Artículos, Informes y presentaciones en Congresos
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Acceso Abierto Ejemplo de estimación cuantitativa del contenido relativo de minerales del grupo de las arcillas(Comisión de Investigaciones Científicas de la Provincia de Buenos Aires (CICBA), 1971) Aristarain, L. F.Se presentan los métodos de preparación de las muestras, los criterios de identificación de los diferentes minerales y la discusión del método utilizado para efectuar la estimación cuantitativa del contenido relativo de minerales del grupo de las arcillas en perfiles de depósitos de caliche (= tosca). - Artículo
Acceso Abierto Análisis del contenido de carotenoides florales de plantas que crecen en la provincia de Buenos Aires (Argentina)(1982) Natalucci, Claudia LuisaFlowers of nineteen wild and cultivated species growing in the Province of Buenos Aires have been investigated for their total carotenoid, carotene, mono- and dihidroxycarotenoid contents. Yellow and orange floral varieties of Tagetes erecta L. were also studied for comparative purposes. Carotenes are the main fraction in six species and xanthophylls in the others. Within the latter is Ranunculurs repens L., with a total carotenoid content even higher than the orange variety of T. erecta. - Artículo
Acceso Abierto Nuevas localidades de peces de agua dulce de la República Argentina, V(1984) López, Hugo; Miquelarena, Amalia; Menni, Roberto Carlos; Casciotta, Jorge RafaelEn el presente trabajo se mencionan nueve localidades nuevas para diez especies de peces de agua dulce de la Argentína, pertenecientes a seis familias. Con el criterio utilizado en anteriores trabajos de la serie, se incluyen las referencias posteriores a Ringuelet et al. (1967), salvo en el caso de Aphyocharax dentatus tratado recientemente por Miquelarena et al. (1981) y Trichomycterus corduvense por Menni et al. (en prensa). Para dos localidades se proveen datos ambientales. - Comunicacion
Acceso Abierto Effect of hypothyroidism on the composition and turnover rate of islet phospholipids(1984) Cortizo, Ana María; Garcia, M.E.; Pasquini, J.M.; Gagliardino, J.It has already been demonstrated that the pancreatic B cells of hypothyroid rats have a reduced capacity to release insulin in response to glucose (l). This impaired B cell function may be partly due to a diminished rate of glucose oxidation and net calcium uptake associated with ultrastructural alteration of the pancreatic islets (2). To identify further other factors responsible for this diminished B cell secretory function, we studied the composition and the turnover rate of phospholipids in islets obtained from hypothyroid rats. - Artículo
Acceso Abierto Proteasas de bromeliaceae: I. Estudio preliminar de la fracción proteolíticamente activa presente en frutos de Bromelia laciniosa Mart.(1984) Buttazzoni de Cozzarin, Marta Susana; Caffini, Néstor Oscar; Priolo de Lufrano, Nora Silvia; Natalucci, Claudia LuisaProteolitically active preparations obtained from matute fruits of Brornelia Iaciniosa Mart. were analyzed by molecular sieve chromatography (Sephadex G-75, Superhe). Best resolution and higher activity are achieved by direct trituration of fruits with cold acetone. Proteolytic capacity is notably diminished in case of unripe fruits. - Artículo
Acceso Abierto Regulación hormonal del metabolismo de glucosa en islotes de langerhans(1985) Borelli, María Inés; Cortizo, Ana María; Gagliardino, Elma Edith P. de; Garcia, María Elisa; Gagliardino, Juan JoséSe ha estudiado simultáneamente la secreción de insulina y el metabolismo de glucosa en islotes aislados, obtenidos de ratas normales, ratas con diversas insuficiencias endocrinas (adrenalectomizadas, ovariectomizadas y radioyodotiroidectomizadas), como así también grupos de animales con deprivación hormonal seguida de hormonoterapia sustitutiva. Los islotes provenientes de todos los grupos de animales con déficit endocrino mostraron alteraciones concordantes en ambos parámetros y la correlación entre los cambios en la secreción de insulina y el metabolismo de glucosa fue altamente significativa. Todos los cambios observados en estos animales hormono-deficientes fueron corregidos mediante la terapia sustitutiva específica. Estos resultados sugieren que probablemente las diversas hormonas estudiadas podrían alterar la secreción de insulina a través de una modificación en la capacidad de los islotes para metabolizar la glucosa (AU) - Artículo
