Implementation of the IPPP–CLOPPA–INDO/S method for the study of indirect nuclear spin coupling constants and its application to molecules containing tin nuclei Botek, Edith L.; Aucar, Gustavo Adolfo; Cory, Marshall G.; Zerner, Michael C. The inner projection of the polarization propagator, using contributions from localized orbitals, IPPP–CLOPPA, and using the intermediate neglect of the differential overlap model parameterized for spectroscopy, INDO/S, was implemented and used to calculate indirect nuclear spin coupling constants. The resulting model was tested on a group of small- and medium-size model compounds by comparing its performance with that of other semi-empirical methods and experiments where available. It is shown that in general the INDO/S approximation with the use of S N 2 (0) and r N −3 atomic parameters taken from the INDO and AM1 approaches is the most suitable scheme to describe coupling constants. The introduction of atomic parameters for S N 2 (0) and r N −3 in the case of heavy nuclei like Sn, is a critical step. The correction of the bonding beta parameter for this nucleus was also necessary within the INDO/S approximation to improve the accuracy and to better account for indirect relativistic effects. The application of this parameterization was accomplished in a series of tetrastannacyclohexanes and different pathways for coupling transmission were analyzed.

Peptide models XXV. Side-chain conformational potential energy surface, E = E(χ1, χ2) of N-formyl-L-aspartic acidamide and its conjugate base N- formyl-L-aspartatamide in their γ(L) backbone conformations Salpietro, Salvatore J.; Perczel, Andràs; Farkas, Od̈ön; Enriz, Ricardo Daniel; Csizmadia, Imre Gyula Ab initio molecular computations were carried out on the γ(L) backbone conformation of N-formyl-L-aspartic acidamide and its conjugate base N- formyl-L-aspartatamide at the HF/3-21G level of theory. All side-chain conformations were explored for the parent amino acid diamide and its conjugate base. Propionate ion, propionic acid, 3,3-difluoropropionate ion and 3,3-difluoropropionic acid were used to model the side-chain in the anionic and neutral compounds.

Evaluation of hydrogen transfer in FCC catalysts. A new approach for cyclohexene as a test reactant de la Puente, Gabriela; Sedran, Ulises Anselmo The conversion of cyclohexene over different commercial FCC catalysts in a batch fluidized-bed reactor under very short contact times at 300°C, was described by means of a simple lumped kinetic model that accounted for the observed yield patterns. The main branch of reaction starting from the adsorption of cyclohexene was used to assess an index based on kinetic parameters that defines the relative significance of hydrogen transfer reactions in a set that also includes proton transfer and cracking reactions. Complementary experiments with pulses of reactant on a fixed-bed reactor allowed to establish the best temperature to obtain maximum sensitivity to hydrogen transfer. The same evolutions were observed for the relationships between the index of hydrogen transfer and the paired acid site density with the Y zeolite unit cell size, confirming that two regions can be defined separated by unit cell sizes of about 24.28–24.30 Å, the correlations being stronger at low values of this parameter.

Unitary quasifinite representations of W_{\infty} Kac, Victor; Liberati, Jose Ignacio We classify the unitary quasi-finite highest-weight modules over the Lie algebra W and realize them in terms of unitary highest-weight representations of the Lie algebra of infinite matrices with finitely many nonzero diagonals.

Mineral composition of perennial vegetation of shrub patches in northeastern Patagonia del Valle, Hector Francisco; Rosell, Ramon Antonio This study was conducted to (1) quantify the mineral composition of litter, new leaves, and stems of two plant species (Atriplex lampa and Prosopis alpataco) in shrub patches, occurring with common abundance in the northeastern Patagonian region, and (2) determine the spatial and temporal variabilities of the mineral elements. There were 240 vegetal samples collected from six different sites, all within about 15 km. The essential nature of 15 mineral elements for litter and plant parts was analyzed. Composition varied significantly for P, Ca, Mg, Na, K, Cu, Zn, Mo, and B between species; N between seasons; and S, Al, Fe, Mn, and Cd among sites. Also Na, K, and B showed secondary variations derived from a seasonal effect, as did P, Ca, Mg, Cu, Zn, and Mo, but associated with secondary differences among sites.

