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Displaying 51 - 75 of 843 items.

Leonard Hayflick (1928- )

Leonard Hayflick studied the processes by which cells age during the twentieth and twenty-first centuries in the United States. In 1961 at the Wistar Institute in the US, Hayflick researched a phenomenon later called the Hayflick Limit, or the claim that normal human cells can only divide forty to sixty times before they cannot divide any further. Researchers later found that the cause of the Hayflick Limit is the shortening of telomeres, or portions of DNA at the ends of chromosomes that slowly degrade as cells replicate.

Format: Articles

Subject: People

Robert Geoffrey Edwards (1925-2013)

Robert Geoffrey Edwards worked with Patrick Christopher Steptoe to develop in-vitro fertilization (IVF) techniques during the 1960s and 1970s in the United Kingdom. Louise Brown, the world' s first "test-tube baby," was born as a result of Edwards and Steptoe's IVF techniques in 1978, and since then more than four million children have been born using IVF techniques. Publicity and controversy accompanied Edwards and Steptoe's work as conservative religious institutions expressed concern over the morality of the IVF procedure.

Format: Articles

Subject: People, Reproduction

Paternal Sperm Telomere Elongation and Its Impact on Offspring Fitness

Telomeres are structures at the ends of DNA strands that get longer in the DNA of sperm cells as males age. That phenomenon is different for most other types of cells, for which telomeres get shorter as organisms age. In 1992, scientists showed that telomere length (TL) in sperm increases with age in contrast to most cell of most other types. Telomeres are the protective caps at the end of DNA strands that preserve chromosomal integrity and contribute to DNA length and stability.

Format: Articles

Subject: Theories

George W. Beadle's One Gene-One Enzyme Hypothesis

The one gene-one enzyme hypothesis, proposed by George Wells Beadle in the US in 1941, is the theory that each gene directly produces a single enzyme, which consequently affects an individual step in a metabolic pathway. In 1941, Beadle demonstrated that one gene in a fruit fly controlled a single, specific chemical reaction in the fruit fly, which one enzyme controlled.

Format: Articles

Subject: Theories

"'Doing the Month': Confinement and Convalescence of Chinese Women After Childbirth" (1978), by Barbara L.K. Pillsbury

In 1978 Social Science and Medicine published Barbara L.K. Pillsbury's article, 'Doing the Month': Confinement and Convalescence of Chinese Women After Childbirth, which summarized the results of Pillsbury's study on Chinese childbirth customs. Pillsbury, a professor of cultural anthropology at San Diego State University in San Diego, California, conducted over eighty interviews with people in Taiwan and China, including civilians, herbalists, and physicians over a four-month period in 1975.

Format: Articles

Subject: Publications

Max Ludwig Henning Delbruck (1906–1981)

Max Ludwig Henning Delbrick applied his knowledge of theoretical physics to biological systems such as bacterial viruses called bacteriophages, or phages, and gene replication during the twentieth century in Germany and the US. Delbrück demonstrated that bacteria undergo random genetic mutations to resist phage infections. Those findings linked bacterial genetics to the genetics of higher organisms. In the mid-twentieth century, Delbrück helped start the Phage Group and Phage Course in the US, which further organized phage research.

Format: Articles

Subject: People

York v. Jones (1989)

In the case York v. Jones (1989), the United States District Court for the Eastern District of Virginia was one of the first US courts to address a dispute over a cryopreserved preembryo. Steven York and Risa Adler-York (the Yorks), a married couple, provided their gametes to doctors who created the preembryo, which the court referred to as a pre-zygote, as part of an in vitro fertilization (IVF) program at the Howard and Georgeanna Jones Institute for Reproductive Medicine (Jones Institute) in Norfolk, Virginia.

Format: Articles

Subject: Legal

John Craig Venter (1946- )

John Craig Venter helped map the genomes of humans, fruitflies, and other organisms in the US in the late 1990s and early 2000s, and he helped develop an organism with a synthetic genome. In February 2001, Venter and his team published a human genome sequence after using a technique known as Expressed Sequence Tags, or ESTs. Venter worked to bridge commercial investment with scientific research. Venter founded a number of private companies, including the for-profit Celera Genomics, headquartered in Alameda, California, as well as research institutes, such as the not-for-profit J.

