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Displaying 326 - 350 of 1035 items.

Jerold Lucey (1926– )

Jerold Lucey studied newborn infants in the United States in the twentieth century. In the 1960s and 1970s, Lucey studied phototherapy as a treatment for jaundice, a condition in infants whose livers cannot excrete broken down red blood cells, called bilirubin, into the bloodstream at a fast enough rate. In addition to his work in jaundice, Lucey was the editor in chief for the journal Pediatrics of the American Academy of Pediatrics.

Format: Articles

Subject: People

Arthur William Galston (1920–2008)

Arthur W. Galston studied plant hormones in the United States during the late-twentieth century. His dissertation on the flowering process of soybean plants led others to develop Agent Orange, the most widely employed herbicide during the Vietnam War, used to defoliate forests and eliminate enemy cover and food sources. Galston protested the spraying of those defoliants in Vietnam, as they could be harmful to humans, animals, and the environment.

Format: Articles

Subject: People

Robert Guthrie (1916–1995)

Robert Guthrie developed a method to test infants for phenylketonuria (PKU) in the United States during the twentieth century. PKU is an inherited condition that causes an amino acid called phenylalanine to build to toxic levels in the blood. Untreated, PKU causes mental disabilities. Before Guthrie’s test, physicians rarely tested infants for PKU and struggled to diagnosis it. Guthrie’s test enabled newborns to be quickly and cheaply screened at birth and then treated for PKU if necessary, preventing irreversible neurological damage.

Format: Articles

Subject: People

Leonard Colebrook (1883–1967)

Leonard Colebrook was a physician who researched bacteria and infections in England during the twentieth century. In 1936, Colebrook deployed the antibiotic Prontosil to treat puerperal fever, a disorder that results from bacterial infections in the uterine tracts of women after childbirth or abortions. Colebrook also advanced care for burn patients by advocating for the creation of burn units in hospitals and by using antisepsis medication for burn wound infections. Colebrook’s work on treatments for puerperal fever reduced cases of puerperal fever throughout the world.

Format: Articles

Subject: People

"A Diffusible Agent of Mouse Sarcoma, Producing Hyperplasia of Sympathetic Ganglia and Hyperneurotization of Viscera in the Chick Embryo" (1953), by Rita Levi-Montalcini and Viktor Hamburger

"A Diffusible Agent of Mouse Sarcoma, Producing Hyperplasia of Sympathetic Ganglia and Hyperneurotization of Viscera in the Chick Embryo," by Rita Levi-Montalcini and Viktor Hamburger, appeared in 1953 in the Journal of Experimental Zoology. The paper provided the first evidence that nerve growth factor is a diffusible substance. Nerve growth promoting tumors were implanted into developing embryos to determine whether the tumors stimulated growth by direct contact or by a diffusible substance.

Format: Articles

Subject: Experiments

Jeffrey Keenan (1961- )

Jeffrey Keenan is the Director of the Southeastern Center for Fertility and Reproductive Medicine and the main developer behind the National Embryo Donation Center (NEDC) in Knoxville, Tennessee. This non-profit organization focuses on embryo donation and embryo adoption.

Format: Articles

Subject: People, Reproduction

Estrogen and the Menstrual Cycle in Humans

Estrogen is the primary sex hormone in women and it functions during the reproductive menstrual cycle. Women have three major types of estrogen: estrone, estradiol, and estriol, which bind to and activate receptors within the body. Researchers discovered the three types of estrogen over a period of seven years, contributing to more detailed descriptions of the menstrual cycle. Each type of estrogen molecule contains a slightly different arrangement or number of atoms that in turn causes some of the estrogens to be more active than others.

Format: Articles

Subject: Theories, Reproduction

Nicole Marthe Le Douarin (1930- )

Nicole Marthe Le Douarin was one of the first progressive female pioneers of developmental and embryological research. Some of her most notable and ground-breaking work involves grafting quail and chicken embryos together in order to study the developmental fate of each contributing embryo. Le Douarin was born in Brittany, France, on 20 August 1930. As an only child she was inspired by her mother, a school teacher at the time, to develop a passion for learning.

