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Bernard Sachs (1858-1944)

Bernard Sachs studied nervous system disorders in children in the
United States during the nineteenth and twentieth centuries. In the
late 1880s, Sachs described the fatal genetic neurological disorder
called amaurotic family idiocy, later renamed Tay-Sachs disease. The
disorder degrades motor skills as well as mental abilities in
affected individuals. The expected lifespan of a child with
Tay-Sachs is three to five years. In addition to working on
Tay-Sachs disease, Sachs described other childhood neurological and

Format: Articles

Subject: People

The Neuron Doctrine (1860-1895)

The neuron doctrine is a concept formed during the turn of the twentieth century that describes the properties of neurons, the specialized cells that compose the nervous system. The neuron doctrine was one of two major theories on the composition of the nervous system at the time. Advocates of the neuron doctrine claimed that the nervous system was composed of discrete cellular units. Proponents of the alternative reticular theory, on the other hand, argued that the entire nervous system was a continuous network of cells, without gaps or synapses between the cells.

Format: Articles

Subject: Theories

My Father, My Son (1986), by Elmo Zumwalt, Jr., Elmo Zumwalt III, and John Pekkanen

My Father, My Son is a dual autobiography by father and son Elmo Russell Zumwalt Jr. and Elmo Russell Zumwalt III published by Macmillan Publishing Company in 1986, detailing their experiences during the Vietnam War and particularly with Agent Orange, an herbicide used for defoliation and crop destruction during the war. As a commander in the Navy, Zumwalt Jr. ordered the use of Agent Orange in South Vietnam, where Zumwalt III was stationed.

Format: Articles

Sidney Q. Cohlan (1915-1999)

Sidney Q. Cohlan studied birth defects in the US during the twentieth century. Cohlan helped to discover that if a pregnant woman ate too much vitamin A her fetus faced a higher than normal risk of teratogenic effects, such as cleft palate. A teratogen is a substance that causes malformation of a developing organism. Cohlan also identified the teratogenic effects of several other substances including a lack of normal magnesium and prenatal exposure to the antibiotic tetracycline.

Format: Articles

Subject: People

Dorothy Andersen (1901–1963)

Dorothy Andersen studied cystic fibrosis in the United States during the early 1900s. In 1935, Andersen discovered lesions in the pancreas of an infant during an autopsy, which led her to classify a condition she named cystic fibrosis of the pancreas. In 1938, Andersen became the first to thoroughly describe symptoms of the medical condition cystic fibrosis.

Format: Articles

Subject: People

Neurospora crassa

Object is a digital image. It displays a laboratory workbench. On it is a loaf of bread with bread mold growing on it. There is also a set of beakers showing the bread mold raised in culture media. There is also a microscope, and a magnification box that shows an image microscopic bread mold.

Neurospora crassa is a red mold that scientists use to study genetics. N. crassa commonly grows on bread as shown in the top left corner of this figure. To culture the mold in lab, researchers grow it in glassware such as test tubes, Erlenmeyer flasks, and petri dishes, as shown in the top right corner of the figure. In the glassware, researchers place a gel, called a medium, of agar, sucrose, salts, and vitamins. The mold grows on the medium, and cotton stoppers prevent anything from contaminating the mold.

Format: Graphics

Subject: Organisms

Beadle's One Gene-One Enzyme Hypothesis

Object is a digital image with two panes, one on top of the other, both of which picture the area within a cell between the nucleus and the cell membrane. The top pane represent three genes within the cell nucleus, each of which produces a distinct kind of enzyme outside of the nucleus. Those enzymes then function in three distinct kinds of metabolic reactions. The bottom pane represents the same situation, except the second gene is damaged by x-rays and can't produce its enzymes. As a result, two of the three metabolic reactions fail to happen.

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

Chloroplasts

Object is a digital image of a chloroplast. There are two boxes, one atop the other. In the top box is an image of a chloroplast, which is roughly ovoid. A scale bar indicates that the chloroplast is roughly 5 micrometers in length. The outer membrane is colored light green, and the inner membrane is a different shade of light green. The top right parts of the outer and inner membranes are cut away to reveal dozens thylakoids within, which are all dark green and look like tires. They are stacked on top of each other to form ten granums.

Chloroplasts are the organelles in plant and algal cells that conduct photosynthesis. A single chloroplast has an outer membrane and an inner membrane, with an intermembrane space in between. Within the inner membrane, interconnected stacks of thylakoids, called granum, float in a protein rich fluid called the stroma. These thylakoid stacks contain chlorophyll, a pigment which converts sunlight into usable energy for plants and free oxygen from water. The stacks are sites of light reactions within a plant cell.

