Ilustres Científicos Iberoamericanos


Luis Walter Alvarez

(Born June 13, 1911, San Francisco. Deceased Sept. 1, 1988, Berkeley, Calif.), American experimental physicist who was awarded the Nobel Prize for Physics in 1968 for work that included the discovery of many resonance particles (subatomic particles having extremely short lifetimes and occurring only in high-energy nuclear collisions).

Alvarez studied physics at the University of Chicago (B.S., 1932; M.S., 1934; Ph.D., 1936). He joined the faculty of the University of California, Berkeley, in 1936, becoming professor of physics in 1945 and professor emeritus in 1978. In 1938 Alvarez discovered that some radioactive elements decay by orbital- electron capture; i.e., an orbital electron merges with its nucleus, producing an element with an atomic number smaller by one. In 1939 he and Felix Bloch made the first measurement of the magnetic moment of the neutron, a characteristic of the strength and direction of its magnetic field.

Alvarez worked on microwave radar research at the Massachusetts Institute of Technology, Cambridge (1940-43), and participated in the development of the atomic bomb at the Los Alamos Scientific Laboratory, Los Alamos, N.M., in 1944-45. He suggested the technique for detonating the implosion type of atomic bomb. He also participated in the development of microwave beacons, linear radar antennas, the ground-controlled landing approach system, and a method for aerial bombing using radar to locate targets. After World War II Alvarez helped construct the first proton linear accelerator and developed the liquid hydrogen bubble chamber in which subatomic particles and their reactions are detected.

In about 1980 Alvarez helped his son, the geologist Walter Alvarez, publicize Walter's discovery of a worldwide layer of clay that has a high iridium content and which occupies rock strata at the geochronological boundary between the Mesozoic and Cenozoic eras; i.e., about 66.4 million years ago. They postulated that the iridium had been deposited following the impact on Earth of an asteroid or comet and that the catastrophic climatic effects of this massive impact caused the extinction of the dinosaurs. This widely publicized theory remained controversial, but it stimulated further research into the causes of the demise of the dinosaurs.

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Baruj Benacerraf

(Born Oct. 29, 1920, Caracas, Venez.), immunologist whose contributions to an understanding of the mechanisms and genetic basis of the immunologic response and especially of its role in certain diseases known as the autoimmune diseases brought him a share (with George Snell and Jean Dausset) of the 1980 Nobel Prize for Physiology or Medicine.

From the age of five until the outbreak of World War II Benacerraf lived in Paris. In 1940 he entered Columbia University, from which he graduated in 1942. He became a naturalized U.S. citizen in 1943, while a student at the Medical College of Virginia. After receiving his M.D. in 1945 and interning at Queens General Hospital in New York City, he served in the U.S. Army in 1946-48. After a year of research at Columbia and six at the Htpital Broussais in Paris, he joined the faculty of New York University School of Medicine in 1956, advancing to professor of pathology in 1960. In 1968-70 he was chief of the immunologic laboratory of the National Institute of Allergy and Infectious Diseases, National Institutes of Health. From 1970 he held the Fabyan chair of comparative pathology at Harvard.

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Juan de la Cierva

(Español, Ingeniero, Inventor del autogiro)

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Franklin Chang-Díaz

(Costarricense, Físico, Astronauta)

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Bernardo Alberto Houssay

(Born April 10, 1887, Buenos Aires, Arg. Deceased Sept. 21, 1971, Buenos Aires.), Argentine physiologist, who received (with Carl and Gerty Cori) the 1947 Nobel Prize for Physiology or Medicine for his discovery of the role played by pituitary hormones in regulating the amount of blood sugar (glucose) in animals.

Working with dogs that had been rendered diabetic by excision of the pancreas (1924-37), Houssay found that removal of the adenohypophysis (the anterior, or frontal, lobe of the pituitary body, located beneath the brain) greatly relieved the symptoms of the disease and made the animal unusually sensitive to insulin. He demonstrated that injection of pituitary extracts into normal animals induces diabetes by increasing the amount of sugar in the blood, indicating that the secretions of the gland oppose the action of insulin.

Appointed professor of physiology (1910) and director of the physiological institute (1919) at the University of Buenos Aires, Houssay was one of 150 Argentine educators dismissed from their posts by the 1943 military coup of Gen. Juan Persn. Although he was reinstated in 1945, he was asked to submit his resignation a year later. He founded (1944) and directed (from 1946) the Institute of Biology and Experimental Medicine, Buenos Aires, a leading physiological research centre. His best known book is Human Physiology (1951).

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Rodolfo Llinás Riascos

(Colombiano, Biólogo)

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Michael López-Alegría

(Español, Astronauta)

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César Milstein

(Born Oct. 8, 1926, Bahma Blanca, Argentina), Argentine immunologist who in 1984, with Georges Kvhler and Niels K. Jerne, received the Nobel Prize for Physiology or Medicine for his work in the development of monoclonal antibodies.