Acceso Abierto Proteasas de Bromeliaceae: II. Separación, caracterización y fraccionamiento de una proteasa aislada de frutos de Bromelia Hieronymi Mez.(1985) Priolo de Lufrano, Nora Silvia; Buttazzoni de Cozzarin, Marta Susana; Caffini, Néstor Oscar; Natalucci, Claudia LuisaA partir de frutos verdes de Bromelia hieronymi Mez se obtuvieron dos preparaciones proteolíticamente activas, que manifiestan su máximo poder caseinolítico a 60ºC y pH 6.85, observándose un segundo pico a pH 7.57. Al ser sometidas a cromatografías de intercambio aniónico (DEAE-Sephacel) ambas preparaciones se resuelven en tres fracciones activas: la primera de ellas es la de mayor potencialidad proteolítica, pero no es contenida por el intercambiador usado, aunque si por uno catiónico (SP Sephadex C50), que la descompone en dos fracciones proteicas, una de las cuales retiene la capacidad caseinolítica - Artículo
Acceso Abierto Proteasas de Bromeliaceae: III. Condiciones óptimas de acción, estabilidad y purificación de la proteasa aislada de frutos de Bromelia laciniosa Mart.(1986) Priolo de Lufrano, Nora Silvia; Buttazzoni de Cozzarin, Marta Susana; Caffini, Néstor Oscar; Natalucci, Claudia LuisaA partir de frutos maduros de Bromelia Laciniosa Mart., se obtuvo una proteasa que manifiesta su máxima actividad caseinolítica a 60 ºC y pH 6,4. El agregado de cisteína incrementa notoriamente la capacidad proteolítica y aumenta la estabilidad de la enzima a temperaturas elevadas. El pasaje de la proteasa no purificada a través de Sephadex G-75 permite separar tres fraccione,una de las cuales (peso molecular 15.000-20.000) retiene la actividad proteolítica: esta última se resuleve en al menos tres fracciones (solamente una de ellas activa) por intercambio iónico sobre DEAE-Sephacel con gradiente lineal de cloruro de sodio 0,2-0,8 M - Artículo
Acceso Abierto Mecanismo de acción de hormonas tiroideas sobre el páncreas endócrino(1987) Cortizo, Ana MaríaEl rol de las hormonas tiroideas en la Diabetes Mellitus y la función endocrina del páncreas fue estudiado por primera vez en 1944 por B. A. Houssay (1 ). Trabajando con perros parcialmente panceatectomizados, sometidos a tratamiento con hormonas tiroideas, observó que adquirían una forma de diabetes irreversible, que persistía aún después de interrumpir el tratamiento tiroideo. Llamó a ésta Diabetes Meta.tiroidea ; su mecanismo parecía ser un agotamiento pancreático consecutivo a una sobreestimulación (2). Sus estudios se extendieron en animales sometidos a tiroidectomía y pancreatectomía subtotal simultánea, observando que no se reducía la severidad de la diabetes, sino que la operación exacerbaba los síntomas, la enfermedad progresaba más rápidamente y finalmente morían en hiperglucemia. A partir de estos experimentos, las hormonas tiroideas han sido consideradas como hormonas diabetogénicas. Numerosos investigadores han observado la intolerancia a la glucosa asociada con una disfunción tiroidea, tanto a nivel clínico como experimental (3-11). Pero el mecanismo por el cual las hormonas tiroideas llevan a cabo estos cambios es hasta hoy desconocido. - Artículo
Acceso Abierto Lipid composition of normal male rat islets(1988) Díaz, Graciela B.; Cortizo, Ana María; Garcia, María Elisa; Gagliardino, Juan JoséLipid composition was studied in fresh isolated isolets from normal male rats. Extractable lipids represent 1856 μg per mg islet protein. In such extracts, phospholipids and neutral lipids reprsent 13.5% and 86.5%, respectively. Phosphatidylcholine (45.8%) and phosphatidyl-ethanolamine (20.6%) were the major components of the phospholipid fraction, and phosphatidylinositol (8.9%) was the minor component. Esterified cholesterol (38.5%), cholesterol (25.5%) and free fatty acids (24.4%) were the major components