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Displaying 901 - 925 of 1218 items.

"The Premenstrual Syndrome" (1953), by Raymond Greene and Katharina Dalton

In 1953, Raymond Greene and Katharina Dalton, who were doctors in the UK, published The Premenstrual Syndrome in the British Medical Journal. In their article, Dalton and Greene established the term premenstrual syndrome (PMS). The authors defined PMS as a cluster of symptoms that include bloating, breast pain, migraine-headache, fatigue, anxiety, depression, and irritability. The article states that the symptoms begin one to two weeks before menstruation during the luteal phase of the menstrual cycle, and they disappear upon the onset of the menstrual period.

Format: Articles

Subject: Publications, Reproduction

Hox Genes and the Evolution of Vertebrate Axial Morphology Experiment (1995)

In 1995, researchers Ann Burke, Craig Nelson, Bruce Morgan, and Cliff Tabin in the US studied the genes that regulate the construction of vertebra in developing chick and mouse embryos, they showed similar patterns of gene regulation across both species, and they concluded that those patterns were inherited from an ancestor common to all vertebrate animals. The group analyzed the head-to-tail (anterior-posterior) axial development of vertebrates, as the anterior-posterior axis showed variation between species over the course of evolutionary time.

Format: Articles

Subject: Experiments

Mechanistic Realization of the Turtle Shell

Turtle morphology is unlike that of any other vertebrate. The uniqueness of the turtle's bodyplan is attributed to the manner in which the turtle's ribs are ensnared within its hard upper shell. The exact embryological and genetic mechanisms underpinning this peculiar anatomical structure are still a matter of debate, but biologists agree that the evolution of the turtle shell lies in the embryonic development of the turtle.

Format: Articles

Subject: Processes

Franklin Paine Mall (1862-1917)

Franklin Paine Mall was born into a farming family in Belle Plaine, Iowa, on 28 September 1862. While he attended a local academy, an influential teacher fueled Mall's interest in science. From 1880-1883, he studied medicine at the University of Michigan, attaining his MD degree in 1883. William J. Mayo, who later became a famous surgeon and co-founder of the Mayo Clinic in Rochester, Minnesota, was a classmate of Mall's. Throughout his studies at Michigan, he was influenced by Corydon L. Ford, a professor of anatomy, Victor C.

Format: Articles

Subject: People

Hans Adolf Eduard Driesch (1867-1941)

Although educated as a scientist who studied with both August Weismann and Ernst Heinrich Haeckel, Hans Adolf Eduard Driesch was first employed as a professor of philosophy and became a strong proponent of vitalism. Driesch was born on 28 October 1867, the only child of Josefine Raudenkolb and Paul Driesch. He grew up in a wealthy merchant family in Hamburg, Germany, where he was educated at the humanistic Gymnasium Gelehrtenschule des Johanneums that had been founded by a friend of Martin Luther.

Format: Articles

Subject: People

Slime Mold Video

This video is composed of a sequence of films created by John Tyler Bonner in the 1940s to show the life cycle of the cellular slime mold Dictyostelium discoideum. As only the second person to study slime molds, Bonner frequently encountered audiences who had never heard of, let alone seen, the unusual organism.

Format: Articles

Subject: Processes

The Ponseti Method to Treat Club Foot

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: Technologies

Julia Barlow Platt (1857-1935)

Julia Barlow Platt studied neural crests in animal embryos and became involved in politics in the US during the nineteenth and twentieth centuries. She researched how body and head segments formed in chicks (Gallus gallus) and spiny dogfish (Squalus acanthias). Platt observed that in the mudpuppy (Necturus maculosus), the coordinated migration of neural crest cells in the embryo produced parts of the nervous system, bones, and connective tissues in the head.

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

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

"The Limited In Vitro Lifetime of Human Diploid Cell Strains" (1964), by Leonard Hayflick

Leonard Hayflick in the US during the early 1960s showed that normal populations of embryonic cells divide a finite number of times. He published his results as 'The Limited In Vitro Lifetime of Human Diploid Cell Strains' in 1964. Hayflick performed the experiment with WI-38 fetal lung cells, named after the Wistar Institute, in Philadelphia, Pennsylvania, where Hayflick worked. Frank MacFarlane Burnet, later called the limit in capacity for cellular division the Hayflick Limit in 1974.