Milstein became interested in science after reading about the work of Antonie van Leeuwenhoek and Louis Pasteur when he was a schoolboy. He attended the universities of Buenos Aires and Cambridge (Ph.D., 1960) and was on the staff of the National Institute of Microbiology in Buenos Aires (1957-63). Thereafter he was a member of the Medical Research Council Laboratory of Molecular Biology, Cambridge, and held dual Argentine and British citizenship.

Milstein and Kvhler, who was at Cambridge on a fellowship, made their discovery of the technique for producing monoclonal antibodies in 1975. It involved the fusion of short-lived, highly specific lymphocytes (antibody-producing cells) with the cells of a myeloma, a type of tumour that can be made to reproduce indefinitely. The resulting hybrid cells retained the two desired properties: like the lymphocytes, they secreted a single species of antibody molecules, and, like myeloma cells, they perpetuated themselves, providing potentially unlimited amounts of any desired antibody. This technique enabled the production of large quantities of pure, uniform antibodies that are able to recognize single antigenic determinants (i.e., a single characteristic of a particular microbial invader in the body).

In 1994 Milstein was made a Companion of Honour.

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Mario Molina

(Mejico-Americano, Nobel en Quimica 1995)

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Antonio Monitz

(portugues, Nobel en Fisiologia/Medicina 1949)

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Ellen Ochoa

(Estadounidense, Ingeniera Electrica, Inventora, Astronauta)

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Severo Ochoa

(Born Sept. 24, 1905, Luarca, Spain. Deceased Nov. 1, 1993, Madrid.), molecular biologist who received (with the American biochemist Arthur Kornberg) the 1959 Nobel Prize for Physiology or Medicine for discovery of an enzyme in bacteria that enabled him to synthesize ribonucleic acid (RNA), a substance of central importance to the synthesis of proteins by the cell.

Ochoa was educated at the University of Madrid, where he received his M.D. in 1929. He then spent two years studying the biochemistry and physiology of muscle under the German biochemist Otto Meyerhof at the University of Heidelberg. He also served as head of the physiology division, Institute for Medical Research, at the University of Madrid (1935). He investigated the function in the body of thiamine (vitamin B ) at the University of Oxford (1938-41) and became a research associate in medicine (1942) and professor of pharmacology (1946) at New York University, New York City, where he became professor of biochemistry and chairman of the department in 1954. From 1974 to 1985 he was associated with the Roche Institute of Molecular Biology; thereafter he taught at the Autonomous University of Madrid. Ochoa became a U.S. citizen in 1956.

Ochoa made the discovery for which he received the Nobel Prize in 1955, while conducting research on high-energy phosphates. He named the enzyme he discovered polynucleotide phosphorylase. It was subsequently determined that the enzyme's function is to degrade RNA, not synthesize it; under test-tube conditions, however, it runs its natural reaction in reverse. The enzyme has been singularly valuable in enabling scientists to understand and re-create the process whereby the hereditary information contained in genes is translated, through RNA intermediaries, into enzymes that determine the functions and character of each cell.

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Manuel Patarroyo

(Colombiano, Descubridor de posible vacuna contra malaria)

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Santiago Ramón y Cajal

(Born May 1, 1852, Petilla de Aragón, Spain. Deceased Oct. 17, 1934, Madrid), Spanish histologist, who (with Camillo Golgi) received the 1906 Nobel Prize for Physiology or Medicine for establishing the neuron, or nerve cell, as the basic unit of nervous structure. This finding was instrumental in the recognition of the neuron's fundamental role in nervous function and in gaining a modern understanding of the nerve impulse.

Ramón y Cajal served as professor of descriptive anatomy at the University of Valencia (1884-87) and as professor of histology and pathological anatomy at the Universities of Barcelona (1887-92) and Madrid (1892-1922). He improved Golgi's silver nitrate stain (1903) and developed a gold stain (1913) for the general study of the fine structure of nervous tissue in the brain, sensory centres, and the spinal cords of embryos and young animals. These nerve-specific stains not only enabled Ramón y Cajal to determine the fine structure of the retina of the eye and to trace the structure and connections of nerve cells in gray matter and the spinal cord but have also been of great value in the diagnosis of brain tumours.

In 1920 King Alfonso XIII of Spain commissioned the construction of the Institute Cajal in Madrid, where Ramón y Cajal worked until his death. Among his many books concerning nervous structure is Estudios sobre la degeneracisn y regeneracisn del sistema nervioso, 2 vol. (1913-14; The Degeneration and Regeneration of the Nervous System, 1928).