of the neutral lipid fraction. Fatty major components of the neutral lipid fraction. Fatty acids esterified to phospholipids account for 619.7 pmol/islet, and, 2710 pmol/islet were esterified to neutral lipids. In the phospholipid fraction, saturated and unsaturated fatty acids were in a similar proportion. Conversely, in the neutral lipids, two-thirds of the fatty acids were unsaturated. The ω6 family was the main component of the phospholipid unsaturated fatty acids. In the ω6 and ω3 families, the long-chain fatty acids represent the main components. In the neutral lipid fraction, a different percentage of each family was found: ω3>ω6>ω9. The long-chain polyunsaturated fatty acids were also predominant species in the ω6 and ω3 families. Further studies on the lipid composition of islets, obtained from rats with normal and altered islet functions, could provide new insights into the knowledge of the mechanism of insulin secretion. - Artículo
Acceso Abierto Proteasas de Bromeliaceae: V. Separación y purificación de sulfhidril - proteasas presentes en frutos de Bromelia balaasae Mez(1988) Caffini, Néstor Oscar; Priolo de Lufrano, Nora Silvia; Buttazzoni de Cozzarin, Marta Susana; Natalucci, Claudia LuisaAlmost mature fruits of Bromelia serra Griseb., blade homogenized (Waring blender) with cold acetone (-20ºC), provide a light, proteolitically active acetone powder (1, 93g%, w/w). Extractives obtained by gentle stirring with phosphate buffer pH 6,4 containing 5 mM cysteine and 5 mM EDTA (protein content 8, 24 g per 100 g of powder) show good thermal stability at moderates temperatures and highest caseinolytic activity at pH 6.0-7.8. Gel- filtration (Sephadex G-75, Superfine) allows to separate one active fraction which is resolved in two new, more pursed fractions through ion-exchange chromatography (DEAE Sephacel and CM Sepharose). - Artículo
Acceso Abierto Proteasas de Bromeliaceae: V. Separación y purificación de sulfhidril - proteasas presentes en frutos de Bromelia balaasae Mez(1988) Priolo de Lufrano, Nora Silvia; López , Laura María Isabel; Caffini, Néstor Oscar; Natalucci, Claudia LuisaAlmost ripe fruits of Bromelia balansae Mez (Bromeliaceae) were blade homogeneized within cold (-20 O C ) acetone, providing a crude preparation that could be partialiy solubllized in phosphate buffer (pH 6,4) containing EDTA and cysteine 5 mM. Solutions hydrolize casein (maximum a c t ~ t ypH 6.25-8.5O), the activity being enhanced by addition of cysteine. The crude enzyme was purified by molecular sieve chromatography (Sephadex G-75, Superfme) and ion exchange chromatography (DEAE- and CM-Sepharose). Three proteolitically active fractions were thus obtained - Comunicacion
Acceso Abierto Proteasas presentes en el látex de frutos de Maclura pomifera (Raf.) Schneid. (Moraceae)(1989) López , Laura María Isabel; Natalucci, Claudia Luisa; Caffini, Néstor OscarLatex obtained by superficial incisions of Machra pomifera fruits, received on cold neutral phosphate buffer and centrifuged to remove gummy material, affords a crude extract with higher proteolylic activity between pH 8.75 and 10.6 and a notably thermal stability that can be advantageously kept as lyophyhed powder. Acetone precipitation followed by ion exchange chromatography (DEAE-Sepharose CL-6B and CM-Sepharose CL-6B) allows the purification of three active fractions. - Artículo
Acceso Abierto Changes induced by glucose in the plasma membrane properties of pancreatic islets(1990) Cortizo, Ana María; Paladini, A.; Díaz, G.B.; García, M.E.; Gagliardino, J.J.Partially purified membranes obtained from rat pancreatic isolated islets preincubated for 3 min with 3.3 and 16.6 mM glucose were labelled with 1,6-diphenyl-1,3,5-hexatriene to study fluorescence polarization. Other islets, incubated for 5 min with the same glucose concentration, were extracted and phospholipids separated by thin-layer chromatography. The composition of phospholipids of fatty acids was then studied by gas-liquid chromatography. Arrhenius plots of the microviscosity in membranes obtained from islets exhibited two components, a steeper