Copper-zinc superoxide dismutase activity in red blood cells and serum in demented patients and in aging Sacerdote de Lustig, Eugenia; Serra, Jorge Alberto; Kohan, Silvia; Canziani, Gabriela Alicia; Famulari, Arturo L.; Dominguez, Raul Omar The activity of the enzyme copper-zinc superoxide dismutase (Cu-Zn SOD) has been investigated in serum and red blood cells (RBC) homogenate obtained from demented patients with associated vascular lesions (VD), demented patients with probable Alzheimer's disease (DAT) and healthy controls (CG) of the same age. The increase in SOD activity was statistically significant ( P < 0.01) in RBCs homogenate of DAT and VD patients, when compared to controls, but no differences appear between the two diseased groups. Additionally, a statistically significant increase in SOD activity ( P < 0.01) in DAT patients above 70 years as compared to those 50–70 years old, and a relation between SOD and age were found. No changes in SOD activity with age in healthy controls nor in vascular dementia group were detected. A statistically significant increase in Circulating SOD activity ( P < 0.01) was observed in vascular patients compared to controls. The observed increase in DAT Circulating SOD activity (against CG) was not significant. The increased levels of Cu-Zn SOD, probably represent a general alteration of the oxidative processes characteristic of these dementias and suggest that the enzyme might be used as a marker.

Acción de L. Casei y L. Acidophilus sobre LB productores de IgA en mucosa intestinal: Relación con la capacidad de protección frente a enteropatógenos Medici, Marta Graciela; Valverde, Marta Hercilia; Perdigon, Gabriela del Valle Demostramos anteriormente que la alimentación previa a ratón con L. casei fue efectiva en la protección contra enteropatógenos, con incremento de niveles de IgA-s con dosis de 2,4 x 109 cel y que L. acidophillus no protege frente a infecciones y no aumenta los niveles de IgA-s.

El doble mensaje de los mastocitos para los tumores Sacerdote de Lustig, Eugenia; Lauria de Cidre, Lilia Susana En relación a los tumores, los linfocitos han sido la gran vedette del tratamiento biológico del cáncer en esta última década, mientras que otras células del sistema inmune han sido descuidadas.

Angiogenic activity by spleen cell supernatants from tumor‐bearing and tumor‐resected mice Davel, Lilia; Miguez, Marta; Jasnis, María Adela; Eiján, Ana María; Oisgold Dagá, Sara; Sacerdote de Lustig, Eugenia Supernatants of cultured spleen cells (SCS) from small tumor‐bearing mice (STBM) and large tumor‐bearing mice (LTBM) are able to enhance tumor growth as well as accelerate tumor takes in vivo when inoculated 24 h before tumor implant. After tumor resection enhancing activity disappears at a rate depending on the size of the resected tumor. Spleen cells from tumor‐bearing mice also evoke a complex vascular response, lymphocyte‐induced angiogenesis (LIA) elicited via the release of lymphokines from activated T cells. As angiogenic factors promote tumor development we investigated if SCS from tumor‐bearing and tumor‐resected mice contain factors capable of evoking a LIA response. Angiogenic activity was detected by SCS of small and large tumor‐bearing mice as well as in large tumor‐resected mice. On the other hand, SCS from small tumor‐resected mice are not able to evoke an angiogenic response. Possibly, the large antigenic burden in LTRM stimulate the immune system in a different way than in STRM. We can suggest that the different behavior of spleen cells after small and large tumor removal can be explained by quantitative or qualitative changes in the spleen subpopulations.

No me digan sabio: es una palabra pasada de moda Peicovich, Esteban

Action of glycosidases on the saccharide moiety of the glucose—containing dolichyl diphosphate oligosaccharide Ugalde, Rodolfo Augusto; Staneloni, Roberto Julio; Leloir, Luis Federico

Oligosaccharides containing glucose and mannose in glycoproteins of the thyroid gland Staneloni, Roberto Julio; Leloir, Luis Federico

Interferon in Breast Cancer Sacerdote de Lustig, Eugenia; Cortada de De La Peña, Nuria; Canonico, Abel The interferon production ability by leukocytes in vitro from 37 patients with mammary cancer was studied. The leukocytes were derived from patients between 27 and 80 years of age, 6 months and up to 28 years after removal of the primary tumor. The interferon titer of 34/37 human breast cancer leukocytes was 2–8 times lower than that of 35 normal donor leukocytes and 3 non-neoplastic diseases. No correlation between interferon titers, the patient's age, and the histologic tumor features was observed; however, interferon production was observed to return to normal in those patients who had a long remission period or whose tumors were locally confined. Interferon response of patients under different therapy was modified: radiotherapy affected interferon production more severely than chemotherapy. A tendency for association between the skin DNCB test and interferon response was found. An inverse correlation was observed between interferon titers and the PHA-induced transformation index.; È stata studiata la produzione d'interferon in vitro dei linfociti di 37 pazienti con cancro mammario. I leucociti provenivano da pazienti tra 27–80 anni, e la rimozione del tumore primitivo datava da 6 mesi a 28 anni. Il titolo d'interferon dei leucociti di 34 su 37 casi, ha presentato valori da 2 a 8 volte minori di quelli di 35 soggetti normali e di 3 pazienti non-tumorali. Non è stato possibile stabilire una relazione tra il titolo d'interferon, l'età del paziente e le caratteristiche istologiche del tumore. Si è osservato comunque un ritorno a valori normali nei pazienti che hanno presentato lunghi periodi di remissione o con un solo tumore localizzato. La risposta interferon rispetto alla terapia è modificabile: Ia radioterapia incide sopra la produzione d'interferon più severamente della chemioterapia. È stata osservata inoltre la tendenza ad una associazione tra test cutaneo al DNCB e la risposta all'interferon, mentre una correlazione inversa è stata osservata tra titolo d'interferon ed indice di trasformazione blastica indotta dalla fitoemoagglutinina.

