Aristides Leão
Encyclopedia
Aristides de Azevedo Pacheco Leão (August 3, 1914 – December 14, 1993, Rio de Janeiro
) was one of the most noted Brazil
ian biologist
s and scientist
s, one of the founders of the Biophysics Institute of the Federal University of Rio de Janeiro and the discoverer of cortical spreading depression
, an electrophysiological
phenomenon of the central nervous system
, which received his name.
Leão was born to an intellectual family in Rio de Janeiro. He started to study medicine
at the University of São Paulo
, but had to interrupt it, due to a bout with tuberculosis
. Under the influence of his uncle, Antonio Pacheco Leão, who was the director of the Botanical Gardens of Rio de Janeiro, he decided instead to follow a research career and went to the USA to study further and to obtain a masters (1942) and a doctorate (1943) in physiology
at the Harvard Medical School
, with an experimental investigation on epilepsy
in the cerebral cortex
of rabbit
s. In collaboration with his supervisors, Arturo Rosenblueth
and Hallowell Davis
, he analyzed the cycle of excitability of cortex neuron
s (nerve cells) after the convulsive phenomena, and was the first to identify an important phenomenon, that of a decrease of the excitability which spread in increasing circles around the initial focus, which he named spreading depression. The phenomenon was soon named as Leão's wave and brought great attention after his work was published in 1944 in one of the main neurophysiology
journals (for the rest of his life, Dr. Leão became one of the most cited neuroscientists in the world, and his original paper is considered one of the classics in the field).
Upon returning to Brazil, he continued his experiments with spreading depression, in the department of physiology of the medical school of the University of Brazil (presently the Federal University of Rio de Janeiro). Already in 1947 he could publish his first international paper on a research developed entirely in his new Brazilian lab, which was put together with great difficulty due to the lack of resources and specialized equipment, Some of his lifelong colleagues, such as Dr. Hiss Martins Ferreira joined him at that time. He was responsible in the succeeding years to add a great number of students to his group, such as and Drs. Romualdo José do Carmo, Gilberto de Oliveira Castro and others.
Together with Prof. Carlos Chagas Filho
(1910-1922), another influential neurophysiologist and biophysicist, Dr. Leão founded the Laboratory of Biophysics, which later became the world-famous Institute of Biophysics, a great cradle of two generations of Brazilian scientists and a center of excellence in neurophysiological research.
Dr. Leão was also an important and influential scientific leader. He was for 15 years the president of the Brazilian Academy of Sciences
and a member of the scientific council of the Brazilian National Research Council
(CNPq) for many years.
He is described as a gentle, calm and systematic man, with outstanding wit and culture, very much respected and loved by his colleagues and students. He was also an accomplished amateur naturalist
and devoted ornithologist, specialized in tropical bird
s. He died of respiratory failure
at 79 years of age, in Rio de Janeiro.
Rio de Janeiro
Rio de Janeiro , commonly referred to simply as Rio, is the capital city of the State of Rio de Janeiro, the second largest city of Brazil, and the third largest metropolitan area and agglomeration in South America, boasting approximately 6.3 million people within the city proper, making it the 6th...
) was one of the most noted Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
ian biologist
Biologist
A biologist is a scientist devoted to and producing results in biology through the study of life. Typically biologists study organisms and their relationship to their environment. Biologists involved in basic research attempt to discover underlying mechanisms that govern how organisms work...
s and scientist
Scientist
A scientist in a broad sense is one engaging in a systematic activity to acquire knowledge. In a more restricted sense, a scientist is an individual who uses the scientific method. The person may be an expert in one or more areas of science. This article focuses on the more restricted use of the word...
s, one of the founders of the Biophysics Institute of the Federal University of Rio de Janeiro and the discoverer of cortical spreading depression
Cortical spreading depression
Cortical spreading depression is a wave of electrophysiological hyperactivity followed by a wave of inhibition, usually in the visual cortex.The term is used by neuroscientists to represent at least one of the following cortical processes:...
, an electrophysiological
Electrophysiology
Electrophysiology is the study of the electrical properties of biological cells and tissues. It involves measurements of voltage change or electric current on a wide variety of scales from single ion channel proteins to whole organs like the heart...
phenomenon of the central nervous system
Central nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
, which received his name.
Leão was born to an intellectual family in Rio de Janeiro. He started to study medicine
Medicine
Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....
at the University of São Paulo
University of São Paulo
Universidade de São Paulo is a public university in the Brazilian state of São Paulo. It is the largest Brazilian university and one of the country's most prestigious...
, but had to interrupt it, due to a bout with tuberculosis
Tuberculosis
Tuberculosis, MTB, or TB is a common, and in many cases lethal, infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis. Tuberculosis usually attacks the lungs but can also affect other parts of the body...