slope below 18 degrees C and a gentler slope above 18 degrees C, indicating greater flow activation energy at temperatures below the transition point. Exposure of islets to 16.6 mM glucose significantly increased the flow activation energy (delta E), below and above the transition point. Islets incubated for 5 min with 16.6 mM glucose showed an increase in the percentage composition of 12:0 and 18:2 together with a decrease in the 20:2 W6 and 22:3 W3 fatty acids esterified to phospholipids. Regardless of these changes, no significant alterations occurred in the proportion of saturated fatty acids or in the double bond index; these measurements therefore did not account for the effects of glucose concentration in flow activation energy. The thermotropic changes reported here might be the consequence of some degree of disorder induced by glucose upon the membrane structure. This order alteration could either favor the membrane fusion which occurs during the emiocytosis or only reflects the consequence of such a process. - Artículo
Acceso Abierto Vectorial insulin secretion by pancreatic β-cells(1990) Cortizo, Ana María; Espinal, Joseph; Hammonds, PeterMorphological studies of pancreatic β-cells have suggested the presence of discrete sensory and secretory domains. In the present study we now provide functional evidence by demonstrating polarity of insulin release by HIT-T15 cells. A significant diffusion barrier across a twin chamber culture system was verified in the presence of confluent HIT-T15 cells. When stimulated with sulphonylurea, ionophore or high potassium, insulin was preferentially released into the lower chamber irrespective of whether secretagogues were added to the upper or lower chambers. Vectorial insulin secretion may be a significant determinant of islet hormone paracrine interactions in the maintenance of glucose homeostasis. - Artículo
Acceso Abierto Stimulated release of arachidonate and prostaglandins is vectorial in MDCK epithelial cells(1992) Cortizo, Ana María; Besterman, J.M.; Leitner, P.P.; Chandrabose, K.A.The receptor mediated activation of phospholipase A2by appropriate ligands results in the synthesis and release of eicosanoids, a class of potent bioregulatory molecules. Madin-Darby canine kidney cells (MDCK) are polarized epithelial cells, with structurally and functionally distinct plasma membrane domains separated by tight junctions. Using MDCK cells grown in dual sided chambers, we show in this report, that a) the receptor mediated release of prostaglandins and arachidonate into the extracellular medium is predominantly unidirectional, b) the direction of release is agonist specific, and c) the magnitude of the response due to a given agonist is cell-domain specific. These characteristics, if operativein vivo, would contribute towards the optimal function of trans-cellular metabolism of eicosanoids already demonstrated. - Artículo
Acceso Abierto Comparative Study of IGFBP Properties in Toad and Rat Sera(1993) Cortizo, Ana María; Braziunas, D.; Jasper, H.; Gagliardino, J.J.The levels ofIGF-Ihave been simultaneously measured byradioimmunoassayin samples of the toadBufo arenarumand of normal male Wistar rats. In addition, the different fractions of IGF-I binding proteins (IGFBP) and their binding properties have been identified by ligand blot and Scatchard analysis in the serum of both species. In the toad, we have measured levels of IGF-I (2.78 ± 0.48 ng/ml) similar to those previously reported in amphibians but far below those found in rats. IGFBP levels were estimated at 129 ± 23 and 4249 ± 321 pg/ml in toad and rat serum samples. Two main IGFBP fractions of 30-34 kDa, accompanied by a minor component of 24 kDa and seldom by another of 40 kDa, were identified in toad serum. In rat serum—as already reported—three bands of 40, 30, and 24 kDa were identified, the first being the main component and the last the minor one. The Scatchard analysis of a competitive binding assay showed two types of binding sites in toad serum: one of high affinity-low capacity (Ka1= 1.6 × 1010M-1;R1= 1.2 × 10-11M) and another with low affinity-high