Format: Graphics

Subject: Theories, Processes

Jelly Fish and Green Fluorescent Protein

Object is a digital image that represents green fluorescent protein at various levels of organization within an organism. On the left of the image is a blue circle, in which there is a jelly fish, with some of its parts aglow. From one such part, a zoom circle juts to the right, in which is represented a strand of DNA from the jelly fish. From that circle, a black arrow points to the right and to a new zoom circle, this one representing the primary amino acid sequence coded for by the DNA sequence and that eventually folds into the protein.

The crystal jellyfish, Aequorea victoria, produces and emits light, called bioluminescence. Its DNA codes for sequence of 238 amino acids that forms a protein called Green Fluorescent Protein (GFP). FP is folded so that a part of the protein, called the chromophore, is located in the center of the protein. The chemical structure of the chromophore emits a green fluorescence when exposed to light in the range of blue to ultraviolet.

Format: Graphics

Subject: Theories, Processes, Organisms, Technologies

The Formation of Reticular Theory

In the nineteenth century, reticular theory aimed to describe the properties of neurons, the specialized cells which make up the nervous system, but was later disconfirmed by evidence. Reticular theory stated that the nervous system was composed of a continuous network of specialized cells without gaps (synapses), and was first proposed by researcher Joseph von Gerlach in Germany in 1871.

Format: Articles

Subject: Theories

Southern Gastric Brooding Frog

Object is a painted image of two southern gastric brooding frogs facing each other. The one on the left has a transparent middle to reveal tadpoles swimming inside of it. The one on the right shows a more mature juvenile crawling out of the mouth.

The Southern Gastric Brooding Frog (Rheobotrahcus silus) was a frog species that lived in Australia. It was declared extinct in 2002. Once adult males fertilized the eggs of females, the females swallowed their eggs. The stomachs of the females then functioned somewhat like wombs, protecting the eggs while they gestated. Once the eggs developed into juveniles, female frogs performed oral birth and regurgitated their young.

Format: Graphics

Subject: Organisms

DNA and X and Y Chromosomes

Object is a digital image that represents how DNA partly constitutes a Y-chromosome. Image shows different parts of an unbroken strand that begins with the smallest parts on the left side of the image, and eventually forms the Y-chromosome on the right side of the image, so that the chromosome looks like a kite with a long tail. On the left side of the image, a DNA double helix is enlarged to reveal the paired nucleotides within. The width of the helix is 2 nanometers. As the helix continues to the right, it bends downwards, and it gets smaller and seemingly further way from the viewer.

Y-chromosomes exist in the body cells of many kinds of male animals. Found in the nucleus of most living animal cells, the X and Y-chromosomes are condensed structures made of DNA wrapped around proteins called histones. The individual histones bunch into groups that the coiled DNA wraps around called a nucleosome, which are roughly 10 nano-meters (nm) across. The histones bunch together to form a helical fiber (30 nm) that spins into a supercoil (200 nm). During much of a cell's life, DNA exists in the 200 nm supercoil phase.

Format: Graphics

Subject: Theories, Processes

Mitochondria

Object is a digital image of a mitochondrion. There are two boxes, one atop of the other. In the top box is the mitochondrion with a scale bar that indicates that the organelle is 1 micrometer in length. The image depicts the mitochondrion�s outer membrane, which is roughly ovoid in shape and is colored a transparent orange to reveal the inner membrane within, colored red. The top left quarter of the outer membrane and the inner membrane are cut away to reveal the cristae. In the bottom box is a round animal cell, colored teal.

Mitochondria are organelles found in the cytoplasm of eukaryotic cells. They are composed of an outer membrane and an inner membrane. The outer membrane faces the cellular cytoplasm, while the inner membrane folds back on itself multiple times, forming inner folds, called cristae. The space between the two membrane layers is called the intermembrane space, and the space within the inner membrane is called the matrix.

Format: Graphics

Subject: Theories, Processes

Roberto Caldeyro-Barcia (1921–1996)

Roberto Caldeyro-Barcia studied fetal health in Uruguay during the second half of the twentieth century. Caldeyro-Barcia developed Montevideo units, which are used to quantify intrauterine pressure, or the force of contractions during labor. Intrauterine pressure is a useful measure of the progression of labor and the health of a fetus.

Format: Articles

Subject: People

Human Papillomavirus (HPV) Strains 16 and 18

The Human Papillomavirus (HPV) strains 16 and 18 are the two most common HPV strains that lead to cases of genital cancer. HPV is the most commonly sexually transmitted disease, resulting in more than fourteen million cases per year in the United States alone. When left untreated, HPV leads to high risks of cervical, vaginal, vulvar, anal, and penile cancers. In 1983 and 1984 in Germany, physician Harald zur Hausen found that two HPV strains, HPV-16 and HPV-18, caused cervical cancer in women. In the early twenty first century, pharmaceutical companies Merck & Co.