. Under the influence of his uncle, Antonio Pacheco Leão, who was the director of the Botanical Gardens of Rio de Janeiro, he decided instead to follow a research career and went to the USA to study further and to obtain a masters (1942) and a doctorate (1943) in physiology
Physiology
Physiology is the science of the function of living systems. This includes how organisms, organ systems, organs, cells, and bio-molecules carry out the chemical or physical functions that exist in a living system. The highest honor awarded in physiology is the Nobel Prize in Physiology or...
at the Harvard Medical School
Harvard Medical School
Harvard Medical School is the graduate medical school of Harvard University. It is located in the Longwood Medical Area of the Mission Hill neighborhood of Boston, Massachusetts....
, with an experimental investigation on epilepsy
Epilepsy
Epilepsy is a common chronic neurological disorder characterized by seizures. These seizures are transient signs and/or symptoms of abnormal, excessive or hypersynchronous neuronal activity in the brain.About 50 million people worldwide have epilepsy, and nearly two out of every three new cases...
in the cerebral cortex
Cerebral cortex
The cerebral cortex is a sheet of neural tissue that is outermost to the cerebrum of the mammalian brain. It plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. It is constituted of up to six horizontal layers, each of which has a different...
of rabbit
Rabbit
Rabbits are small mammals in the family Leporidae of the order Lagomorpha, found in several parts of the world...
s. In collaboration with his supervisors, Arturo Rosenblueth
Arturo Rosenblueth
Arturo Rosenblueth Stearns was a Mexican researcher, physician and physiologist, who is known as one of the pioneers of cybernetics.- Biography:...
and Hallowell Davis
Hallowell Davis
Hallowell Davis was an American physiologist and otolaryngologist and researcher who did pioneering work on the physiology of hearing and the inner ear. He served as director of research at the Central Institute for the Deaf in St...
, he analyzed the cycle of excitability of cortex neuron
Neuron
A neuron is an electrically excitable cell that processes and transmits information by electrical and chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells. Neurons connect to each other to form networks. Neurons are the core components of the nervous...
s (nerve cells) after the convulsive phenomena, and was the first to identify an important phenomenon, that of a decrease of the excitability which spread in increasing circles around the initial focus, which he named spreading depression. The phenomenon was soon named as Leão's wave and brought great attention after his work was published in 1944 in one of the main neurophysiology
Neurophysiology
Neurophysiology is a part of physiology. Neurophysiology is the study of nervous system function...
journals (for the rest of his life, Dr. Leão became one of the most cited neuroscientists in the world, and his original paper is considered one of the classics in the field).
Upon returning to Brazil, he continued his experiments with spreading depression, in the department of physiology of the medical school of the University of Brazil (presently the Federal University of Rio de Janeiro). Already in 1947 he could publish his first international paper on a research developed entirely in his new Brazilian lab, which was put together with great difficulty due to the lack of resources and specialized equipment, Some of his lifelong colleagues, such as Dr. Hiss Martins Ferreira joined him at that time. He was responsible in the succeeding years to add a great number of students to his group, such as and Drs. Romualdo José do Carmo, Gilberto de Oliveira Castro and others.
Together with Prof. Carlos Chagas Filho
Carlos Chagas Filho
Carlos Chagas Filho was a Brazilian physician, biologist and scientist active in the field of neuroscience. He was internationally renowned for his investigations on the neural mechanisms underlying the phenomenon of electrogenesis by the electroplaques of electric fishes...
(1910-1922), another influential neurophysiologist and biophysicist, Dr. Leão founded the Laboratory of Biophysics, which later became the world-famous Institute of Biophysics, a great cradle of two generations of Brazilian scientists and a center of excellence in neurophysiological research.
Dr. Leão was also an important and influential scientific leader. He was for 15 years the president of the Brazilian Academy of Sciences
Brazilian Academy of Sciences
The Brazilian Academy of Sciences is the national academy of Brazil. It is headquartered in the city of Rio de Janeiro and was founded in 1916....
and a member of the scientific council of the Brazilian National Research Council
Conselho Nacional de Desenvolvimento Científico e Tecnológico
The Conselho Nacional de Desenvolvimento Científico e Tecnológico is an organization of the Brazilian federal government under the Ministry of Science and Technology, dedicated to the promotion of scientific and technological research and to the formation of human resources for research in the...
(CNPq) for many years.
He is described as a gentle, calm and systematic man, with outstanding wit and culture, very much respected and loved by his colleagues and students. He was also an accomplished amateur naturalist
Natural history
Natural history is the scientific research of plants or animals, leaning more towards observational rather than experimental methods of study, and encompasses more research published in magazines than in academic journals. Grouped among the natural sciences, natural history is the systematic study...
and devoted ornithologist, specialized in tropical bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s. He died of respiratory failure
Respiratory failure
The term respiratory failure, in medicine, is used to describe inadequate gas exchange by the respiratory system, with the result that arterial oxygen and/or carbon dioxide levels cannot be maintained within their normal ranges. A drop in blood oxygenation is known as hypoxemia; a rise in arterial...
at 79 years of age, in Rio de Janeiro.
External links
- Biography. Ciência Hoje On-Line, in Portuguese. January 2003.
- Aristides Leão. Notables of Brazilian Science and Technology, Canal Ciência (in Portuguese).