capacity (Ka2= 1.9 × 108M-1;R2= 1.9 × 10-10M). The percentage fraction of these binding sites occupied by IGF-I was 13.5%. The figures for K1and K2were lower and those for R1and R2were higher in rat than in toad serum. The percentage fraction of occupied ratIGFbinding sites was 3.6%. The IGF carrier levels (IGFBP5) estimated in our laboratory in samples of rat and toad serum gave figures that were almost 33 times lower in the latter than in the former. Hence, the fraction of free and bound IGF-I in toad and rat blood might be different. Our results provide new evidence of the presence and the properties of IGFBP in amphibians, confirming the wide distribution of this carrier among different species and its possible role as modulator of IGF-I biological effects. - Artículo
Acceso Abierto Vanadium Compounds(1994) Cortizo, Ana María; Salice C, Viviana; Etcheverry, Susana B.The direct effect of different vanadium compounds upon alkaline phosphatase (ALP) activity was investigated~ Vanadate and vanadyl inhibited both the soluble and particulate ALP activity from UMR.106 cells and front bovine intestinal ALP. We have also shown the inhibition of ALP activity in the soluble fraction of osteoblasts by peroxo and hydroperoxo vanadium compounds. ALP activity in the particulate fraction was not inhibited by these species; nor was the bovine intestinal ALP. Using inhibitors of Tyr-phosphatase (PTPases), the soluble ALP was partially characterized as a PTPase. The major activity in the particulate fraction represents the bone-specific ALPactivity. This study demonstrates that different forms of vanadium are direct inhibitors of ALP activity. This effect is dependent on the enzymatic activity investigated and on the origin of the ALP. - Artículo
Acceso Abierto Modelos, parámetros farmacocinéticos y penetración en leche de Ceftazidima administrada por vía endovenosa en bovinos lecheros en producción(1994) Buschiazzo, Perla M. de; Rubio, Modesto Carlos; Rule, Roberto; Buschiazzo, HéctorPenetration of ceftazidime in milk and pharmacokinetic parameters and models were determined. Five healthy lactating dairy cows producing 10 ± 2 liters per day were injected intravenously with a bolus administration of a dosage of 10 mg/kg body weight. Blood and milk samples were collected during 24 hours after ceftazidime administration. Concentration of ceftazidime in serum and milk were quantified by HPLC. The pharmacokinetic parameters calculated were: percentage of penetration in milk (47.7 ± 38.2%), volume of distibution in steady state (489.8 ±136.9 ml.kg-1), area under the curve far serum and milk (261.3 ± 124.1 and 115.3 ± 74.4 µg.ml.h-1, respectively) and blood clearance (72.5 ± 18.1 m1.h-1.kg-1. The coefficient of correlation of serum concentrations (CC) and the Akaike information criteria (AIC) were used to discriminate the pharmacokinetic model better adapted to describe the curve of ceftazidime conceniration over time. The hicompartimental model (CC=0,998 and AIC = 34.3) was the most appropriate to obtain the best fitted curve to describe the serum concentration of ceftazidime over time after intravenous administration in lactating dairy cows. - Artículo
Acceso Abierto Estudio preliminar de "Macrodontina", una nueva cisteinilproteinasa aislada de frutos de Pseudananas macrodontes (Morr.) Harms (Bromeliaceae)(1994) Brullo, Adriana; Hilal, Rosana M.; Caffini, Néstor Oscar; Natalucci, Claudia LuisaFrom inmature fruits of Pseudananas macrodontes (Morr.) Harms, known as ihvirá in the northeast of Argentina, has been isolated and partially characterized a sulfhydril-protease highly active between pH 7 and 10. The acetonic precipitates are quite stable at temperatures below 45ºC and not affected by freezing or liophylization. Anionic exchange chromatography (DEAE-Sepharose Fast Flow) affords two active fractions, both well resolved by gel filtration (Sephadex G-75). The electrophoretic pattern (SDS-PAGE) of the acetonic precipitate shows six protein fractions, between 14 and 67 kDa, but the zymogram reveals the presente of three active fractions, of about 27,30, arid 54 kDa.