Format: Articles

Subject: People

Hamburger-Hamilton Staging Series (1951)

In 1951 Viktor Hamburger and Howard Hamilton created an embryonic staging series from a combination of photographs and drawings from other researchers. The Hamburger-Hamilton stages are a sequence of images depicting 46 chronological stages in chick development. The images begin with a fertilized egg and end with a fully developed chick. The Hamburger-Hamilton staging series was produced in order to replace a previous chick staging series created in 1900. The earlier attempt lacked specific details and staged the chick embryo by using only morphological characteristics.

Format: Articles

Subject: Processes

Bicoid

Bicoid is the protein product of a maternal-effect gene unique to flies of the genus Drosophila . In 1988 Christiane Nüsslein-Volhard identified bicoid as the first known morphogen . A morphogen is a molecule that determines the fate and phenotype of a group of cells through a concentration gradient across that developing region. The bicoid gradient, which extends across the anterior-posterior axis of Drosophila embryos, organizes the head and thorax.

Format: Articles

Subject: Processes

Alexis Carrel's Tissue Culture Techniques

Alexis Carrel, the prominent French surgeon, biologist, and 1912 Nobel Prize laureate for Physiology or Medicine, was one of the pioneers in developing and modifying tissue culture techniques. The publicized work of Carrel and his associates at the Rockefeller Institute established the practice of long-term tissue culture for a wide variety of cells. At the same time, some aspects of their work complicated the operational procedures of tissue culture.

Format: Articles

Subject: Technologies

Edward Donnall Thomas (1920-2012)

Edward Donnall Thomas, an American physician and scientist, gained recognition in the scientific community for conducting the first bone marrow transplant, a pioneering form of hematopoietic stem cell transplantation (HSCT). Bone marrow transplants are considered to be the first successful example of tissue engineering, a field within regenerative medicine that uses hematopoietic stem cells (HSCs) as a vehicle for treatment. Prior to Thomas's groundbreaking work, most blood-borne diseases, including certain inherited and autoimmune diseases, were considered lethal.

Format: Articles

Subject: People

The Hedgehog Signaling Pathway in Vertebrates 

The hedgehog signaling pathway is a mechanism that regulates cell growth and differentiation during embryonic development, called embryogenesis, in animals. The hedgehog signaling pathway works both between cells and within individual cells.

Format: Articles

Subject: Theories

“The Emergence of Developmental Psychopathology” (1984), by Dante Cicchetti

In 1984, Dante Cicchetti published “The Emergence of Developmental Psychopathology,” an article in which he argued that the previously amorphous study of developmental psychopathology was emerging as a unified discipline. According to Cicchetti, developmental psychopathology describes an interdisciplinary field that studies abnormalities in psychological function that can arise during human development.

Format: Articles

Subject: Publications

The Discovery of p53 Protein

The p53 protein acts as a pivotal suppressor of inappropriate cell proliferation. By initiating suppressive effects through induction of apoptosis, cell senescence, or transient cell-cycle arrest, p53 plays an important role in cancer suppression, developmental regulation, and aging. Its discovery in 1979 was a product of research into viral etiology and the immunology of cancer. The p53 protein was first identified in a study of the role of viruses in cancer through its ability to form a complex with viral tumor antigens.

Format: Articles

Subject: Experiments

"Male Development of Chromosomally Female Mice Transgenic for Sry gene" (1991), by Peter Koopman, et al.

Early 1990s research conducted by Peter Koopman, John Gubbay, Nigel Vivian, Peter Goodfellow, and Robin Lovell-Badge, showed that chromosomally female (XX) mice embryos can develop as male with the addition of a genetic fragment from the Y chromosome of male mice. The genetic fragment contained a segment of the mouse Sry gene, which is analogous to the human SRY gene. The researchers sought to identify Sry gene as the gene that produced the testis determining factor protein (Tdf protein in mice or TDF protein in humans), which initiates the formation of testis.

Format: Articles

Subject: Experiments

“Studies on the Chemical Nature of the Substance Inducing Transformation of Pneumococcal Types: Induction of Transformation by a Desoxyribonucleic Acid Fraction Isolated from Pneumococcus Type III” (1944) by Oswald Avery, Colin MacLeod and Maclyn McCarty

In 1944, Oswald Avery, Colin MacLeod, and Maclyn McCarty published an article in which they concluded that genes, or molecules that dictate how organisms develop, are made of deoxyribonucleic acid, or DNA. The article is titled “Studies on the Chemical Nature of the Substance Inducing Transformation of Pneumococcal Types: Induction of Transformation by a Desoxyribonucleic Acid Fraction Isolated from Pneumococcus Type III,” hereafter “Transformation.” The authors isolated, purified, and characterized genes within bacteria and found evidence that those genes were made of DNA and not protein.