Format: Articles

Subject: Theories

Martin Couney and Incubator Exhibits from 1896 to 1943

During the late 1800s and early 1900s, physician Martin Couney held incubator exhibits to demonstrate the efficacy of infant incubators throughout the US and
Europe. At his exhibits, Couney demonstrated that isolating premature infants in an incubator ward
could significantly decrease premature infant mortality and increased the use of incubators in the
US.

Format: Articles

Subject: Organizations, Places

William Stewart Halsted (1852-1922)

William Stewart Halsted was a surgeon at Johns Hopkins Hospital in Baltimore, Maryland, during the late 1800s and early 1900s. In 1894 Halsted described his procedure for treating breast cancer by removing the breast tissue, chest muscles, and lymph nodes in the armpit, a procedure he named radical mastectomy, and that became the standard of care for treating breast cancer until 1970.

Format: Articles

Subject: People

"A Proposal for a New Method of Evaluation of the Newborn Infant" (1953), by Virginia Apgar

In 1953, Virginia Apgar published the article "A Proposal for a New Method for Evaluation of the Newborn Infant" about her method for scoring newborn infants directly after birth to assess their health and whether medical intervention was necessary. Apgar worked at the Presbyterian Hospital in New York City, New York, as an obstetrical anesthesiologist, a physician who administers pain medication during childbirth.

Format: Articles

Subject: Publications

"The Contagiousness of Puerperal Fever” (1843), by Oliver Wendell Holmes

In 1843, physician Oliver Wendell Holmes wrote and published The Contagiousness of Puerperal Fever, an essay about puerperal fever, a disease that occurs mainly as a result of bacterial infection in the uterine tract of women after giving birth or undergoing an abortion. In the essay, Holmes argues that puerperal fever is spread through birth attendants like physicians and midwives who make contact with the disease and carry it from patient to patient. The article was published in The New England Quarterly Journal of Medicine and Surgery in 1843.

Format: Articles

Subject: Publications

James Young Simpson (1811–1870)

James Young Simpson was one of the first obstetricians to administer anesthesia during childbirth in nineteenth century Scotland. Before his work in the 1800s, physicians had few ways to reduce the pain of childbirth. Simpson experimented with the use of ether and chloroform, both gaseous chemicals, to temporarily relieve pain. He found that those chemicals both successfully inhibited the pain women felt during childbirth and pain during other surgeries. Patients under the influence of chloroform fell asleep and were unaware of the intense pain of childbirth.

Format: Articles

Subject: People

HIP Randomized Breast Cancer Screening Trial (1963–1982)

From 1963 to 1982, researchers in New York City, New York, carried out a randomized trial of mammography screening. Mammography is the use of X-ray technology to find breast cancer at early stages. The private insurance company Health Insurance Plan of Greater New York, or HIP, collaborated with researchers Sam Shapiro, Philip Strax, and Louis Venet on the trial. The researchers’ goal was to determine whether mammography screening reduced breast cancer mortality in women. The study included sixty thousand women aged forty to sixty-four.

Format: Articles

Subject: Experiment

“Screening for Breast Cancer with Mammography” (2013), by Peter Gøtzsche and Karsten Jørgensen

Screening for Breast Cancer with Mammography is a Cochrane systematic review originally published by Peter Gøtzsche and Karsten Jørgensen in 2001 and updated multiple times by 2013. In the 2013 article, the authors discuss the reliability of the results from different clinical trials involving mammography and provide their conclusions about whether mammography screening is useful in preventing deaths from breast cancer.

Format: Articles

Subject: Publications

“Infant Survival After Cesarean Section for Trauma” (1996), by John A. Morris, Jr. et al.

In the May 1996 edition of The Annals of Surgery, John A. Morris and his collaborators published “Infant Survival After Cesarean Section for Trauma,” in which they evaluate the use of emergency cesarean sections for the treatment of pregnant trauma patients. During a cesarean section, a physician removes a fetus from a pregnant woman through an incision in her abdomen and uterus. When a pregnant woman experiences trauma, physicians can perform an emergency cesarean section to remove the fetus and administer medical treatments that would not be possible while the woman is pregnant.

Format: Articles

Subject: Publications

"Risks and Benefits of Estrogen Plus Progestin in Healthy, Postmenopausal Women: Principal Results from the Women's Health Initiative Randomized Controlled Trial" (2002), by Jacques Rossouw et al.

In 2002, the Writing Group for the Women's Health Initiative Investigators published the article Risks and Benefits of Estrogen Plus Progestin in Healthy, Postmenopausal Women: Principal Results from the Women's Health Initiative Randomized Controlled Trial in The Journal of the American Medical Association.

Format: Articles

Subject: Publications

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