Format: Articles

Subject: People

“General Considerations for the Clinical Evaluation of Drugs” (1977), by the United States Food and Drug Administration

The United States Food and Drug Administration, or FDA, published 'General Considerations for the Clinical Evaluation of Drugs,' in September 1977. The document defined acceptable practices for investigators who studied new drugs. Specifically, the document outlined the common clinical trial methods. Clinical trials are studies to test whether a new drug is safe before doctors can prescribe it to patients. Prior to 1977, the Protection of Human Subjects Rule primarily regulated clinical drug trials, but it did not specify who could and could not be included in clinical trials.

Format: Articles

Subject: Publications

Stem Cell Tourism

When James Thomson of the University of Wisconsin announced in 1998 that he had derived and cultured human embryonic stem cells(hESCs), Americans widely believed-and accepted-that stem cells would one day be the basis of a multitude of regenerative medical techniques. Researchers promised that they would soon be able to cure a variety of diseases and injuries such as cancer, diabetes, Parkinson's, spinal cord injuries, severe burns, and many others. But it wasn't until January 2009 that the Food and Drug Administration approved the first human clinical trials using hESCs.

Format: Articles

Subject: Theories, Ethics

Roy John Britten (1919-2012)

Roy John Britten studied DNA sequences in the US in the second
half of the twentieth century, and he helped discover repetitive
elements in DNA sequences. Additionally, Britten helped propose
models and concepts of gene regulatory networks. Britten studied the
organization of repetitive elements and, analyzing data from the
Human Genome Project, he found that the repetitive elements in DNA
segments do not code for proteins, enzymes, or cellular parts.
Britten hypothesized that repetitive elements helped cause cells to

Format: Articles

Subject: People

The Yale Embryo

In 1934 a fourteen-day-old embryo was discovered during a postmortem examination and became famous for being the youngest known human embryo specimen at the time. The embryo was coined "the Yale Embryo," named after the location where it was discovered, Yale University in New Haven, Connecticut. During the early twentieth century, the rush to collect embryos as well as to find younger and younger embryos was at an all time high, and the Yale Embryo is representative of the this enthusiasm.

Format: Articles

Subject: Processes, Reproduction

Beadle's One Gene-One Enzyme Hypothesis

Between 1934 and 1945, George Beadle developed a hypothesis that each gene within the chromosomes of organisms each produced one enzyme. Enzymes are types of proteins that can catalyze reactions inside cells, and the figure shows that each enzyme controls a stage in a series of biochemical reactions. The top box in this figure represents a normal process of enzyme production and biochemical reactions, and the bottom box shows how Beadle's experiments affected the normal biochemical process.

Format: Graphics

Subject: Theories, Processes

Fetal Surgery

Fetal surgeries are a range of medical interventions performed in utero on the developing fetus of a pregnant woman to treat a number of congenital abnormalities. The first documented fetal surgical procedure occurred in 1963 in Auckland, New Zealand when A. William Liley treated fetal hemolytic anemia, or Rh disease, with a blood transfusion.

Format: Articles

Subject: Disorders, Ethics, Reproduction

York v. Jones [Brief] (1989)

The court treated frozen embryos possessed by an in vitro fertilization clinic as property owned by the parents and held under a bailment contract by the clinic. As such, the contract between the parties controlled disposition of the embryos but when the contract ended, control of the embryos reverted back to the parents. This decision had little effect on subsequent embryo cases because the circumstances were so unusual. Neither party contended the embryos had any rights.

Format: Articles

Subject: Legal, Reproduction

Gamete Intra-Fallopian Transfer (GIFT)

Various techniques constitute assisted reproduction, one of which is gamete intra-fallopian transfer (GIFT). The first example of GIFT involved primates during the 1970s; however, the technology was unsuccessful until 1984 when an effective GIFT method was invented by Ricardo Asch at the University of Texas Health Sciences Center and the procedure resulted in the first human pregnancy. The GIFT technique was created in hopes of generating an artificial insemination process that mimicked the physiological sequences of normal conception.

Format: Articles

Subject: Technologies, Reproduction

“Miscarriage of Medicine: The Growth of Catholic Hospitals and the Threat to Reproductive Health Care” (2013), by Lois Uttley, Sheila Reynertson, Larraine Kenny, and Louise Melling

In 2013, Lois Uttley, Sheila Reynertson, Larraine Kenny, and Louise Melling published “Miscarriage of Medicine: The Growth of Catholic Hospitals and the Threat to Reproductive Health Care,” in which they analyzed the growth of Catholic hospitals in the United States from 2001 to 2011 and the impact those hospitals had on reproductive health care. In the US, Catholic hospitals are required to abide by the US Catholic Church's Ethical Guidelines for Health Care Providers, also called the Directives.