Lipid intermediates in protein glycosylation Parodi, Armando José A.; Leloir, Luis Federico The oligosaccharide moieties of animal glycoproteins that involve linkage between carbohydrate and asparagine are built up on dolichol pyrophosphate before incorporation into the protein. The use of dolichol pyrophosphate in place of the commoner nucleoside diphosphate as the sugar carrier may be because the former is more compatible with the hydrophobic environment of the membrane where the glycoprotein synthesis occurs.

In vitro synthesis of particulate glycogen from uridine diphosphate glucose Parodi, Armando José A.; Mordoh, Jose; Krisman, Clara R.; Leloir, Luis Federico

Role of the sympathicoadrenal system in the hemodynamic response to exercise in dogs Ashkar, E.; Stevens, J. J.; Houssay, Bernardo Alberto Twelve dogs that ran well on a motor-driven treadmill were vagotomized and sympathectomized from TI-TT plus LB-L6 and subjected to either unilateral adrenalectomy and contralateral adrenal demedullation (W-A) or denervation of cranial mesenteric and common hepatic arteries (SN-MH). After recovery, cardiac output determinations (direct Fick) and continuous recording of mean aortic blood pressure, heart rate, and oxygen consumption were made at rest and during exercise at 7.5 km/hr- 10% gradient Heart rate increased from 113 to 126 beats/min in the medulloadrenalectomized dogs and from 98 to 147 beats/min in dogs with hepatomesenteric denervation. Mean blood pressure did not vary substantially with exercise in either series of animals, averaging at rest 89 mm Hg in dogs with adrenal medullectomy and 128 mm Hg in dogs with intact adrenals. The resting cardiac index was similar in both groups (2.61 liters/min per m2) and increased about 200 y0 during exercise in medulloadrenalectomized animals as compared with 330y0 in dogs with hepatomesenteric denervation. During exercise, energy cost was essentially similar although peripheral resistance decreased about 75y0 in both groups.

Isolation of adenosine diphosphate D-glucose from corn grains Recondo, Eduardo F.; Dankert, Marcelo; Leloir, Luis Federico

Biosynthesis of glycogen from uridine diphosphate glucose Leloir, Luis Federico; Cardini, Carlos E.

A modified colorimetric method for the estimation of N-acetylamino sugars Reissig, José L.; Strominger, Jack L.; Leloir, Luis Federico

La libertad académica y la investigación científica en la América Latina: conferencia dada en la Universidad de Columbia, New York, Estados Unidos, 1955. Houssay, Bernardo Alberto Las naciones americanas se independizaron movidas por anhelos de libertad y de gobierno propio. Nacieron bajo el signo de la libertad que desde entonces fue y debe seguir siendo su auténtica misión y su destino. La libertad como la vida necesita conquistarse, perfeccionarse y conservarse permanentemente. La libertad se edifica y mantiene mediante una lucha incesante contra las fuerzas que tienden a restringirla o avasallarla. La característica más genuina de la América independiente fue el culto de la libertad y a ella debe sus adelantos y su papel en la historia. Contra ella conspiran los que procuran volver al dogmatismo y autoritarismo colonial o bien quieran adoptar los que se han desarrollado recientemente o pugnan por implantarlos en las grandes naciones que luchan por el dominio de sus doctrinas ideológicas o por la extensión de su poder político y material. La democracia auténtica es la que permite el máximo de libertad individual y de desarrollo de la personalidad humana, asegurando la mayor igualdad posible de oportunidades y ante la ley. En ella cada uno puede tener el máximo de iniciativa y acción, con la única obligación moral de hacer lo más que pueda para el bien de sus semejantes. Las naciones señeras - leaders - lo serán y se mantendrán por su cultura y su poder, pero sobre todo por su conducta recta que despierte la admiración, la amistad y la emulación, y porque respeten debidamente a los demás pueblos y a su libertad.