Format: Articles

Subject: Publications

Karl Landsteiner (1868-1943)

Karl Landsteiner studied blood types in Europe and in the United States in the late nineteenth and early twentieth centuries. Landsteiner won the Nobel Prize in Physiology or Medicine in 1930 for detailing immunological reactions in the ABO blood group system. The ABO blood group system divides human blood into one of four types based on the antibodies that are present on each cell. Landsteiner's work with blood types led physicians to safely perform blood transfusions and organ transplants.

Format: Articles

Subject: People

Ignacio Vives Ponseti (1914-2009)

Ignacio Vives Ponseti developed a noninvasive method for treating congenital club foot in the US during the late 1940s. Congenital club foot is a birth deformity in which one or both of an infant's feet are rotated inward beneath the ankle, making normal movement rigid and painful. Ponseti developed a treatment method, later called the Ponseti method, that consisted of a series of manipulations and castings of the club foot performed in the first few months of life.

Format: Articles

Subject: People

Dennis Lo (1963- )

Dennis Lo, also called Yuk Ming Dennis Lo, is a
professor at the Chinese University of Hong Kong in Hong Kong,
China. In 1997, Lo discovered fetal DNA in maternal
plasma, which is the liquid component of a pregnant woman's
blood. By 2002, Lo distinguished the DNA differences between pregnant women
and their fetuses, enabling scientists to identify fetal DNA in pregnant
women's blood. Lo used his discoveries to develop several
non-invasive and prenatal genetic tests, including tests for blood

Format: Articles

Subject: People, Reproduction

Equilibrium Density Gradient Centrifugation in Cesium Chloride Solutions Developed by Matthew Meselson and Franklin Stahl

Matthew Meselson, Franklin Stahl, and Jerome Vinograd, developed cesium chloride, or CsCl, density gradient centrifugation in the 1950s at the California Institute of Technology, or Caltech, in Pasadena, California. Density gradient centrifugation enables scientists to separate substances based on size, shape, and density. Meselson and Stahl invented a specific type of density gradient centrifugation, called isopycnic centrifugation that used a solution of cesium chloride to separate DNA molecules based on density alone.

Format: Articles

Subject: Technologies

Mary-Claire King (1946– )

Mary-Claire King studied genetics in the US in the twenty-first century. King identified two genes associated with the occurrence of breast cancer, breast cancer 1 (BRCA1) and breast cancer 2 (BRCA2). King showed that mutated BRCA1 and BRCA2 genes cause two types of reproductive cancer, breast and ovarian cancer. Because of King’s discovery, doctors can screen women for the inheritance of mutated BRCA1 and BRCA2 genes to evaluate their risks for breast and ovarian cancer.

Format: Articles

Subject: People

Germ Layers

A germ layer is a group of cells in an embryo that interact with each other as the embryo develops and contribute to the formation of all organs and tissues. All animals, except perhaps sponges, form two or three germ layers. The germ layers develop early in embryonic life, through the process of gastrulation. During gastrulation, a hollow cluster of cells called a blastula reorganizes into two primary germ layers: an inner layer, called endoderm, and an outer layer, called ectoderm.

Format: Articles

Subject: Theories, Processes

In the Womb: Identical Twins (2009), by National Geographic

National Geographic's documentary In the Womb: Identical Twins focuses on the prenatal development of human identical twins. Director Lorne Townend uses three-dimensional (3D) and four-dimensional (4D) ultrasound imaging and microscopy to depict twin development , genetic and epigenetic variations in the fetuses, and methods of fetal survival in the confines of the womb. Artist renditions of scientific data fill in areas of development inaccessible to the imaging tools.

Format: Articles

Subject: Outreach, Reproduction

Intracytoplasmic Sperm Injection

Intracytoplasmic Sperm Injection (ICSI) is an assisted reproductive technique (ART) initially developed by Dr. Gianpiero D. Palermo in 1993 to treat male infertility. It is most commonly used in conjunction with in vitro fertilization (IVF) or a less commonly used technique called zygote intrafallopian transfer (ZIFT). In natural fertilization, the sperm must penetrate the surface of the female egg, or oocyte.

Format: Articles

Subject: Technologies, Reproduction