Format: Articles

Subject: Experiments

Light Therapy for Neonatal Jaundice

Light therapy, also called phototherapy, exposes infants with jaundice, a yellowing of the skin and eyes, to artificial or natural light to break down the buildup of bilirubin pigment in the blood. Bilirubin is an orange to red pigment produced when red blood cells break down, which causes infants to turn into a yellowish color. Small amounts of bilirubin in the blood are normal, but when there is an accumulation of excess bilirubin pigment, the body deposits the excess bilirubin in the layer of fat beneath the skin.

Format: Articles

Subject: Technologies

Julia Barlow Platt's Embryological Observations on Salamanders' Cartilage (1893)

In 1893, Julia Barlow Platt published her research on the origins of cartilage in the developing head of the common mudpuppy (Necturus maculosus) embryo. The mudpuppy is an aquatic salamander commonly used by embryologists because its large embryonic cells and nuclei are easy to see. Platt followed the paths of cells in developing mudpuppy embryos to see how embryonic cells migrated during the formation of the head. With her research, Platt challenged then current theories about germ layers, the types of cells in an early embryo that develop into adult cells.

Format: Articles

Subject: Experiments, Theories, Processes

"Presence of Fetal DNA in Maternal Plasma and Serum" (1997), by Dennis Lo, et al.

In the late 1990s researchers Yuk Ming Dennis Lo and his colleagues isolated fetal DNA extracted from pregnant woman’s blood. The technique enabled for more efficient and less invasive diagnoses of genetic abnormalities in fetuses, such as having too many copies of chromosomes.

Format: Articles

Subject: Experiments

"The Developmental Capacity of Nuclei Taken from Intestinal Epithelium Cells of Feeding Tadpoles" (1962), by John B. Gurdon

In 1962 researcher John Bertrand Gurdon at the University of Oxford in Oxford, England, conducted a series of experiments on the developmental capacity of nuclei taken from intestinal epithelium cells of feeding tadpoles. In the experiments, Gurdon conducted nuclear transplantation, or cloning, of differentiated cells, or cells that have already specialized to become one cell type or another, in tadpoles. Gurdon's experiment showed that differentiated adult cells could be induced to an undifferentiated state, where they could once again become multiple cell types.

Format: Articles

Subject: Experiments

"Veterans and Agent Orange Update 1996: Summary and Research Highlights" by the US National Academy of Sciences' Institute of Medicine

In March 1996, the National Academy of Sciences of the United States released 'Veterans and Agent Orange Update 1996: Summary and Research Highlights,' which summarized research on the health effects of Agent Orange and other herbicides used in the Vietnam War. In their 1996 report, the National Academy connects Agent Orange exposure with two health conditions: spina bifida, a birth defect that occurs when the spinal cord develops improperly, and peripheral neuropathy, a nervous system condition in which the peripheral nerves are damaged.

Format: Articles

Subject: Publications

“An Extended Family with a Dominantly Inherited Speech Disorder” (1990), by Jane A. Hurst et al.

In 1990, researcher Jane Hurst and her colleagues published “An Extended Family With a Dominantly Inherited Speech Disorder,” in which they proposed that a single gene was responsible for a language disorder across three generations of a family. Affected individuals of the family, called the KE family, had difficulty producing, expressing and comprehending speech. Hurst and her team studied the KE family and the disorder at the Department of Clinical Genetics at the Great Ormond Street Hospital for Children in London, England.

Format: Articles

Subject: Publications, Disorders

Harald zur Hausen's Experiments on Human Papillomavirus Causing Cervical Cancer (1976–1987)

From 1977 to 1987, Harald zur Hausen led a team of researchers across several institutions in Germany to investigate whether the human papillomavirus (HPV) caused cervical cancer. Zur Hausen's first experiment tested the hypothesis that HPV caused cervical cancer rather than herpes simplex virus type 2 (HSV-2), the then accepted cause. His second and third experiments detailed methods to identify two previously unidentified HPV strains, HPV 16 and HPV 18, in cervical cancer tumor samples. The experiments showed that HPV 16 and 18 DNA were present in cervical tumor samples.

