermatozoide que están asociados a la enzima Guanilil ciclasa, vía proteína G, así como receptores de tipo olfatorio, rodopsina cinasa y arrestina. El estudio de la quimiotaxis permite además de entender algunos procesos de fecundación en gametos humanos y aplicarlos en los programas de reproducción asistida, puede ser de gran importancia en los programas de control prenatal