Format: Articles

Subject: Publications

Early Infantile Autism and the Refrigerator Mother Theory (1943-1970)

In 1943, child psychiatrist Leo Kanner in the US gave the first account of Early Infantile Autism that encouraged psychiatrists to investigate what they called emotionally cold mothers, or refrigerator mothers. In 1949, Kanner published Problems of Nosology and Psychodynamics of Early Infantile Autism. In that article, Kanner described autistic children as reared in emotional refrigerators. US child psychiatrists claimed that some psychological or behavioral conditions might have origins in emotional or mental stress, meaning that they might be psychogenic.

Format: Articles

Subject: Disorders, Theories

Edward B. Lewis (1918-2004)

Edward B. Lewis studied embryonic development in Drosophila, including the discovery of the cis-trans test for recessive genes, and the identification of the bithorax complex and its role in development in Drosophila. He shared the 1995 Nobel Prize in Physiology or Medicine with Christiane Nüsslein-Volhard and Eric F. Wieschaus for work on genetic control of early embryonic development.

Format: Articles

Subject: People

The Aschheim-Zondek Test for Pregnancy

Throughout history many different methods have been devised for the early detection of pregnancy. From the time of the Ancient Egyptians, inspection of the urine has been a popular place to start. However, it was not until the discovery of hormones in the early twentieth century that the development of truly reliable pregnancy tests occurred. Prior to 1978, when the first home pregnancy tests became available in the United States, pregnancy testing was done in hospital laboratories using various methods, one of them being the Aschheim-Zondek, or A-Z test.

Format: Articles

Subject: Technologies, Reproduction

James Alexander Thomson (1958- )

James Alexander Thomson, affectionately known as Jamie Thomson, is an American developmental biologist whose pioneering work in isolating and culturing non-human primate and human embryonic stem cells has made him one of the most prominent scientists in stem cell research. While growing up in Oak Park, Illinois, Thomson's rocket-scientist uncle inspired him to pursue science as a career. Born on 20 December 1958, Thomson entered the nearby University of Illinois Urbana-Champaign nineteen years later as a National Merit Scholar majoring in biophysics.

Format: Articles

Subject: People

Tay-Sachs Disease

In 1881 British opthalmologist Warren Tay made an unusual observation. He reported a cherry-red spot on the retina of a one-year-old patient, a patient who was also showing signs of progressive degeneration of the central nervous system as manifested in the child's physical and mental retardation. This cherry-red spot is a characteristic that would eventually come to be associated with metabolic neurological disorders like Sandhoff, GM-1, Niemann-Pick, and, to the credit of Tay, the lysosomal storage disorder known as Tay-Sachs disease.

Format: Articles

Subject: Disorders

Beadle and Ephrussi Show that Something Besides Eye Tissue Determines Eye Color in Fruit Flies

In the 1930s, George Beadle and Boris Ephrussi discovered factors that affect eye colors in developing fruit flies. They did so while working at the California Institute of Technology in Pasadena, California. (1) They took optic discs (colored fuchsia in the image) from fruit fly larvae in the third instar stage of development. Had the flies not been manipulated, they would have developed into adults with vermilion eyes.

Format: Graphics

Subject: Experiments, Organisms

Beadle and Ephrussi’s Technique to Transplant Optic Discs between Fruit Fly Larvae

In 1935, George Beadle and Boris Ephrussi developed a technique to transplant optic discs between fruit fly larvae. They developed it while at the California Institute of Technology in Pasedena, California. Optic discs are tissues from which the adult eyes develop. Beadle and Ephrussi used their technique to study the development of the eye and eye pigment. (1) The experimenter dissects a donor larva, which is in the third instar stage of development, and removes the optic disc (colored red) with a micropipette.

Format: Graphics

Subject: Technologies, Experiments, Organisms

Neonatal Respiratory Distress Syndrome and Its Treatment with Artificial Surfactant

Neonatal respiratory distress syndrome, previously called hyaline membrane disease, is a respiratory disease affecting premature newborns. Neonatal respiratory distress syndrome involves shallow breathing, pauses between breaths that last a few seconds, or apnea, and a bluish tinge to the infant’s skin. The syndrome occurs when microscopic sacs called alveoli in infant lungs do not produce surfactant, a liquid that coats the inside of the lungs and helps them inflate during breathing.

Format: Articles

Subject: Disorders