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Gregorio Weber

Early on the morning of July 18, 1997, at home and surrounded by family and friends, Gregorio Weber died of leukemia at the age of 81. Born in Buenos Aires, Argentina in 1916, Weber completed his M.D. degree at the University of Buenos Aires in 1942 and his Ph.D. in Biochemistry in 1947 at Cambridge University

Weber's career had two distinct periods. In the first, from 1947 to 1975, he contributed to the development of fluorescence instrumentation and to the theory and procedures of determination of quantum efficiency, fluorescence polarization, fluorescence spectrum, and also to the analytical determination of the number and character of the components of composite fluorescence. The latter has been an indispensable tool in the examination of natural systems where the origin of the fluorescence is always heterogeneous. The fluorescence polarization techniques developed by Weber have been applied to numerous problems of clinical investigation, to the diagnostic determination of drugs and metabolites in the blood and to the sequence of amino acids in proteins and of bases in the nucleic acids. Weber devoted a great deal of time and effort to improving the determination of fluorescence lifetimes and created the "cross correlation" technique of phase fluorometry that forms the current basis of the phase measurements of lifetimes. In recent times it has lead to applications in microscopy and even to the macroscopic imaging of tissues (E. Gratton and coworkers).

From 1965 onwards, initially in collaboration with H.G. Drickamer, he applied high pressure fluorescence spectroscopy to the study of molecular complexes and proteins. Weber and collaborators, in papers published from 1980 to the present, demonstrated that most protein made up of subunits can be dissociated by application of hydrostatic pressure, and opened in this way a new method of study of protein aggregates, which is already influencing the approach to problems of both physiology and pathology. In these studies quite unexpected properties of protein aggregates have been revealed and it is no exaggeration to say that a completely new approach to many related problems in biology and medicine has been suggested by those new observations. For example, Weber and his collaborators in Urbana, Rio de Janeiro and Göttingen demonstrated the possibility of destroying the infectivity of viruses without affecting their immunogenic capacity and have thus opened the possibility of developing viral vaccines that contain without covalent modification all the antigens present in the original virus.

As a result of his investigations employing fluorescence techniques in conjunction with perturbations by pressure and temperature, Weber presented, in the last few years of his life, a novel way of looking at the folding and association of proteins.


En la mañana del 18 de Julio de 1997, rodeado de su familia y amigos, Gragorio Weber muere de leucemia, a la edad de 81 años. Nacido en Buenos Aires, Argentina en 1916, terminó sus estudios de Medicina en la Universidad de Buenos Aires en 1942 y obtuvo su PhD en Bioquimica en la Universidad de Cambridge en 1947 .

La carrera de Weber puede dividirse en dos períodos. En el primero, desde 1947 hasta 1975, contribuyó tanto en aspectos teóricos como instrumentales al desarrollo de la fluorescencia: determinación de eficiencia cuántica, polarización de la fluorescencia, espectros de fluorescencia, así como también a la determinación analítica del número y tipo de componentes en una senial de fluorescencia compuesta. Esta última herramienta ha sido indispensable para el análisis fluorescencia en sistemas naturales, donde el origen de la fluorescencia es siempre heterogéneo. Las técnicas de polarización de fluorescencia desarrolladas por Weber han sido aplicadas en la resolución de numerosos problemas en biomedicina: diagnóstico de drogas y metabolitos en sangre, secuenciación de aminoácidos en proteínas y bases en ácidos nucleicos. Weber dedicó también tiempo y esfuerzos a mejorar la determinación de tiempos de vida y en crear la técnica de "correlacion cruzada" de fluorometría de fase que es actualmente la base de las mediciones por fase de tienpo de vida de fluorescencia, y que en los últimos años a sido la base para el desarrollo de aplicaciones en microscopía e incluso imágenes en tejidos. (Gratton y colaboradores).

Desde 1965 en adelante, inicialmente en colaboracion con H.G. Drickamer, utilizó la espectroscopía de fluorescencia bajo alta presión en el estudio de complejos moleculares y proteínas. Las publicaciones de Weber y colaboradores desde 1965 en adelante, han demostrado que la mayoría de las proteínas compuestas de subunidades pueden ser disociadas al aplicar sobre ellas presión hidrostática, iniciandose de esta manera una nueva metodología para el estudio de las proteínas oligoméricas, metodología que ha influenciado areas como la fisiología y la patología.

En estos estudios se encontraron propiedades inesperadas de los agregados protéicos, y no sería exagerado decir que estas observaciones han conducido a una nueva visión en el estudio de problemas tanto en medicina como en biología. Así, Weber y colaboradores en Urbana, Rio de Janeiro y Gottingen demostraron la posibilidad de destruir la efectividad viral sin destruir su capacidad inmunogénica, observación que abrió la posibilidad de vacunas virales que contienen todos los antígenos originalmente presentes en el virus pero sincapacidad infectiva.

Como resultado de sus investigaciones usando las técnicas de fluorescencia junto con alta presión y temperatura, Weber presentó en los últimos años de su vida, una nueva forma de mirar el plegamiento y la asociación de proteinas.

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(-- Al Servidor Ciencia Chile