Format: Articles

Subject: Experiments

Rosalyn Sussman Yalow (1921-2011)

Rosalyn Sussman Yalow co-developed the radioimmunoassay (RIA), a method used to measure minute biological compounds that cause immune systems to produce antibodies. Yalow and research partner Solomon A. Berson developed the RIA in the early 1950s at the Bronx Veterans Administration (VA) Hospital, in New York City, New York. Yalow and Berson's methods expanded scientific research, particularly in the medical field, and contributed to medical diagnostics. For this achievement, Yalow received the Nobel Prize in Physiology or Medicine in 1977.

Format: Articles

Subject: People

Sonja Vernes, et al.'s Experiments On the Gene Networks Affected by the Foxp2 Protein (2011)

In 2011, Sonja Vernes and Simon Fisher performed a series of experiments to determine which developmental processes are controlled by the mouse protein Foxp2. Previous research showed that altering the Foxp2 protein changed how neurons grew, so Vernes and Fisher hypothesized that Foxp2 would affect gene networks that involved in the development of neurons, or nerve cells. Their results confirmed that Foxp2 affected the development of gene networks involved in the growth of neurons, as well as networks that are involved in cell specialization and cell communication.

Format: Articles

Subject: Experiments

"A molecular wound response program associated with regeneration initiation in planarians" (2012), by Danielle Wenemoser et al.

In 2012, a team of scientists across the US conducted an experiment to find the mechanism that allowed a group of flatworms, planarians, to regenerate any body part. The group included Danielle Wenemoser, Sylvain Lapan, Alex Wilkinson, George Bell, and Peter Reddien. They aimed to identify genes that are expressed by planarians in response to wounds that initiated a regenerative mechanism. The researchers determined several genes as important for tissue regeneration.

Format: Articles

Subject: Experiments

Cerebral Organoid as a Model System in the Study of Microcephaly

Scientists use cerebral organoids, which are artificially produced miniature organs that represent embryonic or fetal brains and have many properties similar to them, to help them study developmental disorders like microcephaly. In human embryos, cerebral tissue in the form of neuroectoderm appears within the first nine weeks of human development, and it gives rise to the brain and spinal cord.

Format: Articles

Subject: Technologies

Stem Cells

According to the US National Institutes of Health (NIH), the standard American source on stem cell research, three characteristics of stem cells differentiate them from other cell types: (1) they are unspecialized cells that (2) divide for long periods, renewing themselves and (3) can give rise to specialized cells, such as muscle and skin cells, under particular physiological and experimental conditions. When allowed to grow in particular environments, stem cells divide many times. This ability to proliferate can yield millions of stem cells over several months.

Format: Articles

Subject: Processes

Apoptosis in Embryonic Development

Apoptosis, or programmed cell death, is a mechanism in embryonic development that occurs naturally in organisms. Apoptosis is a different process from cell necrosis, which is uncontrolled cell death usually after infection or specific trauma. As cells rapidly proliferate during development, some of them undergo apoptosis, which is necessary for many stages in development, including neural development, reduction in egg cells (oocytes) at birth, as well as the shaping of fingers and vestigial organs in humans and other animals. Sydney Brenner, H. Robert Horvitz, and John E.

Format: Articles

Subject: Theories

"Experimental Studies on Congenital Malformations" (1959), by James G. Wilson

The article Experimental Studies on Congenital Malformations was published in the Journal of Chronic Diseases in 1959. The author, James G. Wilson, studied embryos and birth defects at the University of Florida Medical School in Gainesville, Florida. In his article, Wilson reviewed experiments on birds and mammals from the previous forty years to provide general principles and guidelines in the study of birth defects and teratogens, which are things that cause birth defects.

Format: Articles

Subject: Publications